【作者】 杨东升；

【导师】 王群；

【作者基本信息】 北京工业大学 ， 材料学， 2002， 硕士

【摘要】 本论文探索了AlN陶瓷的烧结技术，利用本实验室原位合成技术合成的AlN粉末制备出了高致密，高导热的AlN陶瓷。 研究了AlN陶瓷的常压烧结技术。通过热力学条件和相图的分析，选择Y2O3、Li2O、CaO、B2O3等氧化物作为烧结助剂。研究了烧结助剂、烧结温度、保温时间等工艺条件对AlN材料的致密度和物相组成的影响。研究表明：在烧结过程中，烧结助剂能与AlN颗粒表面的Al2O3层反应生成低熔点的铝酸盐液相(如YAG)，进而通过液相烧结促进致密化。通过XRD分析发现，在较低的烧结温度下，烧结助剂未能充分发挥作用。另外，本文对低温烧结助剂的选择作了初步的尝试，选择了CaO—CaF2—SiO2体系作为烧结助剂。结果表明：该助剂系统对烧结有一定的促进作用，但作用不够显著。 研究了AlN陶瓷的放电等离子烧结(SPS)技术。研究表明：SPS是一种快速、高效的烧结技术。与传统的烧结方式相比，大大降低了烧结温度和保温时间。常规烧结中所使用的烧结助剂系统在SPS烧结时，同样起着促进致密化的作用，且作用机理类似。在SPS烧结过程中，烧结主要是发生在烧结升温阶段，随着烧结时间的延长，对烧结体的致密度影响不大。对SPS试样的XRD分析表明：由于碳势气氛的影响，烧结过程中形成的第二相分解、挥发，并最终消失。 研究了AlN陶瓷的热导率与显微结构的关系。研究结果表明：晶粒生长发育完善，晶粒轮廓呈清晰尖锐的多边形状，晶粒呈完整的拔出状，晶粒均匀性好，晶界相和气孔少且晶界相分布均匀，AlN相连通性较好的试样具有较高的热导率。更多还原

【Abstract】 The sintering process of AIN ceramics was studied in this paper. AIN ceramics with high density and high thermal conductivity were obtained by using the AIN powder as material, which was produced in our studio through in-situ synthesis technology.The conventional sintering process of AIN ceramics was studied. Through the analysis of thermodynamic conditions and phase diagrams, some oxides, such as Y2O3, Li2(X CaO> BiOs, were selected as additives. The effects of additives type, sintering temperature, holding time on the density and composition of AIN ceramics were investigated. The results show that the additives can form aluminates (e.g. YAG) with the A^Oa coating on the surface of AIN particles, which density the AIM ceramics by LPS mechanism. It was demonstrated by XRD analysis that the additives do not work adequately at lower temperature. In addition, we made an attempt in selecting low-temperature sintering aids. The results show that the additive system takes a limited effect in sintering process.The Spark Plasma Sintering (SPS) of AIN ceramics was studied. The results show that the SPS was a fast and effective sintering technology. Compared with the conventional sintering process, the SPS process can short consolidation time and lower the sintering temperature. The additives that were used in traditional sintering took a similar effect in SPS process. The consolidation process took place mainly at the stage of elevating temperature. The density of compacts doesn’t increase with the holding time. The XRD analysis of the specimen with SPS process shows that with the presence of carbon in atmosphere, the second phase formed in sintering processdecomposes and evaporates from the AlN grain boundary.The relationship between the thermal conductivities of AlN ceramics and their microstructures was studied. The different microstructure characters of AIN samples show that, if grains grow perfectly, and have clear, acute and multilateral morphology, grain boundary phase is little and homogenously distributed, AlN phase is contiguous, the sample would have higher thermal conductivity.更多还原