Influence of acidic media and chlorides on protective properties of epoxy coatings

Abstract

Abstract Organic coatings are used as one of the key surface protection methods to protect cast iron pipelines against corrosion due to their cost efficiency and a variety of applications. In most metallic systems that are protected by organic coatings, the performance depends on the response of the coating to corrosion stresses to which they are exposed during operation. One of the most dangerous factors causing chemical damage to coatings are the acidic and chloride aggressive media. Such damage reduces the protection effectiveness thus leading to blistering, cracking, increase in pore volume and number, as well as loss of adhesion. Moreover, the influence of aggressive media impairs also aesthetic characteristics. In the experimental part of the paper, analyses of the physical and chemical properties of epoxy coatings applied on the metal substrate in phosphoric acid, acetic acid and 3.5 wt% NaCl solutions were carried out. The test results showed that the physical properties of epoxy coatings were satisfactory in the acidic medium, but electrochemical tests in 3.5 wt% NaCl solution showed reduced corrosion protection.