Ceramics-Silikáty 59, (3) 233 - 237 (2015)

This paper reports the fabrication of a novel SiO₂/zirconium phosphate (ZrP)-B₂O₃-SiO₂ double-layer coating on Cf/SiC composites via brushing and sol-gel routes for achieving better anti-oxidation performance. The composition of raw materials and sintering temperature were studied to explore the possibility of development of ZrP coatings to meet the demand for oxidation resistance at high temperature. It was attempted to improve the self-healing ability of coatings via an additional SiO₂ layer. Such double-layer coatings developed were characterized by Scanning Electron Microscopy (SEM), Energy Dispersive Spectrometer (EDS), X-ray Diffraction (XRD). The results showed that such coating was composed of a ZrP-B₂O₃-SiO₂ multi-phase inner layer and a SiO₂ outer layer. Better oxidation resistance was observed for coatings with higher contents of ZrP powders. After static oxidation at 1500^oC for 20 min, the flexural strength of specimens containing 80 wt. % ZrP was up to 314.6 MPa, retaining 89.1 % of the original value of Cf/SiC composites.