Effect Of Additives On Microstructure And Properties Of WC-Co Cemented Carbide Sintered By Microwave

Cemented carbide is a kind of powder metallurgy material with high hardness and high wear resistance prepared by powder metallurgy with hard phase and bonding phase.Cemented carbide known as the industrial teeth.Wear resistance and toughness in common cemented carbide is a contradiction:With the increase of Co content,the alloy strength is enhanced and the hardness and wear resistance of the alloy are reduced,and vice versa.Ultrafine grain cemented carbidecemented carbide has high comprehensive properties:high hardness,high wear resistance and good toughness and strength.Controlling grain growth during WC sintering is very important for the preparation of ultrafine cemented carbide.Microwave sintering has its own characteristics in controlling grain growth due to its unique heating mode.In addition,Co is rare in reserves and expensive in price.Partial replacement of Co by Ni can reduce the production cost of cemented carbide and meet the requirements of alloy toughness.In this study,ultra-fine crystal WC-10Co cemented carbide was prepared by microwave sintering.The phase composition,element distribution and microstructure of cemented carbide were determined by SEM,XRD,EDS and other analytical methods.The density,cobalt magnetic force,coercivity magnetic force,hardness,fracture toughness and bending strength of cemented carbide were measured.The wear resistance of the alloy was determined by tribometer and 3d profiler.The corrosion resistance of the alloy was analyzed by electrochemical workstation.The microwave sintering process parameters of superfine grain WC-10Co cemented carbide were determined.The effect of Ni partial replacement of Co on microstructure and properties of cemented carbide was studied.Finally,the effects of rare earth oxides and metallic carbides as grain growth inhibitors on the superfine cemented carbide doped with Ni were studied by adding Y₂O₃ and Cr₃C₂.The results show that under the microwave sintering condition,the heating rate is75?/min,the sintering temperature is 1300?,the holding time is 10 min,the cemented carbide has been completely densified,the density reaches 99.7%,and the vickers hardness reaches 1899.5 kg/mm².The grain size of tungsten carbide is small,with an average grain size of 500 nm.When the Ni content was 1%,the comprehensive performance of Ni partial cobalt alloy was relatively good,and the electrochemical corrosion performance was improved,but the mechanical properties of the alloy were partially reduced.By doping Y₂O₃ and Cr₃C₂,WC grains can be refined,bond phase can be strengthened,and grain boundary strength can be enhanced.In addition,when the addition amount of Y₂O₃ and Cr₃C₂ is 0.5%,the WC grain size of the alloy reaches 444 nm and 450 nm respectively.At this time,the mechanical properties,wear resistance and corrosion resistance of the alloy are best improved.