Characteristics of barrier anodized coatings on 6061 aluminum alloy

We have evaluated the characteristics of anodic coatings on 6061 aluminum alloy. We grew these coatings using a high voltage (950 V) low current density (1–2 mA cm^-2) high resistivity (45–75 kΩ cm) process in an electrolyte consisting of a solution of ammonium tartrate in ethanol. Coating properties which we subsequently characterized include thickness, density, morphology, entrained and adsorbed impurities, dielectric constant, breakdown strength and leakage curent. A comparison of the coatings on 6061 aluminum alloy with coatings grown using similar conditions on commercially pure 1100 aluminum alloy indicates that the alloying components in 6061 aluminum affect subsequent coating morphology and dielectric properties. The coatings displayed useful dielectric properties. The fact that these coatings were grown on 6061 aluminum alloy, which is a common industrial alloy used because of its relatively high strength and machinability, may recommend these coatings for a variety of practical applications.