Replacement Materials for Chromates in Coatings and Sealants

Use of chromates as corrosion inhibi.tors in coatings, adhesives and sealants is a well established technology. However, toxicity and waste disposal problems have led to the urgent need for development of an environmentally benign substitute for chromium compounds in coatings and sealants, which is the subject of this SBIR. This pa'per discusses the state-of-the-art technical approaches to the solution and suggests: (1) Grafting of metal surface with ^%surface active agent", such as quaternary chelating agents and giianidines to passivate potenttally active corrosion sites on the metal surface. (2) Converting the metal oxide layer, which is formed as a corrosi(jn product on the metal surface, into a protective layer for the surface beneath. The paper also discusses material selection criteria, formulation hypotheses, and proof of concept testing for the development of a rion- toxic and environmentally safe inhibitors to be used in chemical conversion coating of aluminum and aluminum alloy (MIL-C-5541), primer coating of metals (M1L-P-23377), and corrosion inhibiting sealing compounds (M1L-8-81733). Future development efforts, as well as developmental directions in optimizing corrosion resistant properties, are suggested.