| 摘要 |
PURPOSE: To improve strength, toughness, oxidation resistance and hardness by incorporating oxide of a specified group IIIa element of the Periodic Table and SiO2 . CONSTITUTION: A sintering aid is obtd. by blending 2-7mol% at least Yb2 O3 or Er2 O3 as oxide (Re2 O3 ) of a group IIIa element of the Periodic Table with SiO2 in a molar ratio of 1.7-4 based on Re2 O3 . A binder is added to a powdery mixture of silicon nitride powder having <=2wt.% oxygen content and >=99.9wt.% purity with the sintering aid and they are compacted, fired at 1,600-2,000 deg.C for 0.5-10hr in a nonoxidizing atmosphere and rapidly cooled from 1,800 deg.C to 1,000 deg.C to obtain the objective silicon nitride-based colored ceramics consisting of α- or β-silicon nitride grains having 0.1-5μm average minor axis size and an average aspect ratio of >=2 and a glassy grain boundary phase among the silicone nitride grains. |
