SURFACE TREATMENT OF IRON MEMBER FOR INCREASING CORROSION AND WEAR RESISTANCE

摘要

PURPOSE:To obtain a surface layer with superior corrosion and wear resistances by forming a nitride layer on the surface of an iron member and immersing the member in an oxidizing salt bath to form an oxide coat having a prescribed thickness on the surface of the nitride layer. CONSTITUTION:An iron member such as carbon steel member is nitrided to form a nitride layer, and it is immersed in an oxidizing salt bath prepared by adding sodium nitrate to sodium hydroxide as a principal component to form an oxide coat having 1-2mum thickness on the surface of the nitride layer. The oxide surface may be lapped and immersed in the oxidizing salt bath again to form an oxide coat. By this method the uniform oxide coat is formed on the iron member by the relatively short time treatment, and the corrosion and wear resistances can be increased.