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本文通过对具有不同烧结密度的热压SiC—TiC复相陶瓷在氮气氛中进行热等静压后处理,从理论上(依据热力学数据)分析了闭合SiC—TiC复相陶瓷开孔孔隙的可能性,并用实验予以证实;同时,还研究和讨论了热等静压后处理工艺对陶瓷烧结体某些物理和力学性能(密度、强度和断裂韧性)以及氧化行为的影响。实验结果表明:SiC和TiC在高的氮气压力和温度下,可以分别氮化成Si_3N_4和TiN;对于预烧结相对密度约为95％的热压SiC—TiC复相陶瓷,在200MPa氮气压力下于1850℃氮化1小时后,室温强度由345MPa提高到686MPa,断裂韧性高达7.9MPa·m~(1/2),其抗氧化性能也有明显改善。
In this paper, hot pressed SiC-TiC multiphase ceramics with different sintering densities were subjected to hot isostatic pressing (HIP) post-treatment in nitrogen atmosphere. The possibility of opening pores in closed SiC-TiC multiphase ceramics was analyzed theoretically (based on thermodynamic data) In addition, some physical and mechanical properties (density, strength and fracture toughness) and oxidation behavior of the sintered ceramics were studied and discussed. The experimental results show that SiC and TiC can be respectively nitrided into Si_3N_4 and TiN at high nitrogen pressure and temperature. For hot-pressed SiC-TiC multiphase ceramic with pre-sintering relative density of about 95% After 1 hour of nitridation, the room temperature strength increased from 345MPa to 686MPa, fracture toughness up to 7.9MPa · m ~ (1/2), and its oxidation resistance also improved significantly.