为了增韧Si3N4基陶瓷材料, 以钨(W)作为第二相材料, Y2O3-Al2O3作为烧结助剂, 采用气压烧结法制备了W/Si3N4复合陶瓷材料。研究了W含量对W/Si3N4复合陶瓷材料致密性、力学性能以及结构的影响。结果表明: 在W含量小于5%(质量分数)时, 样品致密度均达97%以上; 在W含量为5%(质量分数)时, 获得的W/Si3N4复合陶瓷材料综合性能最佳, 弯曲强度、硬度和断裂韧性分别为(670.28±40.00) MPa、(16.42±0.22) GPa和(8.04±0.16) MPa·m1/2, 相比于未添加金属W的Si3N4陶瓷材料分别提高了38.08%、13.08%和44.34%; 通过分析W/Si3N4复合陶瓷材料样品抛光面和压痕裂纹的微观结构, 发现W的引入能促使裂纹在扩展路径上更易发生偏转、分叉等增韧机制, 消耗裂纹扩展能量, 从而改善Si3N4陶瓷的断裂韧性。

To toughen Si3N4-based ceramic materials, W/Si3N4 composite ceramic materials were prepared in this article by the pneumatic sintering method with tungsten (W) as the second phase material and Y2O3-Al2O3 as sintering additive. Then the effect of W content on the compactness, mechanical properties, and microstructure of W/Si3N4 composite ceramic materials was investigated. The results indicate that the densities of samples all reach more than 97% when the W content is less than 5% (mass fraction). The most outstanding overall performance of W/Si3N4 composite ceramic materials is obtained when W content is 5% (mass fraction), and the bending strength, hardness, and fracture toughness are (670.28±40.00) MPa, (16.42±0.22) GPa, and (8.04±0.16) MPa·m1/2, respectively, which are 3808%, 13.08%, and 44.34% higher than Si3N4 ceramic materials without the addition of metal W. By analyzing the microstructure of the polished surface and indentation cracks of W/Si3N4 composite ceramic material samples, it is found that the introduction of W can trigger toughening mechanisms such as deflection and bifurcation of cracks in the propagation path, and consume crack expansion energy, thus improving the fracture toughness of Si3N4 ceramics.