低温烧结α/βSi_3N_4复相陶瓷及力学性能研究

Fabrication of α/β Si_3N_4 Composites at Low Temperature and Its Mechanical Properties

以MgSiN2为烧结助剂,在1 600～1 750 ℃下,热压烧结制备α/β Si3N4 复相陶瓷,并研究其力学性能与相组成及显微结构之间的关系.结果表明,显微硬度随α-Si3N4 质量分数的增加而增加α-Si3N4质量分数为60%时,显微硬度达到最大,随α-Si3N4质量分数继续增加,显微硬度变化很小,约为23 GPa.随着β-Si3N4质量分数的增加,断裂韧性先增加后又下降,抗弯强度先增加而后变化不大.

α/β Si3N4 composites were sintered by hot pressing at 1 600-1 750 ℃ using MgSiN2 as additives,and the relationship between mechanical properties and phase composition,microstructure was investigated. Microhardness increased with the increase of the content of α-Si3N4,achieved the highest value when the content of α-Si3N4 is about 60%,and tended to a steady value （about 23 GPa） with further increase of the content of α-Si3N4. With the increase of the content of β-Si3N4, fracture toughness increased and then decreased,and strength increased first and then had little change.