AlCoCrFeNiZrx (x = 0, 0.1, 0.2, 0.3, and 0.5) high-entropy alloys (HEAs) were prepared by a non-consumable vacuum arc melting technology, and the microstructure and corrosion behavior were investigated by XRD, SEM, immersion tests, and electrochemical measurements. The results indicate that galvanic corrosion of the AlCoCrFeNiZrx alloys occurred in 0.5 M H₂SO₄ solution, and only 0.1 mol of the added Zr could greatly improve the corrosion resistance of the alloys. The corrosion properties of the AlCoCrFeNiZrx HEAs had similar change tendencies with the increase in the Zr content in the immersion tests, potentiodynamic polarization measurements, and electrochemical impedance analysis, that is, the corrosion resistance of the AlCoCrFeNiZrx alloys in a 0.5 M H₂SO₄ solution first increased and then decreased with the increase in the Zr content. The Zr0.1 alloys were found to have the best selective corrosion and general corrosion resistance with the smallest corrosion rate, whereas the Zr0.3 alloys presented the worst selective corrosion and general corrosion resistance with the highest corrosion rate from both the immersion tests and the potentiodynamic polarization measurements.

Si₃N₄/TaC composite MAO coatings were fabricated by microarc oxidation (MAO) on a Ti–6Al–4V (TC4) alloy in a phosphate-based electrolyte containing Si₃N₄/TaC mixed particles. The influence of the amount of Si₃N₄/TaC particles on the microstructure, composition, tribological behavior, and corrosion properties of the MAO coatings has been investigated. Morphological research of the MAO coatings was carried out using scanning electron microscopy (SEM), with the surface porosity analyzed by ImageJ software. X-ray diffraction (XRD) was used for the detection of the phase characteristic of the MAO coatings, and an abrasive wear test and electrochemical measurements were conducted in the artificial seawater solution by the ball-on-disc friction tester and the electrochemical workstation, respectively. The results showed that Si₃N₄/TaC particles could be successfully incorporated into the composite coatings, and the addition of Si₃N₄/TaC particles greatly reduced the porosity of the coatings, thus improving both tribological and corrosion properties of the composite MAO coatings. The composite MAO coating with the addition of 1 g/L Si₃N₄ + 0.5 g/L TaC particles showed the best tribological property and the optimum corrosion properties.

Micro-arc oxidation (MAO) ceramic coatings were prepared on TC4 titanium alloys by adding CuSO₄ to a (NaPO₃)₆ base solution. The microstructures of the MAO coatings were characterized by scanning electron microscopy (SEM), energy dispersive (EDS), and X-ray photoelectron spectroscopy (XPS). The corrosion resistance and wear resistance of these coatings were evaluated via hydrochloric acid immersion of weight deficit and friction tests. Those results indicated the presence of Cu in the MAO coating in the form of CuO and Cu₂O. Incorporation of CuSO₄ results in a thickness and roughness increase in the coating. The coating has a lower coefficient of friction (0.2) upon the addition of 4 g/L of CuSO₄. The antibacterial properties of the MAO coatings were maximized at 6 g/L of CuSO₄. However, the corrosion resistance of the copper-doped MAO coating did not exceed the undoped coating. This study shows that the addition of CuSO₄ to the electrolyte successfully prepared copper-containing micro-arc oxidation coatings, which improved the wear resistance and antibacterial properties of the coating.

Novel composite coatings were fabricated on 6061 aluminum alloy substrates by two steps combining micro-arc oxidation (MAO) plus electroless copper plating (Cu). Different MAO + Cu composite coatings were compared. Cu continuously and evenly covered an aluminum oxide surface during processing thus changing the surface topography. The adhesion of MAO + Cu composite coating was tested by the pull-out method. The best adhesion strength of the composite coating can reach industrial requirements. The effects of the composite coatings on friction were investigated using a ball-on-disc test method. It is found that copper in composite coatings plays a lubricating effect during the wear process under dry sliding. Furthermore, the mechanisms by which the observed advantages were produced are discussed.

为了提高钛合金表面微弧氧化层在海洋环境中的抗腐蚀和耐磨损性能, 在硅酸盐系电解液中添加不同浓度的粒径在1 μm左右的TaC微粒, 制备了TaC掺杂微弧氧化层. 通过扫描电子显微镜、能谱仪和X射线光电子能谱仪等对微弧氧化层的形貌、元素组成及其化学状态进行表征与分析, 并对比评价了钛合金表面TaC掺杂微弧氧化层的厚度、表面粗糙度、硬度、耐磨性以及耐蚀性. 结果表明: 通过向电解液中添加TaC微粒, 钛合金表面微弧氧化层中存在TaC和Ta₂O₅; 较未添加TaC微粒制备微弧氧化层, 其表面形貌更为致密, 硬度提高了约83.2%, 在模拟海水中的摩擦系数由0.2降到了0.148, 由磨粒磨损转变为粘着磨损, 腐蚀电流密度下降了2个数量级, 并通过构建微弧氧化层在模拟海水中的磨损和腐蚀失效模型, 揭示了微弧氧化层中掺入TaC微粒对改善其抗腐耐磨性能的内在机理.

By contrast with the traditional method of adding hard particles into micro arc oxidation (MAO) coating to improve its wear performance, this study introduced copper into the MAO coating on TC4 alloy by adding copper pyrophosphate to enhance the wear property in a marine environment and the antibacterial property. The results demonstrated that the MAO coating with copper pyrophosphate addition showed a porous structure, and Cu was mainly concentrated around micropores. CuO and Cu₂O were formed in this MAO coating. This MAO coating with Cu had a high bonding strength to the substrate. Although the hardness of the coating with Cu had been reduced, it could reduce the friction coefficient and enhance the wear property in simulated seawater due to the lubrication of Cu. Furthermore, this MAO coating with Cu addition had obvious antibacterial and bactericidal effects due to the antibacterial effect of Cu.