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以Cfg,SiC,B4C,TiO2为原料,热压工艺为1750~1 900℃×30 min,25 MPa,制备了C-SiC-B4C复合材料,并研究了材料的组织与性能.结果表明随热压温度升高,复合材料的体积密度、抗折强度、断裂韧性均升高;相同热压温度下随Cfg含量增加,其抗折强度降低、断裂韧性升高.在1 900℃热压,原料质量配比(质量分数,%)为Cfg20,SiC 61.7,B4C 12.3和TiO26时,复合材料的综合力学性能最佳,抗折强度为142.5MPa,断裂韧性为4.8 MPa.m21.复合材料的主晶相为层状结构的Cfg,在Cfg层间为SiC,B4C和原位生成的TiB2颗粒.复合材料的增韧机制主要为Cfg与陶瓷相的热膨胀不匹配产生的热应力导致的弱界面分层诱导韧化作用.
The C-SiC-B4C composites were prepared by Cfg, SiC, B4C and TiO2 as hot-pressing process at 1750-1 900 ℃ for 30 min and 25 MPa, and the microstructure and properties of the composites were investigated. With the increase of temperature, the bulk density, flexural strength and fracture toughness of the composites increase. With the increase of Cfg content, the flexural strength decreases and the fracture toughness increases at the same hot pressing temperature. When the mass ratio (mass fraction) is Cfg20, SiC 61.7, B4C 12.3 and TiO26, the composite has the best mechanical properties, the flexural strength is 142.5MPa and the fracture toughness is 4.8 MPa.m21. The main crystal of the composite Phase is Cfg of layered structure, and SiC, B4C and in-situ TiB2 particles are formed between Cfg layers.The toughening mechanism of the composites is mainly due to the weak interfacial delamination due to the thermal stress caused by the thermal expansion mismatch between Cfg and the ceramic phase Induction of toughening.