不锈钢钝化原理（The principle of stainless steel passivation）.doc

不锈钢钝化原理（The principle of stainless steel passivation） The stainless steel workpiece is placed in the air to form an oxide film, but the protective coating is not perfect. It is usually necessary to thoroughly clean, including alkaline wash and pickling, and then use oxidant passivation to ensure the integrity and stability of the passivation film. One of the purposes of pickling is to create favorable conditions for passivation treatment to ensure the formation of high quality passivation film. Because by acid pickling surface of stainless steel with an average of 10 microns thick layer of surface corrosion, acid dissolving rate of defective parts of the chemical activity of higher than other parts on the surface, so the pickling can make the entire surface evenly balanced, some original cause corrosion hidden trouble was removed. But more importantly, through pickling passivation, made of iron and iron oxide ratio of chromium and chromium oxide priority to dissolve, remove the poor chromium layer, the surface enrichment of the chromium in stainless steel, the rich chromium passivation membrane potential can be up to + 1.0 V (SCE), close to the potential of precious metals, improve the stability of resistance to corrosion. Different passivation treatment also affect the composition and structure of the membrane, thus affecting stainless, such as by electrochemical modification, can make the passivation membrane has a multilayer structure, formed in the barrier layer CrO3 or Cr2O3, or glassy state of oxide film formation, make the most effectively with a stainless steel corrosion resistance. The study of 316L steel passivated film photoelectron spectroscopy (XPS) was introduced in Beijing. Passivation of stainless steel surface layer is dissolved and the adsorption of water molecules, for some reason under the catalysis of oxidant, forming oxide and hydroxide, and with the composition of stainless steel reaction conversion of cr, Ni, Mo element, the final form stabl