Investigation Of Effects Of Electrical Field And Elements(Fe And Co) On The Wettability Of Copper On Tungsten

Cu-W composites are widely used as materials for high voltage contact,electronic sealing and hot depositing due to excellent electric and thermal conductivity,low thermal expansion.Because the melting point of W is much more higher than that of Cu as well as the mutual insolubility,Cu-W composites are generally fabricated by infiltration.During the process of infiltration to produce Cu-W composites,the wettability between the liquid and the solid can decide many properties of the material,such as compaction,hardness,conductance and the combinative intensity of Cu and W.Nowadays,there are few reports in detail about the effect of various factors on the wettability between Cu and W.Drop-sellite method is used to study the wettability between Cu and W under different factors,such as tempreture,different gases,adding different content of Co and Fe elements as well as electrical filed.Frist,the effects of adding different contents of Co and Fe elements respectively on the wetibality is studied under different tempretures,exprimatentions are carded out under the conditions of vacuum and Ar gas respectively.It showes that the adding elements have greatly reduced the contact angles between Cu and W and it contiously reduced with the increasing content of element on the same tempreture.The micro- structure of the interface between Cu and W is studied with EDS and EDS,it showes that there is a continuously-changed district of alloyed elements and the micro-dardness in the interface area.It finds that the alloyed elements reduced the surface tention of Cu and the interface tention between Cu and W,it also finds that they promote the diffusiton of Cu and W elements in the interface district as well as the combation of Cu-Cu and Cu-W,so that the wettibality is improved.Secondly,the effects of electrical field on the wettibality is studied under the condition of Ar gas.the exprimatention is carried out on the tempreture of 1200℃.It showes that the contact angles are continuously reduced with the increasingly electrical intention,it also showes that the effect of electrical field isnot as notable as the effect of alloyed elements.The micro-structure of the interface is also studied with EDS and SEM.It finds that the electrical field promotes the diffusiton of Cu and W elements in the interface district as well as the formation of interface alloyed layer through many chymic mechanism,it also reduces the surface tention of Cu and the interface tention between Cu and W.So that the electrical field improved the wettibality of Cu and W.Thirdly,the contact angles between Cu and W under different tempretures and gases are studied.Bacause tempreture has different effects on the diffusion of elements,surface tention of the drops,the formation of precursor,viscosity of liquids,the contact angles between Cu and W under different tempretures are somewhat different.Because the gas has different effects on the oxygenation,the formation of precursor,the melting points of drops,the contact angles between Cu and W under different gases are somewhat different too.