Composite coatings were deposited on AZ91 magnesium alloys by micro arc oxidation (MAO) and the MAO-hydrothermal treatment (HT). The MAO process of Mg alloys was performed in the silicate/phosphate-based electrolyte with graphite particles size of 5-10 and 75 µm and then the obtained samples were submitted to hydrothermal treatment at 150°C in the graphite-ethanol mixture. The structural and morphological properties of composite coatings were analized X-ray diffraction (XRD) and scanning electron microscopy (SEM). The wear resistance was examined with ball-on-disc tribometer. The addition of graphite to the MAO electrolyte solution increased the coating thicknesses and compactness and the surface morphologies acquired relatively a homogeneous appearance. The coating surfaces were enriched in graphite by HT and the wear test results showed that the wear resistance of the graphite-doped MAO-HT composite coatings was significantly improved.

通过微弧氧化（MAO）和MAO-水热处理（HT）将复合涂层沉积在AZ91镁合金上。Mg合金的MAO工艺是在具有5-10和75 µm石墨颗粒的硅酸盐/磷酸盐基电解液中进行的，然后将获得的样品在150℃的石墨-乙醇混合物中进行水热处理。对复合涂层的结构和形貌进行了X射线分析（XRD）分析和扫描电子显微镜（SEM）分析。用圆盘摩擦计检查耐磨性。向MAO电解质溶液中添加石墨增加了涂层的厚度和致密性，并且表面形态获得了相对均匀的外观。