| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a silicon nitride sintered compact suitable for a rolling bearing member excellent in processability in addition to mechanical strengths, abrasion resistance, and rolling life characteristics comparable to or higher than these of a conventional silicon nitride sintered compact in which the dispersion state of an auxiliary agent component can be controlled even when forming the sintered compact using a silicon nitride powder raw material which is low in purity and price. <P>SOLUTION: The silicon nitride sintered compact prepared by mixing a silicon nitride powder manufactured by the metal nitriding method and a sintering auxiliary agent, and sintering the mixture contains 2-5 mass% of a rare earth element as a sintering auxiliary agent component, 1-5 mass% of an Al element, and 0.5-5 mass% of at least one element selected from the group consisting of Ti, Zr, Hf, W, Mo, Ta, Nb, and Cr wherein the porosity is not greater than 1%, the maximum length of silicon nitride crystal particles composing the silicon nitride sintered compact is not greater than 40 μm, the segregated agglutinate part of the auxiliary agent component in a crystal structure of the silicon nitride sintered compact is not greater than 20 μm, the silicon nitride sintered compact contains 10-3,500 ppm of Fe and 10-1,000 ppm of Ca as impurities, the fracture toughness value of the silicon nitride sintered compact is not less than 6 MPa m<SP>1/2</SP>, the flexural strength is not less than 600 MPa, and the crush strength is not less than 150 N/mm<SP>2</SP>. <P>COPYRIGHT: (C)2011,JPO&INPIT |
