基于纳米压痕测试的超细晶Si_2N_2O-Si_3N_4陶瓷室温蠕变特性

目的陶瓷材料由于其固有硬脆性,难以利用传统单轴拉伸与压缩实验测试其蠕变性能,而纳米压痕测试技术对试样形状尺寸没有特殊要求,因此利用纳米压痕测试技术研究Si2N2O-Si3N4超细晶陶瓷的室温蠕变性能。方法针对1600,1650,1700℃条件下烧结制备的Si2N2O-Si3N4超细晶陶瓷,采用纳米压痕技术测试材料在最大载荷分别为5000,6000和7000μN条件下的载荷-位移曲线,并通过拟合计算获得了3种材料室温蠕变应力指数。结果 3种材料均呈现明显的加载效应。结论研究表明,在相同载荷下,压入深度和蠕变位移都随着材料烧结温度的升高而增大,且相同材料的蠕变应力指数,随着保压载荷的增大而减小。对比分析发现,在1600℃条件下烧结制备的Si2N2O-Si3N4超细晶陶瓷,晶粒细小均匀,晶界数多,室温下表现出较强的蠕变性能。

Room Temperature Creep Property of Ultrafine- grained Si2N2O-Si3N4Composites Based on Nanoindentation Technology

Objective Creep property of ceramics materials could be hardly measured by uniaxial tensile or compression test due to its inherent brittleness and high hardness. Nanoindentation technology has no demands on shape and dimensions of the test specimen and can be used for testing the creep property of ultrafine- grained Si2N2O- Si3N4 composites. Methods Loading- displacement curves of ultrafine- grained Si2N2O- Si3N4 composites,which were fabricated by hot press sintering at 1600 ℃,1650 ℃,and 1700 ℃,were obtained by nanoindentation experiments with the maximal load of 5000μN,6000 μN,and 7000 μN,respectively. Loading effect was obviously reflected according to room- temperature creep stress indexes of the three different materials obtained by fitting and calculation method. Conclusion The research showed that indentation depth and creep displacement increased with increasing sintering temperature under the same loading condition,and the creep stress indexes of the same material decreased with increasing maintaining pressure. The contrastive analysis has shown that ultrafine- grained Si2N2O- Si3N4 composites sintered at 1600 ℃ had the best creep property at room temperature because of the uniform fine grain and more crystal boundary.