高导热氮化硅晶粒原位自形生长调控及致密化堆积研究

项目名称： 高导热氮化硅晶粒原位自形生长调控及致密化堆积研究

项目编号： No.51272122

项目类型： 面上项目

立项/批准年度： 2013

项目学科： 一般工业技术

项目作者： 宁晓山

作者单位： 清华大学

项目金额： 89万元

中文摘要： 氮化硅陶瓷在导热绝缘封装材料领域也有其不可替代的地位。并且随着氮化硅陶瓷热导率的提高，其应用领域有望进一步拓展。由于氮化硅晶粒各向异性生长形成杂乱堆积的棱柱状晶体，氮化硅陶瓷晶粒间的晶界相薄膜的厚度远远超过其平衡晶界层厚度，而已有理论计算和实验表明该晶界相薄膜厚度对氮化硅陶瓷的热导率有着巨大的影响。减小晶界相厚度需要控制原位自生氮化硅晶粒的形状以及晶粒尺寸级配才能实现。本项目拟对β氮化硅原料粉在奥氏熟化过程中发生的晶粒形貌演变及其动力学进行系统研究，通过改变烧结助剂种类及配比、改善烧结及热处理工艺等，控制氮化硅晶粒的各项异性生长，获得长径比较小的氮化硅晶粒。另外通过调整原料粉颗粒级配研究其对烧结及热处理后晶粒分布的影响，通过原料粉的合理级配控制原位奥氏熟化后的晶粒的级配，改变晶界相厚度。在此基础上开展晶界相厚度对氮化硅陶瓷热导率的影响影响研究。

中文关键词： 陶瓷；氮化硅；热导率；自形生长；放电等离子烧结

英文摘要： Silicon nitride ceramics as a newly developed insulating and thermal conductive material has many excellent properties that other materials can not match. To raise the thermal conductivity of silicon nitride ceramics can further enlarge the applicable area of the ceramics. The thickness of grain boundary film between β-Si3N4 grains is much large than that of the equilibrium one, owing to the nature of random packed faceted grains in the ceramics. A theoretical calculation and some experiment results reveal that the thick grain boundary film is extremely harmful to the thermal conductivity of silicon nitride ceramics. To minimize the thickness of the film, the random packed faceted grains must be adjusted. This project aims at studying the morphological change of the β-Si3N4 grains on Ostwald ripening during sintering and a heat treatment of the β-Si3N4 raw powders; and to reduce the aspect ratio of the grains by changing sintering additives and the processing parameters of both the sintering and the heat treatment. Besides that, the powders of different sizes will be blended to study the grains size distribution after Ostwald ripening, in order to moderate the grain size of the ceramics, and to minimize the thickness of the grain boundary film. Based on these work, the impact of the grain boundary film on the th

英文关键词： ceramics；Si3N4；thermal conductivity；idiomorphic growth；SPS