Improvement of corrosion properties of plasma in an aluminum alloy 6061-T6 by phytic acid anodization temperature

Abstract

We report on the formation of anodic aluminum oxide (AAO) film using phytic acid (C6H18O24P6), a naturally obtainable and non-toxic organic acid electrolyte. When the temperature of the phytic acid electrolytes changes from 0 °C to 20 °C, the pore size increases, and the AAO film becomes less dense because the growth rate of the AAO film increases. In particular, when the temperature of the phytic acid electrolyte is above 15 °C, the AAO film changes dramatically. According to XRD analysis, the alpha-alumina intensity was relatively higher in the AAO film grown at low-temperatures (0, 5, 10 °C) than high-temperatures (15, 20 °C). It was possible to obtain a result that the properties were better. The microstructural change of the AAO film according to the temperature of the phytic acid electrolytes affected the breakdown voltage and the number of contamination particles that are generated, which are important properties for plasma corrosion protection coating materials. The AAO film grown in the low-temperature has the most suitable properties for use as a plasma corrosion protection coating material. Notably, the breakdown voltage of the AAO film is 0.45 kV at 14.9 μm thickness, with no observable crack on its surface after the plasma corrosion test. These findings provide significant evidence to support the application of phytic acid as an electrolyte to grow AAOfilms, and the AAOfilm grown in a phytic acid bath can be applied as a plasma corrosion protection coating material.