【摘要】 以冲击波合成的γ-Si₃N₄粉体为原料,Y₂O₃-Al₂O₃-La₂O₃体系作烧结助剂,在5.7GPa、1370～1670K的高温高压条件下,进行了γ-Si₃N₄粉体的烧结.研究了不同烧结温度对γ-Si₃N₄稳定性、相对密度、力学性能及显微结构的影响.结果表明:γ-Si₃N₄在1420～1670K的条件下,完全相变为β-Si₃N₄,在1370K左右的条件下,发生部分向β-Si₃N₄相变.在5.7GPa,1370K的条件下,烧结样品的相对密度与维氏硬度分别为98.83%和21.09GPa.更多还原

【Abstract】 Silicon nitride ceramics was prepared by super-high pressure using theγ-Si₃N₄ powders synthesized by the shock-wave technique as raw materials and with Y₂O₃-Al₂O₃-La₂O₃ mixtures as additives at 5.7GPa from 1370K to 1670K.The stability,relative density,mechanical properties and microstructure of the compacts synthesized at different temperatures were investigated.The results show thatγ-Si₃N₄ is completely transformed toβ-Si₃N₄ at temperature from 1420K to 1670K,and partly transformed toβ-Si₃N₄ at 1370K.Micro-analysis indicates that the typical microstructure of sintered Si₃N₄ is mainly composed ofβ-Si₃N₄ rod crystals with disordered orientation and uniform microstructures.The relative density and Vickers hardness in the as-sintered （5.TGPa,1370K） samples are 98.83% and 21.09GPa,respectively.更多还原