Effects of the La2O3 addition contents on the ablation performance of in-situ La-doped ZrC-SiC-ZrSi2 coating for C/C-ZrC-SiC composites

• Published in: Surface & coatings technology 2023-01, Vol.452, p.129104, Article 129104
• Main Authors: Ma, Jingchao, Kou, Sijie, Ma, Yujie, Ma, Xu, Luan, Chenghua, Deng, Juanli, Fan, Shangwu, Liu, Chidong, Cheng, Laifei
• Format: Article
• Language: English
• Subjects: Ablation behavior; C/C-ZrC-SiC composites; In-situ La-doped ZrC-SiC-ZrSi2 coating; La2O3 addition contents
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2022.129104

The C/C-ZrC-SiC composites coated by the La-doped ZrC-SiC-ZrSi2 coatings containing different La contents were fabricated by reactive melt infiltration (RMI) combined with gradient pack cementation in a one-step process. The composites' ablation behaviors under the oxyacetylene flame were comparatively studied. The effects of the La2O3 addition contents on the microstructure and phase composition evolution on the surface of the composites caused by ablation were investigated. The results indicated that the C/C-ZrC-SiC composites with an in-situ La-doped ZrC-SiC-ZrSi2 coating prepared by the mixed powders with 15 wt% La2O3 (15LZS) showed a better ablation performance. After ablation for 120 s, their mass and linear ablation rates were − 0.62 ± 0.15 mg/s and − 2.42 ± 0.24 μm/s, respectively. Such good ablation resistance should owe to appropriate La contents on the surface of the 15LZS. During ablation, the La elements could promote the formation of a dense oxide layer, which was composed of the m-ZrO2, t-ZrO2, and Zr0.9La0.1O1.95 phases. It could efficiently inhibit oxygen diffusion and endure the mechanical denudation of the oxyacetylene flame. •The C/C-ZrC-SiC composites with in-situ La-doped ZrC-SiC-ZrSi2 coatings containing different La contents were fabricated by the RMI.•The composites prepared by the mixed powders with 15 wt% La2O3 showed a better ablation performance after ablation under the oxyacetylene torch.•The evolution of phases and morphologies and the ablation mechanism of composites during ablation were systematically studied.