METHOD OF TOOL HARDENING Russian patent published in 1995 - IPC

FIELD: metallurgy. SUBSTANCE: prior to ionic nitriding and after it, the tool backing is additionally treated by argon glow-discharge plasma, which at first removes the thin defective surface layer and then improves the conditions of nitriding by reducing unfavorable tensile residual stresses in the tool surface layer, and after nitriding it provides for a thorough ionic etching of the backing surface by clearing it of the thin (about 1 μm thick) layer of nitrides and causing a worsening of adhesion of the coating to the backing because of their chemical inertness. Then, after the workpiece is transferred to the chamber of ionic-plasma coating and after the backing is cleaned and heated precipitation of multilayer coating from titanium nitride or similar compounds is accomplished. EFFECT: considerably enhanced reliability and resistance of the tool to alternating loads arising in the process of cutting. 1 tbl