New route to synthesize ZrB₂ coatings by reactive chemical vapor deposition method using Zr-BCl₃-H₂-Ar reagents

A ZrB₂ coating was deposited for the first time from a Zr-BCl₃-H₂-Ar system by reactive chemical vapor deposition (RCVD) technique under a low pressure condition, and the effects of temperature and BCl₃ and H₂ fluxes on the RCVD of ZrB₂ were systemically evaluated. The temperature mainly affected the deposition rate, morphology, and infiltration ability of the coating and the conversion rate of ZrB₂ particles. The reaction rate and the nucleation and growth of ZrB₂ particles significantly varied with BCl₃ flux. The H₂ flux affected the nucleation, growth, and conversion rate of ZrB₂. A dense and smooth ZrB₂ coating was deposited at 1273 K, and the BCl₃ and H₂ fluxes were 80 mL/min and 150 mL/min, respectively. The deposition mechanism was elucidated from the experimental conditions. The ZrB₂ deposition was controlled by surface reaction kinetics at low temperatures and by diffusion at high temperatures.