Papers by Keyword: W-Cu

Abstract: In this research, the W-40wt.%Cu composite tape-casting films were prepared through the vacuum hot-press sintering method, and the effect of sintering temperature on the microstructures and properties of the W-40wt.%Cu composite samples was studied. Microstructures of the W-40wt.%Cu tape-casting film and the prepared samples were analyzed by field emission scanning electron microscopy (FE-SEM). The phase of the samples was investigated by X-ray diffraction (XRD). The relative density, Vickers hardness, bending strength and electrical conductivity of the samples were investigated. The results show that the relative density of the W-40wt.%Cu composite materials enhances with the increasing of the sintering temperature, at the same time the mechanical and electrical properties are better with the increasing of the sintering temperature. The W-40wt.%Cu composites prepared at the condition of 900°C-200MPa-2h have the relative density of 97%, the bending strength of 507.3MPa, the Vickers hardness of 376.2HV and the electrical conductivity of 32.5% IACS, respectively.

Abstract: In this paper, the W-Cu functionally graded material (FGM) was prepared by using the non-aqueous tape-casting technique combined with vacuum hot-pressing sintering. The graded composite material with high density, uniform transition and graded component was designed by 7 layers with the copper content range from 40 to 100 wt. %. Then the structures and properties of the composite were characterized. The scanning acoustic microscope (SAM) results for the W-Cu graded material showed that the interface between different layers was of high smoothness and parallel. The SEM-EDS results of cross section show that the W and Cu content changed gradually along the laminating direction after sintering. The equivalent electrical conductivity and the equivalent thermal conductivity of the W-Cu graded material were 0.3976×10⁸ S/m and 323.5 W/(m·K), respectively, which were much higher than that of the W-40 wt. % Cu homogeneous composite. The Vickers hardness of the high tungsten content surface and the high copper surface were 163 HV and 80 HV, respectively, which were same with that of the homogeneous material.

Abstract: High-performance copper-coated tungsten composite powders were successfully prepared using electroless plating at an appropriate pH in the plating bath. The effect of pH value in the plating bath on the microstructure and purity of the coated Cu layer was studied systematically. With the increase of pH in the bath, the surface roughness, particle size and average grain size of coated Cu increased, and the particle shape gradually changed from round into square block. At pH 12–12.5, coated Cu was highly pure with very little oxygen content (less than 0.09 wt.%). The promotion effect of the increased pH on both main electroless plating reaction and side reactions causes the changes of surface morphology, average grain size of Cu and the oxygen content in the composite powders.

Abstract: The sintered microstructure homogeneity of W-15wt%Cu nanocomposite powders prepared from W-CuO mixture was investigated. The increment of heating rate considerably affected the homogeneity of sintered microstructure. In case of the higher heating rate, the microstructure was more homogeneous than that of the lower heating rate by reason of Cu- exudation during heating-up process.