Influence of hydrothermal treatment on the microstructure and oxidation resistance of a Zn4B2O7·H2O (4ZnO·B2O3·H2O) coating for C/C composites. (3rd May 2016)

• Record Type: Journal Article
• Authors: Yang, Liuqing; Huang, Jianfeng; Cao, Liyun; Fei, Jie; Ouyang, Haibo; Li, Cuiyan; Wu, Jianpeng; Hao, Wei
• Is Part Of: Materials at high temperatures. Volume 33:Number 3(2016)
• Page Start: 283
• Page End: 287
• Publication Date: 2016-05-03
• Subjects: C/C composites -- Zinc borate -- Antioxidant modification -- Hydrothermal treatment; Materials at high temperatures -- Periodicals; High temperatures -- Periodicals; 620.1121705
• DOI: 10.1080/09603409.2016.1190899
• Languages: English
• ISSNs: 0960-3409

Abstract

Abstract : Antioxidant modification for C/C composites by in situ hydrothermal synthesise at 140 °C of a 4ZnO·B2 O3 ·H2 O crystallite coating has been successfully achieved. The influence of hydrothermal time on the phase composition, microstructure of the as-prepared Zn4 B2 O7 ·H2 O (4ZnO·B2 O3 ·H2 O), and its antioxidant modification for C/C composites were investigated. Samples were characterised by XRD, SEM, isothermal oxidation test and TG-DSC. Results show that, 4ZnO·B2 O3 ·H2 O crystalline coating is achieved on the surface of C/C composites after the hydrothermal treatment at 140 °C for time in the range of 2–12 h. A smooth and crack-free 4ZnO·B2 O3 ·H2 O layer can be obtained when the hydrothermal time reaches 8 h. Isothermal oxidation test demonstrates that the oxidation resistance of C/C composites is improved. The as-modified composites exhibit only 1.52 g·cm −2 weight loss after oxidation at 600 °C for 15 h, while the non-modified one shows a 6.57 g·cm −2 weight loss after only 10 h oxidation. For the uncoated C/C composite the oxidation rate is approximately linear with time (non-protective oxidation), thus at 15 h exposure one can estimate the mass loss to be 6.57 g·cm −2 after 10 h for direct comparison with the coated samples.