PURPOSE: To form Ti and Cr carbide coatings having excellent wear resistance and corrosion resistance by forming Ti layer at high temp. after forming Cr coating layer on the surface of an iron and steel material and carbonizing Cr and Ti.
CONSTITUTION: The surface of the iron and steel material parts is polished by wet-type polishing paper from rough polishing paper to fine polishing paper in order and at last, a mirror finishing is executed by a buff-polishing using alumina paste. Successively, on this surface, Cr is applied by hard chromium plating or chromizing coating treatment and this Cr coating surface is mirror-finished, too. A heat resistant steel wire-made net basket 2 is inserted into a cylindrical heat resistant steel-made retort 1, and the iron and steel-made parts 4 having mirror-finished Cr coating layer is hung down into the wire net basket 2 and Fe-Ti powder 3 mixed with a halide is filled into the gap between the basket 2 and the retort 1. The retort 1 is put in an electric furnace and Ar gas is blown as carrier gas and heat treatment is executed at 950≤ for 6hr. On the surface of the iron and steel-made parts 4, the double coating layer composed of Cr3C2 layer and TiC layer is formed by diffusion of C into the parts 4.
YOSHIDA KAORU
TAKISHIMA NOBUO
MIZUMURA KAORU
