A Novel Physical Model for Describing Thermal Conductivity of Composite Materials: Application to the Measured Values in a Two-Phase WC-Co System

The method for describing the thermal conductivity of composite materials as a function of the grain size, temperature and composition remains undeveloped until now. Cemented carbide is one typical composite material. In order to remedy the current situation of understanding and facilitate designing cemented carbides with a desirable thermal conductivity, experiment and a newly developed physical model for assessing the thermal conductivity for WC-Co system were carried out in this work. The present physical model can produce results in good agreements with the 109 values of thermal conductivities for WC-Co system measured in the present work as well as from the literature. The good performance of the presently developed physical model indicates that it provides a reasonable way to evaluate the thermal conductivity for composite materials, which is also promising to be extended to multi-phase composite materials. By using this model, the thermal conductivity for pure WC was extrapolated for the first time, which lays a good foundation for studying the thermal conductivity of WC-based materials. Meanwhile, the thermal resistivities dependent on the temperature for the interfaces of WC/Co and WC/WC were also obtained by the present model for the first time. Moreover, several industrial WC-Co alloys as function of grain size and temperature were predicted by the physical model, which considerably contributes to designing cemented carbides with desirable thermal conductivities.