Effect of laser and shot blasting modification of steel surface on the adhesion strength of epoxy protective coatings

Corrosion poses a significant adverse impact on the oil extraction industry. Consequently, scientific research into the study and improvement of technologies for protecting metal structures from corrosive damage remains highly relevant. The most common method for protecting the internal surfaces of pipelines involves applying a polymer layer based on various organic film-forming compounds. Traditionally, shot blasting technology has been used to prepare steel surfaces for the application of paint coatings; however, this process is associated with negative environmental impacts and non-uniform deformation of the treated surface. A modern alternative is laser cleaning technology, which eliminates the drawbacks of the traditional method but lacks sufficient scientific and practical data detailing the operational characteristics of polymer coatings during service. This study investigated the adhesive strength of a polymer layer based on epoxy-novolac resins cross-linked with an amine-containing hardener, applied to grade St20 steel plates cleaned via shot blasting and laser technologies. Enhanced steel grit was employed as the abrasive material. Two types of fiber-optic lasers—pulsed and continuous-wave—were used for the laser cleaning process. Surface roughness of the steel plates post-cleaning was evaluated using a profilometer. The adhesive strength of the polymer layer was determined via a normal pull-off test using a dolly. The research demonstrated the influence of the chosen steel surface modification technology on the degree of cleaning and the depth of surface microrelief. Additionally, the effect of microrelief on the adhesive strength of the protective polymer layer was revealed.