As there are no proprietary additives in the trivalent bath, the rinse water may be recycled.

Hydroxide sludge generation is reduced ten to twenty times because trivalent chromium generally operates at a chromium content of about 4-20 g/L vs.

Disposal costs are significantly reduced for trivalent chromium plating.

The exposure limit for trivalent chromium is an order of magnitude higher than that of hexavalent chromium.

Therefore, meeting air quality regulations is easier and working conditions are greatly improved. Trivalent chromium is non-toxic, non-hazardous and is not an oxidizer.Additional advantages to the additive-free trivalent chromium plating process relative to hexavalent chromium plating include: The advantage of our approach is centered on developing a drop-in replacement using an environmentally benign trivalent chromium electrolyte and controlling the deposition process through use of sophisticated waveforms engineered to deliver the desired chromium coating properties rather than the use of novel material systems or carcinogenic hexavalent chromium plating technologies. As for new platable material systems, they require the use of potentially toxic materials including nickel and cobalt,3 which can create manufacturing and environmental problems due the need for new process specification sheets and environmental exposure initiatives. Additionally, HVOF systems are extremely expensive to implement at industrial and governmental depot facilities. HVOF technology is limited by the geometry of the part, requiring that the regions that need to be coated are non-complex and be located within line-of-sight to the spray head. The USEPA identified hexavalent chromium as one of 17 'high-priority' toxic chemicals based on their known health and environmental effects, production volume and potential for worker exposure1 which were targeted for 50% reduction by 1995.2 The urgency of this issue was further underscored by a recent memorandum from the Under Secretary of Defense, referring to the need to minimize or eliminate the use of hexavalent chromium as an “extraordinary situation,” requiring the government and industry to “go beyond established hazardous materials management processes” and “more aggressively mitigate the unique risks to operations now posed by hexavalent chromium.”Ĭurrent wear resistant coating solutions include alternative technologies like high velocity oxyfuel (HVOF) or new platable material systems such as cobalt-phosphorus alloys. We have developed a green manufacturing process** that meets the stated EPA needs by improving an existing process while utilizing a novel green approach that eliminates worker exposure to the carcinogenic hexavalent chromium bath. Our work continues to address the need for a drop-in replacement chromium plating process that can coat complex, hard-to- access surfaces such as the interior of landing gear, using an environmentally benign trivalent chromium bath. Specifically, recent efforts in plating chromium on the internal surfaces of cylindrical parts will be presented, as well as wear test data. In this paper are results from our development program aimed at achieving properties comparable to existing hexavalent chromium plating for functional applications. However, hexavalent chromium baths have come under increasing scrutiny due to the toxic nature of the bath, effects on the environment and workers’ health. Hexavalent chromium plating has been used for many years to provide hard, durable coatings with excellent wear and corrosion resistance properties.

This paper discusses recent research work on the development of a functional trivalent chromium plating process from a trivalent-based electrolyte to replace hexavalent chromium plating. Functional Trivalent Chromium Electroplating of Internal Diametersĭetails By Kagajwala, Hall, Inman, Taylor, Griffin, Cushnie, Taylor, Jaworowski and Bonivel Plating

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