Improvement of stainless steels adhesive bonding using anodizing treatments

We have studied the influence of anodic oxidation in sulfuric and nitric en vironment on bonding an epoxy resin with an AISI 304 (XSCrNi18-10) stainles s steel, It is shown that the grain boundaries are attacked during the anod ic oxidation treatment and that the thickness of the secondary passivity fi lm increases in correlation to an enrichment in Cr and a hydration of the s urface. A good correlation is obtained between the physico-chemical paramet ers of the surfaces and the durability of assemblies, Thus, in order to obt ain the best results, a microroughness (engraving the grain boundaries) mus t be combined with a high surface chromium content.