【摘要】 本文研究了 1740～1780℃范围内以Al₂O₃-Y₂O₃ 为烧结助剂的 Si₃N₄ 的无压烧结性能。结果表明:加少量Al₂O₃-Y₂O₃的Si₃N₄,即使含量<6.5％,只要工艺措施适当,也可获得高密度（相对密度达96～99％）的氮陶瓷,强度为500～600MN/m²（部分达到700MN/m²）。 试验表明,使用粒度细,α相含量高的Si₃N₄ 原料,采用Si₃N₄+BN+MgO 的埋粉,以及保温时间适当,是促进烧结的有效措施。研究指出:添加少量Al₂O₃-Y₂O₃ 外加剂的 Si₃N₄ 是以液相烧结为主。 用X射线衍射,扫描电镜和电子探针等检验了Si₃N₄的显微结构,表明 Al₂O₃已进入β-Si₃N₄ 晶格,形成β’-Si₃N₄固溶体,晶格参数随 Al₂O₃ 加入量增加而增大。更多还原

【Abstract】 Pressureless sintering of Si₃N₄ with Al₂O₃ and Y₂O₃ as sintering aids at temperature of1740～1780℃ has been studied.The results show that Si₃N₄ added less than 6.5% of Al₂O₃Y₂O₃ can be sintered at 1760℃ for 2～3 hours under 0.5～0.7 pressure gauge of N₂ to obtaina highly dense nitrogen ceramics,which will have a relative density of 96～99% and abending strength of 500～600MN/m²,some even exceeding 700 MN/m². Si₃N₄ of high a phase content and fine particles used are the causcs for high sinterabi-lity.The powder bed with composition of 77Si₃N₄+20BN+3MgO is effective for reducingweight loss and increasing densification. The microstructure of specimens has been studied by use of X-ray diffraction,SEM andelectron probe.The results show that Al₂O₃ has been dissolved in the lattice of β-Si₃N₄,forming β′-Si₃N₄ solid solution.The lattice parameters increase with the amount of additionof Al₂O₃.更多还原