TaC增强铁基梯度复合材料的原位生成及其磨粒磨损特性

Abrasive Wear Characteristics of Surface Gradient Composites of TaC Reinforced Iron Matrix Prepared by In-Situ Technology

以高纯钽板为原料,采用原位反应法在HT300表面制备了碳化钽增强表面梯度复合材料。用扫描电子显微镜、X射线衍射仪、显微硬度计和磨粒磨损试验机对复合层的微观形貌、物相组成、显微硬度以及磨粒磨损性能进行了表征。结果表明:所得复合层的总厚度约为475μm。最表层为碳化钽致密陶瓷层,厚度约为170μm,其颗粒尺寸小于1μm,体积分数近似95%,显微硬度最高值达2328HV0.1;次表层为碳化钽颗粒分散层,其颗粒尺寸为0.5~1.5μm,体积分数从90%逐渐减小至基体,显微硬度由915HV0.1降低至410HV0.1;复合层与基体之间呈现良好的冶金结合。铁基表面碳化钽陶瓷增强梯度复合材料的耐磨性比灰口铸铁基体有大幅度提高;复合层的磨损是局部塑性变形、显微切削和增强颗粒的部分破碎等因素综合作用的结果。

Tantalum carbide gradient composite was fabricated via in-situ reaction of pure tantalum plate with gray cast at high temperature. The morphology, phase constituent, microhardness, and relative abrasion resistance of the composite were characterized by scanning electron microscopy, X-ray diffraction, microhardness tester and abrasive wear testing machine. The results show that the thickness of the gradient composite is about 475 μm. The cast 170 μm thick surface layer is a dense ceramic layer consisted of ~95% submicron TaC particles, and the highest micro-hardness value of which is 2328HV0.1; In the sub-layer, there exists a gradient distribution of TaC particles from 90% to 0% in volume fraction, correspondingly the microhardness value decreased from 915HV0.1to 410HV0.1, and the size of the TaC particles increased to 0.5-1.5 μm; the interface between the composite and matrix exhibits a perfect metallurgical bonding. The TaC reinforced iron matrix surface gradient composite shows far superior wear resistance than the gray cast iron. The wear mechanism is mainly related with the local plastic deformation,micro cracking caused by misrouted broken carbide particles.