无压烧结碳化硅复合材料的制备与性能研究

The Research on Preparation Process and Properties of SiC Composites by Pressureless Sintering

以部分碳化钛为增强相投入到碳化硅基体材料中,并投入微量炭黑和碳化硼为烧结活化剂,利用无压固相烧结技术制造了碳化硅基陶瓷复合材料。评测了其力学性能,凭借扫描电镜(SEM)观测了试样的断口形貌与表观形貌,并探讨了其氧化行为。结果表明:在碳化硅中投加部分碳化钛,对复合材料的力学性能有非常大地益处,于9 wt%时达到顶峰,弯曲强度497 MPa,相对密度98.9%,断裂韧性4.79 MPa·m^(1/2)。复合材料的显微组织构造紧致密实,TiC颗粒在SiC材料中的离散作用而激发的钉扎效果和裂纹偏移转向为其主要的增韧原理。在设定的氧化条件下(1200℃保温2 h),试样表面形成了一层较为致密并可以弱化氧化进程的氧化膜层。

SiC ceramic composites were fabricated by the pressureless solid-phase sintering technology with added parts of titanium carbide as reinforcement phase and put in a tiny amount carbon black and boron carbide as sintering activators.The mechanical properties of the samples were evaluated.The fracture morphology and apparent morphology were observed and the oxidation behavior of the samples was also discussed by the scanning electron microscopy(SEM).The results show that adding part of titanium carbide to SiC has great benefit on the mechanical properties of the composites and reaches the peak at 9 wt%,the bending strength is 497 MPa,the relative density is 98.9%,and the fracture toughness is 4.79 MPa.m^(1/2).The microstructure of the composites is compact.The main toughening principles of the composites are the binding effect and crack deflection which caused by the dispersion of TiC particles in SiC materials.Under the set oxidation conditions(at 1200℃ for holding 2 h),a relatively dense oxide layer was formed on the surface of the samples which can weaken the oxidation process.