GUIDE TO
CLEAN TECHNOLOGY
ALTERNATIVE METAL FINISHES
July 1992
United States Environmental Protection Agency
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NOTICE
This Guide to Clean Technology: Alternative Metal Finishes summarizes
information collected from U.S. Environmental Protection Agency programs, peer-
reviewed journals, industry experts, vendor data, and other sources. The original
Quality Assurance/Quality Control (QA/QC) procedures for the reports and
projects summarized in this guide range from detailed, reviewed Quality Assur-
ance Project Plans to standard industrial practice. Publication of the guide does
not signify that the contents necessarily reflect the views and policies of the U.S.
Environmental Protection Agency, nor does mention of trade names or commer-
cial products constitute endorsement or recommendation for use.
This document is intended to provide guidance in identifying new approaches for
pollution prevention in metal finishing operations. Final selection of a technology
will be shop- and process-specific and, therefore, will be done by the individual
users of metal finishing processes. Compliance with environmental and occupa-
tional safety and health laws is the responsibility of each individual business and
is not addressed in this document.
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FOREWORD
Today's rapidly developing and changing technologies and industrial products
and practices frequently carry with them the increased generation of materials
that, if improperly dealt with, can threaten both public health and the environ-
ment. The U.S. Environmental Protection Agency (EPA) is charged by Congress
with protecting the Nation's land, air, and water resources. Under a mandate of
national environmental laws, the agency strives to formulate and implement
actions leading to a compatible balance between human activities and the ability
of natural systems to support and nurture life. These laws direct the U.S. EPA to
perform research to define our environmental problems, measure the impacts,
and search for solutions.
Reducing the use of hazardous metals at the source or recycling the wastes on
site will benefit industry by reducing disposal costs and lowering the liabilities
associated with hazardous waste disposal.
Publications in the U.S. EPA series, Guides to Pollution Prevention, provide an
overview of several industries and describe options to minimize waste in these
industries. Their focus is on the full range of operations in existing facilities.
Many of the pollution prevention techniques described are relatively easy to
implement in current operations without major process changes.
This Guide to Clean Technology: Alternative Metal Finishes summarizes new
commercially available and emerging technologies that prevent and/or reduce the
production of hazardous materials during metal finishing processes. The
technologies described in this document and in other documents in this series
are generally "next generation" clean technologies that sometimes represent
relatively major process changes, requirement for new training, and capital cost
investments compared to the technologies described in the Guides for Pollution
Prevention. The waste minimization techniques characterized in the Guides for
Pollution Prevention should be considered and implemented first. They should
be considered for retrofitting into current operations and for major plant expan-
sions and new grass roots facilities.
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CONTENTS
Section 1 1
Overview
Section 2 11^
Available Technologies
Blackhole™ Technology 15 .
Ion Vapor Deposition (IVD) of Aluminum 19
Non-Cyanide Copper Plating 23
Non-Cyanide Metal Stripping 26
Zinc or Zinc-Nickel Alloy Electroplating 29
Section 3 32
Emerging Technologies
Physical Vapor Deposition (PVD) 36
Nickel-Tungsten-Silicon Carbide Plating 38
Chromium-Free Aluminum Surface Treatments 40
In-Mold Plating 42
Metal Spray Coating 43
Section 4 45
Information Sources
References 45
Trade Associations 48
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SECTION 1
OVERVIEW
What is Clean
Technology?
Why Finish
Metals?
A clean technology is a source reduction or recycling method ap-
plied to eliminate or significantly reduce hazardous waste genera-
tion. Source reduction includes product changes and source con-
trol. Source control can be characterized as input material changes,
technology changes, or improved operating practices.
Pollution prevention should emphasize source reduction technolo-
gies over recycling but, if source reduction technologies are not
available, recycling is a good approach to reducing waste genera-
tion. Recycling should be used where possible to minimize waste
treatment requirements that remain after viable source reduction
options have been evaluated and/or implemented.
The clean technology must reduce the quantity and/or toxicity of the
waste produced. It is also essential that final product quality be
reliably controlled to acceptable standards. In addition, the cost of
applying the new technology relative to the cost of similar technolo-
gies should be considered.
Metal and surface finishing processes are applied in a variety of
industries to improve product appearance, retard corrosion, provide
hardness, protect sensitive components, control reflectivity, control
friction, enable conductivity, or build up material for repair. Indus-
tries that apply metal finishes include:
4 Automotive
* Electronic
* Aerospace
* Telecommunications
* Appliances
Types of finishes and processes that present pollution problems
include:
* Cadmium coatings
*• Cyanide-based solutions
* Chromium plating
Waste disposal regulations for waste generated from metal finishing
operations are becoming more stringent. The amounts of metal
allowed in wastewater discharges are approaching very low levels.
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Overview
Some municipalities now require levels near zero. The metals can
be removed and the other materials destroyed, but the resulting
metal sludge (from typical hydroxide precipitation) is landfilled as a
hazardous waste if not reclaimed.
A wide variety of materials, processes, and products are used in the
metal finishing industry to clean, etch, and plate metallic and non-
metallic surfaces. Typically, workpieces undergo a variety of
physical, chemical, and electrochemical processes. Physical
processes include buffing, grinding, polishing, and blasting. Chemi-
cal processes include degreasing, cleaning, pickling, etching,
polishing, and electroless plating. Electrochemical processes
include plating, electropolishing, and anodizing.
Physical processes such as abrasive blasting, grinding, buffing and
polishing do not contribute as much to hazardous waste generation
as chemical and electrochemical processes. The chemical and
electrochemical processes are typically performed in numerous
chemical baths that are followed by rinsing operations. The most
common hazardous waste sources are rinse water effluent and
spent process baths.
Although the most common hazardous waste stream is industrial
waste treatment sludge, the industrial waste treatment process is
not the source of this waste. The sources are the production
activities that create the waste.
In selecting a metal finish, the process to be performed as well as
the type of waste that might be generated are important consid-
erations.
Pollution
Problem Metal coatings such as cadmium, lead, nickel, and chromium;
solutions such as cyanides; and processes such as etching and
electroplating these substances can generate waste streams requir-
ing treatment. Some hazardous characteristics are shown in
Table 1.
Cadmium is used in plating because it has properties that are
superior to those of other coatings for some applications. It is used
to plate fasteners to help ensure that the parts pass torque-toler-
ance tests. This simulates the action of a power wrench tightening
a nut on a bolt. The nut should tighten quickly under the proper
applied torque and hold securely thereafter. Cadmium is a soft
metal and has natural lubricity; these properties give it good torque.
It also has good corrosion resistance and meets salt-spray test
requirements of the automotive industry. In the past, numerous
military specifications have required the use of cadmium.
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Table 1. Polluting Characteristics of Contaminating Metals
Substance
Toxicity Level
Contaminating Pathways
Cadmium (Cd)
High:
Poisoning from inhalation of fumes or dusts
Immediately dangerous to human health
upon exposure to 1 mg/m3 over an 8-h
period (Chizikov, 1966)
Lethal in air concentrations of 6 mg/m3
Fumes formed at high temperatures in-
dustrial processes such as welding and
brazing
Fumes released from incinerators that
are unequipped with pollution control
devices
Ingestion from cadmium-contaminated
water and foods
Cyanide (Cn) and hydrogen cyanide (HCN)
High: Death can occur within seconds after
inhalation or ingestion.
HCN enters the human body by inhala-
tion, skin absorption, or orally. It is de-
scribed as having the odor of bitter al-
monds, but one of five people cannot
sense this odor, causing it to be all the
more dangerous to them.
Encountered as an industrial waste
through the production of HCN and
when other cyanide compounds are
acidified.
Chromium (Cr)
High: The hexavalent form of chromium is a
carcinogen.
Inhalation of mist formed at plating
bath.
Ingestion of chromium-contaminated
water and food.
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Overview
The major cadmium complex used in electroplating baths is cadmi-
um cyanide, Cd(CN)4"2; other plating electrolytes include cadmium
sulfate, sulfamate, chloride, fluoroborate, and pyrophosphate. Cad-
mium borates are used with a fluoroborate process for electro-
deposition of cadmium on high-strength steels. Cadmium oxide is
used in electroplating baths, dissolved in excess sodium cyanide.
Sodium cyanide is used in electroplating baths for copper, zinc,
cadmium, gold, and silver. Potassium cyanide is also used in
electroplating. Nickel cyanide is used as a brightener in plating of
other metals, and silver cyanide and zinc cyanide are used, respec-
tively, in silver and zinc plating. In the plating process, these metals
form complex cyanides, such as ferrocyanide and ferricyanide
complexes with iron. Although these complexes are less toxic, they
are also resistant to removal by treatment processes, and are
decomposed by ultraviolet light, so that there is a possibility of
generating HCN in wastestreams containing cyanide complexes dis-
charged by industry.
Although electroplating is often assumed to be a major source of
cyanide waste, the figures do not support such a view (Conner,
1990). According to the 1988 TRI Report (U.S.EPA, 1988), cyanide
use in Plating and Polishing (SIC 3471) accounted for under
500,000 pounds, while Blast Furnaces and Steel Mills (SIC 3312),
for example, accounted for over three times this amount.
Cyanide waste generated in metal finishing comes primarily from
copper, zinc, cadmium, silver, and gold plating, where large
amounts of sodium and potassium cyanides and smaller amounts of
metal cyanides are used. A considerable volume of wastewater is
produced in the finishing industry. This waste usually contains
dilute cyanide (10-770 ppm) from rinsing operations.
