Zr-Mo-Si-C四元复合涂层抗氧化烧蚀性能研究

Oxidation and Ablation Resistance of Zr-Mo-Si-C Composite Coating

目的提高C/C复合材料高温抗烧蚀性能。方法通过低压等离子喷涂技术,在石墨基体表面制备出Zr-Mo-Si-C四元复合涂层,采用氧-乙炔火焰烧蚀试验对涂层的抗烧蚀性能进行测试,并通过SEM、EDS、XRD分析了烧蚀前后涂层的物相组成和微观形貌,分析了涂层的抗烧蚀机理。结果涂层在1800℃烧蚀60、180、300 s后均保持良好的涂层状态,线烧蚀率分别为1.2×10^(-3)、0.4×10^(-3)、0.3×10^(-3) mm/s。烧蚀300 s后,涂层截面呈现三个区域,分别为表面烧蚀区、阻挡层和未烧蚀区。结论通过添加Mo Si2作为第二相可显著提高ZrC涂层的抗烧蚀性能,涂层在烧蚀过程中形成三个区域,其中表面烧蚀区和阻挡层能够有效地阻隔烧蚀的进行,未烧蚀区发生的烧结致密化进一步提高了涂层的抗氧化烧蚀性能。

Coating technology is a main method to improve ablation resistance of C/C composites at high temperature. Zr-Mo-Si-C composite coating was prepared on graphite substrate by low pressure plasma spray. The ablation resistance of the coating was tested by oxyacetylene flame. The phase composition and microstructure of the coating were studied by XRD, EDS and SEM, respectively and the ablation mechanism of the composite coating was also analyzed. The coating was in good condition after ablation at 1800 ℃ for 60 s, 180 s and 300 s and the linear ablation was respectively 1.2×10^-3 mm/s, 0.4×10^-3 mm/s and 0.3×10^-3 mm/s. For 300 s＇ ablation, there were three areas on the cross section of the coating, respectively ablative area, barrier layer and non-ablative area. The ablation resistance of Zr C coating can be improved by adding MoSi_2 as the second phase. The coating shows three areas during ablation, ablative area and barrier layer can effectively inhibit the ablation and non-ablative area forms sintering densification to further improve the oxidation and ablation resistance of coating.