Densification and Diffusion Bonding of W-CuComposites by HIP Processing

Applications of HIP technique on W-Cu composites are studied and developed. TheCuinfiltrated W composites without nickel can be densified easily by HIP processing at the tempera-ture below the melting point of copper. The relative density of W-Cu composites increases from 96%-97% to nearly full dense for the materials in which copper contents are more than 30 percent inweight and improves to near 99 percent for W-Cu20 composites. The properties of W-Cu materials ,such as strength, hardness and electrical conductivity, and the homogeneity of properties are im-proved significantly. The diffusion bonding of W-Cu to W-Cu or Cu by HIP processing is also stud-ied. The bonding strength is in correspondence with that of matrix. It is possible to produce largedimension W-Cu workpieces and (W-Cu)-Cu complex layer materials in commercial scale.

Manufacture of high-dispersed W-Cu composite powder by mechano-thermal process

In order to improve the process of co-reduction of oxide powder, a new mechano-thermal process was de-signed to produce high-dispersed W-Cu composite powder by high temperature oxidation, short time high-energymilling and reduction at lower temperature. The particle size, oxygen content and their sintering abilities of W-Cucomposite powder in different conditions were analyzed. The results show that after a quick milling of the oxidepowder for about 3-10 h, the reduction temperature of the W-Cu oxide powder can be lowered to about 650 ℃ from700-750 ℃ owning to the lowering of particle size of the oxide powder. The average particle size of W-Cu powder af-ter reduction at 650 ℃ is about 0.5 μm smaller than that reduced at 750 ℃. After sintering at 1 200 ℃ for 1 h inhydrogen atmosphere, the relative density and thermal conductivity of final products (W-20Cu) can attain 99.5%and 210 W @ m-1 @ K-1 respectively.

The Characterization of W-Cu Composite Coating Prepared by Double-Glow Discharge

In this paper,a W-Cu composite coating was prepared on the Cu substrate through the double-glow discharge technology using a pure W plate as a target.In here argon gas was input into the chamber as the discharge and sputtering gas.The crystal composition and microstructure of W-Cu composite coating were examined by x-ray diffraction(XRD),scanning electron microscopy(SEM).The compose in the cross section was detected by energy dispersive spectrometer(EDS),the distribution of elements along the penetration thickness was then obtained.Then the friction coefficient,the polarization electrochemical corrosion test and the microhardness of W-Cu composite coating was measured.The results indicated that a thick and no-delaminated W-Cu composite coating could be prepared on the Cu substrate by the double-glow plasma technology.

Preparation of highly dispersed superfine W-20 wt% Cu composite powder with excellent sintering property by highly concentrated wet ball-milled process

The ball milling process and the CuWO-WOprecursors were investigated, and a new highly concentrated wet ball-milled process(HWM) was designed. W-20 wt% Cu composite powders with excellent sintering property were synthesized by highly concentrated wet ballmilled process and co-reduction. The powders were characterized by scanning electron microscopy(SEM), X-ray diffraction(XRD), field electron transmission electron microscopy(FESEM) and laser-diffraction diameter tester.The results indicate that particle size of W03-CuO powder mixtures decreases to 390 nm rapidly with the milling time increasing to 5 h. The CuWOprecursors promote the microstructural homogeneity of W and Cu. W-Cu composite powders have a highly dispersed and well sintering property. The particle size of W-Cu powders milled by HWM for 5 h is about 680 nm. High-resolution transmission electron microscopy(HRTEM) result suggests that W phase and Cu phase are mixed at nanometer scale. The above W-Cu composite powders reach the relative density of about 99.3%.