Process parameters correlated characterization of the corrosion fatigue behavior of post-treated ZnAl-coated arc-sprayed systems

热喷涂保护涂层可应用于许多机械应力部件，如支撑结构、轴、涡轮机叶片、热交换器。在许多情况下，除了静态或动态载荷之外，还会发生腐蚀过程的叠加，例如高温腐蚀或电化学腐蚀。在这种情况下，涂层是否设计用于腐蚀保护或磨损保护并不重要，因为应力可以在任何情况下发生。电弧喷涂ZnAl基涂层系统的腐蚀行为已经被广泛研究。然而，所使用的调查方法主要基于简单的腐蚀试验，例如作为盐喷雾试验或电化学腐蚀测量。关于ZnAl基涂层系统在表面技术领域中的技术应用，仅在有限程度上考虑化学-机械耦合载荷谱。在大多数情况下，不考虑在真实的应用中出现的部件或涂层的机械载荷，包括腐蚀性环境条件。然而，可以预期的是，机械负载显著改变层-基底-系统的使用寿命（疲劳）和腐蚀行为。应力或振动裂纹腐蚀等腐蚀机理将引起人们的高度关注。此外，该层和基底的不同电化学电势可导致加速腐蚀。科学上，涂层影响发生的腐蚀机制的程度，以及发生的层-基体相互作用的种类，是感兴趣的。为了研究这些问题，计划在现场进行不同极化的腐蚀疲劳试验。为此，不同的ZnAl基层系统，不同的硬度，层状结构和孔隙率，将开发和分析。此外，它将在何种程度上机器锤击（MHP）作为后处理影响涂层系统的形态和腐蚀疲劳行为进行调查。

Thermally sprayed protective coatings are applied onto many mechanically stressed components such as support structures, shafts, turbine blades, heat exchangers. In many cases, in addition to the static or dynamic loading, a superimposition with corrosion processes, e.g. high temperature corrosion or electrochemical corrosion occurs. Within this context, it does not matter if the coating was designed for corrosion protection or wear protection, since the stresses can occur in either case. The corrosion behavior of arcsprayed ZnAl-based coating systems has already been extensively studied. However, the investigation methods which were used, are predominantly based on simple corrosion tests, such as salt spray tests or electrochemical corrosion measurements. With regard to the technical applications of ZnAl-based coating systems in the field of surface technology, the chemo-mechanically coupled load spectrum is considered only to a limited extent. In most cases, the mechanical loads of the components or of the coatings, which occur in real applications, including the corrosive environmental conditions, are not taken into consideration. Yet, it is to be expected that a mechanical load significantly changes the service life (fatigue) and the corrosion behavior of the layer-substrate-system. Corrosion mechanism such as stress or vibration crack corrosion will be of high interest. Additionally, a different electrochemical potential of the layer and the substrate can lead to accelerated corrosion. Scientifically, the extent to which the coating influences the occurring corrosion mechanisms, as well as the kind of layer-substrate interaction that takes place, are of interest. In order to investigate these questions, in-situ corrosion fatigue tests with different polarizations are planned. For this, different ZnAl-based layer systems, varying in hardness, lamellar structure and porosity, will be developed and analyzed. Furthermore, it will be investigated to which extent machine hammer peening (MHP) as a post-treatment influences the morphology and corrosion fatigue behavior of the coating system.