| 摘要 |
PURPOSE:To obtain a silicon nitride sintered compact improved in wear resistance by firing a molded form of a powder composition comprising Si3N4 material powder and a specific sintering auxiliary. CONSTITUTION:Firstly, a powder composition is prepared by mixing (A) Si3N4 material powder 1-3wt.% in oxygen content with (B) magnesium oxide 0.05-1.3mum in average particle diameter as a sintering auxiliary so that, when the total of the respective amounts of the components A and B and the amount of the SiO2 calculated by assuming that the whole amount of the oxygen existing in the component A react with the Si is represented as 100vol.%, 10-30vol.% thereof is volatilized during firing and not left in the final sintered compact and the remaining 70-90vo1.% thereof form vitreous phase. Then, a molded form of this composition is fired at 1800-1950 deg.C under a pressure of 1.5-9atm to obtain the aimed sintered compact <=9.5mum in the maximum major axis diameter of beta-Si3O4 grain, >=98% in relative density and <=2.0mm in the relief surface wear under the conditions that a material to be cut is FC 20, cutting rate 300m/min, feed 0.34mm/rev, notch size 1.5mm and edge angle 0.15X20 deg.. |
