CERAMIC MATERIAL AND CUTTING TOOLS MADE THEREOF FOR APPLICATIONS DEMANDING GOOD NOTCH WEAR RESISTANCE

摘要

A ceramic material is provided to have the optimum composition for mechanically processing heat-resistant superalloy, and to ensure good notch wear, acceptable flank wear, and sufficient toughness. A ceramic material comprises beta-sialon(Si(6-z)Al_zO_zN), polytype 12H, and an intergranular amorphous or partly crystalline phase, and contains yttrium. The amount of the intergranular phase, determined as the area of the intergranular phase in the SEM picture to the total area of the SEM picture, is 5 to 15%. In the beta-sialon, z is equal to or more than 0.7 and less than 1.5. The amount of the polytype 12H, determined as the ratio of the peak height in the Cu-Kalpha x-ray diffractogram of the 12H at a 2Theta value of 34 ° and the peak height in the same diffractogram of the beta-sialon at a 2Theta value of 33 °, is 2 to 20%. The yttrium is contained in an amount of 3.5-5wt%, preferably 3.9-4.5wt%.