Study On Ceramics Particles Reinforced Iron Matrix Surface Composites

Particles reinforced metal matrix surface composite is one of the hot topics in the field ofcomposites. Researching and developing ceramics particles reinforced steel and iron matrixsurface composites used in wear condition is meaningful in scientific and applicable aspect. Thispaper aims at solving compacting and thickness problems of composites layer by castinginfiltration technique, and the service life problem of guide piece of steel rolling mill isengineering background. WC-Co preformed particles and high Cr cast iron matrix surfacecomposites reinforced with WC-Co preformed particles have been designed and developed basedon the failure analysis of guide piece. The casting infiltration technique for fabricating thecomposites has been developed. The composition, microstructure and mechanical propertiesespecially friction and wear behavior of the composites were studied.The guide piece, which suffered from high temperature oxidation, heat fatigue and abrasivewear, was worn seriously. The results of failure guide piece analysis showed that the main wearmechanism of heat resistant steel guide piece is abrasive wear, and to the high Cr cast iron guidepiece is both abrasive and adhesive wear owing to its low hardness and incompact Cr₂O₃ filmunder high temperature.WC-Co preformed particles have high hardness of HRA90. WC-Co preformed particlesreinforced high Cr cast iron matrix surface composites were successfully obtained utilizingcasting infiltration processing which is simple, convenient and cost-effective. The process isoptimized and the composites have good surface quality. The thickness of PRMMCs layer is upto 5mm～15mm. There is a gently transition layer between PRMMCs layer and matrix layer,which paralleled to the working surface of the casting. Preformed particles are distributeduniformly in PRMMCs layer, and the interface between preformed particles and matrix showedan excellent metallurgical bonding. The structure of PRMMCs was WC, W₂C, M₆C, M₁₂C,M₂₃C₆ carbides and ferrite. Hardness of PRMMCs layer is up to HRA86.3 (HRC69.5).The results of dry friction and wear experiment showed that the composites exhibited muchbetter wear resistance compared to heat resistant steel and high Cr cast iron under theexperimental conditions. Relative wear resistance of the composites is more than 25 times ofhigh Cr cast iron, and more than 9 times of heat resistant steel. On the other hand, the counterpart (45# steel) has less wear loss when against the composites than heat resistant steel or high Crcast iron. In longer time friction and wear experiment, the friction coefficients of composites/45#steel, high Cr cast iron/45# steel and heat resistant steel/45# steel decreased gradually.WC-Co preformed particles reinforced high Cr cast iron matrix surface composites whichexhibits great mechanical properties and wear resistance would be hopeful to be applied innumerous industrial situations where high wear resistance are required.