Study On The Sintering Process And Properties Of NiCrBSi-WC Alloy

For super performance parts with wear-resistance and anti-corrosion, metallurgy sintering process of Ni Cr BSi/Ni Cr BSi-WC mixed powder was researched, and the formability of box furnace and vacuum sintering process of Ni Cr BSi/Ni Cr BSi-WC alloy powder was investigated. The influence of sintering temperature and time on the hardness, metallurgical structure,phases,and major composition of Ni Cr BSi/Ni Cr BSiWC sintered alloy, and the influence of WC addition on Ni Cr BSi-WC sintered properties was discussed by hardness tester, XRD,OM/SEM and EDS. With UMT tester, the wear rule of Ni Cr BSi-WC alloy was investigated. The results show as follows:The hardness of box furnace sintered Ni Cr BSi alloy first increases and then decreases with the increasing of temperature; when the sintering temperature is 1050℃, the hardness reaches the maximum value（59.2HRC）; when the sintering temperature is lower than 1050℃, the hardness also reaches a maximum value with the increasing of sintering time. when the sintering temperature is higher than 1050℃, the hardness decreases with the increasing of sintering time. The microstructure of box furnace sintered Ni Cr BSi alloy is eutectic structure which the Ni₃ Si, Ni₃ B, Cr₇C₃, Cr B, Fe₃ C distribute in γ-Ni substrate.When the vacuum sintering temperature is higher than 950℃, the hardness of Ni Cr BSi alloy decreases with the increasing of sintering time; when the vacuum sintering temperature is lower than 950℃, the hardness of Ni Cr BSi alloy increases with the increasing of sintering time; with the vacuum sintering temperature is 950℃, the hardness of Ni Cr BSi alloy reaches a maximum value（59.1HRC）. The microstructure of vacuum sintered Ni Cr BSi alloy is eutectic structure which the Ni₃ Si, Ni₃ B, Cr₇C₃, Cr B distribute in γ-Ni substrate.The hardness of Ni Cr BSi-WC alloy first increases and then decreases with the increasing of WC addition. When the addition of WC is 35%, the hardness of Ni Cr BSiWC alloy reaches the maximum value（HV1031）. The microstructure of Ni Cr BSi-WC alloy is eutectic structure comprising of Ni_2.9Cr_0.7Fe_0.36,（Fe,Ni）₂₃C₆ and WC, Cr₇C₃, Cr B hard phase. The wear mechansim of Ni Cr BSi-WC alloy is abrasive and adhesive wear.The box furnace sintering method of Ni Cr BSi powder is 1050℃×10min, and vacuum sintering is 950℃×10min, the vacuum sintering method of Ni Cr BSi-30%WC powder is 1050℃×20min, the wear resistance of Ni Cr BSi-35%WC is the best. The strengthening mechanism of Ni Cr BSi-WC sintered alloy is the solidification of the Ni Cr BSi liquid phase including WC solid phase grain, and the Cr₇C₃, Cr B deposition from Ni Cr BSi liquid phase.