Presidential Green Chemistry Challenge: 2013 Small Business Award
Faraday Technology, Inc.
Functional Chrome Coatings Electrodeposited from a Trivalent Chromium Plating Electrolyte
Innovation and Benefits: Chrome plating in many high-performance uses, such as some aircraft parts, still requires hexavalent chromium, a carcinogen, to achieve the necessary performance. Various chrome-free replacements have limitations that preclude widespread adoption. Faraday has developed a plating process that allows high-performance chrome coatings to be made from the less toxic trivalent chromium. This nearly drop-in replacement can reduce millions of pounds of hexavalent chromium without comprising performance.
Summary of Technology: High-performance, functional chrome coatings plated from a hexavalent chromium [Cr(VI)] plating bath are widely used in industrial applications for military and commercial markets. These coatings provide resistance to abrasives and sliding wear in heavy-duty machinery, especially pneumatic tubing. However, Cr(VI) is the most toxic form of chromium due to its carcinogenic properties. Reducing or eliminating the use of Cr(VI) has been a priority for governments and industry for years. A number of alternative non-chrome plating technologies have been developed, but do not provide the performance required for the full range of industrial or military applications.
The FARADAYIC® TriChrome Plating process uses trivalent chromium [Cr(III)], a much less toxic and non-carcinogenic form of chromium, in place of Cr(VI) in the plating baths. This approach maintains the advantages of a functional chrome coating but vastly reduces the hazards associated with the plating process. In the past, Cr(III) had been used for decorative coating when only a thin layer of plating was needed, such as on a car bumper, but such coatings are not suitable for heavy-duty applications where hardness and wear resistance are required.
The conventional Cr(VI) electrodeposition process uses a constant direct current during the entire process. Faraday designed a new electrodeposition process that alternates between a forward (cathodic) pulse followed by a reverse (anodic) pulse and an off period (relaxation). Not only does this process allow for thicker coatings from Cr(III), but it can also be adjusted to affect the structure and properties of the coating. This new process results in a product that exhibits equivalent or improved wear and fatigue performance compared to chrome coatings plated from a Cr(VI) bath. In addition, this new Cr(III) plating process is more efficient that the Cr(VI) plating process and does not produce any Cr(VI) as a byproduct. Yet another advantage to this technology over non-chrome alternatives is that it is a true drop-in replacement technology for Cr(VI) coatings. Only new plating bath electrodes are required. Unlike many non-chrome technologies, Faraday’s process can plate both the inner and outer surfaces of a tube.
Development of the FARADAYIC® TriChrome Plating process has been supported by EPA, through its Small Business Innovation Research Program, the National Center for Manufacturing Sciences, The Boeing Co., Messier-Bugatti-Dowty, United Technologies Research Center and other potential commercial clients. Commercialization of the FARADAYIC® TriChrome Plating process will occur via the existing metal finishing supply chain via partnerships with chemical formulators and chemical vendors. Use of Faraday’s technology could eliminate about 13 million pounds of hexavalent chromium waste each year in the Unites States and as much as 300 million pounds worldwide.
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