Study On Modification Of WC-10Ni Cemented Carbide

The corrosion resistance,oxidation resistance and wear resistance performance of WC-Ni cemented carbide is better than that of WC-Co cemented carbide.In addition,compared to Co resources,Ni resources are relatively abundant,inexpensive,environmentally friendly and non-toxic.Therefore,WC-Ni cemented carbide is undoubtedly a good substitute of WC-Co cemented carbide in many aspects.But there is a certain gap between WC-Ni cemented carbide and WC-Co cemented carbide in mechanical properties.At the same time,there is a property of poor toughness in WC-Ni cemented carbide.Thus the development of WC-Ni cemented carbide is greatly limited,which has greatly restricted its application in many fields.In this paper,vacuum sintering technology and the addition of Si C and Si C/La₂O₃ complex are used as WC grain growth inhibitors to improve the comprehensive mechanical properties of the WC-Ni cemented carbide.The effects of single additive Si C and Si C/La₂O₃ complex additives on the properties of the WC-Ni cemented carbide were studied by means of XRD,SEM and EDS.The sintering process was optimized.The influence of vacuum sintering temperature and heat preservation time on the comprehensive properties of the WC-10 Ni base cemented carbide was studied.The best technology for preparing the comprehensive properties of the WC-10 Ni base cemented carbide was studied.The main conclusions are as follows:1.Nano Si C powder,micron WC and Ni powder were used as the raw material,and the WC-10 Ni cemented carbide composites were prepared by ball milling method and vacuum sintering method.The incorporation of nano Si C is beneficial to the activation of WC lattice,and the sintering densification of the WC grains.At the same time,it is beneficial to prevent the movement of WC grain boundary,restrain the growth of WC grain,and achieve the effect of refining grain,and improve the mechanical properties of the WC-10Ni-Si C cemented carbide composites.2.The WC-10 Ni cemented carbide with the relatively optimum comprehensive properties,i.e,the relative density of 99.2%,vickers hardness 1623 HV,fracturetoughness 12.7 MPa·m1/2 and bending strength 858.3 MPa had been prepared when the vacuum sintering temperature is 1450 ?,nanometer Si C content is 0.5wt %.3.The study of Si C/La₂O₃ co-doped the WC-10 Ni cemented carbide prepared by the vacuum sintering in 1450 ?-1500 ? and different holding time?0-45 min?was studied.The results showed that the comprehensive performance of WC-10Ni-0.5Si C-0.5La₂O₃ cemented carbide were best at sintering temperature1475? and holing time 30 min.Relative density of the prepared WC-10Ni-0.5Si C-0.5La₂O₃ cemented carbide was up to 99.75%.Hardness,fracture toughness,flexural strength reached to 1550 HV,16.19 MPa·m1/2,1829.3MPa,respectively.4.By studying the mechanical properties of the alloy,combining with the analysis of the surface microstructure and fracture morphology,it was found that the composite additives played an important role in improving the comprehensive mechanical properties of the cemented carbide.The big and small WC grains in cemented carbides tended to homogenization at the effective of strengthening action of Si C hard phase particles and coordination with the inhibition of La₂O₃.The main strengthening mechanisms were fine grain strengthening and second phase particle dispersion strengthening;the main toughening mechanism were mainly refinement of hard phase grain,crack branching,microcracks and effect of La₂O₃ on preventing the crack to keep expanding and making crack deflection.