Hexavalent chromium chemicals, such as chromic acid, are fre-
quently used in metal plating applications to provide chromium
coatings exhibiting hardness and aesthetic appeal. Chromium
plating is used to provide a working surface for a part. It is the
standard method for improving the hardness; smoothness; or
resistance'to wear, abrasion, galling, or high temperatures for a
wide variety of substrates. Typical applications are cylinder liners
and pistons for internal combustion engines and cylinders and rams
for hydraulic pistons (Guffie, 1986). Chromium plating will continue
to be needed for specific applications, but alternatives are available
for many of chromium's traditional applications. Design engineers
will be required to be more selective in specifying chromium plating
by exploring alternative technologies.
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Overview
Chromium coatings are electrolytically applied to substrates from an
aqueous solution of chromic acid and sulfuric acid. The most
common form of chromium in the plating baths is hexavalent chro-
mic acid. Chromium metal is deposited on the substrate by a
complex six-electron reduction. The reduction reaction is catalyzed
by the sulfuric acid. Plating from a hexavalent bath reliably produc-
es a bright chromium plating. However, the current efficiency, the
quantity of chromium deposited per unit of electric energy used, the
throwing power, and the ability to produce a uniform coating over a
large area are low. Hydrogen produced by the plating operation
can migrate into the metal substrate and embrittle it. The use of
hexavalent chromium involves operator exposure to chromic acid —
a toxic material - and requires treatment and disposal of chromium
waste.
Solution Clean technologies now exist or are being developed that would
reduce or eliminate the use of cadmium, cyanide, and chromium for
many metal finishing operations. There are two main focuses in de-
scribing clean technologies for metal finishing:
* Alternative finishes (e.g., aluminum, zinc or zinc alloys, and
nickel-tungsten-silicon carbide^replace cadmium and chromium.
* Process changes (Blackhole M Technology, ion vapor depo-
sition, physical vapor deposition, in-mold plating, and metal
spray) use different technologies for metal finishes. The capital
costs may be greater for process changes, but the reduced cost
of disposing of hazardous wastes often makes up for this.
Traditionally, most cadmium plating is done using cyanide because
the baths exhibit excellent throwing power. Other plating solutions
that do not contain cyanide and offer high cathode efficiency at high ,
current density are being tried. These baths contain metallic salts
such as neutral sulfates, acid sulfates, and acid fluoroborates. Non-
cyanide baths are often preferred for cadmium plating of quenched
and tempered high strength steels because less hydrogen is gener-
ated, thus lessening the danger of embrittlement. Ajax Metal
Processing in Detroit plates a large number of parts using a propri-
etary non-cyanide method (Humphreys, 1989).
Incorporating process changes that do not use cyanide baths or
increasing use of cyanide recovery systems will diminish cyanide
pollution.
Sodium cyanide is considered to be a multipurpose ingredient in
many plating operations, but is especially important when plating
the more noble metals. However, many alternatives are now being
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Overview
investigated for pollution control. Some examples are acid fluoro-
borate in cadmium plating, copper pyrophosphate or copper sulfate
in copper plating, gold sulfite in gold and gold alloy plating, silver
succinimide and silver sulfite/thiosulfate in silver plating, and acid
chloride and alkaline noncyanide zinc baths for zinc plating.
It may be possible to replace chromium plating with an alternative
substrate that will provide sufficient hardness or corrosion resis-
tance. For example, advanced ceramic and composite materials
have been tested as replacements for metal parts in internal com-
bustion engines. If an alternative substrate is not available, it may
be possible to produce a coating with the necessary properties
without plating from an aqueous bath. Hard coatings can be ap-
plied by physical vapor deposition (PVD). For example, titanium
nitride is used as a coating to improve the wear resistance of cutting
tools.
PVD coatings are applied in a heated vacuum chamber. A gas
plasma or electric arc heats and vaporizes the metal that is to be
plated onto the substrate. The vaporized metal ions are deposited
onto the substrate as a thin, hard film (Gresham, 1991). PVD
coatings are generally harder and thinner than electrolytically
deposited coatings. The major research need is to develop PVD
coatings that have the required adhesion, hardness and coating
thickness, as well as other required performance characteristics,
uniformly over a large complex part.
Aqueous electroplating with less hazardous metals is another
approach to reducing use of chromium plating. The electroplating
operation is conceptually the same as chromium plating but, of
course, uses different bath composition and plating conditions such
as voltage and current. Possible alternatives include nickel-
tungsten-silicon carbide plating (Schiffelbein, 1991) and molyb-
denum plating (Groshart, 1989).
The major research need is to develop replacements for chromium
that give the required hardness and coating thickness, as well as
other required performance characteristics, at a reasonable cost.
Given the generally low current efficiency, deposition rate, and
throwing power of hexavalent chromium plating, it is likely that alter-
native plating systems will give similar or better production rates'.
There is a continuing trend in the chromium plating industry toward
replacing hexavalent chromium baths with trivalent chromium baths,
although trivalent plating is used mainly for appearance coatings
rather than for hard coatings. The chromium chemicals used in tri-
valent plating are more expensive than those used in hexavalent
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Overview
plating. Some of the higher cost can be offset by the higher current
efficiency and better throwing power of the trivalent process, as well
as by selection of additives and process optimization to reduce
costs.
An impediment to wider acceptance of trivalent chromium was the
color and finish achieved. Trivalent chromium gives a "gray" lus-
trous finish that is acceptable in many applications. While appear-
ance should not be a major concern in most hardness and corrosion
resistance applications, many customers prefer the "blue" finish
typical of chromium plating from a hexavalent bath. Some trivalent
baths are now said to provide a better color match.
Research is needed to optimize trivalent chromium plating and
expand its range of application. The major area of concern is to
develop trivalent chromium plating methods that produce a coating
with similar thickness, hardness, and color to hexavalent chromium
plating. Methods to optimize the trivalent plating bath composition
and operation to reduce costs are needed.
Chromium plating is applied in some cases mainly to improve the
appearance of the part. The plating solutions and procedures for
appearance plating are similar to those for chromium plating.
However, the operating conditions such as plating current and volt-
age are different.
Plated parts could be replaced by brushed aluminum or stainless
alloy parts to eliminate the need for plating; a less hazardous metal
could be applied to reduce the potential for pollution; or refractive
plastics coatings could be used to eliminate metal plating. Because
the appearance plating baths are similar in chemical composition to
the chromium plating baths, optimization and the bath recovery and
recycling approaches for functional chromium will also apply. Ap-
pearance chromium coatings have lower wear resistance and
thermal resistance requirements, so additional options are available
for chromium replacement in appearance applications.
Anodizing with chromic acid is a process for treating aluminum to
give a highly corrosion-resistant coating that offers an excellent
surface for bonding and painting. Anodizing uses electrochemical
methods to form a thin aluminum oxide surface layer that contains
chromium ions. Sodium dichromate as a sealant enhances fatigue
properties after anodizing by depositing an oxydichromate com-
pound into the anodized layers. Chromate solutions can be used to
chemically deposit a thin hydrated chromium oxide film to prepare
metal surfaces for subsequent painting (Evanoff, 1990).
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Overview
What's In
This Guide?
Other Questions
Affecting
Investment Decisions
Who Should Use
This Guide?
This application guide describes clean technologies that can be
used to reduce waste in metal finishing operations. Its objectives
are:
• To identify potentially viable clean technologies that can reduce
waste by modifying the metal finishing process.
• To provide resources for obtaining more detailed engineering
information about the technologies.
The following questions are addressed:
• What alternative metal finishing alternatives are available or
emerging that could significantly reduce or eliminate pollution
being generated from current operations?
4 Under what circumstances might one or more of these alterna-
tives be applicable to your operations?
* What pollution prevention, operating, and cost benefits could be
realized by adapting the technology?
These other considerations will affect the decision to explore one or
more clean technologies for metal finishing:
* Might new pollution problems arise when implementing clean
technologies?
4 Will tighter, more complex process controls be needed?
* Will product quality and operating rates be affected?
* Will new operating or maintenance skills be needed?
4 What are the overall capital and operating cost implications?
To the extent possible, these questions are answered in this guide.
The clean technologies described in this guide are applicable under
different sets of product and operating conditions. If one or more
alternatives seem attractive for your operations, the next step is to
contact vendors or users of the technology to obtain detailed engi-
neering data in order to perform an in-depth evaluation of its poten-
tial for your plant.
This application guide has been prepared for plant process and
system design engineers and for personnel responsible for process
improvement. Process descriptions within this guide will help users
evaluate options so that clean technologies can be considered for
existing plants and factored into the design of new metal finishing
operations.
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Overview
This guide's purpose is to present sufficient information to enable
users to select one or more candidate technologies for further
analysis and in-plant testing. This guide does not recommend any
one technology over any other. It presents concise summaries of
applications and operating information to support preliminary selec-
tion of clean technology 'candidates for testing in specific processes.
Sufficient detail is provided to allow identification of possible tech-
nologies for immediate application to eliminate or reduce waste
production.
The keywords listed below will help you quickly scan the available
and emerging technologies covered.
Keywords
Clean Technology
Pollution Prevention
Source Reduction
Source Control
Recycling
Metal Finishing
Plating
Electroplating
Anodizing
Metal Deposition
Electroless Plating
Etching
Metal Stripping
lonization
Vapor Deposition
Sputtering
Injection Molding
Blackhole™ Technology
Ion Vapor Deposition (IVD) of Aluminum
Non-Cyanide Copper Plating
Non-Cyanide Metal Stripping
Zinc or Zinc/Nickel Alloy Electroplating
Physical Vapor Deposition (PVD)
Nickel-Tungsten-Silicon Carbide Plating
Chromium-Free Aluminum Surface Treatment
In-Mold Plating
Metal Spray Coating
Summary of
Benefits
The clean technologies described in this guide are divided into two
groups based on their maturity — commercially available technolo-
gies and emerging technologies in advanced pilot plant testing.
Table 2 summarizes the pollution prevention, operational, and
economic benefits of these metal finishing process alternatives.
