MATERIALS SCIENCE AND ENGINEERING

DMSE Colloquia, Fall 2009

Tuesday, September 29, 2009 | 10:00 AM | 411 White Building

Replacement of Hexavalent Chromium in Surface Engineering

Craig V. Bishop

Group Leader
World Wide R&D
Atotech, Inc.
Strongsville, OH 44149-3214
U.S.A.

Abstract:

Health and environmental concerns initiated in the late 1970s and reinforced in subsequent decades have necessitated finding alternatives to several substances once commonly employed in surface engineering such as mercury, cadmium, lead, aromatic solvents, halocarbons, cyanide ion, and hexavalent chromium. Finding alternatives to hexavalent chromium has proven to be the most difficult task for industrial research. In the past decade, encouraged by new environmental regulations from Japan and the EU that control the composition of materials not just emissions during manufacture, acceptable alternatives for hexavalent chromium used in passivation of zinc, aluminum, and their alloys as well as thin elemental chromium electrodeposits used for nickel chromium ‘decorative’ plating have been identified and are becoming commonplace. Often these alternatives for hexavalent chromium involve the use of trivalent chromium. Proposed replacements for thick elemental electrodeposits of chromium from hexavalent chromium solution have not been widely accepted, however; despite increasingly severe exposure limits to hexavalent chromium for workers.
Comparison of the performance, composition, anisotropism, nucleation, and metastability of engineered surfaces derived from hexavalent and trivalent chromium solutions, with comparison to the coordination chemistry of the initial ions in solution, helps to understand the problems of replacing hexavalent chromium and may, finally, point to the means of eliminating hexavalent chromium.

Speaker Biography:

Craig Bishop is the owner of an independent Research and Development Company, The Best Mode. He is the retired Group Leader for Functional Chromium/Materials Science Research and Development at Atotech, a subsidiary of Total Petrochemicals. Prior to Atotech he was the Special Projects Director for McGean-ROHCO where he led groups that helped replace lead in printed wiring board coatings, and developed gamma phase NiZn electrodeposits, from alkaline solution, as an alternative to many uses of cadmium electroplating. In the 1980’s he was employed by Lockheed as the Department Manager at the NASA White Sands Test Facility Materials Test Laboratory. In the late 1970’s he worked for the R. O. Hull Co., a Lubrizol subsidiary, and helped develop trivalent chromium alternatives to hexavalent chromium passivation of zinc and zinc alloys. He has received numerous awards from industrial groups and NASA including the Hothersall Medal from the Institute for Metal Finishing, three NASA Certificates of Appreciation, and numerous Group Achievement Awards. He has over 30 U.S. patents in the field of surface engineering. His current interests include advanced surface analysis and the development of low density, carbon rich, electrodeposits using atmospheric carbon dioxide as a carbon source.

Coffee and doughnuts will be served from 9:30 AM.

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