Study On Anodic Oxidation Technology Of Near Eutectic Aluminum Silicon Alloy

The oxide film thickness of near eutectic aluminum silicon alloy are prepared by being oxidized through using different the oxidation time,current density,and electrolyte concentration,then the optimal parameters to oxidized process is determined.Under the optimum parameters,the influence of the concentration of additives on the film thickness and surface morpHology are analyzed by add tartaric acid,the oxalic acid,sulfosalicylic acid,cerium sulfate are added into sulfuric acid electrolyte,aluminum sulfate,nickel sulfate.Through control variety method and screening method,distribution of aluminum,silicon and oxygen on the film are analyzed by FESEM.In order to determine the optimal content of additives,the influence of additives on the corrosion resistance were analyzed through the thermal shock test and the salt spray test and polarization curves.The results shown that the distribution of micro porous on oxide film observed on the surface of near eutectic aluminum silicon alloy with sulfuric acid oxidation with the electrolyte concentration,current density,oxidation time increase.The thickness of the oxide film was increased,it also be changed by the pulse power supply.But the thickness of the oxide film decreased due to the thermal effect and acid etching.The optimum project of near eutectic aluminum silicon alloy are as flow: current density is 3.2A/dm2,the time of rising edge and falling edge 858.36 ns,duty ratio 50%,oxidation time 30 min,the frequency of trapezoidal pulse signals 50 Hz.The oxide film can prevented defectively from being corroded by sulfuric acid and the morpHology of film is improved by adding citric acid,oxalic acid,sulfosalicylic acid,cerium sulfate into the sulfuric acid electrolyte.The corrosion resistance was analyzed in order to determine the optimum additives: oxalic acid is 6g/L,sulfosalicylic acid is 10g/L,and citric acid is 25g/L,cerium sulfate0.7g/L.The oxide film exhibits good quality,the corrosion resistance of near eutectic aluminum silicon alloy has been observably improved by anodic oxidation treatment.The technology has the characteristic of convenient operation,well repeatability,efficient production and convenient application.The selection of the power waveform for the further discussion,the beneficial supplements in the anodic oxidation experiments of aluminum alloy are presented,the applicability of the Al-Si alloy is improved.