You may wish to scan this summary table to select those clean
technologies that best fit your operations and needs. Detailed
discussions of the benefits and operational aspects for each clean
technology are provided in Sections 2 and 3.
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Table 2. Summary of Benefits of the Clean Technologies for Metal Finishing Alternatives
Benefits
Available Technologies
Blackhole™
Technology
Ion Vapor
Deposition
(IVD) of
Aluminum
Non-Cyanide
Copper
Plating
Non-Cyanide
Metal Strip-
ping
Zinc or
Zinc/Nickel
Alloy
Electroplating
Emerging Technologies
Physical
Vapor
Deposition
(PVD)
Nickel-
Tungsten-
Silicon
Carbide
Plating
Chromium-
Free
Aluminum
Surface
Treatment
In-Mold
Plating
Metal
Spray
Coatings
Pollution Prevention:
Replaces cyanide
Replaces loxic metal
Eliminates/reduces
wastewater
Eliminates toxic organics
•
•
•
•
•
•
•
•
8
•
•
•
•
•'
Operational:
Reduced process steps
Batch process
High throughput
t
•
• *
•
•
'"""
•
•
•
•
•
•
•
•
•
Economic:
Relatively low capital
costs
Relatively low operating
costs
Relatively low skill level
to operate
•
•
•
•
•
•
•
•
•
•
•
• .
•
t
•
•
'When using horizontal wet processing system.
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SECTION 2
AVAILABLE TECHNOLOGIES
How to Use the
Summary Tables
Descriptive
Aspects
Operational
Aspects
Five available clean technologies for metal finishing are evaluated in
this section:
* Blackhole™ Technology (electroless copper alternative)
* Ion vapor deposition (IVD) of aluminum as an alternative for
cadmium coatings
* Non-cyanide copper plating as an alternative to cyanide-based
copper plating
* Non-cyanide metal stripper to replace cyanide-based strippers
* Zinc or zinc-nickel alloy electroplating as alternatives to cadmium
electroplating
Tables 3 and 4 summarize descriptive and operational aspects of
these technologies. They contain evaluations or annotations de-
scribing each available clean technology and give users a compact
indication of the range of technologies covered to allow preliminary
identification of those technologies that may be applicable to their
specific situations. Readers are invited to refer to the summary
tables throughout this discussion to compare and contrast technolo-
gies.
Table 3 describes each available clean technology. It lists the
Pollution Prevention Benefits, Reported Applications, Oper-
ational and Product Benefits, and Hazards and Limitations of
each available clean technology.
Table 4 shows key operating characteristics for the available tech-
nologies. The rankings are estimated from descriptions and data in
the technical literature and are based on comparisons to typical
technologies that the clean technologies would replace.
Process Complexity is qualitatively ranked as "high," "medium," or
"low" based on such factors as the number of process steps in-
volved and the number of material transfers needed. Process
Complexity is an indication of how easily the technology can be
integrated into existing plant operations. A large number of process
steps or input materials or multiple operations with complex se-
quencing are examples of characteristics that would lead to a high
complexity rating.
11
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Available Technologies
The Required Skill Level of equipment operators also is ranked as
"high," "medium," or "low." Required Skill Level is an indication of
the relative level of sophistication and training required by staff to
operate the new technology. A technology that requires the opera-
tor to adjust critical parameters would be rated as having a high skill
requirement. In some cases, the operator may be insulated from
the process by complex control equipment. In such cases, the
operator skill level is low but the maintenance skill level is high.
Table 4 also lists the Waste Products and Emissions from the
available clean technologies. It indicates tradeoffs in potential
pollutants, the waste reduction potential of each, and compatibility
with existing waste recycling or treatment operations at the plant.
The Capital Cost column provides a preliminary measure of pro-
cess economics. It is a qualitative estimate of the initial cost impact
of the engineering, procurement, and installation of the process and
support equipment. Due to the diversity of data and the wide varia-
tion in plant needs and conditions, costs will vary for each facility.
Cost analyses must be plant-specific to adequately address factors
such as the type and age of existing equipment, space availability,
production volume, product type, customer specifications, and cost
of capital.
The Energy Use column provides data on energy conversion
equipment required for a specific process. In addition, some gener-
al information on energy requirements is provided.
The last column in Table 4 lists References to publications that will
provide further information for each available technology. -These
references are given in full in Section 4.
The text further describes pollution prevention benefits, reported
applications, operational and product benefits, hazards and limita-
tions, tradeoffs, unknowns, and the current state of development for
each available technology. Technologies in earlier stages of devel-
opment are summarized to the extent possible in Section 3, Emerg-
ing Technologies.
12
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Table 3. Available Clean Technologies for Metal Finishing: Descriptive Aspects
Available
Technology Type
Pollution Prevention Benefits
Reported Applications
Operational and
Product Benefits
Hazards and Limitations
Blackhole™
Technology
Avoids copper
Avoids formaldehyde
Reduces water use
Replaces eleclroless copper metalization of
through-holes prior to electrolytic plating for
PWBs
Uses carbon black suspension to provide a thin
conductive coating
Fewer process steps
Simple process
Less water used
Meets military standards
Process not accepted by all PWB
users
May increase solids loading to
wastewater treatment
Ion Vapor Deposi-
tion (IVO) of Alumi-
num
Alternative tor cadmium
Avoids aqueous waste streams
U.S. DoD Contractors
Incorporated into several military and industri-
al specifications
Two process steps for cleaning and plating, no
rinsing
Permits thicker coatings
Can be used at higher temperatures (925°F)
as compared to 450°F for cadmium
Cannot apply aluminum to deep
recesses
Coating tends to be porous
Chromate conversion coating, or
equivalent, required as with cadmium
or zinc coatings for maximum corro-
sion protection
Non-Cyanide Cop-
per Plating
Avoids cyanide
Widespread industrial use
Better throwing power
Reduced safety risks
Reduces treatment costs
No carbonate problems
Parts need to be deaner before
plating
Less able to provide levelling
Non-Cyanide
Metal Stripping
Avoids cyanide
Kelly Air Force Base
Increasing industrial use
Reduces waste treatment costs
Reduced safety risks
Increased bath life
No carbonate problems
High operating temperature may be
required
Slower stripping rates typical
Stripper may cause undesirable
substrate effects
Zinc or Zinc-Nickel
Alloy Electroplat-
ing
Replacement for cadmium
Many industrial applications
Uses equipment similar to that used in cadmi-
um plating
Comparable corrosion resistance
Better wear resistance (Ni-Zn)
Better ductility (Ni-Zn)
Higher contact resistance
Lower lubricity
Acid zinc coatings have comparative-
ly poor throwing power
13
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Table 4. Technologies for Metal Finishing: Operational Aspects
Available
Technology
Type
Blackhole™
Technology
Ion Vapor
Deposition (IVD)
of Aluminum
Non-Cyanide
Copper Plating
Non-Cyanide
Metal
Stripping
Zinc or Zinc-
Nickel Alloy
Electroplating
Process
Complexity
Low
Medium
Low
Low
Low
Required
Skill Level
Low
High
Low
Low
Low to
medium
Waste Products and
Emissions
• Rinsewater containing
carbon powder and
complexing agents
• Used solution
• No waste product
• Rinsewater
• Used solution
• Rinsewater
• Used solution
• Rinsewater
• Used solution
Capital Cost
• Low
• Solution cost medium
• High
• Low: Use existing tanks
• Solution cost medium
• Low: Use existing tanks
• Solution cost medium
• Use existing tanks
• Solution low to medium
Energy Use
Low
High
Low
Low
Low
Operations Needed
After Application
• Treat wastewater generated
• Electrolytic copper plating (same as
lor eledroless copper)
• May need lubricant for lubricity
requirements
• Chromate conversion coating or
equivalent
• None
• None
• Chromate conversion coating
References
Bracht and Piano. 1990
Olin Hunt, undated
Polakovic, 1988
Ahmed, undated
Carpenter, 1988
Hinton, 1987
Holmes, 1989
Electrochemical Products,
Inc., undated
Kline, 1990
Krishnan, 1990
Udylite, undated
Electrochemicals, Inc.,
undated
Frederick Gumm Chemical
Company, undated
Janikowski et al., 1989
Hanna and Noguchi, 1988
Ko et a)., 1991
Sharpies, 1988
Sizefove. 1991
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BLACKHOLE™ TECHNOLOGY
Pollution Prevention
Benefits
How Does
It Work?
Why Choose
This Technology?
The Blackhole Technology Process is an alternative to the electro-
less copper method. It claims the following qualities that make it
environmentally attractive:
* Fewer process steps
• Reduced health and safety concerns
* Reduced waste treatment requirements
4 Less water required
* Reduced air pollution.
The chemicals used in the low number of process steps avoids the
use of metals and formaldehyde. The small number of process
steps also results in less rinse water used, reducing waste treat-
ment requirements.
The Blackhole Technology Process uses an aqueous carbon black
dispersion (suspension) operating at room temperature to prepare
through-holes in printed wire boards (PWBs) for subsequent copper
electroplating. The carbon film obtained provides the conductivity
needed to electroplate copper in the through-holes. The process
steps are listed in the following paragraphs and compared with the
process steps used for the electroless copper method.
Applications
The Blackhole™ Technology Process eliminates the need for elec-
troless copper metalization of through-holes prior to electrolytic
plating in the PWB industry.
Operating Features
PWBs must be pretreated in the same way as those for electroless
copper for desmear/etchback. Permanganate is the preferred
desmear process for Blackhole™ Technology due to its wide operat-
ing conditions and resultant hole-wall topography.
15
-------
Available Technologies
Basic Function. Conventional plating tanks and horizontal conve-
yorized systems can be used for the Blackhole™ Technology Pro-
cess. The process steps are explained in the following paragraphs.
