| With the continous development of electronic devices toward high power and light weight,this trend requires higher performance for electronic packaging heat sink materials.W-Cu composites using as heat sink materials have a promising application because of its high strength,excellent thermal conductivity,low coefficient of thermal expansion?CTE?and controling performance.However,processing of W-Cu composites with high performance by conventional liquid phase sintering,activated sintering and hot pressing sintering is hindered by high differences between their melting points and extremely limited solubility of tungsten and copper.In order to solve these problems,it is a hopeful solution by synthesizing homogeneous nano-sized W-Cu conposite powders with good sinterability and applying advanced sintering technology.In this article,nano-sized W-Cu precursor powders were synthesized by sol-gel with ammonium metatungstate?AMT?and copper nitrate Cu?NO3?2·3H2O as the raw materials.Following the precursor powders were calcined at 500°C,W-Cu composites were obtained by reducing the oxide composite powders in flowing hydrogen at 800°C.W-Cu composites were rapidly consolidated by HP under different pressure?60120 MPa?,different temperature?9001050°C?and different heat preservation time?13h?.The study found that the phase and elemental distribution of the reduced composite powders were analyzed by XRD,it showed that the nano-sized W-Cu particles have high purty and are uniformly intermixed.Morphology of W-Cu composite powders were characterized by SEM.It was found that composite powders had excellent homogeneity and spherical shape.The average size of W grains and Cu grains was about smaller than 350 nm.The W-Cu composites can reach 99.3%relative density when powders were sintered under120 MPa at 1050°C for 3 h.In this case,W-15 wt.%Cu composites showed excellent thermal conductivity?205 W/m K?,a relatively low thermal expansion(6.5×10-66 K-1),and high micro hardness?446 HV?. |
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