【摘要】 研究了起始粉末中α/ β相组成的变化对所得氮化硅材料显微结构和力学性能的影响 .随着起始粉末中 β相含量的增加 ,显微结构明显细化 ,柱状颗粒数目增加而尺寸减小 ,从具有异常长大柱状颗粒的嵌套结构变为由小柱状颗粒组成的均匀结构 .结果说明可以通过改变起始粉末相组成来控制材料显微结构 .所得材料的力学性能随起始粉末中 β相含量的增加 ,在α/ β相体积比为 50∶50时 ,综合性能最好 .更多还原

【Abstract】 Effect of the phase ratio , α/β in starting powder on microstructural development and mechanical properties of silicon nitride ceramics was investigated. With the increase of β phase content, the microstructure becomes finer, the fine_grained microstructure is developed from pure β -Si 3N 4,whereas the bimodal microstructure is developed from pure α -Si 3N 4 . The results suggest that microstructure can be tailored by changing the phase ratio in starting powder. An optimized region exists for the mechanical properties with the increase of the β -Si 3N 4 phase content,which suggests that control of the size,number and distribution of the β -Si 3N 4 rod_like grains can improve both flexural strength and fracture toughness.更多还原