Thermophysical Properties of Powder-Polymer Mixture for Fabrication of Parts of 42CrMo4 Steel by the MIM Method

Resumo

This article analyzes thermophysical properties of disperse-filled metal polymer composites, also known as feedstocks, which are used in injection molding. Analytical models of specific heat capacity, effective thermal conductivity, and thermal diffusivity of such materials are reviewed. It is mentioned that the existing models can be applied only for an evaluative calculation of thermophysical properties of feedstocks. Differential scanning calorimetry (DSC) has been applied to measurement of temperatures characterizing melting of polyoxymethylene in binder of Catamold 42CrMo4 feedstock used for injection molding of parts of 42CrMo4 steel, an analog of 38KhMA steel. The specific heat of this phase transition has been determined. The temperature dependences of specific heat capacity, effective thermal conductivity, and thermal diffusivity of Catamold 42CrMo4 feedstock have been estimated. The calculated thermal diffusivity and specific heat of the considered feedstock have been verified with experimental data obtained by laser flash analysis (LFA) and DSC. It has been demonstrated that the thermophysical properties of feedstocks differ significantly from those of both metals and unfilled polymers. Specific thermophysical properties of feedstocks lead to variations of norms of technological molding modes applied in the plastics industry and norms of technological molding modes of feedstocks.