Protection Properties of Organosilane-Epoxy Coating on Al Alloy 6101 in Alkaline Solution

Abstract The mechanical property and the corrosion protection of organosilane-epoxy coating on Al alloy 6101 in an alkaline solution are studied. The evaluations include potentiodynamic polarization (PDP) measurements, electrochemical impedance spectroscopy (EIS) studies, effective weight loss, water contact angle, peeling off test, surface adhesion and scratch tests, etc. It is concluded that the optimal ratio of organosilane-epoxy to toluene of the dipping solution is 1 : 4.5. The peeling off strength of this coating on Al alloy is 0.144 F/N, the critical load to scratch damage of the coating surface is 20.982 g, the water contact angle becomes 106°, and the inhibition efficiency of the coated Al in an alkaline solution of NaOH with pH 11 obtained from PDP measurements, EIS and effective weight loss tests show that the protection efficiency of this coating in the base solution reaches about 99% at the optimal ratio of organosilane-epoxy to toluene, which indicates the validity of the coating on this Al alloy.