Mechanisms of the plasma electrolytic oxidation of light-metal-based material compounds

减轻重量是实现技术和社会政治动机的技术系统能耗减少的基础，这些技术系统在服务期间处于运动状态。多材料设计和功能集成正成为轻量化材料和轻量化结构技术努力的焦点。与此相关的是，零件和结构的复杂性以及材料及其表面上的载荷制度的复杂性都增加了。在一个零件或组件中应用各种材料代表了表面处理方面的挑战。每种材料都需要特定的方法来调整和改善其表面性能。材料化合物中的各种材料不能被分离出来进行表面处理，而表面处理通常发生在工艺链的末端。对于铝/镁复合材料，初步研究表明等离子体电解氧化法（PEO）适用于处理材料化合物中存在的异种金属表面。然而，多材料PEO的作用机理尚未确定。特别是在异种金属上同时形成涂层（氧化物的形成和放电的溶解或破坏）的同时发生的化学和电化学反应是主要的科学问题。此外，缺乏关于PEO过程中促进在材料化合物的不同金属组分上形成功能氧化物涂层的能量输入分布的知识。初步研究表明，用于PEO的电解液是一个关键参数。本研究项目旨在阐明铝/镁和铝/钢材料化合物在PEO过程特征条件下（放电、高过电位、交变极化）与电解质之间的相互作用。利用模型实验和电化学测量以及对形成的氧化物涂层的分析，产生了PEO过程中材料化合物行为的基本知识。因此，轻金属基材料化合物的表面可以通过PEO来保护免受各种复杂载荷的影响。

Weight reduction is fundamental for achieving the technically and socio-politically motivated decrease of the energy consumption of technical systems, which are in motion during service. Multi-material design as well as functional integration are becoming a focus of technological efforts concerning both lightweight materials and lightweight construction. Associated therewith, both the complexity of parts and structures and the complexity of load regimes on materials and their surfaces increase. The application of various materials within one part or assembly represents a challenge in terms of surface treatment. Each material requires specific methods for the adjustment and improvement of its surface properties. Various materials in a material compound cannot be separated for the surface treatment, which traditionally takes place at the end of the process chain. For an aluminium/magnesium compound material, preliminary studies showed the suitability of the plasma electrolytic oxidation method (PEO) to treat the surface of dissimilar metals present in a material compound. The acting mechanisms of multi-material PEO, however, have not been established, yet. Especially the concurring chemical and electrochemical reactions during the simultaneous coating formation (oxide formation and dissolution or destruction by discharges) on dissimilar metals are of major scientific concern. Further, a lack of knowledge exists regarding the distribution of the energy input during PEO to facilitate the formation of functional oxide coatings on dissimilar metallic components of a material compound. Preliminary studies indicate that the electrolyte, which is used for the PEO, is a crucial parameter.This research project aims at the elucidation of the interactions between the material compound and the electrolyte under the characteristic conditions of the PEO process (discharges, high overpotentials, alternating polarization) for aluminium/magnesium and aluminium/steel material compounds. The utilisation of model experiments and electrochemical measurements as well as the analysis of the formed oxide coatings generates fundamental knowledge of the behaviour of material compounds in the PEO process. Thus, the surfaces of light-metal-based material compounds can perspectively be protected against various, complex loads by PEO.