鉻酸鹽轉化鋁合金之微生物腐蝕

MICROBIAL CORROSION OF CHROMATED ALUMINUM ALLOYS

鉻酸鹽轉化鋁合金應用於航空及電子器材以防在溫濕環境下之腐蝕、鋁合金以典型方法經重鉻酸鉀轉化後依ASTM方法在不同水活性測其微生物腐蝕作用。鋁材AA 1100及鋁合金AA 6061 表面經鉻酸鹽轉化時，比鉻酸鹽轉化鋁合金AA 2014，AA 2024和AA 7075對微生物腐蝕具較高保護性。鉻酸鹽轉化鋁合金AA 7075在水活性0.901下有顯著腐蝕現象，由EDS表面元素分析知腐蝕區鎂含量下降。腐蝕區之金屬氧化物和生物成分對鋁合金局部腐蝕有相乘效果。

Chromate conversion coating on aluminum alloys has been widely used in aerospace equipments and electronic parts to prevent the atmospheric corrosion in mild environmental conditions. Aluminum alloys were chromated with potassium dichromate by the typical method and microbial corrosions were tested according to the ASTM specification under different water activities. Chromate conversion coating on the surfaces of aluminum AA 1100 and aluminum alloy AA 6061 showed higher protective efficiencies than those of aluminum alloys AA 2014, AA 2024, and AA 7075. The chromated film on aluminum alloy AA 7075 had significant corrosion under water activity 0.901, and magnesium content of the corrosion site decreased through the energy dispersive spectrometer analysis. The presence of metal oxides and biological ingredients in the corrosion site acted as the synergistic effects to enhance localized corrosion of aluminum alloys.