Study of sol-gel process for preparing cerium nano-oxide films on AA7020-T6 Al alloy

摘要

A design of experiment technique, the Taguchi method, has been used to optimise a coating process in order to decrease the corrosion rate and increase the passivity of the coated samples by controlling the coating process's factors. Potentiodynamic polarisation measurements were carried out to determine the corrosion rate and passivity of the coated samples. The optimised coating parameters for corrosion rate are one molar ratio for acid citric/CeCI_3, 300 deg C for heat treatment temperature, 0.02 mol for CeCI_3 concentration and 0 min for time of boiling. The optimised coating parameters for passive region are two molar ratio for acid citric/CeCI_3, 300 deg C for heat treatment temperature, 0.001 mol for CeCI_3 concentration and 60 min for time of boiling. The results showed that the acid citric/CeCI_3 is the most significant factor affecting the corrosion rate while the time of boiling affects significantly on the passive region of the coatings.