Study On Microstructure And Properties Of WC/Fe Wear Resistant Material Prepared By Vacuum Sintering

The WC particle reinforced metal matrix composites were widely used in engineering machinery,mining metallurgy,water conservancy and hydropower industries due to its high hardness and good abrasion resistance,but it was difficult to further expand its application because of the high cost in the actual application caused by the high price of WC.Aiming at the high cost problem,the in-situ synthesized WC/Fe wear-resistant materials were prepared by vacuum sintering using low-cost ferrotungsten as the tungsten source.The effect of sintering temperature,holding time,C/W,Cr content and TiC/TaC content on microstructure and properties of the materials were studied by XRD,SEM,EDS,macro-hardness tester and abrasive wear tester.The results show that:1)For the Fe-62.5W-4.7C alloy system,when sintered at the temperature from1250 ? to 1450 ?,the WC wear resistant materials can be in-situ synthesized,and a small amount of Fe3W3 C phase are observed.The in-situ synthesized WC particles are fine and dispersed in the matrix,and the amount of Fe3W3 C phase increases with the increasing of the sintering temperatures.When sintered at 1350~1400?,the mechanical properties of the materials are the best,the macro hardness is up to 56 HRC,the wear mass loss is the least and the relative wear resistance is 27 times that of Q235 steel.In order to reduce Fe3W3 C content,Fe-62.5W-5C alloy is used and sintered at 1400 ? for different holding time,the only WC hard phase can be in-situ synthesized,which indicates that the C content of the alloy system is located in the carbon content range corresponding to the normal two-phase structure.The in-situ synthesized WC particles are basically triangular prism,and the grain size is mainly concentrated in 1.3~2.5um.Extending the holding time within 0.5~8h has little effect on shrinkage,density,hardness,wear resistance and the grain size of WC,the density and hardness of the materials are around 11.30g/cm3 and 54 HRC,the relative wear resistance is 40~43 times that of Q235 steel.2)For the Fe-62.5W-?C reaction system with different C content,when the carbon tungsten ratio is as low as 0.9 ~ 1.1,the material is WC+?+? triphase structure,? phase decreases with the increasing of C/W.When the carbon tungsten ratio is up to 1.3~1.7,the corresponding material is WC+?+C triphase structure,the C phase increases with the increasing of C/W.Therefore,it is possible to obtain the ideal WC+? two-phase structure by adjusting the C/W between 1.1~1.3.3)Cr is add to promote a refinement of the in situ synthesised WC,and the refining effect increase with the increasing of Cr content,on the other hand,it also promotes the growth of M6 C,and the shap of it is block and rod when the Cr content reaches to 4.5%.Cr added improves the hardness and wear resistance of the material by fine grain strengthening and solid solution strengthening effect.It also improves the acid corrosion resistance of the material by reducing the passivation potential of the alloy.While the compound additive is TiC and TaC which total content is 4%,the hard phase of the composite materials are the synthetic WC,M6 C,extra TiC and TaC,as well as various complex carbides.With the increasing of TiC and decreasing of TaC,the platelet morphology of in-situ synthesized WC and the ring structure appeare and the number of them increase gradually.