HARD CHROMIUM PLATING MEMBER FOR MOLTEN POLYMER

摘要

PURPOSE:To enhance corrosion resistance and quality by heating a member for a molten polymer which has a hard chromium plating layer at the specified temp. and causing a crack in the chromium plating layer and thereafter performing polishing treatment thereon. CONSTITUTION:A member for a molten polymer which has a hard chromium plating layer is heated at the temp. being 10 deg.C or more higher than m.p. of this polymer and also 400 deg.C or below. A crack is caused in the chromium plating layer and thereafter polishing treatment is performed thereon. In such a way, a large crack is forcedly caused on the chromium plating layer and then the crack is closed by performing polishing treatment. Thereby corrosion is not caused in metal of the base material and durability is enhanced and also generation of transfer of the crack is prevented.