Effects of Additive for Anodizing Electrolyte on Anodic Film of High Silicon Aluminum Alloy

摘要

High silicon aluminum alloy, Al-12.7Si-0.7Mg, is newly developed and in urgent need of surfacetreatment techniques. Sulfuric acid concentration, anodization temperature, anodization time andcurrent density being fixed, three kinds of organic acids were investigated as additives of electrolytesfor anodic oxidation of high silicon aluminum alloy. Optimal concentrations of organic acids wereworked out by inspecting their effect on film weight and corrosion time, respectively. The studyshowed that citric acid was the best additive. Voltage-time curves of anodic oxidation for high siliconaluminum alloy in different electrolytes conformed to the typical characteristic curve of aluminumanodic oxidation. Oxide films obtained from sulfuric-citric mixed acid electrolyte were smooth, well- distributed, compact, and exhibited exceedingly low corrosion rate and excellent corrosion resistance.