Study On WC-NiCrMo Cemented Carbide And Its Corrosion And Wear Behavior

In order to obtain an alloy with high wear-resistance and anti-corrosion,sintering process of WC/Ni-Cr-Mo mixed powder in tube furnace with argon atmosphere was studied.The property of WC-20%?8Ni-3Cr-2Mo?,WC-30%?8Ni-3Cr-2Mo?,WC-40%?8Ni-3Cr-2Mo?,WC-50%?8Ni-3Cr-2Mo?,WC-60%?8Ni-3Cr-2Mo?,WC-70%?8Ni-3Cr-2Mo?,WC-80%?8Ni-3Cr-2Mo?,WC-90%?8Ni-3Cr-2Mo?alloy was investigated by hardness test,density test,macro-morphology,microstructure and XRD,also,the influence of milling time,sintering temperature and binder content on the hardness,density,microstructure of WC-?8Ni-3Cr-2Mo?was discussed.At the room temperature,corrosion regularity and corrosion mechanism of WC-20%?8Ni-3Cr-2Mo?,WC-30%?8Ni-3Cr-2Mo?,WC-40%?8Ni-3Cr-2Mo?in the concentrated hydrochloric acid were explored.The effects of the content of binder Ni-Cr-Mo,load and wear time on the wear behavior and the wear mechanism of WC-?8Ni-3Cr-2Mo?alloy were studied using M-2000 friction and wear testing machine.The results show as follows:When milling time is 4 h,the sintering temperature range of WC-?8Ni-3Cr-2Mo?mixed-powder narrows with the increasement of the content of Ni-Cr-Mo powder.The highest sintering temperature of WC-?8Ni-3Cr-2Mo?decreases gradually and the lowest sintering temperature of WC-?8Ni-3Cr-2Mo?increases gradually using the hardness of HV>200 as the standard.The hardness of WC-?8Ni-3Cr-2Mo?alloy decreases gradually at the highest sintering temperature and the density of WC-?8Ni-3Cr-2Mo?alloy fluctuates around 90%.When the content of Ni-Cr-Mo is not more than 40%,WC-?8Ni-3Cr-2Mo?sintered alloy has a smooth appearance and small deformation.The hardness of WC-?8Ni-3Cr-2Mo?sintered alloy increases with the content increasement of WC.The milling time of WC/Ni-Cr-Mo mixed powder has significant effects on the hardness and density of WC-?8Ni-3Cr-2Mo?alloy.When the milling time increased from 4 h to 50 h,the density of WC-30%?8Ni-3Cr-2Mo?alloy increased from 90% to 96.9% and the hardness of the alloy increased from HV 1076 to HV 1491.When the sintering temperature increased from 1400 ? to 1500 ?,the density of WC-20%?8Ni-3Cr-2Mo?sintered alloy increased by 2.7% and the hardness of WC-20%?8Ni-3Cr-2Mo?sintered alloy increased by HV 487.Corroded in concentrated hydrochloric acid,the corrosion rate of WC-?8Ni-3Cr-2Mo?sintered alloy increases with the increase of bonding phase.The corrosion morphology showed that the corrosion cracks appeared on the surface of the bonded phase,the WC spalling left the pits,or the hard phase WC particles were exposed.The corrosion mechanism is that the oxidation reaction of Ni^-2e-=Ni²⁺,Cr-3e-=Cr³⁺,Mo-3e-=Mo³⁺,and the cathode reaction of 2H⁺+2e-=H₂ occurred on the surface of WC.The wear rate of WC-?8Ni-3Cr-2Mo?sintered alloy is mainly in relation to the content of WC.The wear rate of WC-40%?8Ni-3Cr-2Mo?is the highest and the wear rate WC-20%?8Ni-3Cr-2Mo?is the lowest,which is in accordance with the hardness of WC-?8Ni-3Cr-2Mo?sintered alloy.The main wear mechanism of WC-?8Ni-3Cr-2Mo?alloy was adhesive wear.Deformation of metal bonded phase?Ni-Cr-Mo?leads to the adhesion failure with the WC particles falling off,also particles on the wear interface increase the plastic deformation and furrow phenomenon.