显微结构对α-β-SiAlON陶瓷室温力学性能数据离散性的影响

The Effect of Microstructure on the Scatter of the Mechanical Properties Data of α-β-SiAlON

陶瓷材料的力学性能测试数据具有分散性相对较大、重复性较差的特点,它们的各种力学性能指标具有一定的随机性和模糊性。通过测量具有不同显微结构特征的α-β-SiAlON模型材料(β′含量:35wt%或60wt%;晶界相:YAG或M相;晶粒尺寸:0.4μm到1.1μm;柱状β′晶粒长径比:从4.3到8.1)的显微硬度、压痕断裂韧性和弯曲强度,借助强度统计学的方法,研究了材料的显微结构和内部缺陷对这些力学性能数据离散性的影响。发现以上参数的分散性对材料的相组成和显微结构有较强的依赖性。长柱状β′相含量多并且充分长大的α-β-SiAlON的数据离散性明显小于高α′相含量的α-β-SiAlON陶瓷。此外,压痕断裂韧性的数据离散性同弯曲强度的数据离散性存在一定的内在联系,可以采用压痕法进行对比性的材料强度可靠性检验。

The data of mechanical properties of structural ceramics has wide dispersion, low repeatability, certain random and fuzzy characteristic. Based on the model materials for reliability evaluation with different microstructural parameters (β′ phase contents: 35wt% or 60wt%; grain boundary phase: YAG or M phase; mean grain size: from 0.4μm to 1.1μm; aspect ratio of the rod-like β′-grains: from 4.3 to 8.1), the effects of microstructure and internal flaw on the scatter of the measured data of the properties such as strength, indentation fracture toughness and hardness were explored by strength statistics. All parameters listed above depend strongly on the phase composition and microstructure. Samples with higher content of larger aspect ratio rod-like β′-SiAlON phase show narrower dispersion of mechanical properties than those of samples content of high α-SiAlON. Moreover, there is an internal relationship between the scatter of measured data of bending strength and indentation fracture toughness. Indentation method can be used to examine the reliability of ceramics comparatively and qualitatively.