Thermal properties of MB2-WC (M = Ti, Zr, Hf) and tungsten and their stability after deuterium plasma exposure

The thermal properties of ultra-high temperature ceramics (UHTCs) in the MB2-WC (M = Ti, Zr, Hf) system and tungsten were studied for potential application as plasma-facing materials in fusion power plants. The sintered UHTC and tungsten samples were subjected to deuterium plasma or protons irradiation. Thermal diffusivity was measured using the laser flash method, and superficial thermal conductivity was analyzed through atomic force microscopy. Results showed that the thermal properties did not degrade when exposed to relevant environments and remained stable over a range of temperatures, unlike the reference tungsten material. Thermal conductivity ranged from 61 to 68 W m-1 K-1 for TiB2-2(WC-6Co), from 53 to 63 W m-1 K-1 for ZrB2-6WC, from 67 to 75 W m-1 K-1 for HfB2-6WC, and from 180 to 119 W m-1 K-1 for tungsten across the temperature range from room temperature to 1200 ◦C. The increasing trend of thermal effusivity, over 19000 J s-0.5 m-2 K-1 at 1200 ◦C, justifies further testing and of UHTC materials for fusion applications.