| 摘要 |
PROBLEM TO BE SOLVED: To obtain a silicon nitride-based noncorroding material having a high noncorroding property against high temperature fired gas or steam- containing fired gas, and suitably usable as inside wall materials and jigs for equipments such as a gas turbine engine, an incinerator and the like. SOLUTION: This noncorroding material is obtained by the following steps: adding at least >=1.0 wt.% rare earth element oxide to silicon nitride powder and blending them; forming the mixture so as to have a defined shape and baking the formed product so as to make a silicon nitride-based sintered compact having a relative density of >=98% and; heat-treating at least the surface of the sintered compact, which directly contacts with high temperature fired gas or steam-containing fired gas, at 800-1,900 deg.C in a gas atmosphere containing at least SiO2 and/or Al2O3 to form an enriched layer 5 with grain boundary in which a grain boundary phase 4 principally comprising a crystal phase containing rare earth element oxide exists at an areal rate of >=50% and which exists in a range from the contact surface 2 to the depth of >=50 μm. |
