Research On Preparation And Properties Of Composite Ceramic Coatings Of Aluminum Alloy

Micro-arc oxidation technology was used to get a composite ceramic film on the surface of 2A12 alloy in this article.The light MgO and micron level SiO₂ powder were served as agents and added into NaOH and Na₂SiO₃ electrolyte solution.Scanning electron microscopy?SEM?was used to observe the surface interface morphology of the composite ceramic film.X-ray diffraction?XRD?technology was used to analyze the phase composition of the film.Friction and wear testing machine and studio chemical were used to test the friction and corrosion performance of film.The experimental results indicated that the performance of the composite film were better than single-composition film.The orthogonal method was carried out to the optimal electrolyte solution concentration.The optimal concentration were: Na₂SiO₃ 8g/L,KOH 2g/L.Using the quality and thickness of film as indicators to get the optimal electrical parameters Micro-arc oxidation process.The obtained electrical parameters were : 520V?Forward voltage?,30min?The oxidation time?,300HZ?frequency?,30%?duty cycle?.Different content of MgO and SiO₂ powder were added into NaOH and Na₂SiO₃ electrolyte to study the influence of MgO and SiO₂ powder on the Micro-arc oxidation process of 2A12 alloy.The thickness of film were clearly increased due to the addition of MgO and SiO₂ powder.The film increased from 14 um to 26 um when the MgO addition was 25g/L and The film increased to maximum of 23 um when the SiO₂ addition was 4g/L.The MgO can react with ?-Al₂O₃ and produce aluminum-spine which can cause ?-Al₂O₃ disappeared.At a result,the film only has two phase of ?-Al₂O₃ and aluminum-spine.SiO₂ can distributed around the film surface,which can promote the transformation process from ?-Al₂O₃ to ?-Al₂O₃ which make the film surface smoothly.The friction and corrosion performance of film were increased clearly duo to the addition of MgO and SiO₂.The abrasion loss MgO can decrease to half of wear values when the the addition of MgO was 25g/L and it decreased to 50 percent of wear values when the SiO₂ addition was 3g/L.