Microstructure and corrosion-resistance of microarc oxidation filmon SiC_P/ 2024 aluminum matrix composite

SiC_P reinforced aluminum mat rix composites were t reated by microarc oxidation method. The micro-structure and composition of ceramic film were analyzed , and the phase constituent and microhardness profile werealso measured. The corrosion behavior of the composite was evaluated by polarization test . The ceramic film deposi2ted in silicate elect rolyte consist s of mullite ,α-Al₂O₃ , γ-Al₂O₃ and amorphous SiO₂ phases. A few residual SiC_Particles were remained in the film close to the film/ composite interface. The silicon content in the outer layer film israther high , which mainly comes f rom the elect rolyte , while the mullite synthesis in the inner layer film is related tothe oxidation of SiC reinforcement s in the plasma discharge channel. Af ter the microarc oxidation surface t reatment ,the corrosion resistance of the SiC_P/ 2024 composite was significantly improved due to the formation of a continuousthick film.