等离子喷涂ZrC涂层耐烧蚀性能与机理研究

采用等离子喷涂工艺在C/SiC基体材料表面制备了较为致密的W粘结层和ZrC耐烧蚀涂层,利用氧乙炔火焰测试其抗烧蚀性能。结果表明:涂层具有良好的抗烧蚀性能。经烧蚀距离30 mm的氧乙炔烧蚀300 s后,涂层的质量烧蚀率为1.7×10~(-3)g·s~(-1),仅为无涂层试样的68%;线烧蚀率为4.0×10~(-4)mm·s~(-1),仅为无涂层试样的30%。随着烧蚀距离的减小,涂层的质量烧蚀率不断增大,线烧蚀率不断减小。试样表面温度梯度导致涂层存在3种典型烧蚀形貌,中心致密区,过渡区以及边缘疏松区。温度较高的中心区氧化产物为WO_3,其发生熔融并填充涂层内部孔隙和裂纹,形成致密层,且与ZrO_2所产生的协同效应有效降低了机械剥蚀几率,烧蚀以热化学烧蚀为主;温度较低的边缘区烧蚀产物未发生熔融且呈现疏松状,烧蚀主要表现为热化学烧蚀和机械剥蚀。

Ablation Resistant Properties and Mechanism of ZrC Coating Deposited by Plasma-Spraying

The comparatively dense W bonding layer and ZrC ablation-resistant layer were deposited by plasma spraying on C/SiC composite substrate. The ablation resistant properties were tested by oxyacetylene flame. The results show that the coatings have good ablation resistant properties. Ablated by oxyacetylene for 30 mm and 300 s, the mass ablation rate of ZrC coating is 1.7×10-3 g·s-1, only 68% of uncoated specimens; linear ablation rate is 4.0×10-4 mm·s-1, only 30% of uncoated specimens. With decreasing the ablation distance, the coating mass ablation rate increases, and the linear ablation rate decreases. Because of the temperature gradient caused by the oxyacetylene on the surface of the sample, the coating forms three kinds of ablation apparent morphology after ablation, including the central dense area, the transition area and the edge of loose area. In the central region, WO3 is melted due to high temperature, and effectively fills in the holes and cracks of the coating. In the end, a dense layer is formed, whereupon reducing the mechanical denudation, and the thermochemical corrosion plays a major role. In the marginal area, the ablation products are not melted due to low temperature and they are loose. The anti-ablation forms are mainly thermochemical corrosion and mechanical erosion.