The Massachusetts Toxics Use Reduction Institute

Non-Cyanide Plating Processes

University of Massachusetts Lowell
One University Avenue
Lowell, Massachusetts 01854-2866
Telephone: (508) 934-3275
FAX: (508) 934-3050

Today, many metal platers are seeking alternatives to traditional cyanide plating processes. Concerns over occupational health and safety, waste treatment costs, regulatory compliance requirements, and potential liability have encouraged process managers to investigate new, non-cyanide plating technologies.

Non-cyanide-based alternatives are available for cyanide-based copper, zinc, and cadmium plating processes. These substitute processes can reduce regulatory and reporting requirements, lower risks to workers, decrease environmental impact, and reduce corporate liability.

This fact sheet summarizes some viable alternatives to traditional cyanide plating methods. The alternatives presented are not all-inclusive, nor is one alternative recommended over another. The options listed are reasonably available and in most cases permit use of existing equipment with minor capital investment for modifications.

Cadmium Alternatives

Several non-cyanide plating finishes, including zinc, zinc alloy, and tin alloy, provide corrosion protection. These alternatives may be used in place of the toxic cadmium- plating methods; the choice of alternatives depends on desired deposit characteristics.

Copper Zinc Cadmium Zinc Alloy Tin Alloy

General considerations When Using Non-Cyanide Processes

* More than one non-cyanide process may be required to meet all the needs of a single facility.

* Process controls and cleaning practices must be maintained within tighter limits.

* Without the complexing ability of cyanide, periodic removal of iron and other potential contaminants may be required to assure deposit quality. Filtration is generally necessary when using non-cyanide processes.

* The color shades obtained in chromating over non-cyanide deposits do not always match those obtained with the same colors of chromates over cyanide deposits. Customers should be notified when it is important to segregate products with color shade differences.

* Some non-cyanide processes do not satisfactorily adhere to all surfaces and tend to become brittle at high temperatures.

* Alkaline non-cyanide processes generally provide more ductile deposits for subsequent forming operations than do acid non-cyanide processes.

* Acid non-cyanide substitutes usually incorporate more organic brightening agents than alkaline non-cyanide substitutes. In both acid and alkaline non-cyanide processes, higher levels of organic or non-organic brightening agents provide a more cosmetically appealing result. However, chromating may be more difficult with high levels of brighteners, particularly organic brighteners, as a deposit surface film.

* Acid substitution processes require an appropriate (e.g., plastic) liner.

Environmental, Health, and Safely Considerations

Examination of alternatives should include consideration of environmental and health and safety tradeoffs at all stages of production, including raw materials acquisition, processing, and recycling or disposal.

* Material safety data sheets must be reviewed and vendors should be questioned about the presence of ammonia, formaldehyde, or other agents in some substitute-chemistries that may present worker or environmental concerns and which may require redirecting of waste streams for treatment compliance.

Alternatives Matrix

The matrix on the following pages provides comparative information on a wide range of different options. Information on product quality and process parameters is provided for a range of zinc, cadmium, and copper alternatives. These parameters include corrosion protection, finish appearance, color, ductility, plating uniformity, and other process considerations.

References

Resources listed are available from the publishers and may be viewed at the Technology Transfer Center of the Massachusetts Toxics Use Reduction Institute.

Altmayer, Frank. "A Comparison of Several Ideas for Substitutes As Methods of Pollution Prevention." Unpublished paper. Chicago, IL: Scientific Control Labs, Inc., 1992.

Altmayer, Frank. "Comparing Substitutes for Cr and CU, to Prevent Pollution." Plating and Surface Finishing, February 1993, pp. 40- 43.

Altmayer, Frank. "Comparing Substitutes for Cr and CU, to Prevent Pollution, Part Two." Plating and Surface Finishing, March 1993, pp. 32-37.

Altmayer, Frank. "Contamination Prevention: Both Sides." Plating and Surface Finishing, August 1992, pp. 23-25.

Bleeks, Thomas W., and Tamara S. Davidson. "An Alternative to Cyanide Copper." Proceedings, 13th AESF/EPA Conference on Environmental Control for the Surface Finishing Industry, January 27-29, 1992.

Brooman, Eric W. "Alternatives to Cadmium Coatings for Electrical Electronic Applications." Plating and Surface Finishing, February 1993, pp. 29-35.

Graves, Beverly A. "Process of Most Resistance." Products Finishing, July 1992, pp. 46-51.

Krishnan, R.M., S.R. Natarajan, V.S. Muralidharan, and Gurdeep Singh. "Characteristics of a Non-Cyanide Alkaline Zinc Plating Bath." Plating and Surface Finishing, December 1992, pp. 67-70.

Metal Finishing Guidebook and Directory Issue, '93. Vol. 91, No. 1A, January 1993.

Metals Handbook Ninth Ed., Vol. 5, Surface Cleaning, Finishing, and Coating. Metals Park, OH: American Society for Metals, 1982.

Minnesota Office of Waste Management. "Alternatives to the Use of Cyanide Solutions in Electroplating," 1992.

Natorski, Theodore J. "Zinc and Zinc Alloy Plating in the '90s." Metal Finishing, March 1992, pp. 15-17.

Piekunka, Vincent G., and Edward P. Zimmerman. "Making It Work: Non-Cyanide Plating Alternatives." Bedford, MA: Mabbett & Associates, 1993.

Ramachandran, A., and S.M. Mayanna. "New Brighteners for Non- Cyanide Alkaline Zinc Plating Bath." Metal Finishing, February 1992, pp. 61-67.

Smith, Blair A., W. Steve Rapacki, and Tamara S. Davidson. "Heat Treatment Maskant Materials--Evaluation of Non-Cyanide-Containing Electrolytes." Plating and Surface Finishing, August 1992, pp. 11-14.

Sriveeraraghaven, R.M. Krishnan, and S.R. Natarajan. "Corrosion Behavior of Zinc and Cadmium Deposits Obtained from Different Baths." Metal Finishing, August 1991, pp. 51-53.

U.S. EPA. Guide to Cleaner Technology: Alternative Metal Finishes (Draft, May 19933. Cincinnati, OH: U.S. EPA, Office of Research and Development, Risk Reduction Engineering Laboratory.

U.S. EPA. Guides to Pollution Prevention: The Metal Finishing Industry. October 1992. EPA/625/R-92/011. Cincinnati, OH: EPA, CERI Publications Unit.

Zaki, Nabil, and Edward Budman. "Zinc Alloy Plating Today." Products Finishing, October 1991, pp. 46-51.

This fact sheet was compiled using the most current information available at the time of preparation. Users are advised to check with suppliers regarding specific criteria, applications, and environmental, health, and safety concerns.

Technical guidance for this fact sheet was provided by Vincent G. Piekunka. Information was also drawn from "Making It Work: Non-Cyanide Plating Alternatives," prepared for the Massachusetts Toxics Use Reduction Institute by Mabbett & Associates, Inc.

For further information, please contact the Technology Transfer Center at-the Institute.

Massachusetts Toxics Use Reduction Institute University of Massachusetts Lowell One University Avenue Lowell, Massachusetts 01854 Phone: 508-934-3275 Fax: 508-934-3050

The Toxics Use Reduction Institute is a multi-disciplinary research, education, and policy center established by the Massachusetts Toxics Use Reduction Act of 1989. The Institute sponsors and conducts research, organizes education and training programs, and provides technical support to promote reduction in the use of toxic chemicals or the generation of toxic chemical byproducts in industry and commerce.

February 94-4


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Last Updated: April 21, 1997