Infiltration Cuw / Crcu Overall Interface Behavior Of The Material And Cuw Alloy

Combining the excellent property of electrical arc resistance of CuW alloy andthe eminent conductivity and high elasticity of CrCu alloy, CuW/CrCu integratedmaterials are widely used as contact material of high voltage breakers. In this paper,CuW/CrCu integrated materials with 50%, 60%, 70% and 80% W by weight wereprepared by vertical integrated sintering and infiltration technique. The combinationmechanism of CuW/CrCu interfaces was studied. The ingredient and formation of thedark grey substance existed on the CuW/CrCu interfaces were analyzed. The diffusionof Cr through the interfaces of CuW/CrCu, the distribution of Cr in CuW alloy, andthe effect of Cr on the electrical conductivity of CuW alloy were also studied. Thenthe oxidization behavior at low temperature and wear resistance of CuW alloy werestudied. TWo models of the electrical conductivity of CuW alloy and CuW/CrCuintegrated material were established on the basis of physics. The results showed that:1.CuW and CrCu were combined through Cu-Cu couple and Cu-W couple. Ofthe two couples, Cu-Cu couple accounted for the leading status which made largercontributions to the bond strength, While Cu-W couple accouned for the secondarystatus which made less contributions to the bond strength.2.The tensile strength of pressed CuW/CrCu integrated materials decreased withthe increase of W content, and the tensile strength of loosely packed CuW60/CrCuwas smaller than pressed CuW60/CrCu integrated material.3.The oxide impurities probably existed on the interfaces of CuW/CrCu weremainly WO₃, W₃O and SiO₂, and they reduced the bond properties and conductivityof CuW/CrCu integrated materials.4.During the preparation process of CuW/CrCu integrated materials, Cr elementin CrCu alloy diffused into CuW alloy through the CuW/CrCu interfaces, part of Cratoms preferentially combined with W dissolved in each other and distributed aroundthe larger W particles, other few Cr atoms still dissolved in Cu. The contell of Crdiffosed into CuW alloy decreased with the increase of W content and the increase ofdistance from the inierface. During the heat tTedrient of solation and aging, theelectrical conductivity of CuW al1oy increased because of the dissolution andprecipitation of Cr. Wth the increase of W content, the increase tendency of theelectrical conductivity of CuW alloy decreased gradally with the aging time extends.5.Using the electrical conductivity models established in this paPer, we canevaluae the microsrt of CuWCrCu integratCd materials. When the calculationvalues from equation (3-l0) were obviously different from the experimental values,which demonstrated that there were many defects existed in CuW al1oy, we shouldexamine the microstructhe of CuW alloy. When the eXPerimemel values measuredthrough the four-dot direct current double ann electrical bridge were obviously lessthan the values 1isted in Table 3-5(using LI =L2 samples) or the calcu1ation values fromequation (3-20)(using LI rt2 samPles), the bond state betWeen CuW and CrCu waspoor or there may existed some oxides and imPdrities on the interfaces, therefore weshould examine the process of sintering and infiltration.6. Wth the increase of temperthee, the oxidization degree of CuW alloy becamemore serious, ie the oxidiZaion resistance was pooL During the oxidization of CuWalloy, at 300oC, ouly Cu was oxidized, W was not oxidised; While at 400'C, except theoxidization of Cu, W was partly oxidized; at 500C, both Cu and W were seriouslyoxidized. Wth the increase of W content, the oxidization resistance of CuW alloyincreased at 300C while decreased at 400'C and 500oC.7.The wear mechanism bbeen CuW alloy and 45 steel belongs to thecomPosite wear including adhesive wear and abrasive wear. The main wearmechanism changed from the adhesive wear to abrasive wear with the increase of Wcontellt. Wth the increase of W cooteni, the bond State betWWn Cu and W particlesof pressed CuW alloy...