The knowledge of the rupture mechanism of multilayer systems is necessary for improving the bonding of materials, particularly for the ceramic-to-metal junctions, and especially in the case of the ceramic coatings on metallic substrates. For this purpose, coupling experimental measurements of macroscopic interfacial adhesions with numerical tools of fracture mechanics allow understanding how the stress distribution and the cracking mechanisms are influenced by the local environment. This brings an explanation to the cracks initiation and propagation and to the role of local characteristics of the interfacial zone. The present work illustrates this, in the case of alumina coatings strongly bonded to C35 steel substrates previously pre-oxidized in CO2. The experimental tool is based on the “silver print test”. It consists in covering the central part of the samples with a thin layer of silver paint before coating in order to create a defect zone. Concerning the numerical part, the finite element method is used as a powerful tool to describe the mechanical phenomena at the local scale influencing the crack propagation. The obtained numerical results show a good agreement with the experimental observations and they allow a local description of the phenomena influencing the cracking mechanism. Moreover, they lead to a concrete proposition for improving the coatings adherence.

中文翻译：

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C35 钢上氧化铝涂层的破裂：数值模拟

多层系统破裂机制的知识对于改善材料的结合是必要的，特别是对于陶瓷与金属的连接，尤其是在金属基材上的陶瓷涂层的情况下。为此，将宏观界面粘附的实验测量与断裂力学的数值工具相结合，可以了解局部环境如何影响应力分布和开裂机制。这为裂纹的萌生和扩展以及界面区域的局部特征的作用带来了解释。目前的工作说明了这一点，在氧化铝涂层与先前在 CO2 中预氧化的 C35 钢基材上牢固结合的情况下。实验工具基于“银印测试”。它包括在涂层之前用一层薄薄的银漆覆盖样品的中心部分，以产生缺陷区域。关于数值部分，有限元方法被用作描述局部尺度上影响裂纹扩展的力学现象的有力工具。获得的数值结果与实验观察结果非常吻合，它们允许对影响开裂机制的现象进行局部描述。此外，它们为改善涂层附着力提出了具体建议。获得的数值结果与实验观察结果非常吻合，它们允许对影响开裂机制的现象进行局部描述。此外，它们为改善涂层附着力提出了具体建议。获得的数值结果与实验观察结果非常吻合，它们允许对影响开裂机制的现象进行局部描述。此外，它们为改善涂层附着力提出了具体建议。