高度向心织构化SiAlON陶瓷的制备和力学性能研究

Preparation and Mechanical Properties of High-level Radial Textured SiAlON Ceramics

通过在1750℃煅烧环形SiAlON陶瓷坯体,制备了向心织构SiAlON陶瓷。研究了Ni/Co(0 wt.%~2.25 wt.%)添加剂对织构化SiAlON陶瓷的物相组成、织构化程度、显微结构和力学性能的影响。研究结果表明:在平行于晶粒定向的截面(径截面RS)上,引入2.25 wt.%Ni/Co添加剂时SiAlON陶瓷定向指数从0.38提高到0.74;煅烧样品形成了向心织构化的显微形貌特征,在垂直于晶粒定向方向的截面(弦截面TS)上晶粒为等轴状形貌,而在RS面上为排列方向一致的棒状晶粒形貌;织构化SiAlON陶瓷的RS面硬度均高于TS面,随着黏结相含量增加,硬度降低;在RS面垂直于晶粒定向的方向,随着Ni/Co添加剂含量从0wt.%增加到2.25wt.%,断裂韧性从(6.93±0.31)MPa·m^(1/2)增加到(7.52±0.28) MPa·m^(1/2)。

Radial textured SiAION ceramics were prepared from sinter-forging ring-shaped SiAION ceramic green bodies at 1750℃.The effects of Ni/Co(0-2.25 wt.%)additives on phase composition,texture degree,microstructure and mechanical properties of theh textured SiAION ceramics were studied.On the section parallel to the grain orientation(RS,Radial Section),the orientation factor increased from 0.38 to 0.74 in the SiAlON ceramics due to the introduction of 2.25 wt.%Ni/Co.The radial texture microstructure was formed after sinter-forging.On the section perpendicular to the grain orientation direction(TS,Tangential Section),the grains exhibited equiaxed microstructure,while on the RS plane,the grains with rod-like microstructure are aligned in the same direction.The hardness of RS plane for the textured SiAION ceramics is higher than that of TS plane,while the hardness decreases with increasing content of additives.The fracture toughness increases from(6.93±0.31)MPa·m^(1/2)to(7.52±0.28)MPa·m^(1/2) as the Ni/Co additives content increases from 0 to 2.25 wt.%in the direction perpendicular to the grain orientation of the RS plane.