| 摘要 |
PURPOSE:To remarkably simplify and rationalize coating pretreatment by a method wherein iron based member is heated in furnace of reducing atmosphere to clean its surface, is followed by nitriding treatment for rust preventive coating treatment, and then is coated. CONSTITUTION:Iron based member is placed in a heating furnace of reducing atmosphere such as DX gas and heated at 700 deg.C or more for a given period of time. Fats and oils deposited on the member surface are decomposed and combusted, providing cleaning effect greater than degreasing, cleaning and drying treatments. The member, then, in the same furnace or in next chamber, undergoes soft nitriding treatment by maintaining at 500-600 deg.C for a given period of time in the presence of ammonia gas. As rust preventive coating substrate treatment, the process provides nitride substrate layer having rust preventive property and adherence not inderior to phosphoric acid zinc coated layer treatment. Nitriding treatment by pure nitriding or soft nitriding using salt bath may be used. Uniform nitride layer is formed on member edge, end section or complexed shape, as rust preventive substrate. |
