Protective property of epoxy coatings containing polyaniline and laminar basalt in neutral, alkaline, and acidic media

It is very important to develop high performance composite coatings for efficient protection of metals from corrosion. In this work, high performance protection coatings on mild steel using epoxy as matrix containing polyaniline (PANI) and a newly developed laminar basalt (LB) were prepared and characterized. The contact angle, water absorption, adhesion strength, and passive property of the coating were also evaluated. The protection ability of these coatings on mild steel, exposed to 12 wt% sodium chloride (NaCl), 10 wt% sodium hydroxide (NaOH), and 10 wt% hydrochloric acid (HCl) solutions were monitored using electrochemical impedance spectroscopy (EIS), respectively. In neutral solution, the coating containing both PANI and LB (C-PANI-LB) offered very high corrosion protection performance and its impedance at 0.01 Hz was higher than 4.1 × 10 10 Ω · cm 2 after immersed for 60 days. However, in alkaline or acidic solution, C-PANI-LB behaved poorer than pure epoxy coating or PANI contained coatings, which were ascribed to the hydrolysis of LB and deterioration of the epoxy binder in these media.