Hexavalent Chromium - What Else?

by Patrick Benaben
Recipient of the 2011 William Blum NASF Scientific Achievement Award

Presented at NASF SUR/FIN 2012 in Las Vegas, Nev., on June 11, 2012
(with commentary by Dr. James H. Lindsay, NASF Technical Editor)

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Since its inception in 1958, under the auspices of the AES, the NASF Scientific Achievement Award has been given annually to a person who has contributed to the advancement of the theory and practice of electroplating, metal finishing and the allied arts; has raised the quality of the profession; or has been involved in a combination of these. In 2011, the award was given to Dr. Patrick Benaben, full professor at École Nationale Supérieure des Mines, in St. Étienne, France. Over the years, he has been a prolific contributor to surface finishing science and technology, and has focused his research on new electrolytic processes, in particular, on the use of ionic liquids in hard chromium plating and on such materials as high-ordered alumina obtained by anodic oxidation.

Dr. Benaben’s lecture title was Hexavalent Chromium - What Else?, a rather timely topic. He first described the nature of chromium, and the uses of chromium metal in industry and in commerce. Applications in surface engineering included decorative and hard chromium plating, chromium anodizing, chemical conversion and passivation, sealing and etching.

He then went on to note the risks involved in its use, including chromates, fumes from welding of stainless steel and ferrochromium alloys, chromium fumes during electroplating, and others. This led to a discussion of the toxicity, health and regulatory issues of the day.

Given those problems, Dr. Benaben discussed “what else” would serve as substitutes for chromium and its deleterious health effects. He stressed that there are two regimens to consider when considering exposure to toxic forms of chromium: 1) exposure during the processing and 2) exposure in the end product to the general public. The difference is significant, and is often ignored (or at least discounted) in the ongoing debate on such issues.

He notes that, since hexavalent chromium is recognized as one of the more toxic forms of chromium, products that have the potential to release Cr(VI) to the public must be banned, and important work must be done to find alternative processes across the board. On the other hand, in other applications, the public is not directly exposed to Cr(VI). Stainless steel is an obvious example. Dr. Benaben noted that decisions and regulations must be discussed by all interested parties, although he added that such a constructive goal is very difficult to achieve. 

Click here to access an edited version of his presentation, along with commentary provided by Dr. James H. Lindsay, Technical Editor for the NASF.