β-SiAlON及β-SiAlON-SiC复合材料合成的研究

Studies on synthesis of β-SiAlON and β-SiAlON-SiC composites

首先对β-SiAlON及其复合材料的合成试验进行了热力学分析,在不同温度、不同z值条件下采用还原氮化法制备了β-SiAlON以及β-SiAlON-SiC复合材料;XRD和SEM分析表明,不管是以Si、Al、Al2O3还是以Si、Al2O3为原料,在氮气气氛下用Si3N4埋粉,在常温常压下都可以合成较纯的βSiAlON。通过改变z值和控制烧结温度等试验发现,当z=0.6、T=1723K时能合成较纯的β-SiAlON,但随着z值的增加,会有少量的O’SiAlON杂质相生成;通过SEM分析表明,在一定温度下,控制适宜的工艺条件,随着z值的增加,β-SiAlON晶粒间开始析出部分晶须,并逐渐转变为明显交织的棒状结构,从而提高材料的断裂韧性。

Thermodynamic analysis was focused on synthesis of β-SiAlON,β-SiAlON-SiC,One -step procedure was adopted to synthesixz the β-SiAlON and β-SiAlON-SiC composites with different ＂z＂ value at different temperatures based on the thermodynamic analysis ,The formation of pure β-SiAlON and β-SiAlON composites were confirmed by the XRD and SEM analysis ,The results show that the pure β-SiAlON can be As compositon ＂z＂=0.6 and T=1450℃.the composite was purer .However ,as ＂z＂ in β-SiAlON continued to increase .O＇-SiAlON formed .and the crystal pattern of β-SiAlON transformed from granular grains to crystal whisker and then turned to be roo-like structure .resulting in higher fracture toughness.