原位生成Si_2N_2O与β-Si_3N_4晶种协同增韧Si_3N_4复相陶瓷研究

Si_3N_4 Composite Toughened Synergistically by Forming in Situ Si_2N_2O and Adding β-Si_3N_4 Seed

采用原位生成Si2N2O与添加β-Si3N4晶种的方法协同增韧,利用凝胶注模成型、无压烧结制备了Si3N4复相陶瓷材料,研究了协同增韧对材料力学性能和显微结构的影响。结果表明:通过添加5%(质量分数)的SiO2原位生成Si2N2O使材料的弯曲强度和断裂韧度有明显提高,分别达到359.8 MPa和4.67 MPa.m1/2,通过添加5%质量分数的β-Si3N4晶种,得到的Si3N4复相陶瓷材料中柱状β-Si3N4相生长完好、均匀分布,与板状Si2N2O结合良好。综合以上两种增韧机制使材料的力学性能进一步提高,弯曲强度为486.7 MPa,断裂韧度达到6.38 MPa.m1/2。

Si3N4 Composite was fabricated by gelcasting and pressureless sintering, which was toughened synergistically by forming in situ Si2N2O and adding β-Si3N4 seed. The effect of synergistic toughening on mechanical properties and microstructures of the composite was studied. The results indicated that the flexural strength and the fracture toughness, 359.8 MPa and 4.67 MPa·m^1/2respectively, were increased obviously by adding 5wt. % SiO2 to form in situ Si2 N2 O. The mechanical properties could be further improved by adding 5wt. % β-Si3N4seed. In the microstrucute, the long rod-like β-Si3N4 grains grew perfectly evenly distributed in Si3 N, ceramic material well combined with the board-shaped Si2N2O. The flexural strength and the fracture toughness of the Si3N4 Composite could be up to 486. 7 MPa and 6.38 MPa·m^1/2 respectively.