FABRICATION AND PROPERTIES OF SiO2/ZIRCONIUM PHOSPHATE-B2O3-SiO2 ANTI-OXIDATION COATINGS FOR Cf/SiC COMPOSITES

• Published in: Ceramics (Praha) Vol. 59; no. 3; pp. 233 - 237
• Main Authors: Yang, X-J, Zhang, Y-D, Zhang, C-R, Li, B
• Format: Journal Article
• Language: English
• Published: 01.01.2015
• Subjects: Coatings; Composite materials; Demand; Modulus of rupture in bending; Oxidation resistance; Silicon carbide; Silicon dioxide; Zirconium
• ISSN: 0862-5468

Application of Cf/SiC composites at high temperature for e.g. hypersonic aircraft and reentry vehicles requires improved oxidation resistance. The fabrication of a novel SiO2/zirconium phosphate (ZrP)-B2O3-SiO2 double-layer coating on Cf/SiC composites via brushing and sol-gel routes to achieve better anti-oxidation performance is reported. The composition of raw materials and sintering temperature were studied to explore the possibility of developing ZrP coatings to meet the demand for oxidation resistance at high temperatures. An additional SiO2 layer was used in an attempt to improve the self-healing ability of the coatings. The double-layer coatings developed were characterised by SEM, EDS, XRD and results showed that such coatings were composed of a ZrP-B2O3-SiO2 multi-phase inner layer and a SiO2 outer layer. Improved oxidation resistance was observed for coatings with higher contents of ZrP powders. After static oxidation at 1500 C 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.