WC/Fe Matrix Composites By Liquid Phase Sintering

Wear-resistant materials are widely used in some industrial areas like cement,electric power,machinery,mining,chemical and coal.However,with the development of industry,the service condition of wear-resistant materials is getting more complex,which means the traditional materials are not applicative at all.As a result,particle reinforced metal matrix composite,which has the advantages of high tenacity of matrix and high strength and wearing resistance of reinforced particles.In the process of preparing composite material,the property is mainly determined by the choice of the matrix,the morphology of the reinforced particles and the processing method.In this research,Cr16 or Ni28 was chosen as matrix and spherical or granular WC particals as reinforced particles to prepare a high-performance composite.The influence on the composite material properties from the sintering temperature,the matrix,the morphology of the WC particals and heat treatment process were studied.The main findings are as follows:After liquid phase sintering of spherical and granular WC particals and Cr16 and Ni28 powder matrix,the interdiffusion of W,C,Fe and Cr element took place between in the WCs/Crl6 composites(WCs stands for spherical tungsten carbide particals).In the cooling process,M7C3 and Fe3W3C formed.The thickness of the diffusion layer was about 0.207 mm,when cooling down.Besides,the highest hardness value of the WC particals was 1150 HV.The same interdiffusion process happens in the WCs/Ni28 composites,and intermetallic compound of FeNi and new carbide of Fe3W3C formed in that composite.Meanwhile the diffusion layer was about 0.198 mm.With the decreasing of the sintering temperature,the WC and Ni28 combined better,which keeps the completeness of the WC partical and improves the hardness of diffusion layer.The hardness of WC paricals reach 1593 HV.The WCP/Crl6 was bonded well(WCP stands for irregular granular tungsten carbide particals),the interdiffusion happened as well.There formed another carbides(M23C6 and M7C3),is different from the WCs/Cr16 composites.Adding C atems in the Cr 16 matrix can low the sintering temperature and burn loss of WC particals.When the mass fraction of C element is 2.5%,the hardness of WC particals can reach 1790 HV,which is much higher than WCs/Crl6 and WCs/Ni28.What's more,the sintering process was simplier.In this research,the precess was as follows:choosing granular WC as reinforced particles and Cr16+2.5%C(wt.%)as matrix,and sintering at 1270? for 10 minutes.The heat treatment process and property of the WCP/Cr16 composites was studied.Martensitic transformation proceeded after quenching,M7C3,M23C6,M6C,martensite and proeutrctoid carbide exist in the samples.With the lower of quenching temperature,the content of martensite and proeutrctoid carbide increased and the hardness of the matrix increased.As the tempering temperature increasing,the content of proeutrctoid carbide increased.When the samples were treated by 950? quenching followed by 500?tempering,thire impact toughness reachs up to 4.499 J/cm2.But with the increasing of the tempering temperature,the interface bonded worse.The interface bonding best occored at 950? quenching followed by 220? tempering.The compressive strength varied little after different heat treatment system,of which the highest value was 3560 MPa when treated by 1000? quenching followed by 220? tempering.The acrasive resistance of the samples was better when treated by heat treatment and wores less with the rising of tempering temperature.After experiment,the best acrasive resistance occored when treated by 900? quenching followed by 220? tempering,of which the abrasion loss was just 3.275 mm3.In conclusion,considering the overall performance including hardness,acrasive resistance,interface bonding and compressive strength,the best heat treatment process of the WCP/Cr16 composites was quenching at 950? followed by tempering at 220?.