| 摘要 |
PURPOSE:To provide a method of manufacturing of a Si3N4 group cutting tool excellently resistant to breakage. CONSTITUTION:A letter (R) represents here one or more rare earth elements including Y(yttrium). The content of a cutting tool is as follows: ZrO2, in which an oxide of (R) is solidly dissolved by 5 to 20mol.,:0.1 to 10% in volume, ZrN:0.1 to 10% in volume, an R-Mg-Si-Zr-O-N-system combined phase:3 to 15% in volume, and the remainder consists of beta-Si3N4 and inevitable impurities. Green compact of mixed powder, the content of which is as follows: powder of the oxide of (R):1 to 10% in weight, ZrN powder:0.5 to 20% in weight, MgOpowder:0.5 to 5% in weight, SiO2 powder:0.1 to 2% in weight, and the remainder is Si3N4 powder, is primarily sintered in an N2 atmosphere, at 1600 deg. to 2000 deg.C, and at 1 to 50atm. first, and then secondarily sintered in the N2 atmosphere, at 1700 deg. to 2000 deg.C, and at 100 to 2000atm. |
