无压浸渗TiC_(x)/Cu双连续复合材料的高温力学及抗烧蚀性能研究

High-Temperature Mechanical Performance and Ablation-Resistance of Co-Continuous TiC_(x)/Cu Composites Prepared by Pressureless Infiltration

以纳米乙炔炭黑和Ti粉为初始原料,利用原位反应烧结法制备了不同气孔率、非化学计量比的多孔TiC_(x)(x=0.7)预制体,然后通过无压浸渗制备了双连续相TiC_(x)/Cu复合材料。系统分析了TiC_(x)气孔率、陶瓷晶粒尺寸与形貌对TiC_(x)/Cu双连续复合材料物相和微观结构的影响,并测试分析了TiC_(x)/Cu复合材料的常温、高温力学性能以及耐烧蚀性能。研究发现,通过调控预压压力以及烧结温度可以对TiC_(x)预制体气孔率和晶粒尺寸进行调控。TiC_(x)/Cu双连续相复合材料的弯曲强度和断裂韧性随预制体气孔率增加而提高,1600℃/3MPa制备的预制体对应的复合材料,室温弯曲强度达到1052MPa±59MPa,断裂韧性达到11.9MPam^(1/2)±2.7 MPa·m^(1/2),600℃时弯曲强度仍可达到387MPa±11MPa。用氧-乙炔火焰对1700℃/3MPa制备的预制体对应的复合材料进行烧蚀,测得线烧蚀率为0.0485mm/s,烧蚀后TiC_(x)的x值以及晶粒尺寸增大。优异的抗烧蚀性能主要归因于高强、耐高温的TiC_(x)连续陶瓷骨架以及铜的发汗冷却作用,热物理烧蚀、热化学烧蚀以及机械剥蚀是其主要烧蚀机理。

The co-continuous TiC_(x)/Cu composites is prepared by the technique of pressureless infiltration with Cu and non-stoichiometric ratio TiC_(x)(x=0.7)porous preform using in-situ reaction sintering method with acetylene carbon black nano powder and Ti powder as raw materials.The effect of the porosity,morphology and grain size of TiC_(x) preform on the phase and microstructure of co-continuous TiC_(x)/Cu composites have been investigated,the ablation-resistance as well as the room-and-elevated temperature mechanical performances have also been tested and analyzed.The results show that the pre-pressure and temperature of the TiC_(x) preform fabrication have significant influence on its porosity and grain size.As the porosity increases,both of the bending strength and fracture toughness increases,which of co-continuous TiC_(x)/Cu composites with the TiC_(x)(x=O.7)preform fabricated at 1600℃ and 3 MPa at room temperature can achieve 1052 MPa±59 MPa and 11.9 MPa·m^(1/2)±2.7 MPa·m^(1/2),while bending strength still retained 387 MPa±11 MPa at 600℃.The co-continuous TiC_(x)/Cu composites with the TiC_(x) preform fabricated at 1700℃ and 3MPa had the line ablation rate of 0.0485 mm/s after oxy-acetylene flame ablation,with the stoichiometric ratio of TiC_(x) and its grain size significantly increased.The superb ablation-resistance performance of the composites attributed to the high-strength and high-temperature resistance co-continuous TiC_(x) ceramic skeleton and perspiration cooling effect of Cu.The ablation mechanisms include thermophysical ablation,thermochemical ablation,and mechanical exfoliation.