In order to improve the wear and corrosion resistance of micro-arc oxidation (MAO) coating on a Ti-5Al-1V-1Sn-1Zr-0.8Mo alloy, 0–0.20 g/L graphene was added to the electrolyte to prepare micro-arc oxidation coating. The thickness, roughness, micro-morphology, and composition of the MAO coating were characterized, and the wear and corrosion resistance of the coating was tested and analyzed. The results show that with 0.05 g/L of graphene in the electrolyte, the roughness of the coating decreased from 56.76 μm to 31.81 μm. With the increase in the addition of graphene, the microstructure of the coating became more compact, the diameter of micro-holes and micro-cracks decreased, and the corrosion resistance of the coating improved. The wear tests showed that the mass loss of the coating at the early wear stage (0~100 revolutions) was greater than that at the later stage (100~250 revolutions), and the wear resistance of the coating obtained by the addition of 0.10 g/L of graphene was the highest. With 0.10 g/L of graphene, the adhesion force between the coating and the substrate alloy is the largest, reaching 57.1 N, which is 9.98 N higher than that without graphene. After salt spray corrosion for 480 h, the coating with graphene has better corrosion resistance than that of a graphene-free coating.

The present work attempted to produce thick zirconia coatings formed by micro-arc oxidation as a hydrogen permeation barrier on zirconium hydride alloy. A novel multiphase zirconia coating was achieved, exhibiting superior hydrogen permeation barrier performance. The growth dynamics, formation mechanism, and phase evolution behavior of thick zirconia coatings were explored, and the hydrogen permeation barrier performance was evaluated by means of vacuum dehydrogenation experiment. The hydrogen desorption quantity was monitored by analyzing pressure changes with a quadruple mass spectrometer (QMS). Experimental results show that the multiphase coatings were composed of monoclinic ZrO₂ (m-ZrO₂), tetragonal ZrO₂ (t-ZrO₂), and a trace of cubic ZrO₂ (c-ZrO₂). The coatings were generally divided into a dense and uniform inner, intermediate layer, and a porous top layer. The quantitative analysis indicates an increased amount of m-ZrO₂ toward the coating surface and an increased amount of t-ZrO₂ toward the oxide/metal interface. This novel multiphase thick zirconia coating can noticeably improve hydrogen permeation resistance, and the permeation reduction factor (PRF) value is improved by nearly 13 times compared with bare zirconium hydride. It is demonstrated that hydrogen desorption is retarded to some extent in the presence of thick zirconia coating. Hydrogen desorption of the sample with ceramic coating started at 660 °C, which was apparently higher than that of the sample without coating.

Magnesium alloys, notably AZ31B, hold promise for lightweight structural applications in the aerospace, automotive, and biomedical sectors due to their excellent strength-to-weight ratios. The broad adoption of these alloys, however, is hindered by their inherent susceptibility to corrosion, reducing durability and functional integrity in corrosive environments. This study explores anodic oxidation as a viable surface treatment to improve the corrosion resistance of the AZ31B magnesium alloy. Focusing on the impact of oxidation voltage on the oxide film’s structural and electrochemical properties, we aim to optimize these characteristics to enhance the alloy’s utility and lifespan significantly. Through detailed analysis of surface and cross-sectional morphologies, film thickness, phase composition, and corrosion resistance, we identify an optimal oxidation voltage of 17.5 V that notably improves the oxide film’s density and corrosion resistance. Through this research, we contribute to the ongoing efforts to overcome the corrosion vulnerability of magnesium alloys, thereby unlocking their full potential in contributing to more sustainable and efficient technological advancements.

Ceramic coatings on R60705 zirconium alloy were prepared on the surface by the micro-arc oxidation (MAO) technique in electrolytes containing Na₂SiO₃, NaOH, and Na₂EDTA. The growth behavior of the MAO ceramic coatings at different stages, including growth rate, microstructure, and phase composition, was investigated using the method of direct observation of the boundary area. The results showed that the growth of the MAO coatings on R60705 zirconium alloy occurred in both inward and outward directions. At an oxidation time of 5 min, the thickness of the oxidation layer increased fastest, reaching 103.43 μm, with a growth rate of 0.345 μm/s. After 5 min, the growth rate decreased and tended to level off around 15 min, with a thickness and growth rate of 162.7 μm and 0.181 μm/s, respectively. The total thickness of the coatings continuously increased throughout the process, with the outward growth thickness always higher than the inward growth thickness. The composition of the zirconium alloy micro-arc oxidation coatings mainly consisted of monoclinic zirconia (m-ZrO₂), tetragonal zirconia (t-ZrO₂), and a small amount of SiO₂. The main elements in the coatings were Zr, O, and Si. The corrosion resistance of the zirconium alloy micro-arc oxidation coatings increased first and then decreased with increasing oxidation time, with a corrosion current density of 8.876 × 10⁻⁹ A·cm⁻² at 15 min, indicating the best corrosion resistance.

The micro-arc oxidation film on TC4 alloy was prepared using a multifunctional micro-arc oxidation (MAO) power source. The effect of nano-titania colloid addition on the growth process, microstructure, and comprehensive mechanical properties of titanium alloy micro-arc oxidation films was studied by gradient concentration. The results show that, with the increase in titanium dioxide colloid content, the intensity of the discharge phenomenon during the MAO process increases, and the average current density gradually increases. The film thickness is gradually increased from 111.06 μm to 159.8 μm, and the roughness first decreases and then increases. The XRD results show that the rutile content in the film layer is increased with titanium dioxide colloid in the electrolyte. This resulted in an increase in the density of the film, and lead to the corrosion resistance of film improved. When the concentration of titanium dioxide colloid is 1.5 g/L, the comprehensive performance of the film is the best.