Study Of Manufacture Of The Anti-wear And The Decrease Friction Coating On Aluminum Alloys By Micro-arc Oxidation

Micro-arc oxidation (MAO) of aluminum alloys is a new technique that apply micro-plasma discharge to make a ceramic-like coating at aluminum alloys' surface. This coating have high hardness, corrosion resistance and dielectric properties also have well-adhered with the aluminum and its alloys. Therefore, MAO is one of the most prospective new methods of surface treatment for aluminum and its alloys.By the MAO experiment of aluminum alloys in Na2SiO3 solution, this series have studied the law of the growth of the ceramic oxide-film, otherwise, it have studied the effect's law of the coatings' quality in the different composition and concentration of electrolyte also. Using SEM and XRD, I have analyzed the micro-shape and fabric of ceramic oxidation film. Otherwise, I have studied the wearproof effect in the different composition by the test machinery of the pin-disk model.The photos of SEM show that ceramic oxide-film is made up of two layers, the external porous layer and the internal denser one. The denser layer is as about 2/3 thick as the whole layer. The analysis using XRD points out that there are γ-Al₂O₃ and α-Al₂O₃ crystal in the ceramic oxide-film, otherwise, it also include a little of especial function particle that are included the electrolyte.By the analysis of the result of experimentation, it show the thickness of film increased with the electrolyte's concentration, but the hardness first increased and then decreased. At the same time, the uniformity and exquisiteness of the film have decreased. While the concentration of Na₂SiO₃ solution exceeds a certain value, it would ruin the oxidation film for the arc-light discharge.Experimentations indicate that the conductivity of the electrolyte would enhance for KOH concentration increase. While KOH concentration had meet demand, it can improve the quality of coatings and reduce the woke-voltage. Otherwise, it can make electrolyte to change the alkalescence that can make oxide-film to adsorb the especial function particle easily, to make especial function oxide-film. While KOH concentration exorbitancy, it would speed up the progress of oxide-film that made against the growth of oxide-film. At the same time, it would result in arc-light discharge to ruin oxide-film.