CUTTING TOOL TIP MADE OF DIAMOND-COATED TUNGSTEN CARBIDE-BASED SINTERED HARD ALLOY

摘要

PURPOSE:To intensify the adhesive power of a diamond coating layer synthesized in a low pressure vapor phase and to improve the cutting performance of a cutting tool tip consisting of a WC-based sintered hard alloy formed by sintering Co as a binder by subjecting the surface of said cutting tool tip to an etching treatment by an acid, then forming the above-mentioned coating layer thereon. CONSTITUTION:A sintering raw material prepd. by adding 1-4wt% Co as a raw material for a binding phase to WC particles having 2-10mum average grain size and further, mixing a fine carbon material such as carbon black uniformly in a slight amt. therewith is press-molded and is sintered at 1,430-1,500 deg.C. The sintered material is polished to form a throw-away tip and thereafter, the tip is subjected to the etching treatment with a dilute acid soln. of nitric acid, hydrochloric acid, etc., to form the etching layer of 0.1-1mum thickness where Co does not exist on the surface. The diamond layer by the low pressure vapor synthesis is formed with the high adhesive strength on such etching layer, by which the cutting capacity of the tip is improved and the service life thereof is extended.