The Use of Phytic Acid Conversion Coating to Enhance the Corrosion Resistance of AZ91D Magnesium Alloy

Abstract

An environmentally friendly conversion coating based on phytic acid (PA) for AZ91D magnesium alloy was obtained by deposition. The influences of pH, time, PA concentration and temperature on corrosion resistance of PA conversion coating were discussed through orthogonal experiments, and the optimum processing parameters were confirmed. The results showed that pH is the most significant factor that influences the properties of PA conversion coating. Properties of PA conversion was investigated in details by electrochemical tests, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The results indicated that the phytic acid conversion coating provided effective protection to the substrate of AZ91D alloy.