W-CU bimetal composite
Copper-Tungsten (Cu-W) or Tungsten-Copper (W-Cu) is a composite of copper and tungsten, with the percentage variable. Cu and W are almost insoluble with each other. Cu-W combines the properties from each component, such as the high electrical and thermal conductivity, low thermal expansion, the excellent mechanical properties, wear resistance and arc-erosion resistance.
Due to its integrated properties of high hardness and strength, a low thermal expansion coefficient, good arc-resistance arising from W, and high electrical and thermal conductivity from Cu, W–Cu composites offer excellent thermal, electrical, and mechanical performance. This group of materials has been widely applied in civilian industrial fields such as high-voltage electric contact parts, welding electrodes, electronic packaging, and thermal sinks and are also especially demanded in aerospace industries.
Infiltration and liquid phase sintering are conventional methods of preparing W–Cu composite bulk materials. The liquid phase sintering can be further classified as high-temperature liquid phase sintering and activated liquid phase sintering according to whether or not the elements that facilitate sintering densification are used.
In recent years, to refine and homogenize the micro structure of W–Cu composites prepared by liquid phase sintering, several methods have been developed to prepare nanoscale W and Cu metal powders or W–Cu nano composite powder as the sintering material.
To give full play to their respective advantages and improve the overall performance of the W–Cu composite, the ideal microstructure should be composed of inter penetrating W and Cu networks with high homogeneity and a high densification degree.
Properties in the aerospace industry
The recently developed submicron- and nanostructured W–Cu composites exhibit superior performance compared to their conventional coarse-grained counterparts and are expected to further expand applications of this group of materials.
W–Cu composites can be applied in aerospace fields, such as parts used in rocket and missile nozzles. W–Cu composites can bear high-temperature loadings where other materials generally lose function. To ensure high precision and high reliability in aerospace applications, the strength and ablative resistance of W–Cu composites at high temperatures must be deployed, in addition to their high electrical conductivity and high arc and wear resistance. Actually, this is a key point to extending high temperature applications of W–Cu composite materials.