Effects of dopants on properties and microstructure of doped graphite

Ti doped, Si–Ti doped and B4C–Ti–Si doped graphites were developed. The influence of the dopants on the properties and microstructure of these graphites were investigated. All Ti-doped graphites have a high thermal conductivity, with the highest value reaching 285 W/m K for a concentration of 7 wt% Ti in the raw materials. Si added simultaneously with Ti promotes the growth of graphite crystals and lowers the temperature necessary to obtain high performance compared to Ti-doped graphites. A thermal conductivity up to 350 W/m K was observed for Si–Ti doped graphites. B4C–Ti–Si doped graphites have a relatively high mechanical strength while their thermal conductivities are limited to 130 W/m K. For both bi- and tri-element doped graphites, the thermal conductivity and mechanical strength decrease with increasing amount of Si. Almost all Si in the bi- and tri-element doped graphites was depleted during the heat treatment at 2200 °C, resulting in the formation of cavities.