Plasma Electrolytic Oxidation of High-Strength Aluminium Alloys—Substrate Effect on Wear and Corrosion Performance
Plasma Electrolytic Oxidation of High-Strength Aluminium Alloys—Substrate Effect on Wear and Corrosion Performance
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DOI：
10.3390/met8050356
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发表时间：
2018-05
期刊：
影响因子：
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通讯作者：
M. Sieber;F. Simchen;R. Morgenstern;I. Scharf;T. Lampke
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文献类型：
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作者：
M. Sieber;F. Simchen;R. Morgenstern;I. Scharf;T. Lampke
随着材料科学和生产技术的进步以及轻量化设计在工业多个领域的确立，轻金属的应用不再仅仅需要机械强度，还需要对材料的耐磨和腐蚀提供显着的保护。铝上坚硬耐磨的氧化物涂层是通过等离子体电解氧化 (PEO) 产生的。在 PEO 过程中，铝基材会转化为陶瓷氧化物。虽然过去有选择地研究了铜、镁/硅、锌和锌/铜等赋予强度的合金元素在 PEO 工艺中的作用，但合金成分对涂层使用性能的重要性仍然未知。因此，根据 ASTM G65 在橡胶轮测试中的行为以及具有未损坏和磨损涂层的基材在稀 NaCl 溶液中的电流密度电位行为，检查了在广泛使用的商业高强度合金 AlCu4Mg1 (EN AW-2024)、AlMgSi1 (EN AW-6082) 和 AlZn5.5MgCu (EN AW-7075) 上生产的 PEO 涂层的性能。为了给非合金材料提供参考，还对经过调整的 PEO 工艺处理的 Al 99.5 (EN AW-1050) 进行了测试。尽管确定了 PEO 期间金属间相转化以及各种基材上涂层的相组成的差异，但使用性能几乎不取决于所研究的铝材料的合金元素。所有合金样品的橡胶轮测试中的磨损率都很低。电流密度-电位曲线显示，与裸露基材相比，腐蚀电流密度降低了大约一个数量级。最终，涂层先前的磨损不会恶化腐蚀行为。如果技术上纯铝上的 PEO 层是在硅酸盐含量较高且没有额外氢氧根离子的电解质中制备的，且处理时间较长，则可以抵抗测试方案。
With the progress in materials science and production technology and the establishment of light-weight design in many fields of the industry, the application of light metals no longer requires only mechanical strength, but also a significant protection of the material against wear and corrosion. Hard and wear-resistant oxide coatings on aluminium are produced by plasma electrolytic oxidation (PEO). During PEO, a conversion of the aluminium substrate to a ceramic oxide takes place. While the role of strength-giving alloying elements like Cu, Mg/Si, Zn, and Zn/Cu on the PEO process has selectively been subject of investigation in the past, the significance of the alloy composition for the service properties of the coatings is still unknown. Therefore, the performance of PEO coatings produced on the widely used commercial high-strength alloys AlCu4Mg1 (EN AW-2024), AlMgSi1 (EN AW-6082), and AlZn5.5MgCu (EN AW-7075) is examined with regard to their behaviour in the rubber-wheel test according to ASTM G65 and the current density-potential behaviour of the substrates with undamaged and worn coatings in dilute NaCl solution. To give a reference to the unalloyed material the testings were carried out also on Al 99.5 (EN AW-1050) which was treated in an adjusted PEO process. Although differences in the conversion of intermetallic phases during PEO and the phase composition of the coatings on the various substrates are determined, the service properties are hardly depending on the alloying elements of the investigated aluminium materials. The wear rates in the rubber-wheel test are low for all the alloyed samples. The current density-potential curves show a decrease of the corrosion current density by approximately one order of magnitude compared to the bare substrate. Eventually, previous wear of the coatings does not deteriorate the corrosion behaviour. PEO layers on technically pure aluminum can resist the testing regimes if they are prepared in an electrolyte with an elevated silicate content and without additional hydroxide ions, during a longer process time.