The cleaner used is a slightly alkaline solution containing a weak
complexing agent. The solution is operated at 135°F (57°C) to
remove drilling debris from the hole-wall, to clean the copper surfac-
es, and to prepare the hole-wall surface for the subsequent condi-
tioning step.
The conditioner also is a slightly alkaline solution containing a weak
complexing agent, which operates at room temperature. The condi-
tioner is used to neutralize the negative charge on the dielectric
surfaces which helps increase the absorption of the carbon in the
next step.
TM
The Blackhole Technology process step is a slightly alkaline,
aqueous carbon black based suspension operating at room temper-
ature. The viscosity of the solution is very close to that of water.
The carbon particles have a diameter in the size range of 150 to
250 nanometers (1500 to 2500 Angstroms).
PWB manufacturing processes typically use the electroless copper
process to plate through-holes. The electroless copper process
consists of the following operational steps:
I. Acid Cleaner
2. Rinse
3. Micro etch (sodium persulfate solution)
4. Rinse
5. Activator Pre-dip
6. Catalyst
7. Rinse
8. Rinse
9. Accelerator
10. Rinse
11. Electroless copper bath
12. Rinse '
13. Sulfuric acid (10%) dip '
14. Rinse
15. Anti-tarnish dip
16. Rinse
17. Deionized water rinse
18. Forced air dry
These steps are typically done in the above sequence in a process
line that uses an automated hoist to move racks of parts from tank
to tank. All the rinses are single use and generate large quantities
16
-------
Blackhole™ Technology
of wastewater containing copper. The rinses following the
electroless copper bath (Step 11) contain complexed copper, which
is hard to treat by typical wastewater treatment technology, namely
metal hydroxide precipitation.
The Blackhole™ Technology process replaces the electroless cop-
per used for through hole plating with a carbon black dispersion in
water. The Blackhole™ Technology process consists of the follow-
ing process steps:
1. Blackhole™ alkaline cleaner
2. Rinse
3. Blackhole™ alkaline conditioner
4. Rinse
TM
5. Blackhole bath
6. Dry
7. Micro-etch
8. Rinse
9. Anti-tarnish dip
10. Rinse
11. Dry
Steps one through six are performed, then repeated. Steps seven
through twelve are performed. All process steps are done automati-
cally in a horizontal conveyor system or can be done using existing
hoists and bath systems.
Material and Energy Requirements. Some process steps are re-
peated, which reduces the floor space needed for the process
baths. The number of chemicals used also is reduced. The energy
requirements should be about the same, because both processes
use a drier and several heated solutions.
Required Skill Level
The skill level required of system operators is the same as or less
than that for electroless copper processing.
Cost
If existing process .equipment is used, the only installation cost is
the disposal of the electroless copper solutions, cleaning of the
tanks, and replacement with the Blackhole™ Technology process
solutions.
17
-------
Available Technologies
Reported
Applications
The Blackhole Technology process has been available commer-
cially since 1989. The technology is currently used by PWB manu-
facturers and is gaining acceptance. Military Standard MIL-P-
55110D now permits through-hole plating technologies other than
electroless copper.
Operational and Product
Benefits
Hazards and
Limitations
Availability
The Blackhole1
ly Olin Hunt).
Technology process is sold by Mac Dermid (former-
Process Simplification. The technology reduces the number of
different process steps and their associated chemicals and
rinses. This greatly reduces waste streams.
Contamination Reduction. Avoids formaldehyde in the electro-
less copper solution.
Ease of Throughput. The operation using existing equipment
from an electroless copper process line would be about the
same. The use and installation of a horizontal process line
would ease operation, especially if the electroless copper line
was hand-operated.
Acceptable Product Quality. The product quality should not be
affected. The Blackhole™ Technology process is accepted under
MIL-P-55110D.
Lower Operating Costs. Costs for chemicals, water, and waste-
water treatment are reduced.
Potential Health Risk. By using a carbon black suspension, this
technology avoids the use of metals (copper, palladium, and tin)
and formaldehyde. The process solutions contain some chemi-
cals that are irritants. The overall health risk would be reduced
by using the technology.
Potential Peripheral Costs. None.
Tradeoffs
State of
Development
Due to current limited use of this technology, it may not be widely
accepted by all PWB users.
The Blackhole™ Technology is commercially available.
18
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ION VAPOR DEPOSITION (IVD) OF ALUMINUM
Pollution
Prevention
Benefits
Cadmium is a heavy metal that is toxic to humans. In addition,
electroplated cadmium coating processes normally use plating solu-
tions that contain cyanide. Cyanide is highly toxic to humans and
animal life. Aluminum coatings deposited through ion vapor deposi-
tion (IVD) can replace cadmium coatings in some applications to
eliminate the use of both cadmium and cyanide. Aluminum is con-
sidered nontoxic, and the process does not employ or create any
hazardous materials.
How Does
It Work?
Why Choose This
Technology?
Ion vapor deposition (IVD) is a coating method whereby the coating
metal is evaporated and partially ionized before being deposited on
the substrate. A typical IVD system consists of a steel vacuum cha-
mber, a pumping system, a parts holder, an evaporation source,
and a high-voltage power supply. A vacuum is drawn on the
chamber, which is then backfilled with argon. A large negative
potential is then applied between the evaporation source and the
parts to be coated. The argon ions created by the potential differ-
ence help clean the substrate surface.
Then the coating metal typically is heated resistively in a crucible
and exposed to the ionized argon. The ionized gas molecules
collide with the metal vapors and ionize some of the metal mole-
cules. The metal molecules are accelerated toward the substrate,
which results in good adhesion of the coating.
Applications
IVD aluminum coatings can be applied to a wide variety of metallic
substrates, including aluminum alloys. Because deposition is not
limited to "line of sight" applications, parts with complex shapes,
such as fasteners, can be coated. However, coating inside blind
holes, tubes, or deep recesses is difficult.
Operating Features
IVD has the following operating features:
* Large and/or complex parts can be plated.
* The technology is hot limited to "line of sight" applications.
* There is no buildup of the coating on sharp edges, such as
can occur in electroplating.
* Thicker coatings can be applied than when cadmium is used.
19
-------
Available Technologies
Required Skill Level
With some training, operators who have performed cadmium elec-
troplating operations can perform aluminum IVD. Aluminum IVD
involves more decision-making than does cadmium electroplating,
but this difference should not require replacement of operators.
Reported
Applications
Cost
Capital costs for aluminum IVD equipment are higher than those for
cadmium electroplating equipment. However, the aluminum IVD
process requires no pollution control equipment. If pollution control
equipment costs are included in the comparison, the costs for
aluminum IVD are competitive. In comparing costs to other cad-
mium coating processes, costs for the aluminum IVD process are
higher than those for the cadmium physical vapor deposition pro-
cess, but are lower than those for either the low-embrittlement or
diffused nickel-cadmium processes. Costs for cadmium electro-
plating are likely to keep rising due to ever-increasing hazardous
waste disposal costs. In contrast, expanding use of IVD aluminum
probably will lead to cost reductions.
The aluminum IVD process is used by a large number of U.S. De-
partment of Defense contractors and is incorporated into several
military and industrial specifications as an option for cadmium
plating.
Operational and
Product Benefits
Availability
The aluminum IVD process was developed in large part by the
McDonnell Aircraft Company (a subsidiary of McDonnell-Douglas),
St. Louis, Missouri. The equipment developed by McDonnell is
called the lvadizerR. In 1987, McDonnell sold the rights to the pro-
cess to the Abar-lpsen Co. of Bensalem, Pennsylvania. Abar-lpsen
currently manufactures the equipment. Other companies have
licenses to use the technology.
Health and safety risks' are greatly reduced when this technology is
used in place of cadmium electroplating. Cadmium is a significant
health hazard, as is the cyanide bath often used in cadmium elec-
troplating.
For many applications, a chromate conversion coating is used on
both cadmium and aluminum IVD coatings to improve corrosion
20
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Ion Vapor Deposition
resistance and adherence of subsequent organic coatings. The use
of chromate conversion coatings generates some hazardous waste.
Switching to an aluminum IVD process should not require increased
use of these coatings.
The greatest advantage of aluminum IVD is that the process gener-
ates no hazardous waste. Therefore, no pollution-control systems
are required. Other potential advantages of aluminum IVD coatings
are listed below:
4 Outperforms cadmium coatings in preventing corrosion in acidic
environments.
* Can be used at temperatures up to 925°F, as compared to 450°F
for cadmium.
* Can be used to coat high-strength steels without danger of hy-
drogen embrittlement because, unlike cadmium electroplating,
the aluminum IVD process does not expose the substrate to
hydrogen gas.
* Can be used in contact with titanium without causing solid metal
conversion problems.
* Can be used in contact with fuels.
* Superior to the vacuum-applied cadmium process in resisting
particle impact (e.g., can withstand burnishing pressures up to 90
psi as compared to 40 psi for vacuum-applied cadmium).
* Permits thicker coatings of several mils compared to about 1 mil
for electroplated and vacuum-applied cadmium, thus increasing
the corrosion resistance of the coating.
* Provides better coating uniformity on edges of parts than does
electroplating.
Hazards and
Limitations Some of the disadvantages of IVD coatings are listed below:
* It is difficult to coat the interiors of blind holes of cavities that
have a depth greater than their diameter.
* Aluminum IVD coatings have higher coefficients of friction than
cadmium coatings. This changes the torque tension relationsh-
ips for fasteners. This problem is manageable with use of
lubricants.
* Unlike cadmium, aluminum IVD cannot be combined with nickel
to provide a more erosion-resistant surface.
* The is no simple way to repair damaged aluminum IVD coatings.
* Aluminum IVD is slower than cadmium electroplating. However,
for high-strength parts, reduced speed is not an issue because
these parts would have to undergo hydrogen embrittlement relief
after cadmium electroplating. Parts coated by aluminum IVD do
not require this time-consuming treatment, thus compensating for
the slower application speed.
