Investigation on a Sol-gel Coating Containing Inhibitors on 2024-T3 Aluminum Alloy

For a long time, chromate incorporated conversion coatings have been drawn special attention in corrosion protection of aircraft-used aluminum alloys. However, ever-increasing environmental pressures requires that non-chromate conversion coatings be developed because of the detrimental carcinogenic effects of the chromate compounds. In recent years, the sol-gel coatings doped with inhibitors were developed to replace chromate conversion coatings, and showed real promise; A sol-gel coating was prepared and its anti-corrosion behavior was investigated using the potentiodynamic scanning （PDS） and the electrochemical impedance spectroscopy （EIS）. It is found that the sol-gel coating obtained by the hydrolysis and condensation of 3-glycidoxypropyltrimethoxysilane （GPTMS） and tetramethoxysilane （TMOS） is prone to form defects if cured at the room temperature, whereas if cured at a higher temperature （100℃）, these flaws can be avoided. Furthermore, it can be seen that addition of anti-foam agents and surfactants will reduce the faults if cured at the room temperature. Effects of the corrosion inhibitors, CeCl3 and mercaptobenzothiazole （MBT）, in the sol-gel coatings on 2024-T3 aluminum alloy were also investigated. Results show that the corrosion resistance of the sol-gel coatings containing CeCl3 proves to be better than that of the pure and MBT added sol-gel coatings by the electrochemical methods.

Investigation on a Sol-gel Coating Containing Inhibitors on 2024-T3 Aluminum Alloy