Study of thermal expansion and thermal conductivity of cemented WC–Co composite

• Coefficient of thermal expansion (CTE) of WC-Co has linear dependence on the cobalt content.
• Thermal conductivity of WC-Co material increases with decreasing cobalt and increasing WC grain size.
• The effects of grain size and cobalt on thermal expansion/conductivity of WC-Co follow the rule of mixture principle.
• Magnetic saturation has no clear effects on CTE, but affects thermal conductivity.

Thermal properties are important to the cemented tungsten carbide product design and the product life. In this study, the thermal expansion and thermal conductivity of WC–Co material were measured using dilatometry and laser flash methods respectively. The effects of cobalt content, WC grain size and magnetic saturation (MS) on the thermal properties of cemented tungsten carbide were investigated. The results show that coefficient of thermal expansion (CTE) of WC–Co is strongly dependent on cobalt content. Grain size and MS have no clear effects on CTE. In contrast, the thermal conductivity of WC–Co is affected by all the factors. Larger grain size and less cobalt lead to higher thermal conductivity. High magnetic saturation increases thermal conductivity. The correlation equations of CTE/thermal conductivity as a function of WC grain size/cobalt content are proposed and discussed in the study. By considering the effects of WC/Co interface on the thermal properties, both thermal expansion and thermal conductivity of WC–Co materials can be explained using the rule of mixture principle.