And stainless steel passive film formation method of stainless steel

摘要

PURPOSE: To attain the superflattening and densifying of passivation film and to form passivation film excellent in degassing characteristics and corrosion resistance by subjecting the surface of a stainless steel to electrolytic polishing treatment, thereafter executing oxidation treatment and successively subjecting iron oxide in the surface to reducing treatment by gaseous hydrogen. ;CONSTITUTION: At the time of forming passivation film on the surface of a stainless steel, at first, the surface of the stainless steel is subjected to electrolytic polishing to remove a working alterated layer and to regulate the surface roughness to about 0.05 to 0.1μm. Next, preferably, an inert gas is introduced, and high temp. baking pretreatment is executed at 300 to 600°C. Then, an oxidizing gas is introduced, and heating is executed at about 350 to 450°C to form oxidized passive coating on the surface of the stainless steel. By this oxidation treatment, a layer largely contg. chromium oxide is formed on the surface of the stainless steel, and a layer contg. iron oxide is formed thereon. Next, the oxidizing gas is exhausted, and gaseous hydrogen is introduced to reduce away the layer on the topmost surface of the passive coating. By this hydrogen treatment, the topmost surface layer of the passivation film is formed into the clean and flat face.;COPYRIGHT: (C)1998,JPO