Journal of Inorganic Materials ›› 2024, Vol. 39 ›› Issue (12): 1357-1366.DOI: 10.15541/jim20240249

Special Issue: 【结构材料】热障与环境障涂层(202412)

• RESEARCH ARTICLE • Previous Articles     Next Articles

Ti-doped Hf(Zr)B2-SiC Anti-ablation Coatings: Preparation and Ablation Resistance Mechanism

GUO Xiaoyang1(), ZHANG Xiaolin1, JIANG Yan1(), TIAN Yuan1, GENG Zhi2   

  1. 1. Key Laboratory of Special Functional Materials Synthesis and Preparation in Liaoning Province, Shenyang University of Chemical Technology, Shenyang 110142, China
    2. Shenyang Xinruite Electromechanical Equipment Co. Ltd., Shenyang 110015, China
  • Received:2024-05-17 Revised:2024-07-13 Published:2024-07-16 Online:2024-07-16
  • Contact: JIANG Yan, lecturer. E-mail: na_jiangyan@sina.com
  • About author:GUO Xiaoyang (1999-), male, Master candidate. E-mail: guoxiaoyang707722@163.com
  • Supported by:
    Liaoning Provincial Department of Education Youth Project(JYTQN2023371)

Abstract:

In order to improve the ablation resistance of carbon-based materials in elevated-temperature and oxygenated environments, Ti-doped HfB2-SiC and ZrB2-SiC composite coatings were prepared on the surface of graphite via a hybrid method involving slurry dipping and reactive infiltration. Phase compositions, microstructures, and element distributions of the composite coatings were studied, and anti-ablation ability of the coating was evaluated at 2300 ℃. Results show that structures of Ti-doped Hf(Zr)B2-SiC composite coatings are very dense after silicon infiltration. Both HfTiB2 and ZrTiB2 ceramic phases are embedded in the coatings, which exhibit no defects and establish robust bonds with the graphite substrates. Residual silicon continuously distributes around Hf(Zr)B2 and SiC particles. After undergoing ablation at 2300 ℃ for 480 s, the mass ablation rates of HfTiB2-SiC and ZrTiB2-SiC composite coating samples are -2.71×10-3 and -4.20×10-1 mg/s, respectively, indicating a slight weight gain. The corresponding line ablation rates are 1.88×10-4 and 3.70×10-4 μm/s, respectively. Following ablation, a Hf-Ti-Si-O multiphase oxide layer composed of HfTiO4-HfO2 as the skeleton and TiO2-SiO2 as the filling phase forms on the surface of HfTiB2-SiC coating. In contrast, a Zr-Ti-Si-O multiphase oxide layer with some micropores, comprising embedded ZrTiO4 and ZrO2 phases and a semi-continuous SiO2 glass phase, develops on the ablative surface of ZrTiB2-SiC coating. High-melting-point phases, such as HfTiO4, HfO2, ZrTiO4, and ZrO2, effectively counteract high-temperature flame erosion. Meanwhile, TiO2 and SiO2, possessing high-temperature fluidity, can seal the pore defects generated by erosion and thereby preventing oxygen from diffusing into the coatings and substrates. Therefore, the synergy between high-temperature skeletons and filling phases significantly enhances the anti-ablation protection of coatings.

Key words: ceramic coating, ablation resistance, slurry dipping, reaction infiltration, multiphase glass layer

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