21
-------
Available Technologies
* Aluminum IVD coatings often take on columnar structures with
porosities high enough to allow access to the base metal. Coat-
ings can be peened with glass beads to make the coating more
dense and minimize this problem, or the coatings can be sealed.
State of
Development The IVD coating for aluminum is commercially available. Aluminum
IVD is a mature technology. New technologies or techniques could
affect the process, but no significant changes are expected in the
aluminum IVD process in the near future.
22
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NON-CYANIDE COPPER PLATING
Pollution
Prevention Benefits
How Does
It Work?
Why Choose
This Technology?
The main benefit of using a non-cyanide copper plating process is
that it eliminates use of cyanide. Spent cyanide plating solutions
require extensive treatment before they can be disposed of. In
contrast, treatment of spent non-cyanide copper plating solution is
simple and straightforward. It requires only treatment with lime or
other calcium-containing compounds prior to disposal.
Non-cyanide copper plating is an electrolytic process similar to its
cyanide-based counterpart. Operating conditions and procedures
are similar, and existing equipment usually will suffice when con-
verting from a cyanide-based to a non-cyanide process.
Applications
Non-cyanide copper plating baths are commercially available for
coating steel, brass, lead-tin alloy, zinc die cast metal, and zincated
aluminum. The process can be used for rack or barrel plating. It
can be used on fasteners, marine hardware, plumbing hardware,
textile machinery, automotive and aerospace parts, masking appli-
cations, electro-magnetic interference (EMI) shielding, and heat
treatment stop-off. It can be used as a complete coating or as a
strike bath only.
Operating Features
Non-cyanide copper plating has the following characteristics:
* Bath temperatures are typically elevated (110 to 140°F)
* The pH is in the range of 8.8 to 9.8.
* Its throwing power is as good as that of cyanide-based process-
es.
* Deposits are matte in appearance with a dense, fine-grained
amorphous microstructure.
* With additives, semi-bright to bright appearances can be ob-
tained.
* Copper ions are in the Cu++ state as compared to Cu+ for the
cyanide-based bath.
Assuming 100% cathode efficiencies, a non-cyanide bath requires
twice the current to plate a given amount of copper' as does a
23
-------
Available Technologies
cyanide bath. However, the current density can be increased to
levels such that plating speed is equivalent to cyanide-based baths.
Required Skill Level
Non-cyanide copper plating requires more frequent bath analysis
and adjustment than does cyanide-based plating. Cyanide-based
copper plating baths are relatively forgiving to bath composition.
The same operating personnel should be capable of operating the
non-cyanide process.
Reported
Applications
Cost
Operating costs for the bath itself are substantially higher for the
non-cyanide process. However, because replacing the cyanide-
based bath with a non-cyanide bath eliminates the need for treat-
ment of cyanide-containing solutions, the cost differential between
the two processes is greatly reduced if not eliminated.
Use of non-cyanide copper plating baths is not widespread in
industry.
Operational and
Product Benefits
Availability
The process is available commercially from several sources. These
sources typically advertise in the following trade journals:
* Metal Finishing
* Plating and Surface Finishing
4 Products Finishing
Non-cyanide copper plating has the following benefits:
* Greatly reduces safety risks to workers.
4 Greatly reduces costs of treating spent plating solutions.
* Dragout to an acidic bath provides no risk of HCN evolution.
* Plating solution does not have to be treated for carbonates.
Replacement of cyanide-based plating baths greatly reduces safety
risks to workers. Cyanide is extremely toxic. Electroplaters are
most at risk through ingestion and inhalation of hydrogen cyanide
(HCN). Skin contact with dissolved cyanide salts is somewhat less
dangerous but will cause skin irritation and rashes. The most likely
24
-------
Non-Cyanide Copper Plating
scenario for exposure to lethal doses of HCN is an accident involv-
ing addition of an acid to a cyanide-containing electroplating bath or
mixing cyanide waste with acid-containing waste streams.
Hazards and
Limitations Without cyanide in the bath, thorough cleaning and activation of the
surface to be coated become more critical. Cyanide-based baths
remove impurities so that the coating is not compromised.
Summary of
Unknowns/State of
Development Non-cyanide copper plating baths typically are developed by man-
ufacturers of the bath solutions. Chemical compositions are outside
the public domain, and their formulae are proprietary. As a result,
very little has been published on development activities. According
to one manufacturer, product improvement will continue for some
time, although no major developments are expected.
25
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NON-CYANIDE METAL STRIPPING
Pollution
Prevention
Benefits
How Does
It Work?
Why Choose This
Technology?
Using cyanide-based metal strippers results in the generation of
cyanide-contaminated solutions that require special treatment and
disposal procedures. Use of a non-cyanide stripper eliminates cya-
nide from the spent stripper solution. In general, these non-cyanide
strippers are less toxic and more susceptible to biological and
chemical degradation than their cyanide-based counterparts. These
features translate into simpler and less expensive treatment and
disposal of spent solutions.
In addition, use of a non-cyanide stripper can simplify removal of
metals from the spent solution. Because of the strong complex they
form with the cyanide ligand, these metals are difficult to remove.
Metal strippers are used to remove previously deposited metallic
coatings from parts. Cyanide-based stripping solutions act by en-
abling or assisting oxidation of the coating metal, after which the
metal complexes with the cyanide ligand and is subsequently
solubilized.
Because the non-cyanide stripping solutions are typically proprietary
formulations, the detailed chemistry of coating removal is not known
for most solutions. Stripping solutions are available for a wide
variety of coating metal/base metal combinations. Some of the
processes are electrolytic; others are not. Processing temperatures,
bath life, ease of disposal and other operating characteristics all
vary widely.
Applications
Metal strippers can be purchased commercially for a wide variety of
coating and substrate metals. The U.S. Air Force has performed
testing on a number of non-cyanide strippers. The Air Force was
particularly interested in nickel and silver non-cyanide strippers.
Several of these have been implemented at Kelly Air Force Base.
26
Operating Features
The wide variety of non-cyanide strippers makes it difficult to gener-
alize about operating features. Some are designed to operate at
ambient bath temperatures, whereas others are recommended for
-------
Non-Cyanide Metal Stripping
temperatures as high as 180°F. Processes range from acidic to ba-
sic. In general, the same equipment was used for cyanide-based
stripping can be used for non-cyanide stripping. However, with
acidic solutions, tank liners may be needed to prevent corrosion.
Required Skill Level
Personnel who use cyanide-based strippers should be able to use
non-cyanide strippers. For example, the U.S. Air Force reported
that, for the non-cyanide metal strippers implemented at Kelly Air
Force Base, no higher skill level was required.
Cost
Non-cyanide strippers will have the following impacts on cost:
4 Waste treatment costs will be reduced. If cyanide-based solu-
tions are not used elsewhere in the facility, the cyanide treatment
system can be eliminated as a result of a switch to non-cyanide
strippers.
* No large capital outlay is required to switch to a non-cyanide
stripper because the equipment requirements are generally the
same.
* There is a slight increase in the costs of the makeup solutions.
Reported
Applications Manufacturers have only a limited use history on their non-cyanide
products. This indicates that use is not yet widespread. However,
use of the product has been growing at a rate of 20 to 30% per
year, according to one manufacturer.
Availability
A partial list of companies from which non-cyanide strippers are
available is listed below in alphabetical order. This listing does not
constitute a recommendation.
* Circuit Chemistry Corp.
* Electrochemical, Inc.
* Frederick Gumm Chemical Company
* Kiesow International
* MacDermid Inc.
* Metalline Chemical Corp.
* Metalx Inc.
* OMI International
4 Patclin Chemical Company
* Witco Corporation
27
-------
Available Technologies
Operational and
Product Benefits
Hazards and
Limitations
Summary of
Unknowns/State of
Development
Non-cyanide metal strippers have the following benefits:
* Significant potential for reducing waste treatment costs
* Often easier to recover metals from spent solutions
* Bath life can be longer because higher metal concentrations can
be tolerated
• No problems with carbonation of the solutions.
One of the main incentives of eliminating cyanide-based stripping
processes is to reduce health hazards to personnel. Cyanide is an
extremely toxic substance. While cyanide in solution is itself very
toxic, one of the main dangers for electroplaters is an accidental
addition of an acid into the cyanide bath, which results in the forma-
tion of hydrogen cyanide gas, HCN. Skin contact with dissolved
cyanide salts is less dangerous than inhaling HCN or ingesting
cyanide, but it will cause skin irritation and rashes.
Facilities considering a switch to a non-cyanide stripper must, of
course, look at the health and safety aspects of the substitute, such
as high operating temperature, corrosivity, and so on.
Non-cyanide metal strippers have some disadvantages:
4 For some strippers, recommended process temperatures are
high enough to cause safety problems. Operating at lower
temperatures can result in a loss of effectiveness.
* Stripping rates for certain coatings may be lower than for cya-
nide-based counterparts.
* The stripper may cause undesirable effects on the substrate
metal, even if the manufacturer has recommended it for the
application in question.
A major market for non-cyanide strippers is for removing nickel
coatings. Non-cyanide nickel strippers are largely a mature product.
Future development will be oriented toward adjusting the product to
handle different metal coatings (e.g., silver) and substrates.
28
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ZINC OR ZINC-NICKEL ALLOY ELECTROPLATING
Pollution
Prevention Benefits
How Does
It Work?
Why Choose This
Technology?
In certain cases, zinc or zinc alloy electroplating can replace cadmi-
um coatings. Cadmium is a heavy metal that is toxic to humans. In
addition, electroplated cadmium coating processes are normally per-
formed in plating solutions containing cyanide. Cyanide is highly
toxic to humans and animal life. If an acid or non-cyanide alkaline
zinc or zinc-nickel coating process can be used in place of a cya-
nide-based cadmium electroplating process, then use of both
cadmium and cyanide is eliminated.
