挤压铸造制备Al_2O_3颗粒增强钢基复合材料

Preparation of Al_2O_3 Particulate Reinforced Steel Matrix Composites by Squeezing Casting

通过在模具内表面涂覆较厚陶瓷保温层,利用挤压铸造成功制备了Al2O3颗粒增强钢基复合材料。利用陶瓷保温层对钢液进行控温处理,解决了钢基复合材料挤压铸造时因钢液冷却速度快、浸渗能力差,导致复合材料制备困难等问题。在8MPa的挤压力下,成功地制备了6mm厚、Al2O3的体积分数为56%的Al2O3p/40Cr表层复合材料。结果表明,所制备的复合材料组织致密、晶粒细小;基材和复合材料层间的宏观界面过渡自然、连续性好,颗粒和基体间的微观界面结合紧密;复合层比40Cr基材的耐磨性提高了8.7倍。

A1203 particulate reinforced steel matrix composites were fabricated successfully by squeezing casting through coating a thermal insulating ceramic layer on the internal surface of the mold. The cool- ing rate of the molten steel can be decreased greatly with the help of the ceramic layer, and the key prob- lems in fabrication of steel matrix composites, such as very high cooling rate, poor infiltration ability with the molten steel, which result in difficulty in fabrication of the composites, are solved. The A12O3p/40Cr steel matrix composites with 6 mm in thickness and 56% A1203 particles in volume fraction were successfully fabricated by squeezing casting with 8 MPa pressure. The as-cast and heat treated mi- crostructure, hardness, wear resistance of the composites prepared were investigated. The results show that the compact microstructure in the composites with fine grain can be observed. The macro-interface between the substrate and composites layer is tranferred naturally, and the micro-interface between A1203 particles and the matrix exhibits dense without any cavities. The wear resistance of the compos- ites is 8.7 times higher than that 40Cr substrate.