Abstract

In this study, a SiC/ZrB₂ multilayer coating with a functional gradient structure was prepared on graphite to increase the ablation resistance. The SiC coating as the inner layer was applied by the reactive melt infiltration method. Then, a ZrB₂ outer layer coating was applied by argon gas shrouded plasma spray. The effect of the shielding gas flow rate on the amount of oxides and quality of the ZrB₂ coating was studied. To evaluate the ablation resistance of the coatings, the specimens were exposed perpendicular to an oxy-propane flame for 60 second with a temperature of 2473 K and heat flux of 3000 kW/m². The single-layer SiC coating showed 24.24 pct mass loss. The results indicated that applying the ZrB₂ coating significantly improved the ablation resistance and reduced the mass ablation rate. In the plasma spray process, by applying the argon shrouding with a flow rate of 150 L/min, the oxidation of ZrB₂ phase decreased from 41.6 to 4.8 pct. In addition, the weight loss and mass ablation rate decreased from 12.79 and 1.857 × 10⁻³ g/cm²/s to 0.12 pct and 0.0393 × 10⁻³ g/cm²/s, respectively. The improvement of the ablation resistance of the coating prepared by argon gas shrouded plasma spray could be attributed to the lower amount of oxides and pores in the as-sprayed coating and better cohesion of splats.

中文翻译：

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等离子喷涂法制备SiC / ZrB 2多层涂层的烧蚀行为

摘要

在这项研究中，在石墨上制备了具有功能梯度结构的SiC / ZrB ₂多层涂层，以提高抗烧蚀性。通过反应熔体渗透法涂覆SiC涂层作为内层。然后，通过氩气覆盖的等离子喷涂涂覆ZrB ₂外层涂层。研究了保护气体流速对ZrB ₂涂层的氧化物含量和质量的影响。为了评估涂层的抗烧蚀性，将样品垂直于氧丙烷火焰暴露2秒钟，温度为2473 K，热通量为3000 kW / m ²。单层SiC涂层显示24.24 pct质量损失。结果表明，应用ZrB ₂涂层显着改善了抗烧蚀性并降低了质量烧蚀率。在等离子喷涂过程中，通过以150 L / min的流速施加氩气罩，ZrB ₂相的氧化从41.6降至4.8 pct。另外，重量损失和质量消融速率分别从12.79和1.857×10 ^-3 g / cm ² / s降低到0.12 pct和0.0393×10 ^-3 g / cm ² / s。氩气包覆等离子喷涂制备的涂层的抗烧蚀性的提高可以归因于喷涂后涂层中氧化物和孔的数量减少，以及碎片的粘结性更好。