Zinc and zinc-nickel alloy electroplating processes are very common
and have a long history in the electroplating industry. Recently,
however, they have been examined specifically as a possible
replacement for cadmium coatings. The ideal cadmium coating re-
placement would be a non-cyanide-based process, because this
would also eliminate cyanide waste treatment costs.
Three alternative zinc and zinc-nickel processes have shown prom-
ise as replacements for cadmium coatings: •
* Acid zinc
4 Chloride-based zinc or zinc-nickel alloy
4 Alkaline, non-cyanide zinc or zinc-nickel alloy
Applications
The ability of an alternative coating to replace cadmium depends on
the properties required for the application in question. In some
cases, none of the replacement coatings identified above may
serve. For example, if the cadmium coating is being used for its
low coefficient of friction or for its low electrical contact resistance,
none of the candidates mentioned above may be suitable. On the
other hand, with suitable chromate conversion coatings, alternative
coatings can have as good and in some cases better resistance to
corrosion as measured in salt spray tests.
Operating Features
Some of the operating features of the three alternative processes
mentioned above are listed in Table 5.
29
-------
Available Technologies
Table 5. Operating Parameters of Selected Alternatives to Cadmium Coatings
Coating
Add zinc
Chloride-based zinc-nickel alloy
Alkaline non-cyanide zinc-nickel alloy
Relative pH
acidic
slightly acidic
alkaline
Temperature, °C
15-30'
30-35'
23-30'
Predominant
sulfate
chloride
hydroxyl "
Required Skill Level
No increase in skill level is expected as a result of switching to a
zinc or zinc-nickel coating process. These processes are conven-
tional electroplating processes that would require little or no retrain-
ing. Increased attention to bath monitoring and adjustment may be
necessary because these processes are less forgiving than are
cyanide baths.
Reported
Applications
Cost
Existing electroplating equipment could be employed for any of
these processes. Therefore, no large capital expenditures would be
required to switch. However, a switch to an acid bath would require
•tank linings to existing tanks or possibly new tanks to provide the
necessary resistance to corrosion.
The costs associated with cyanide waste treatment would be
eliminated for any line in which a cyanide-based cadmium process
were replaced.
Acid .zinc baths have been used for a long time in zinc plating.
Non-cyanide alkaline baths and chloride-based baths for zinc
coatings are newer developments driven mainly by the desire to
eliminate cyanide from the plating process. Use of zinc-nickel
alloys has gained interest because of their potential to replace
cadmium, particularly in Japan and other countries, where use of
cadmium coatings has been outlawed.
Availability
Acid zinc, chloride zinc or zinc-nickel, and alkaline non-cyanide zinc
or zinc-nickel plating systems are commercially available from
manufacturers.
30
-------
Zinc or Zinc-Nickel Alloy Electroplating
Operational and
Product Benefits
Hazards and
Limitations
Summary of
Unknowns/State of
Development
Replacing a cyanide-based cadmium coating with one of the pro-
cesses outlined above would benefit electroplating workers by
eliminating exposure to both cadmium and cyanide.
Among other benefits are the following:
• Corrosion resistance is as good as cadmium for many applica-
tions.
* Zinc-nickel alloys have better wear resistance than cadmium.
4 Zinc coatings have better ductility than cadmium.
Zinc and zinc-nickel alloy electroplating processes have the follow-
ing disadvantages:
* Electrical contact resistance is higher than for cadmium.
* Zinc and zinc-nickel alloy coatings do not have the lubricity that
cadmium coatings have.
* Acid zinc coatings have comparatively poor throwing power, and
deposits are not fully bright.
The processes outlined above are well-deveioped, commercially
available processes. Only recently, however, have these processes
been considered as replacements for cadmium coatings. More
work needs to be done in the area of directly comparing these coat-
ings to cadmium coatings for given applications.
31
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SECTION 3
EMERGING TECHNOLOGIES
How to Use the
Summary Tables
Descriptive
Aspects
Operational
Aspects
Five emerging clean process changes for metal finishing are evalu-
ated in this section:
4 Physical vapor deposition (PVD) of materials to replace chromi-
um plating
4 Nickel-tungsten-silicon carbide platings to replace chromium
coatings
* Chromium-free, aluminum surface treatments to replace chromi-
um-based surface treatments
* In-mold plating to replace electroless plating followed by electro-
lytic plating
4 Metal spray coating to replace electroplating
Tables 6 and 7 summarize descriptive and operational aspects of
these technologies. They contain evaluations or annotations de-
scribing each emerging technology and give a compact indication of
the range of technologies covered to allow preliminary identification
of those that may be applicable to specific situations. Readers are
invited to refer to the summary tables throughout this discussion to
compare and contrast technologies.
Table 6 describes each emerging clean technology. It lists the
Pollution Prevention Benefits, Reported Applications, Oper-
ational and Product Benefits, and Hazards and Limitations of
each.
Table 7 shows key operating characteristics for the emerging tech-
nologies. The rankings are estimated from descriptions and data in
the technical literature.
Process Complexity is qualitatively ranked as "high," "medium," or
"low" based on such factors as the number of process steps in-
volved and the number of material transfers needed. Process
Complexity is an indication of how easily the technology can be
integrated into existing plant operations. A large number of process
steps or input chemicals or multiple operations with complex se-
quencing are examples of characteristics that would lead to a high
complexity rating.
32
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Table 6. Emerging Clean Technologies for Metal Finishing: Descriptive Aspects
/
Emerging
Technology Type
Physical Vapor Deposition
Nickel-Tungsten-Silicon
Carbide Plating
Chromium-Free Aluminum
Surface Treatments
In-Mold Plating
Metal Spray Coating
Pollution
Prevention Benefits
• Avoids plating solutions
• Eliminates rinsing
• Chromium alternative
• Eliminates chromium
• Eliminates etching, sensitizing
solutions, and electroless
plating
• Avoids plating solutions
• Eliminates rinsing
Reported
Applications
• Titanium nitride
• Undergoing testing
• Industry - aluminum cans;
aircraft components
• Undergoing development
• Industry
Operational and
Product Benefits
• Reduces process steps
• Avoids hydrogen
embrittlement
• Higher current efficiencies
than chromium plating
• Better throwing power
• Better wear resistance
• Limited operation data
available
• Reduces process steps ->
• Reduces number of waste
streams
• Reduces process steps
• Avoids hydrogen
embrittlement
Hazards and
Limitations
• Applies thin coatings
• High vacuum required
• Corrosion resistance
• Internal stresses
• Complex shapes
• Corrosion resistance
• Complex shapes
• Limited data available
• High cost
• Limited applications
CO
03
-------
CO
Table 7. Emerging Clean Technologies for Metal Finishing: Operational Aspects
Emerging
Technology Type
Physical Vapor Deposition
(PVD)
Nickel-Tungsten-Silicon
Carbide Plating
Chromium-Free Aluminum
Surface Treatments
In-Mold Plating
Metal Spray Coatings
Process
Complexity
Medium
Medium
Low to Medium
Medium
Medium
Required
Skill Level
Medium
Medium
Low
Medium
Medium
Waste Products
and Emissions
None from deposition
Avoids chromium use
Avoids chromium use
Avoids etching, sensitizing
solutions, and electroless
copper
None from deposition
References
Comello, 1992
Gresham, 1991
Hermanek, 1987
Johnson, 1989
Key, 1991
Werner, 1992
Schiffelbein, 1991
Bibber, 1991
Hinton, 1991
E. Brooman, Battelle personal
communication, 1992
Hermanek, 1987
Key, 1991
Weiner, 1992
-------
Emerging Technologies
The Required Skill Level of equipment operators also is ranked as
"high," "medium," or "low." Required Skill Level is an indication of
the level of sophistication and training required by staff to operate
the new technology. A technology that requires the operator to
adjust critical parameters would be rated as having a high skill
requirement. In some cases, the operator may be insulated from
the process by complex control equipment. In such cases, the
operator skill level is low but the maintenance skill level is high.
Table 7 also lists the Waste Products and Emissions from the
emerging clean technologies. It indicates tradeoffs in potential
pollutants, the waste reduction potential of each, and compatibility
with existing waste recycling or treatment operations .at the plant.
The last column in Table 7 lists References to publications that will
provide further information for each emerging technology. These
references are given in full in Section 4.
The text further describes operating characteristics, reported appli-
cations, operational and product benefits, and known and potential
hazards and limitations. Technologies in later stages of develop-
ment are discussed in Section 2, Available Technologies.
35
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PHYSICAL VAPOR DEPOSITION (PVD)
Hexavalent chromium is extremely toxic and is a known carcinogen.
Health and safety considerations as well as rising disposal costs
have prompted the plating industry to consider alternatives for
coating processes that involve hexavalent chromium. Physical
vapor deposition (PVD) of alternative materials is one candidate for
replacing chromium electroplating.
Physical vapor deposition is a process by which atoms are removed
by physical means from a source and deposited on a substrate.
The thoroughly cleaned workpiece is placed in a vacuum chamber,
and a very high vacuum is drawn. The chamber is heated to
between 400 and 900°F, depending on the specific process. A
plasma is created from an inert gas such as argon. The workpiece
is first plasma-etched to further clean the surface. The coating
metal is then forced into the gas phase by one of the three methods
described below:
4 Evaporation — high-current electron beams or resistive heaters are
used to evaporate material from a crucible.
* Sputtering - surface of the source material is bombarded with
energetic ions, usually an ionized inert gas such as argon.
* Vacuum Arc - the source material is significantly ionized, typically
by a cathodic arc plasma.
The process often involves introduction of a gas such as oxygen or
nitrogen into the chamber to form oxide or nitride deposits, respec-
tively. PVD coatings are typically thin coatings between 2 and 5
microns.
