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Cohesion of Dissimilar Splats in Hybrid Plasma-Sprayed Coatings: A Case Study for Al2O3-TiO2
Journal of Thermal Spray Technology ( IF 3.1 ) Pub Date : 2022-04-22 , DOI: 10.1007/s11666-022-01401-4
Radek Musalek , Tomas Tesar , Jonas Dudik , Jan Medricky , Jaroslav Cech , Frantisek Lukac

Hybrid plasma spraying combines deposition of coarse dry powders and liquids, i.e., suspensions or solutions, thus expanding range of microstructures and functional properties achievable by thermal spraying. One of the crucial questions is how the miniature liquid-originated splats bond to the coarse splats deposited from powders and how their interaction influences the overall coating integrity. In this paper, cohesion of hybrid coatings was studied on model coatings deposited from Al2O3 powder and TiO2 suspension. Spraying distance and deposition temperature were varied as these two process variables influence the bonding between the splats in both conventional and liquid plasma spraying and the same may be expected for hybrid plasma spraying. Coatings without additional miniature splats were also prepared for comparison. Cohesion of the coatings was studied by four independent mechanical tests using different loading modes, namely tensile adhesion/cohesion test, cavitation test, conventional hardness test and instrumented indentation test. Results showed that interfaces between the dissimilar splats are not equivalent and that the coating strength greatly depends not only on the presence of the miniature TiO2 phase but also on the loading mode and involved interaction volume. When compared to the reference conventional coating deposited from Al2O3 powder, hybrid coatings were found to be less durable in adhesion/cohesion test but more durable in cavitation test and comparable in both hardness tests. Miniature TiO2 splats tended to be more strongly bonded to the above-laying Al2O3 splats than to the below-laying ones as large Al2O3 droplets possess greater ability to partially remelt previously deposited TiO2 than vice versa and even to form Al2TiO5 compound. Importance of splats deposition sequence and their remelting ability were confirmed also by the simplified analytical model.



中文翻译:

混合等离子喷涂涂层中异种斑块的内聚力:Al2O3-TiO2 的案例研究

混合等离子喷涂结合了粗干粉末和液体(即悬浮液或溶液)的沉积,从而扩大了可通过热喷涂实现的微观结构和功能特性的范围。关键问题之一是微型液体产生的板片如何与粉末沉积的粗板片结合,以及它们的相互作用如何影响整体涂层的完整性。本文在Al 2 O 3粉末和TiO 2沉积的模型涂层上研究了混合涂层的内聚力。暂停。喷涂距离和沉积温度是变化的,因为这两个工艺变量会影响传统和液体等离子喷涂中的板片之间的结合,并且对于混合等离子喷涂可能会出现同样的情况。还准备了没有额外微型碎片的涂层以进行比较。涂层的内聚力通过使用不同加载模式的四个独立的机械测试来研究,即拉伸附着力/内聚力测试、气蚀测试、常规硬度测试和仪器压痕测试。结果表明,异种板之间的界面不相等,涂层强度在很大程度上不仅取决于微型 TiO 2的存在。阶段还要论加载方式和涉及的交互量。与由 Al 2 O 3粉末沉积的参考常规涂层相比,发现混合涂层在附着力/内聚力测试中的耐久性较差,但在气蚀测试中更耐用,并且在两种硬度测试中具有可比性。小型 TiO 2片倾向于与上面铺设的 Al 2 O 3片比与下面铺设的片更牢固地结合,因为大的 Al 2 O 3液滴比反之亦然具有更大的部分重熔先前沉积的 TiO 2的能力,甚至形成 Al 2 TiO 5化合物。简化的分析模型也证实了 splats 沉积顺序及其重熔能力的重要性。

更新日期:2022-04-25
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