A pH-responsive intelligent coating based on composite CaCO3 microspheres for long-term corrosion protection of Q235 carbon steel

Abstract The aim of this work is to develop an eco-friendly pH-responsive intelligent coating with long-term corrosion protection by a convenient method. Herein, an eco-friendly and long-term pH-responsive intelligent anti-corrosion coating (BTA-CaCO3@TA coating) is fabricated through the addition of a hydrophilic pH-responsive release material (BTA-CaCO3@TA microspheres) into a waterborne epoxy resin coating. The electrochemical impedance spectroscopy results indicated that BTA-CaCO3@TA microspheres could endow the coating with long-term corrosion protection. The |Z|f=0.01Hz values of the BTA-CaCO3@TA coating after 130 days of immersion were still higher than those of the pure waterborne epoxy resin coating at the beginning of immersion. The excellent long-term protection performance was related to the good dispersibility of BTA-CaCO3@TA microspheres in the waterborne coatings, the TA conversion film and the BTA inhibitor protection film, which formed on the steel surface in situ. This synergistic strategy demonstrated its future application for protecting metals from corrosion.