Effects of simplified pretreatment process on the morphology of W-Cu composite powder prepared by electroless plating and its sintering characterization

Tungsten-copper (W-Cu) composite powder was prepared by electroless plating with a simplified pretreatment. Morphologies and coposition of the original W, simply pretreated W, W-Cu composite powder, and sintered W-u samples were analyzed by field emission scanning electron microscopy (FE-SEM), and energy dispersion spectrometry (EDS). Cold compaction was carried out under the pressure of 400 MPa while sintering at 1200 C. The relative density and electrical conductivity of the sintered samples were investigated. The results show that the defect formed on the surface of the simply treated W powder favors the adsorption, nucleation, and growth of Cu grain in subsequent electroless copper plating. Cellular projection at the same conditions on the surface of the simply treated W powder increased with the increase in HF content up to a certain range. The W-Cu composite powder obtained after electroless copper plating became more even; however, continued increase in HF content to a certain value caused the decrease in the number of defects that formed on the surface of pretreated W powder as well as the decrease in the amount of Cu grains adsorbed on the surface of W powder during electroless copper plating, but the number of free and not be adsorbed Cu grains were increased. Lastly, the obtained evenness degree of the W-Cu composite powder was reduced. At 1200 C and 400 MPa, the sintered specimen exhibited optimum performance, with the relative density reaching as high as 95.04% and superior electrical conductivity of IACS at 53.24%, which doubles the national average of 26.77%. (C) 2014 Elsevier B.V. All rights reserved.