SiC陶瓷的SPS烧结机理研究

Study on SPS Sintering Mechanism of SiC Ceramic

利用放电等离子烧结炉在不同温度下对SiC陶瓷进行烧结,烧结温度分别为1250、1450、1650、1850℃,升温速度均为200℃/min,升到温度后立即冷却。基于烧结后SiC陶瓷的扫描电镜观察,对SiC陶瓷的放电等离子烧结机理进行了初步探讨。研究结果表明,随着烧结温度的提高,SiC陶瓷的致密化程度逐渐提高,在1250℃和1450℃烧结的试样微观组织中很难发现烧结现象,但在小颗粒间发生局部的烧结痕迹,在1650℃烧结的试样微观组织中存在小颗粒的烧结现象,大颗粒间仍然没有烧结,颗粒形貌基本保持原始粉末的形貌,而在1850℃烧结的试样微观组织中存在大量的烧结颈现象,而且颗粒形貌呈球形。因而SiC陶瓷的放电等离子烧结机理可能是低温下的焦耳热烧结机理和高温下的放电和焦耳热共同作用机理。

SiC ceramic was prepared by spark plasma sintering technology （SPS） at different temperatures. The sintering temperatures were 1250, 1450, 1650, and 1850 ℃, respectively. The heating rate was selected as 200 ℃/min. The microstructure of the sintered SiC samples was examined by SEM and the SPS sintering mechanism of SiC ceramic was discussed. The results show that the densification of SiC ceramic improves gradually with increasing of sintering temperature. The sintering phenomenon is hardly found in the microstructure of sintered samples at the temperature of 1250 ℃ and 1450 ℃. In the microstructure of sintered samples at the temperature of 1650 ℃, the sintering phenomenon of some fine particles is examined, while no sintering behavior is found between the coarse particles. When the sintering temperature increases to 1850 ℃, a large numbers of sintering necks occur in the microstructure and the morphology of SiC particles changes from sharp-angled to spheric. The SPS sintering mechanism of SiC ceramic may be Joule Heat mechanism at low temperature and conjunct mechanisms of Joule Heat and Spark at high temperature.