A SILICON-NITRIDE SINTERED BODY OF WHICH THE INNER/OUTER LAYER'S MICRO-STRUCTURE IS CONTROLLED AND A METHOD FOR MANUFACTURING THEREOF

摘要

PURPOSE: A silicone nitride sintered body is provided, which has improved mechanical properties such as strength, hardness, abrasion-resistance and the like by controlling the fine structure of the inner layer and the outer layer. And its preparation method is also provided. CONSTITUTION: The silicone nitride sintered body, which is obtained from silicone nitride powder and 2-16 wt.% of Yb2O3 sintering aid, comprises: (i) an inner layer having a fine particle structure; and (ii) an outer layer which has a mixture structure of a large-sized particle and a fine particle. The method comprises steps of: (i) mixing silicone nitride powder with 2-16 wt.% of Yb2O3 sintering aid; (ii) ball-milling the mixture powder of the step (i) to prepare a slurry; (iii) drying the slurry and then classifying the dried slurry; (iv) molding the obtained powder of the step (iii) under hydrostatic pressure; and (v) sintering the molded body of the step (iv) at a temperature of 1,800-1,950 deg.C.