ROBERT W. LOGAN
Published: 1962
Total Pages: 23
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An investigation was made of electrodeposition methods for applying thin (.0006 - 0010-in.) polytetrafluoroethylene (TFE) coatings to steel substrates. The electrodeposited films are intended to serve as dry lubricant and preservative coatings for a wide variety of U.S. Navy nd U.S. ARINE Corps equipment. Thin, smooth, crack-free films within the above thickness range have been produced by anode electrodeposition from TFE baths stabilized with perfluorooctanoic acid. However, these coatings are poorly adhered to steel substrates. Additives to this bath, such as small amounts of fluorinated ethylene propylene (FEP) and/or large amounts of chrome oxide green pigment, result in a slight improvement in the adhesion. This increase is accomplished without appreciably lowering the critical cracking thickness (CCT) necessary to produce crack-free films in the required thickness range. The adhesion, however, is still less than that exhibited by sprayed TFE finishes employing a primer and a further increase is required. Other additives to the plating baths, surface modification of the steel substrate by chemical etchants and/or chromium-containing coatings have ot yet proved successful. (Author).