Effect Of Arsenic On Microstructure And Properties Of WC-Co Cemented Carbide

Previous research of our research group has found that adding a certain amount of arsenic can significantly refine tungsten powder.While conventional wisdom suggests that arsenic is a kind of common impurity element in tungsten metallurgy process,and its content is strictly controlled in tungsten products.In this study,by changing the adding amount of arsenic and through adding arsenic to the raw materials of secondary tungstate?APT?,the presence of arsenic in the process of tungsten metallurgy was reproduced,and APT-As composite precursor powder was prepared.After calcination,hydrogen reduction,carbonization and low-pressure sintering process,the corresponding nano W powder,ultrafine WC powder and super fine crystalline WC-Co cemented carbide were obtained.Systematically studying the influence law of arsenic on tungsten products in terms of physical features,morphology and performance,so as to provide theoretical and experimental basis for the preparation of tungsten products by directly using arsenic as a useful element in ores.the results showed that:1.After calcination and hydrogen reduction of APT-As composite precursor powder,W powder was obtained,its particle size was small and evenly distributed.With the increase of arsenic addition,the refinement effect of arsenic element on W powder was more significant.When the As addition was 1.0%,nano W powder was obtained,and the mean particle size was only 73 nm.however,the average particle size of conventional W powder prepared under the same conditions was 1.34?m.In order to inhibit the grain growth.2.After carbonization in 1400? of W powder containing arsenic,the WC powder was obtained.its particle size is small and distributed evenly,no abnormal coarse particles.When the As additive amount is 0.3%,the average particle diameter of WC powder was 0.24?m?the average particle diameter of conventional WC powder was 0.90?m?.When carbonization was carried out in low temperature at1300?,the refinement effect of arsenic element on WC powder was more significant with the increase of arsenic addition.When the As addition was 0.3%,the mean particle size of WC powder was only 0.14?m.3.The grain size,hardness and bending strength of WC-Co-0.3%As hard alloy prepared by low pressure sintering were 0.72?m,91.14 HRA and 2320 MPa,the corresponding blank sample of WC-Co hard alloy were 0.78?m,91.10 HRA and2171 MPa.The addition of the As improved the bending strength of cemented carbide in the case of no loss of hardness and no coarse grain.This may be related to the presence of As which existed in the Co phase in the form of WAs_2,pinning the Co phase.In order to inhibit the grain growth,under the condition of the addition of inhibitor,The crystal grain size,hardness,and bending strength of hard alloy with the addition of 1.0%As were 0.31?m,93.1 HRA,and 1947 MPa,respectively.