Chromium and a variety of other metals have been successfully
used as coatings with PVD. Titanium nitride is a prime candidate
for replacing chromium coatings using PVD. Titanium nitride is
much harder than chromium but can be cost effectively applied in
much thinner coatings. Because of the thin, hard nature of the
coating, titanium nitride is inferior to chromium as a coating in high-
point or line-load applications. Titanium nitride coatings also do not
provide as much corrosion protection as do thicker, crack-free
chromium coatings. They are also highly colored and do not look
metallic.
Titanium nitride coatings, along with other PVD coatings, do not
subject the substrate to hydrogen embrittlement. In addition, the
throwing power of chromium electroplating baths is poor. PVD
results in a thin, uniform coating that is much less likely to require
36
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Physical Vapor Deposition
machining after application. However, PVD is a line-of-sight coating
process, and parts with complex shapes are difficult to cast.
Titanium nitride coatings have already gained wide acceptance in
the cutting tool industry. They are now being examined by a variety
of industries, including the aerospace industry.
37
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NICKEL-TUNGSTEN-SILICON CARBIDE PLATING
The nickel-tungsten-silicon carbide (Ni-W-SiC) composite electro-
plating process is a patented process (Takada, 1990) that can be
used to replace chromium coatings. Nickel and tungsten ions be-
come absorbed on the suspended silicon carbide particles in the
plating solution. The attached ions are then adsorbed on the
cathode surface and discharged. The silicon carbide particle
becomes entrapped in the growing metallic matrix.
The composition and operating conditions for the Ni-W-SiC plating
bath are given in Table 8.
Table 8. Composition and Operating Conditions for Ni-W-SiC Composite Plating
Composition
Nickel sulfate, NiSCy6H20
Sodium tungstate, Na2WO4-2H20
Ammonium citrate, NH4HC6H507
Silicon Carbide (0.8 — 1.5 u,m parti-
cles)
pH (adjust with ammonium hydroxide
or citric acid)
Bath temperature
Cathode current density
Operating Conditions
30 - 40 g/l
55 - 75 g/l
70 -110 g/l
10 -50 g/l
6.0-8.0
150-175°F
100-300 ASF
Chromium electroplating processes generate toxic mists and waste-
water containing hexavalent chromium. Hexavalent chromium has a
number of toxic effects including lung cancer and irritation of the
upper respiratory tract, skin irritation and ulcers. These toxic
emissions are coming under increasingly stringent regulations and
are difficult to treat and dispose of. In addition to hazardous waste
reduction, the Ni-W-SiC process has the following benefits:
*' Higher Plating Rates - The Ni-W-SiC process exhibits much
higher plating rates than for chromium. Plating rates ranged from
1.7 to 3.3 mils/hr at 300 ASF, compared to the typical chromium
plating rate of less than 1 mil/hr.
38
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Nickel-Tungsten-Silicon Carbide Plating
4 Higher Cathode Current Efficiencies - Current efficiencies are
approximately double those for chromium plating. Current effi-
ciencies range from 24 to 35%, whereas typical chromium plating
current efficiencies range from 12 to 15%.
* Better Throwing Power — Cathode current efficiencies for the Ni-
W-SiC process increase with decreasing current density. This
results in much better throwing power than for chromium plating.
In chromium plating baths, current efficiency increases with
current density, which results in poor throwing power.
* Better Wear Resistance - Precipitation-hardened and relief-baked
Ni-W-SiC composite coatings all showed better wear resistance
than a chromium coating in tests using a Taber Abraser.
The main disadvantage of Ni-W-SiC process uncovered so far is
that the plating bath is more susceptible to metallic and biological
contamination. This technology is in a very early stage of devel-
opment. As a result, many questions remain to be answered before
widespread use will occur. Some of the unknowns include:
* Effect of the coating process on hydrogen embrittlement of parts
* Effect of coating on fatigue life of part
* Corrosion resistance of coated parts
* Maximum thickness of coating before cracking or flaking occurs
t Effect of coating parameters on internal stresses in deposit
* Lubricity of coated parts
* Maximum service temperature for coating
* Stripping techniques for coated parts
* Processing techniques for promoting adhesion to various surfac-
es
4 Grinding characteristics
* Ability to plate complex shapes
4 Repair of damaged coatings
* Facility requirements.
39
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CHROMIUM-FREE ALUMINUM SURFACE TREATMENTS
One of the many uses of chromium in the metal finishing industry is
to treat metal surfaces for corrosion protection or to improve adhe-
sion of subsequent organic coatings. Unfortunately, chromates, the
form of chromium used for treatment, are carcinogenic and highly
toxic. Small amounts of chromic acid or potassium dichromate will
cause kidney failure, liver damage, blood disorders and eventually
death. Prolonged skin exposure can cause rashes, blisters, and
other dermatological problems. Chromate mists entering the lungs
may eventually cause lung cancer.
These health and safety considerations and the increasing cost of
disposal of chromium-containing finishing wastes have prompted
users to look at alternatives to treatment of aluminum with chroma-
tes. Although a number of alternative treatments have been exam-
ined, very few are even close to the corrosion protection afforded by
chromate conversion coatings. Even fewer have been developed to
the point where their commercial viability can be assessed.
One of the few commercially proven, non-chromate surface treat-
ments for aluminum is an inorganic conversion coating based on
zirconium oxide. This treatment usually involves immersion of the
substrate in an aqueous solution containing a polymeric material
and a zirconium salt. The zirconium deposits on the surface in the
form of a zirconium oxide. These coatings have been used on
aluminum cans for some time, but they have not been tested in the
kind of environments in which chromate conversion coatings are
typically used. Wider application of this coating must await this type
of testing.
Another process showing promise is the SANCHEM-CC chromium-
free aluminum pretreatment system developed by Dr. John Bibber
of Sanchem, Inc. This process can be summarized as follows:
* Stage One - Use of boiling deionized water or steam to form a
hydrated aluminum oxide film.
* Stage Two - Treat in proprietary aluminum salt solution for at
least 1 minute at 205°F or higher.
* Stage Three - Treat in a proprietary permanganate solution at
135 to 145°F for at least one minute.
A fourth stage of the process exists for cases where maximum.
corrosion resistance is required for certain aluminum alloys. The
developers claim that the film produced by this process closely
matches the performance of a chromate conversion process.
40
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Chromium-Free Aluminum Surface Treatments
Some of the other possible alternatives to chromate conversion
coatings that have been examined are molybdate conversion
coatings, rare earth metal salts, silanes, titanates, thioglycollates,
and alkoxides. These alternatives are discussed in detail in Hinton
(1991).
41
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IN-MOLD PLATING
In-mold plating is the name given to a process developed and
patented by Battelle, Columbus/Ohio. This process combines high-
speed plating and injection molding to apply metal coatings to
plastics in the following manner. First, the mold is cleaned and
prepared, then a plating fixture is placed on top and a metal, such
as copper or zinc, is applied by a high-speed plating technique.
When the required thickness has been reached, the mold cavity is
emptied, the deposit is rinsed and dried in situ, and the coated mold
is transferred to the injection molding machine. A plastic is then
injected, the mold cooled and a metal-coated plastic part ejected.
The plastic typically is a thermosetting resin, but it may be filled with
particles or fibers to improve stability or toughness. Similarly, a
foamed plastic can be used because the coated mold surface
defines the surface of the finished part, not the plastic material.
Besides injection molding, the process can be adapted for compres-
sion molding. The process has several advantages:
* It has fewer process steps than conventional techniques for
plating plastics.
* It does not generate any. waste etching or sensitizing solutions
that contain organics, heavy metals, or precious metals.
• It avoids the use of electroless copper to initially metalize the
surface.
* It deposits only the amounts of metal required and only in the
areas that require coating*, thus it conserves materials and
energy.
* It provides a very broad range of metal coating and plastic combi-
nations that can be processed.
The system can be totally contained and integrated, such that waste
materials are minimized. For example, rinse waters containing
metal ions can be evaporated and returned to the plating bath, pro-
vided that cations such as sodium, calcium, and magnesium do not
build up to unacceptable levels.
Although in-mold plating is not available commercially, several
companies are exploring its use in such applications as decorative
finishes, plumbing and architectural hardware, and EMI/RFI/ESO
protection for electronic components.
A variation of this technique makes it possible to plate circuit patterns in the mold cavity. These
patterns can then be incorporated into molded components.
42
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METAL SPRAY COATING
Metal spray coating is a group of related techniques whereby
molten metal is atomized and directed toward a substrate with
sufficient velocity to form a dense and adherent coating. Metal
spray coating has been used in a wide variety of applications, as
shown in Table 9. The technique avoids use of plating solutions
and associated rinses, thereby reducing wastes. However, the
parts to be sprayed still need to be cleaned prior to spraying.
Table 9. Applications of Metal Spray Coating
Application
Wear Resistance
Dimensional
Restoration
Corrosion
Resistance
Thermal Barriers
Abrasion
Dielectrics
Conduction
RFI/EMI Shielding
Medical Implants
Materials Applied
Metals, carbides, ceramics, and plastics are used to resist abrasion, erosion, cavitation,
friction, and fretting. Coating hardness range from < 20 to > 70 Rc are attainable on
practically any substrate.
Coatings can be applied up to 0.100 inch thick to restore worn dimensions and mismachined
surfaces.
Ceramics, metals, and plastics resist acids and atmospheric corrosion either by the inert
nature of the coating or by galvanic protection. Nonporous coatings must be applied.
Zirconia (ZrO2) coatings are applied to insulate base. metals from the high-temperature
oxidation, thermal transients, and adhesion by molten metals.
Softer coatings such as aluminum, polyester, graphite, or combinations are used for clearance
control, allowing rotating parts to "machine in" their own tolerance during operation.
Alumina (AI2O3) is generally used to resist electrical conductivity. These coatings have a
dielectric strength of 250 V/mil of coating thickness.
