Performance Of WC-based Carbide And Its Application In Hard Seal Ball Valves

Ball valve as a valve,in addition to the general application of industrial pipelines,also plays an important role in the West-East Gas Pipeline,coal oil engineering and aerospace industry.However,the current hard seal ball valve because of corrosion,strong wear lead to shorter life problem,and to extend the life of the ball valve has become research hotspot.In this paper,WC-based carbide is used in the ball valve ball and seat,and make a preliminary study for the actual working conditions.In this article,four kinds of WC-based cemented carbides were prepared by low-pressure sintering technology,and Co and Ni were used as the binder.The contents of WC in the alloy were 84 wt.%,88 wt.%,90 wt.% and 92 wt.% respectively.The contents of the Co-bonded phase were 14 wt.% and 10 wt.%,respectively.And the content of Ni-based binder were 8wt.% and 6wt.%.Optical microscopy(OM),Scanning electron microscopy(SEM),Energy dispersive spectroscopy(EDS)and X-ray diffraction(XRD)were studied for the microstructure and phase comp osition of the alloy.Vick ers har dness tester was used to test the hardness of the alloy.The corrosion resistance of the alloy was measured by the surface comprehensive performance tester.The corrosion resistance of the alloy was measured by electrochemical workstation.The life of the alloy and the valve seat were measured by the switch experiment.The experimental results draw the following conclusions.(1)Low-pressure sintered pure nano-WC-based cemented carbide,alloy grain size increases with the increase in WC content.The hardness of the alloy increases with the increase of WC content,and the bending strength is independent of the content of WC.(2)With the WC content increased,the alloy wear resistance enhanced.Under low load,the alloy almost does not wear;under the load,the wear mechanism of the alloy is abrasive wear;under high load,the main wear mechanism of the alloy is adhesive wear.(3)At room temperature,WC-6Ni and WC-14 Co meet the needs of wear-resistant ball valve,which is put into p roduction and used for ball valve seat and angle valve internal.Under low temperature conditions,the temperature dropped from 20℃ to-110℃,WC-based hard alloy hardness increased slightly.but at-196℃ when the hardness dropped significantly,so the alloy is not suitable for ultra-low temperature conditions.(4)The corrosion resistance of the alloy in acidic medium is: WC-14 Co <WC-10 Co <WC-8Ni <WC-6Ni.The corrosion resistance of the alloy in alkaline medium is: WC-10 Co <WC-6Ni <WC-8Ni <WC-14 Co.The corrosion resistance of the neutral medium is: WC-14 Co <WC-10 Co <WC-6Ni <WC-8Ni.WC-based hard alloy corrosion resistance is very good,in three kinds of media corrosion resistance were: acidic medium <neutral medium <alkaline medium.So the alkaline environment can be considered when using WC-based carbide prepared valve.