Microstructure Analysis and Preparation of B<sub>2</sub>O<sub>3</sub>-Modified ZrSiO<sub>4</sub>/SiC Oxidation Resistant Coatings

A B 2 O 3 -modified ZrSiO 4 outer coating was prepared by Pulsed arc Discharge Deposition on the surface of SiC bonding layer coated carbon fiber reinforced carbon (C/C) composites. The phase compositions of the prepared coatings were analyzed by X-ray diffraction (XRD), the morphologies of the multi-layer coatings were observed by scanning electron microscopy (SEM). The influence of pulsed arc discharge deposition electric voltage and time on the phase composition, microstructure of the mixed coatings was particularly investigated. And the invalidation behavior of the as-prepared coating coated samples at 1273K was analyzed. XRD results show that the outer layer of the coating was mainly composed of B 2 O 3 and ZrSiO 4 phase. When the deposition electric voltage was 400V, single deposition time was 8 min, total time was 32min, the structure and thickness of the outer layer was compact and uniform. The coating prepared at optimal technological conditions could effectively protect C/C composites from oxidation at 1273K in air for 600min with a weight loss of 4.063%. The failure of the coating at intermediate temperature is due to the generation of some cross-cracks in the coating and sectional volatilization of B 2 O 3 .