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• A new model for obtaining thermal conductivity of composite materials is developed. • The model includes all key factors i.e. grain size, composition and temperature. • The thermal conductivities for WC-Co and WC-Ag systems are evaluated by the model. • For the first time, the thermal conductivity of pure WC is obtained. • The model contributes to designing materials with a desirable thermal conductivity. In the present work a new thermal conductivity model is developed for two-phase composite materials, which are consisted of a continuous matrix and dispersed 3D-particles separated from each other by the matrix as a function of grain size and volume ratio of the dispersed particles at different temperatures. The model is applied to reproduce experimental thermal conductivity values of cemented carbide systems WC-Co and WC-Ag. Good agreement was found between measured thermal conductivity data originating from both this work and recent literature and the calculated ones only using semi-empirical parameters for the interfacial thermal resistance (ITR) values at WC/Co, WC/Ag and WC/WC interfaces as a function of temperature. Additionally, the temperature and grain size dependence of the thermal conductivity for WC is established for the first time. The model works well for the case when the matrix (Ag) has a higher thermal conductivity compared to that of the WC particles and also for the case when the matrix (Co) has a lower thermal conductivity compared to that of the WC particles. The new model forms a physically sound basis for further development / materials design of cemented carbides and particle-reinforced composite materials. [Display omitted] [ABSTRACT FROM AUTHOR]

Based on a unique method to synthesize WC–Co composite powder by in-situ reactions of metal oxides and carbon, the effects of the carbon addition in the initial powders on the phase constitution, microstructure and mechanical properties of the cemented carbides were investigated. It is found that with a suitable carbon addition the pure phase constitution can be obtained in the sintered bulk from the composite powder. The mechanical properties of the cemented carbides depend on the phase constitution and the WC grain structure. To obtain the excellent properties of the WC–Co bulk, it is important to obtain the pure phase constitution from the appropriate carbon addition in the initial powders and a suitable grain size. [Copyright &y& Elsevier]