Enhancement of oxidation resistance via titanium boron carbide coatings on diamond particles

Abstract

The protective titanium boron carbide (TiBC) coatings were formed on diamond particles during high temperature process. The composition and bond state of the TiBC coatings on the diamond particles were investigated. The oxidation resistance of the TiBC-coated diamonds was measured by the thermogravimetric analysis. The results reveal that the boron content is very important for the adhesion of the TiBC coating on diamonds. The TiBC coating with 60 at.% boron protected the diamond from oxidation for more than 1 h when heating at 1000 °C in air atmosphere. In contrast, a weight loss was observed once after heating to 1000 °C for the TiBC-coated diamond with 11 at.% boron. During annealing of the coated diamond in air, the priory formed B2O3 and TiO2 protected the diamond from oxidation through acting as oxygen barrier layers. In addition, the formation of fluid B2O3 was benefited to avoid the delamination of TiO2 caused by volume expansion during oxidation. Meanwhile, the existence of TiO2 provided an enduring protection by reducing the evaporation of B2O3.