文档介绍：摘要
碳化硅陶瓷具有高温强度高、抗氧化性强、耐磨损性好、热膨胀系数小、硬度高、抗热震和耐化学腐蚀等优良特性,因此,在很多领域得到广泛应用。然而,SiC是一种共价键性很强的化合物,其自扩散系数极小,可烧结性很差。在传统的粉末冶金SiC烧结工艺条件下,如果不加入适当的添加剂,纯SiC是很难烧结致密化。采用超高压烧结方法可以在较低温度、较短时间、低烧结助剂添加量下获得高致密度、高性能的陶瓷。
本文利用高压六面顶压机对SiC陶瓷的高压烧结,对SiC陶瓷的高压烧结工艺及性能进行了初步的研究,并进行了理论分析,探索了其显微结构与性能之间的关系。通过对SiC复相陶瓷的相对密度和XRD谱的研究分析,发现高压烧结的SiC陶瓷材料具有优良的性能,主要体现在导热性能和韧性在,有良好的应用前景。
与常压相比,高压烧结可以有效的降低金属陶瓷的烧结时间和烧结制度,增进致密化,进而达到改进性能的目的。六面顶高压烧结技术是一种快速、高效的烧结技术,大大降低了烧结温度和缩短了烧结时间,并且可制备出接近理论密度的复相陶瓷材料。采用超高压烧结工艺可以烧结获得无烧结助剂添加的高致密度SiC陶瓷(致密度92%~100%)。烧结工艺对陶瓷的性能有明显的影响,实验结果表明:Al2O3是SiC烧结的有效烧结助剂,在低添加量下(约2wt%)即可实现陶瓷的全致密烧结。烧结工艺对添加了烧结助剂陶瓷性能的影响与纯SiC的烧结类似,但获得的陶瓷的致密度普遍较高。
关键词:SiC陶瓷高温高压技术烧结性能物相分析(XRD谱)
ABSTRACT
SiC ceramics is a good material with high temperature strength, oxidation resistance, wear resistance, thermal expansion coefficient, high hardness, thermal shock and chemical resistance and other excellent properties, therefore, has been widely used in many fields. However, SiC is a covalent bond pound, the self-diffusion coefficient is extremely small, the sinterability is poor. SiC sintered in the conventional powder metallurgy process conditions, without the inclusion of suitable additives, pure SiC densification is difficult. Using ultra-high pressure sintering method can lower the temperature, the shorter the time, the low sintering additives added amount obtained by a high-density and high-performance ceramic.
In this paper, based on six sides high-pressure jacking machine of SiC ceramics high pressure sintering, high pressure sintering process and the performance of SiC ceramics has carried on the preliminary research, and has carried on the theoretical analysis, to explore the relationship between its microstructure and properties. Through the relative density of SiC pound phase spectrum and XRD analysis, found that high pressure sintering SiC ceramic material with excellent performance, mainly reflected in the performance of thermal conductivity and toughness in, has the good application prospect.
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