自反应喷射成形制备TiC-TiB_2复合陶瓷

Self-reactive spray formed TiC-TiB_2 composite ceramic preform

提出了一种新的低成本自反应喷射成形技术,制备出TiC-TiB_2复合陶瓷材料坯件,研究了材料的组织结构对性能的影响.结果表明,反应喷射成形坯件的组织具有快速凝固特征,主要由浅灰色连续基体相TiC_(0.3)N_(0.7)、尺寸为100 nm-1μm呈柱状分布的黑色颗粒TiB_2、少量分布于基体相边界的白色相组织TiO_2以及少量黑色的不规则孔洞四部分组成.喷射沉积坯件的孔隙率为2.3%,显微硬度为2029HV_(0.2),断裂韧性为6.0 MPa·m^(1/2).向喷射体系中添加20%(质量分数)的Al-Ni合金使材料的孔隙率下降到1.7%,断裂韧性提高到7.7 MPa·m^(1/2),显微硬度下降到1259HV_(0.2).由于自反应喷射成形坯件的晶粒细小,其断裂韧性高于反应烧结与自蔓延高温合成方法制备的TiC-TiB_2复合陶瓷材料.

A new technology, self-reactive spray forming, was proposed to prepare ceramic materials and TiC-TiB2 composite ceramic preforms were prepared by the new technology. The microstructure of the preforms was observed and the properties of porosity, micro-hardness and fracture toughness were investigated. The results showed that the preforms are composed of four kinds of structures： French grey continuous base phase TiC0.3N0.7, black columnar grain TiB2 with the size of 100 nm-1μm, white structure TiO2 distributing along the boundary of the base phase, and a few of black anomalous pores. The average porosity of the preforms is 2.3%, micro-hardness is 2029HV0.2 and fracture toughness is 6.0 MPa-m1/2. The porosity decreased to be 1.7%, fracture toughness increased to be 7.7 MPa-m1/2, and the micro-hardness decreased to be 1259HV0.2 by adding 20%（mass fraction） Al-Ni alloy to the sprayed system. Due to the fine grain size, the fracture toughness of the self-reactive spray formed preforms is higher than that of the TiC-TiB2 composite ceramic fabricated by reactive sintering and self-propagating high-temperature synthesis.