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以氧化铝、氮化硅为主原料,以金属铝、金属硅为结合相,Nd2O3、CeO2为添加剂,在埋碳条件下制备了金属塑性相结合Al2O3-Si3N4-Nd2O3(CeO2)复合材料,并利用XRD、SEM等手段研究了复合材料的烧结性能、力学性能、相变过程和显微结构。结果表明:烧结温度越高,复合材料的相对密度和抗弯强度越大;添加剂Nd2O3和CeO2的引入还显著促进了复合材料的致密化,提高了抗弯强度,降低了烧结温度。在碳化合成过程中,1450℃前金属铝和金属硅首先被碳化,生成非金属强化相,1550℃时Si3N4开始部分碳化形成SiC,1650℃时有固溶体SiAlON增强相生成。XRD分析和SEM观察表明添加剂Nd2O3和CeO2的引入能明显促进SiAlON增强相的生成和晶粒生长,复合掺杂(Nd2O3+CeO2)的效果最明显。
In this paper, Al2O3-Si3N4-Nd2O3 (CeO2) composites were prepared by using alumina and silicon nitride as raw materials, aluminum and silicon as the binder phase, Nd2O3 and CeO2 as additive, The sintering, mechanical properties, phase transition and microstructure of the composites were studied by means of XRD and SEM. The results show that the higher the sintering temperature, the greater the relative density and bending strength of the composites. The addition of Nd2O3 and CeO2 additives can significantly promote the densification of the composites, increase the flexural strength and decrease the sintering temperature. During the carbonization process, the metal aluminum and metal silicon before carbonation at 1450 ℃ were carbonized first to form a non-metallic reinforcing phase. At 1550 ℃, Si3N4 began to partially carbonize to form SiC, and solid-solution SiAlON reinforcing phase was formed at 1650 ℃. The results of XRD and SEM show that the addition of Nd2O3 and CeO2 can obviously promote the growth of SiAlON phase and the grain growth. The effect of composite doping (Nd2O3 + CeO2) is the most obvious.