Materials are selected for their intrinsic thermal or electrical conductivity. Copper, aluminum,
and silver are frequently used for this application.
These conductive coatings are designed to shield electronic components against radio-
frequency or electromagnetic interference. Aluminum and zinc are often selected.
Relatively new porous coatings of cobalt-base, titanium-base, or ceramic materials are applied
to dental or orthopedic devices to provide excellent adhesive bases or surfaces for bone
ingrowth.
The individual techniques vary mainly in how the coating is melted
and in the form of the coating prior to melting. The three basic
means for melting the metal are as follows:
* Molten Metal - The metal is heated by some suitable means
.(either resistance heating or a burner) and then supplied to the
atomizing source in molten form.
43
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Emerging Technologies
* Fuel/Oxidant - Oxygen/acetylene flames are typically used. The
metal melts as it is continuously fed to the flame in the form of a
wire or powder. The flame itself is not the atomizing source.
Instead, the flame is surrounded by a jet of compressed air or
inert gas that is used to propel the molten metal toward the
substrate.
* Electric arc - In this method an electric arc is maintained be-
tween two wires that are continuously fed as they melt at the arc.
Compressed air atomizes the molten metal at the arc and propels
it toward the substrate. DC plasma arc spraying and vacuum
plasma spraying are variations of this technique in which an inert
gas (usually argon) is used to create a plasma between the elec-
trodes.
The technologies for thermal spraying of metals are well developed,
but they tend to have their own market niche and are not typically
thought of as a replacement for electroplating. As the costs of
hazardous waste treatment and disposal rises, however, this family
of techniques may become cost-effective replacements for coating
applications currently performed by electroplating. The coatings can
be applied to a wide range of substrates, including paper, plastic,
glass, metals, and ceramics with choice of suitable materials and
control of the coating parameter.
44
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SECTION 4
References
INFORMATION SOURCES
Ahmed, Nadir A.G. Undated. "IVD Coating Technology for Corro-
sion Protection." Proceedings of 73rd Annual AESF Technical
Conference, Paper B-3, 22 pages.
Bibber, John W. 1991. "Sanchem-CC A Chrome-Free Aluminum
Pretreatment System." 6th Annual Aerospace Hazardous Waste
Minimization Conference, June 25-27, 1991.
Bracht, William and Anthony Piano. 1990. "Can Chemistry Be
Environmentally Attractive?" Printed Circuit Fabrication, Vol. 13,
No. 6, June 1990.
Carpenter, C.J., 1988. Technology Assessment of Selected Haz-
ardous Waste Minimization Process Changes. Air Force Engineer-
ing & Services Center, ESL-TR-87-45, March, 1988.
Chizhikov, D.M. 1966. Cadmium [trans. D.E. Hayler], Pergamon
Press, Oxford, p. 17.
Comello, Vic. 1992. "Tough Coatings Are a Cinch with New PVD
Method," R&D Magazine, January, pp.59-60.
Conner, J.R. 1990. Chemical Fixation and Solidification of Hazard-
ous Wastes. Van Nostrand and Reinhold, New York.
Electrochemical Products,1 Inc. Undated. E-Brite 30/30. Electro-
chemical Products, Inc., 17000 Lincoln Ave, New Berlin, Wl 53151.
Product information.
Electrochemical, Inc. Undated. Nickelsol Process. Electrochem-
icals, Inc., 751 Elm St., Youngstown, OH 44502. Product informa-
tion.
Evanoff, S.P. 1990. "Hazardous Waste Reduction in the Aero-
space Industry." Chemical Engineering Progress. April: 51-52.
Frederick Gumm Chemical Company. Undated. Clepo Nickel Strip
17, Clepro 204, Frederick Gumm Chemical Company, 538 Forest
St., Kearny, NJ 07032. Product information.
45
-------
Information Sources
Gresham, Robert M. 1991. "Physical Vapor Deposition Surface
Treatments as an Environmentally Friendly Alternative to Hard
Chrome Plating." Presented at 6th Annual Aerospace Hazardous
Waste Minimization Conference, June 25-27, 1991.
Groshart, Earl. 1989. "Molybdenum — A Corrosion Inhibitor."
Metal Finishing. 57(1), January.
Guffie, Robert K. 1986. "Hard Chrome Plating." Products Finish-
ing. 51(2), November.
Hanna, Farid and Hiroomi, Noguchi, 1988. "Acid Zinc Plating Baths
with High Throwing Power," Metal Finishing, November, pp. 33-35.
Hermanek, Frank J. 1987. "Thermal-Spray Coatings," Products
Finishing, Part I, Jan. 1987. pp. 58-64, Part II, Feb. 1987, pp. 60-65.
Hinton, B.R.W., et al. 1987. "Ion Vapor Deposited Aluminium
Coatings for the Corrosion Protection of Steel," Corrosion Australas-
ia, June, pp. 12-17.
Hinton, Bruce R.W. 1991. "Corrosion Prevention and Chromates:
The End of an Era?" Metal Finishing, Part I, September, pp. 55-61;
Part 11 October, pp. 15-20.
Holmes, V.L, D.E. Muehlberger and J.J. Reilly. 1989. The Substi-
tution of IVP Aluminum for Cadmium," Air Force Engineering &
Services Center, Report No. ESL-TR-88-75, August.
Humphreys, P.G. 1989. "New Line Plates Non-Cyanide Cadmium."
Products Finishing, May, pp. 80-90.
Janikowski, S.K., et al. 1989. Noncyanide Stripper Placement'
Program, Air Force Engineering & Services Center, ESL-TR-89-07,
May.
Johnson, Philip C. 1989. "Physical Vapor Deposition of Thin
Films." Plating and Surface Finishing, June, pp. 30-33.
Key, J.F. 1991. "Spray Forming as an Alternative to Electroplating."
Presented at 6th Annual Aerospace Hazardous Waste Minimization
Conference, June 25-27, 1991.
Kline, George A. 1990. "Cyanide-Free Copper Plating Process,"
US Patent 4,933,051. June 12, 1990.
46
-------
Information Sources
Ko, C.H., C.C. Chang, LC. Chen, and T.S. Lee, 1991. "A Compari-
son of Cadmium Electroplate and Some Alternatives." Plating and
Surface Finishing, October, pp. 46-50.
Krishnan, P.M. 1990. "A Noncyanide Copper Plating Electrolyte
For Direct Plating on Mild Steel," Bulletin of Electrochemistry, 6(11),
November, pp. 870-872.
Olin Hunt. Undated.. Blackhole™ Technology. Olin Hunt, 5 Garret
Mountain Plaza, West Paterson, NJ 07424. Product information.
Polakovic, Frank. 1988. "Blackhole™ - A Description and
Evaluation." Presented at IPC Fall Meeting, October 24-28, 1988,
Anaheim CA., IPC-TP-754.
Schiffelbein, Daniel V. 1991. "Evaluation of Ni-W-SiC Plating as
Replacement for Chromium Plating." Presented at the 6th Annual
Aerospace Hazardous Waste Minimization Conference, June 25-27,
1991.
Sharpies, Thomas E., 1988. "Zinc/Zinc Alloy Plating." Products
Finishing, April, pp. 50-56.
Sizelove, R.R. 1991. "Developments in Alkaline Zinc-Nickel Alloy
Plating." Plating and Surface Finishing, March, pp. 26-30.
Takada, K. 1990. "Method of Nickel-Tungsten-Silicon Carbide
Composite Plating." U.S. Patent 4,892,627, January.
Udylite. Undated. Cupral™. Udylite, 21441 Hoover Rd, Warren,
Ml 48089. Product information.
U.S. Environmental Protection Agency. 1988. 1988 Toxics Release
Inventory (TRI) Releases/Transfers Database. Washington DC.
Weiner, Milton. 1992. "Thermal Sprayers," Metal Finishing, Part I,
February, pp. 29-31; Part II, March, pp. 45-47.
47
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Information Sources
Trade
Associations
Table 10 shows the trade associations and the technology areas
they cover. Readers are invited to contact these trade associations
and request their assistance in identifying one or more companies
that could provide the desired technological capabilities.
Table 10. Trade Associations and Technology Areas
Trade Association
Technology Areas Covered
Contact
American Electroplaters' and Surface
Finishers' Society
Metal and surface finishing
12644 Research Parkway
Orlando, FL 32826
tel. (407)281-6441
American Society of Electroplated
Plastics
Plating on plastics
1104 14th St. NW, Suite 1100
Washington, DC 20005
tel. (202)371-1323
fax (202) 371-1090
Association for Finishing Processes of
the Society of Manufacturing
Engineers
Industrial finishing operations
P.O. Box 930
One SME Drive
Dearborn, Ml 48121
tel. (313) 271-1500
Federated Societies for Coating
Technology
Decorative and protective (organic)
coatings
492 Norristown Road
Bluebell, PA 19422
'tel. (215) 940-0777
Institute for Interconnecting and
Packaging Electronic Circuits
Plating (printed circuit board fabrica-
tion)
7380 North Lincoln Avenue
Lincolnwcod. IL 60646-1705
tel. (708) 677-2850
fax (708) 677-9570
institute of Metal Finishing
Metals finishing
Exeter House
Holloway Head
Birmingham B1 1VQ England
tel. i02D'622-7388
Metal Finishing Suppliers Association
Metal finishing supplies
801 N. Cass Ave.
Westmount. IL 60559
tel. (708) 387-0797
fax (708) 387-0799)
National Association of Metal
F:mshers
Metal finishing operations
111 E. Wacker Drive
Chicago. IL 60601
tel. (312) 644-6610
Society of Vacuum Coalers
Vacuum coating
•i-6 Live Oak Loop. N'E
Albuquerque. NM 37112-1407'
•ei. i505i 298-7624
;ax ,5051 298-7942
48
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