Preparation and interface structure of CTC_p/Cr26 composites with the pinning effect

Using the cast tungsten carbide particles (CTC_P) and reduced iron powder as the raw materials, the porous ceramic preforms with honeycomb structure were prepared by the loose sintering process; then, CTC_p/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 CTC_P 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 CTC_p 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.