Fabrication, Microstructure And Properties Of Ti₃SiC₂-based Composites

Ti₃SiC₂single-phase materials and Ti₃SiC₂-based composites containing SiC andTiC respectively were successfully fabricated with Ti、Si、SiC、TiC and carbon blackpowders as raw materials by reactive hot pressing method. Phase constituent,microstructure, mechanical properties and the synthesis reaction mechanism of Ti₃SiC₂materials were investigated, and effect of the content of SiC and TiC on thedensification, phase constituent, microstructure, mechanical properties and electricalconductivity of the composites were researched. Conclusions as follows:（1） The reaction hot-pressed sintering method was used to prepare Ti₃SiC₂materials with four kinds of raw material system. The main phase of Ti₃SiC₂materialswas Ti₃SiC₂and minor phase was TiC. Ti₃SiC₂content was over93.8wt%in bulkTi₃SiC₂material, the flexural strength and fracture toughness obtained successfully byhot-pressing was of449MPa and4.67MPa·m1/2respectively. The results showed that theideal processing parameters to synthetise Ti₃SiC₂was1500℃for3hours using Ti, Siand TiC as raw materials.（2） The main phase of SiC/Ti₃SiC₂composites was Ti₃SiC₂and SiC, containing asmall amount of impurity phase TiC. The mechanical test showed that the introductionof Ti₃SiC₂could improve mechanical properties of SiC/Ti₃SiC₂composites due to thedispersion enhancement of SiC when dispersed uniformly in matrix. But its additioncontent should not be too high.（3） The main phase of TiC/Ti₃SiC₂composites was Ti₃SiC₂showing good chemicalcompatibility between Ti₃SiC₂and TiC. When the additional content of TiC reach to30wt%, the flexural strength and fracture toughness of TiC/Ti₃SiC₂composite are 406.9MPa,3.7MPa·m^1/2respectively.（4） The electrical conductivity of bulk Ti₃SiC₂material was4.18×10⁶S/m. With theincrease of second phase content, the electrical conductivity of SiC/Ti₃SiC₂andTiC/Ti₃SiC₂composite decreased gradually.（5） The conductive mechanism of composite was that conductive particlescontacted to form a continuous network structure. With increasing Ti₃SiC₂contentconduction channels was formed and the conductivity of the materials was enhanced.