Preparation Of W(WC)Cu Alloy By W/WC Composite Powder In Situ By Gas Phase Carbonization

The electrical contact is the core component of high pressure and ultra high voltage electrical appliances.The wide application of WCu contact material in high voltage electrical switch is mainly due to its excellent performance,it has advantages in tungsten with high melting point,high density,low expansion coefficient and copper with high electrical conductivity,high thermal conductivity.At present,China's per capita electricity consumption has been far more than 4000 kWh,and with the "smart manufacturing" and "industrial 4.0" advanced,in the next long period of time China's electricity consumption growth rate will remain above 3.5%."13th Five-Year Plan"requires that:by 2020 to fully build a"reasonable structure,advanced technology,flexible and reliable,cost-effective" modern distribution network.So the rapid development of the grid puts forward higher requirements on the performance and service life of WCu contacts.Therefore,developing WCu contact material with high performance and long life is a problem that we must solve.In this paper,the W powder is treated in the initial stage of preparation WCu alloy,and the carbonaceous gas is produced by thermal decomposition of the PF as the carbon source.The carbonaceous gas is pyrolyzed into C to deposit on the W particle surface in situ generation the tungsten carbide particles.The particles as a third component strengthen the WCu alloy.Investigated the effects of different carbonization methods on carbonation products at different carbonization temperatures and carbonization times.And the optimal W/WC composite powder was selected for the preparation of W(WC)Cu alloy,and tested its basic electrical and mechanical properties.Research indicates:(1)Increasing carbonization temperature is beneficial to form WC.Because W2C is formed at temperature,a large number of W2C gradually transformed into WC.Experiments show that when the temperature reaches 1000?,the product is mainly WC.(2)The prolongation of carbonization time can effectively change W2C to WC,so that the resultant phase is WC-based.The shorter carbonation time is insufficient to allow the C completely react with the W particles,and the resultant is WC/W2C.And at 1000?,the carbonization time was finally increased to 2h,and C on the surface of the W particles had sufficient time to diffuse into the particles and converted to WC by reaction with W2C.(3)W powder with tungsten oxide on the surface was reconstituted and hydrogenated at 750?for 5h to produce W/W2C powder.And the W/W2C composite powder with nanometer grade was obtained by reduction and carbonization of tungstic acid formed by completely oxidizing W powder.(4)W(WC)Cu prepared by W/WC composite powders through gas phase carbonization has a hardness of 210HB and a conductivity of 53.5%IACS,compared with the traditional WCu composite material its hardness increased by 19%,while the conductivity decreased by only 6.8%,also far higher than the national standard(GB/T8320-2003:42%IACS).And W(WC)Cu alloys have higher and more stable breakdown strength compared with WCu alloys without WC.