中文摘要：

以Si3N4，AIN和TiO2为原料，Y2O3和Al2O3为烧结助剂，通过添加柠檬酸铵作为TiO2的分散剂，采用原位反应合成法制备TiN体积分数为5％的Si3N4-TiN复相陶瓷，在高温烧结过程中原料中的TiO2和AIN反应生成TiN。通过扫描电子显微镜观察了柠檬酸铵分散剂用量对Si3N4-TiN复相陶瓷显微结构的影响。结果表明：添加柠檬酸铵分散剂降低原料混合粉体中TiO2的团聚，获得组分均匀的Si3N4-TiO2-AIN复合粉体，从而提高Si3N4-TiN复相陶瓷中TiN相在Si3N4基体中的分散性，烧结后获得显微结构均匀的Si3N4-TiN复相陶瓷。当在体系中添加0.20g柠檬酸铵分散剂可以显著改善Si3N4-TIN复相陶瓷的显微结构，TiN晶粒被控制在0.2-0.3μm。

英文摘要：

Dense and homogenous Si3N4-TiN composites （5 % TiN, in volume） were prepared by using the in situ synthesis method and using Si3N4, AIN and TiO2 mixtures containing Y2O3 and Al2O3 as sintering auxiliary agents. In the prepared Si3N4-TiN composites, TiN grains were formed from nanosized TiO2 and AIN powders during the sintering process, in which ammonium citrate was used as the dispersing agent for raw TiO2 powders. The effects of varying dosages of ammonium citrate on the microstructures of the Si3N4-TiN composites were investigated by scanning electron microscopy. The results show that the citrate ions can modify the surface of TiO2 particles and protect the TiO2 particles in the mixed slm-ry to reduce the aggregation of TiO2 particles, and a homogenous Si3N4-TiO2-AIN mixture can be prepared by sintering. Si3N4-TiN ceramics with a uniform distribution of TiN grains were obtained. It is found that the microstructure of the Si3N4-TiN composite could be improved significantly by using 0.20 g ammonium citrate in the system, and TiN grains distributed throughout Si3N4 matrix were 0.2-0.3μm in diameter.