A Nanosized WO3 and CuO powder mixture is prepared using novel high-energy ball milling in a bead mill to obtain a W-Cu nanocomposite powder, and the effect of milling time on the structural characteristics of WO3-CuO powder mixtures is investigated. The results show that the ball-milled WO3-CuO powder mixture reaches at steady state after 10 h milling, characterized by the uniform and narrow particle size distribution with primary crystalline sizes below 50 nm, a specific surface area of 37 m2/g, and powder mean particle size (D50) of 0.57 μm. The WO3-CuO powder mixtures milled for 10 h are heat-treated at different temperatures in H2 atmosphere to produce W-Cu powder. The XRD results shows that both the WO3 and CuO phases can be reduced to W and Cu phases at temperatures over 700oC. The reduced W-Cu nanocomposite powder exhibits excellent sinterability, and the ultrafine W-Cu composite can be obtained by the Cu liquid phase sintering process.

Recently, the fabrication process of W-Cu nanocomposite powders has been researched to improve the sinterability by mechanochemical process (MCP), which consists of ball milling and hydrogen-reduction with W- and Cu-oxide mixture. However, there are many control variables in this process because the W oxides are hydrogen-reduced via several reduction stages at high temperature over 80 with susceptive reduction conditions. In this experiment, the W-15 wt%Cu nanocomposite powder was fabricated with the ball-milling and hydrogen-reduction process using W and CuO powder. The microstructure of the fabricated W-Cu nanocomposite powder was homogeneously composed of the fine W particles embedded in the Cu matrix. In the sintering process, the solid state sintering was certainly observed around 85 at the heating rate of 1/min. It is considered that the solid state sintering at low temperature range should occur as a result of the sintering of Cu phase between aggregates. The specimen was fully densified over 98% for theoretical density at 120 for 1 h with the heating rate of 1/min.

Recently, the fabrication process of the W-Cu nanocomposite powders has been studied to improve the sinterability through the mechanical alloying and reduction of W and Cu oxide mixtures. In this study. the W-Cu composites were produced by mechanochemical process (MCP) using mixtures with two different milling types of low and high energy, respectively. These ball-milled mixtures were reduced in atmosphere. The ball-milled and reduced powders were analyzed through XRD, SEM and TEM. The fine W-Cu powder could be obtained by the high energy ball-milling (HM) compared with the large Cu-cored structure powder by the low energy ball-milling (LM). After the HM for 20h, the W grain size of the reduced W-Cu powder was about 20-30 nm.

Electrical contact property of the W-20wt%Cu contact materials manufactured by liquid phase sintering of nanocomposite W-Cu powders was investigated and discussed in terms of microstructural development during performance test. Nanocomposite powders were prepared by hydrogen reduction of ball milled W-Cu oxide mixture. They underwent complete densification and microstructural homogenization during liquid phase sintering. As a consequence, the W-Cu contacts produced from nanocomposite powders showed superior contact property of lower arc erosion and stable contact resistance. This might be mostly due to the fact that the arc erosion by evaporation of Cu liquid droplets and surface cracking remarkably became weakened. It is concluded that the improvement of anti-arc erosion of the composite specimen is basically attributed to microstructural homogeneity.