LUBRICANT FOR HIGH-TEMPERATURE PLASTIC WORKING

PROBLEM TO BE SOLVED: To provide a lubricant for high-temp. plastic working which does not cause the seizure, abrasion, and roughening on a tool surface in the high- temp. plastic working of a steel material or a nonmetallic material by incorporating a solid lubricant surface-treated with a titanium-based and/or an aluminum- based surface-treating agent into the same. SOLUTION: A dispersion prepd. by dispersing a solid lubricant (e.g. calcium carbonate, graphite, talc, glass, boron nitride, or mica) having a particle size of 20 μm or lower in a solvent (e.g. hexane or benzene) is mixed under stirring with 0.5-2.0 wt.% titanium-based and/or aluminum-based surface-treating agent at 10-30 deg.C for 10-30 min. Then, the solvent is removed from the dispersion and the resultant product is dried, thus giving a surface-treated solid lubricant contg. titanium and/or aluminum, the active component of the surface-treating agent, in a concn. of 1.5×10 wt.% or higher. The objective lubricant is prepd. by mixing 1-90 wt.% surface-treated solid lubricant above-obtd. with 10.0-99.9 wt% bas grease comprising a base oil (e.g. mineral oil or a synthetic ester) and/or a thickener and a mineral oil.