Prepear And Study On The Wear Behaviors Of WC Strengthen Al₂O₃/TiC Composites

Al₂O₃/TiC composites were prepared by hot pressing sintering, using α-Al₂O₃and TiC as raw materials. The effects of sintering temperature and the content of TiCon microstructure and mechanical properties had been analyzed by X-ray diffraction（XRD）, scanning electron microscopy （SEM）, three-point bending test, single edgenotched beam method, etc. And we added WC to this composite to research theeffects of the content of WC on composites’ mechanical properties. We used Si3N4ceramic balls as the friction pair to research the content of WC effects on friction andwear properties of Al₂O₃/TiC/WC composites, then the friction and wear mechanismof the composites will be preliminary revealed.At sintering temperature of1600℃, with the ratio of TiC increasing, themechanical properties of Al₂O₃/TiC composites increase firstly and then decrease.The properties reaching a maximum at the ratio of TiC is20wt%. The flexturestrength and fracture toughness of the composites is509.45MPa and5.27MPa·m1/2.At sintering temperature of1600℃, when the ratio of TiC is determined to20wt%,with the ratio of WC increasing, the mechanical properties of Al₂O₃/TiC/WCcomposites increase firstly and then decrease. At the ratio of WC is10wt%, theflexture strength and fracture toughness of the composites reaching in a maximumvalue,534.7MPa and5.34MPa·m1/2.The XRD analysis shows that the Al₂O₃/TiC composites contain α-A1₂O₃phaseand TiC phase. It indicates that there is no chemical reaction in the process ofpreparation and the chemical compatibility of α-A1₂O₃and TiC is good. When weadd WC to the composites to prepare Al₂O₃/TiC/WC composites, there is still nochemical reaction in the process of preparation.The fractures SEM images of Al₂O₃/TiC composites show that the major fracture mechanism of the composites is intergranular fracture. And in the region ofTiC, there exist the transcrystalline fracture. With the ratio of TiC increasing, thetranscrystalline fractures increase. The fractures SEM images of Al₂O₃/TiC/WCcomposites show that the fracture mechanism is the same with Al₂O₃/TiC composites.Al₂O₃/TiC/WC composites with different WC content friction and wearperformance study shows that with the increase of WC content, the frictioncoefficient of the composite material decrease firstly and then increase. Then, thewear rate of composite materials and wear diameter of ceramic ball increase firstlyand then decrease. And at the WC content for10wt%composites friction coefficient,wear rate and the wear diameter of the ball reached the minimum value（0.45、2.3×10-8g/N m、0.81mm）.Al₂O₃/TiC/WC composite friction and wear mechanism is mainly caused by thebrittle fracture of abrasive wear. Adding the WC composites wear rate（W） is in directproportion to fracture toughness（KIC）. And without the WC composites do notconform to the law. The wear rate of composites（W） and the ratio（E/Hv） of modulusof elasticity（E） and vickers hardness（Hv） present inverse proportion.