Rinseable Chromate coatings have historically been the treatment of choice for aluminum automotive refrigeration components because of their excellent corrosion resistance. Major efforts have been underway to develop alternative non-chrome aluminum treatments to provide performance equivalent to chrome without the generation of expensive and hazardous wastes.
The approach to eliminate Chromate effluents has been two-fold. As a first step, a chrome-bearing non-rinseable treatment was developed which provides all the benefits of a Chromate treatment while substantially reducing the amount of hexavalent chrome in the effluent. However, since this “Dried-In-Place” system still utilizes chromium compounds in its operation, it is considered to be only an intermediate step in the total elimination of chrome in the manufacturing process. This paper will describe the results of several years' manufacturing experience with a non-rinseable chrome coating used on air conditioner condensers.
A second, and more long-term approach, is the use of a completely chrome-free coating process, which will totally eliminate all chromium compounds from the manufacturing environment. This paper will also describe the promising performance achieved in a co-operative effort between automotive manufacturers and vendors in the development of a truly chrome-free treatment system for automotive refrigeration components.