A new model for thermal conductivity of “continuous matrix / dispersed and separated 3D-particles” type composite materials and its application to WC-M (M = Co, Ag) systems

•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.