无压烧结制备Al_2O_3/SiC纳米复合陶瓷

Fabrication of Nano-Al_2O_3/SiC Composites Prepared by Pressureless Sintering

用沉淀法包裹微米级SiC颗粒,通过常压、埋烧制备Al_2O_3/SiC纳米复合陶瓷。通过XRD、TG和 SEM等分析了煅烧和烧结过程中相组成的变化、烧成收缩和显微结构。结果表明:利用SiC 粉埋烧及碳粉制造还原气氛,含8wt％SiC(平均粒径为5mm)的复合粉末经800℃煅烧、成型,试样于1550℃,2h烧结,可制备Al_2O_3/SiC纳米复合陶瓷,其相对体积密度达95.2％,在烧结过程中由SiC氧化形成的无定形SiO_2及与基质氧化铝反应形成的莫来石前躯体可大大促进烧结。

Al2O3/SiC nano-composites were prepared by coating micrometric SiC particles with Al(OH)3 precipitation followed by preg-sureless sintering in SiC powder bed at 1550℃ for 2h. The phase composites and microstructure were characterized by XRD and SEM. And their sintering behavior was monitored by dilatometry to optimize the sintering schedule. The results indicated that composite powder containing 8wt% SiC with an average size of 5mm calcined at 800℃ could be sintered to 95.2% of the theory density. Amorphous SiO2 resulted from the oxidation of SiC and mullite precursor formed by the reaction between matrix Al2O3 and SiO2 could effectively promote the sintering.