关键词: 氮化硅结合碳化硅, 抗热震性能, 密度分布, 断裂韧性

Abstract: This work aims at improving the thermal shock resistance of Si₃N₄-SiC refractories.Si₃N₄-SiC specimens were prepared through two means:vacuum vibration casting and machine pressing,using industrial SiC particles and Si powder as raw materials and nitridation-firing at 1 400 ℃ for 8 h.The properties and density distribution of the specimens were characterized,and a water quenching method combined with a residual fracture toughness test program was designed to evaluate the thermal shock resistance of the Si₃N₄-SiC refractories.The comparison results indicate that the vacuum vibration cast specimens have better general properties and higher fracture toughness retention ratio,more uniform density distribution and less crack sources than the traditional pressed specimens,hence the vacuum vibration cast specimens have better thermal shock resistance than the traditional pressed ones.

Key words: silicon nitride bonded silicon carbide, thermal shock resistance, density distribution, fracture toughness