具有钉扎效应的CTCP/Cr26复合材料制备及界面结构

Preparation and Interface Structure of CTCp/Cr26 Composites with the Pinning Effect

摘要:

以铸造碳化钨颗粒（Cast Tungsten Carbide Particle，CTCP）与还原铁粉为原料，采用松装烧结工艺制备具有蜂巢状结构的多孔陶瓷预制体；通过铸渗法制备了CTCP/Cr26铁基表层复合材料；采用扫描电镜、X射线衍射仪、电子探针等手段分析了预制体和复合材料的显微组织。结果表明：高温烧结过程中还原铁粉中的Fe与CTCP中的W2C发生反应，在CTCP表面形成了烧结壳层，壳层内侧的物相组成为WC+Fe3W3C，壳层外侧的物相是Fe3W3C；壳层相互连接使预制体具有较高强度，铸渗过程中高强度的预制体能够抵抗高温液态金属的热冲击，从而保证了复合材料中预制体的蜂巢状结构；制备的复合材料中CTCp与金属基体的界面形成明显的过渡层，过渡层的物相组成为WC+Fe3W3C，过渡层的形成是烧结壳层在高温金属液中发生溶解与析出的结果

Abstract:

Using the cast tungsten carbide particles (CTCP) and reduced iron powder as the raw materials, the porous ceramic preforms with honeycomb structure were prepared by the loose sintering process; then, CTCp/Cr26 ferrous matrix composites with honeycomb structure were prepared by the casting infiltration process. The microstructure of the perform and the composites were analyzed by SEM, XRD and EPMA. The results show that a sintered shell is formed from the reaction of Fe and W2C in the CTCP during loose sintering process; finally, WC plus Fe3W3C phases are located on the inside surface of the shell and the Fe3W3C shell is located between the particles. Therefore, the strength of preforms is enhanced because the shell layer is connected to each other by sintered shell. Besides, the preform can resist the rush of liquid metal and maintain the honeycomb structure during cast infiltration process. A transition layer is formed in the interface of CTCp and the matrix, which is constituted by WC and Fe3W3C. The formation mechanism of the transition layer is the dissolution and precipitation result of the sintered shell in the hot liquid metal.