以Al-B4C-C为烧结助剂的SiC陶瓷液相烧结研究

尝试以含Ａｌ、Ｂ、Ｃ的化合物为烧结助剂进行了α－ＳｉＣ粉末的无压烧结，研究了烧结助剂中Ａｌ和Ｂ的配比、烧结温度、保温时间等因素对烧结体密度和力学性能的影响．结果表明，最佳保温时间为１ｈ；当烧结温度为１８５０℃以上时，烧结体的相对密度达到了９０％；当Ａｌ／Ｂ＝３和 ４时，烧结体的性能相对较好．ＸＲＤ显示了Ａｌ_８Ｂ_４Ｃ_７相的存在，表明在烧结过程中反应生成了Ａｌ_８Ｂ_４Ｃ_７，烧结机制是液相烧结．扫描电镜照片显示了断面结构和晶粒形貌．

Liquid-Phase Sintering of SiC with Al-B4C-C as Sintering Aids

SiC ceramics were prepared by pressureless sintering with Al, B and C as sintering aids. The effects of the mol ratio of Al and B, the sintering temperature and sintering time on the relative density and bending strength of the samples were studied. The fracture surface structure and the grain shape of the samples were displayed by SEM photographs. The experimental result shows that the most appropriate sintering time is 1h, and the relative density of the samples reaches to 90% when the sintering temperature is above 1850℃. It also shows that the samples have the best prformance when the mol ratio of Al and B is between 3/1 and 4/1. The XRD pattern shows Al₈B₄C₇ is in existence, which indicates that Al₈B₄C₇ is produced during sintering, so that the sintering mechanism is liquid-phase sintering.