【摘要】 用计算机运控的激光导热仪,系统地研究了工艺诸因素对热压氮化硅材料导热性能的影响;根据实验结果,用经验方程对其主晶相（α-Si₃N₄,β-Si₃N₄）和晶界相在热处理前后的导热系数进行了近似计算。指出,氮化硅的β相具有比α相明显高的导热系数,这是工艺因素影响导热性能的主要原因;热处理后氮化硅材料导热性能改善的本质,是晶界相晶化程度的提高,导致热载体声子散射的减弱;添加剂均导致氮化硅材料导热性能的降低,降低程度则由添加剂的阳离子能否与Si₃N₄形成固溶体以及它在晶界晶化的难易程度而定;导热性能对热震前后氮化硅材料出现微裂纹等显微结构变化相当敏感,可望用来评价和预测材料的抗热震能力。以上结果与X射线微区分析、X射线衍射和高分辨率电镜等的实验结果相吻合。更多还原

【Abstract】 The effect of processing conditions of hot-pressed Si₃N₄ on its thermal conductivity wereexamined systematically by computerized laser thermal diffusivity measurement apparatus.The thermal conductivity of the main crystalline phases （α-Si₃N₄,β-Si₃N₄） and their grainboundary phases before and after heat treatment were calculated approximately fromour experimental results with an empirical formula.These data show that the thermalconductivity of β-Si₃N₄ is much higher than that of α-Si₃N₄ which has been found to be thepredominate factor affecting the thermal conductivity of Si₃N₄ made under different pro-cessing conditions. The thermal conductivity of Si₃N₄ can be significantly improved byheat treatment because of the further crystallization at the phase boundaries. Thus thephonon scattering is attenuated.All additives decrease the thermal conductivity of Si₃N₄ incommensuration with the capability of their cations in forming solid solution with Si₃N₄and the degree of crystallization of the additive at the phase boundaries. The microcracksappeared in Si₃N₄ due to severe thermal shock can be sensitively detected by thermal con-ductivity measurements. Therefore the latter can be profitably used as the criteria of theantithermal shock property of the materials. These results agree well with the experimen-tal results obtained from X-ray microanalysis and high resolution electron microscopy.更多还原