Boron carbide coatings on diamond particles

Boron carbide (B4C) coatings on diamond offer potential for obtaining homogeneous B4C-diamond composites with improved properties. A method was developed for coating diamond particles with B4C at 1150 °C under argon atmosphere for dwell times of 2–6 hours in a powder mixture of boric acid (H3BO3) and amorphous boron. The B4C coating showed very good adhesion to the diamond substrate, and an unusual five-fold symmetry thought to be due to a twinned growth mechanism. The sudden onset of nucleation at T > 1000 °C is ascribed to the stabilising effect of hydrogen from the decomposition of H3BO3 on the diamond surface reactivity.

Research Highlights
► Boron carbide coatings grown on diamond
► At 1150 °C in 6 hours under argon
► Boron carbide coating showed five-fold symmetry
► Good adhesion to diamond substrate
► Thermodynamically stable species of boron, oxygen and carbon calculated