Chemical and electrical interaction mechanisms during the plasma electrolytic (PEO) mixed oxide formation on magnesium

镁上等离子电解（PEO）混合氧化物形成过程中的化学和电相互作用机制

• 批准号: 421508739
• 负责人: Professor Dr.-Ing. Thomas Lampke
• 金额: --
• 依托单位: Professur Werkstoff- und Oberflächentechnik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/421508739?language=en
• 关键词: Chemical; electrical; interaction; mechanisms; during

Magnesium is the lightest metallic engineering material and therefore offers an enormous potential to save weight in mobile systems. Beyond that, magnesium is easy to recycle. Excellent casting process properties and a good damping capacity towards electromagnetic and mechanical oscillations predestine magnesium materials for the construction of machine casings as well as framework and encasements for sensible sensory, optical and entertainment electronic devices. Despite the positive processing and application properties listed here, the application spectrum of magnesium alloys is currently limited due to their low resistance towards corrosive and tribological stress. Plasma electrolytic oxidation is a promising and environmentally friendly surface treatment process to encounter these technical challenges. An already successfully finished DFG-project was concerned with the substrate/electrolyte interaction before and during the discharge initiation, as well as the aimed insertion of electrolyte components into the generated PEOcoating. It was shown that by employing highly concentrated electrolytes, very hard and chemically resistant mixed oxide (chemical compositions dominated by electrolyte components rather than substrate components) coatings are producible, which hardness exceed that of MgO layers significantly. However, due to their morphology being afflicted with local defects, such coatings will negatively affect the resulting corrosion- and wear resistance. This reveals further research needs. A characterisation of the complex coat-forming processes as well as the interactions of chemical and electrical process parameters during the plasma electrolyte coating procedure is only possible by empirical means, according to the state of the art and in lack of a consistent process model. Therefore, the proposed project is aiming towards the research of action mechanisms of interacting chemical and electrical processes during the plasma electrolytic oxidation of magnesium under formation of mixed oxides. To reach this goal, the process needs to be characterised and understood in detail. For that, the charge throughput of the pulses necessary for coating formation are to be broken down into electro- and plasma-chemical parts, and specific process stages like the coat-healing Softsparking and cathodic discharges need to be systematically recorded. On this basis, hybrid pulse patterns adjusted to the individual process stages will be developed. The data foundation generated during the project will subsequently be used to create a model concept which describes the underlying mechanisms. Based on the obtained conclusions and using environmentally friendly electrolytes, adherent and low-defect mixed oxide coatings are to be generated on magnesium substrates and to be qualified for corrosively and tribologically demanding applications.

镁是最轻的金属工程材料，因此为节省移动系统的重量提供了巨大的潜力。除此之外，镁很容易回收。出色的铸造过程属性以及用于电磁和机械振荡的良好阻尼能力，用于构建机器套管的镁材料以及框架和框架，用于明智的感觉，光学和娱乐电子设备。尽管此处列出了积极的处理和应用特性，但由于对腐蚀性和摩擦学压力的耐药性低，目前镁合金的应用范围受到限制。血浆电解氧化是遇到这些技术挑战的有前途且环保的表面处理过程。已经成功完成的DFG项目与放电启动之前和期间的基板/电解质相互作用有关，以及将电解质组件插入到产生的Peocooating中。结果表明，通过使用高浓缩的电解质，非常硬和化学抗性的混合氧化物（由电解质组件而不是底物组件主导的化学成分）是可生产的，它们的硬度超过了MGO层的硬度。但是，由于它们的形态患有局部缺陷，因此这种涂层会对由此产生的腐蚀和耐磨性产生负面影响。这揭示了进一步的研究需求。根据技术的状态，在缺乏一致的过程模型的情况下，只有经验手段才有可能，在等离子体电解质涂层过程中的化学和电气过程参数的相互作用才有可能。因此，拟议的项目旨在研究在混合氧化物形成下镁的血浆电解氧化过程中相互作用的化学和电过程的作用机制。为了实现这一目标，需要对该过程进行详细的特征和理解。为此，要分解成涂层形成所需的脉冲的电荷吞吐量分为电和等离子体化学部分，并且需要系统地记录特定的过程阶段，例如涂层软板和阴极放电等特定的过程阶段。在此基础上，将开发针对单个过程阶段的混合脉冲模式。随后将在项目期间生成的数据基础来创建描述潜在机制的模型概念。基于获得的结论和使用环保的电解质，将在镁底物上产生粘附和低缺陷的混合氧化物涂层，并有资格用于腐蚀性和互动苛刻的应用。