Analysis of the compaction process of copper clad tungsten powders

Abstract

The paper analyzes the pressing process of a composite powder of the tungsten-copper system using the basic mathematical equations describing the deformation processes of a porous body as a function of density and pressing pressure. Several theoretical dependences describing different pressing mechanisms are considered, taking into account modern approaches, namely the discrete-contact model and the continuum model of a continuous medium. The most well-known equations, including those of Balshin M.Y., Zhdanovich G.M., and Shtern M.B., are analyzed. It is established that most of them have limited applicability, remaining valid for individual stages of the pressing process and significantly depend on the mechanical properties of the material that determine the predominance of elastic or plastic deformation. At the same time, most equations are focused on single-component powders, which does not correspond to the practice of powdered parts production processes. To test the theoretical dependencies, copper-clad tungsten powder was obtained by chemical vapor deposition from solution. The technological parameters of the cladding process (composition, solution concentration, and deposition time) that determine the quality of the resulting coatings were determined. The morphology of the particles of clad powders and the structure of tungsten-copper pressings were investigated. It is shown that tungsten powder forms a relatively dense framework with a copper layer, respectively, the structure of composite powder pressings is as close as possible to a continuous continuum and is correctly described by an equation based on the theory of continuity of the medium, It has been established that the compaction character of copper-clad tungsten powder differs from that of single-component tungsten powder, which is due to the fact that plastic deformation mechanisms prevail for tungsten-copper composite powders.