Techniques for Removing Surface Contaminants in Thin Film Deposition

Abstract

This paper describes the way to clean bearing surfaces so coatings can be applied to increase wear life. The paper describes the origin of contamination and the techniques of removing them. Typically, bearing surfaces are cleaned in a vapor degreaser consisting of trichlorethylene solvent or by alcohol to remove any oil and grease and then they are pretreated by phosphating, sand blasting, vapor honing, hand polishing, acid etching and electro-etching. Mechanical processes such as sand blasting, vapor honing, and hand polishing cannot be used on a substrate thinner than approximately 0.2 mm, but the acid etching and electro-etching can be used on thin foil substrates and in other specialized applications. In vacuum deposition processes, the surfaces are cleaned in a vacuum prior to deposition so the cleaned surface is not exposed to air before coating and, therefore, the bond is very good.