Y-α/β-Sialon陶瓷材料及疲劳特性研究

Y-α/β-Sialon Ceramics and Its Fatigue Behavior

本文通过组份设计，选用Si3N4、AIN和Y2O3等粉末为原料，在1800～1950℃进行气氛加压烧结（GPS），制备了性能优良的Y-α/β-Sialon陶瓷材料；利用XRD、EDAX和HREM详细地研究了相组成和晶界特性，其主晶相为β-Sialon和α-Sialon，晶界由少量的J－Y4Si2O7N2结晶相以及微量的玻璃相构成；并进一步探讨了材料在循环疲劳载荷下Vickers压痕短裂纹扩展特性，结果表明，最大应力强度因子与裂纹扩展速率之间呈V型扩展行为，并对外加应力水平非常敏感．

The investigations were mainly focused on the phase composition, microstructure and fatigue behavior of fully-dense Y-α/β-Sialon ceramics prepared from powder mixtures of Si3N4, AlN and Y2O3 by using gas pressure sintering technique.The results obtained show that the typical microstructure of mixed Y-α/β-Sialon ceramics consists of needle-like grains of the β-phase and equi-axed α-Sialon grains with a small amount of glassy phase and J-Y4Si2O7N2[102] crystalline phase on grain boundaries.The cyclic fatigue crack growth behavior from microindentation flaws was investiated with gas pressure sintered Y-α/β-Sialon ceramics, A V-shape behavior was observed in the relation between the maximum applied stress intensity factor and crack growth rates which are sensitive to the level of applied stresses.