SILICON NITRIDE SINTERED BODY FOR TOOL AND COATED SILICON NITRIDE SINTERED PRODUCT FOR TOOL

摘要

PURPOSE:To obtain a silicon sintered product superior in the strength at high temp. and the wear resistance by modifying the surface of the silicon nitride sintered body and decreasing an affinity to iron group metals and to obtain a coated silicon nitride sintered body superior in wear resistance and chipping resistance by forming a film on the sintered body and enhancing the adhesive strength of the coated film. CONSTITUTION:The silicon nitride sintered body is such a one that an average element quantity of Ti and/or Hf on the surface of the sintered body is higher than that in the inside of 200mum from the sintered body surface and also the coated silicon nitride sintered body formed with a hard film on the surface is included in this patent. When being used as a cutting tool, the chipping resistance of the silicon nitride sintered body is comparable to that of conventional or comparative product out of this patent but the wear resistance is improved about 45-62% and the coated silicon nitride sintered body is improved about 30-52% in chipping resistance and about 43-97% in wear resistance.