Evaluación de las propiedades de adherencia y anticorrosivas de recubrimientos epoxi con TIO2 nanoparticulado sobre acero ASTM A572

Abstract

The use of composite coatings represents one of the alternatives to mitigate corrosion problems and reduce costs in the industry. This work studies the effect of surface preparation and the addition of nano-loads on the performance of epoxy resin composite coatings and TiO2 nanoparticles, applied on structural steel ASTM Gr 50. For these, the coated plates were subjected to adhesion tests according to ASTM D3359 and ASTM D4541. These plates were introduced in a saline solution with 3.5% w/w NaCl and ISO 4628-2 and 4628-5 were used to evaluate blistering and detachment. The TiO2 nanoparticles (nominal size 21 nm and purity 99.5%) were incorporated in percentages of 0.0.5 and 1% using an ultrasonic equipment. The surface of the structural steel was subjected to 3 surface preparations: sandblasting, pickling and mechanical disc. The coatings were deposited using a dip coating equipment, which was built for this purpose, reaching a nominal thickness of 70 µm. An artificial defect was introduced in accordance with ISO 4628-8, in order to accelerate the corrosion process and to be able to study it. The results showed that sandblasting offers an excellent anchor profile compared to the other two surface preparations. The addition of nanoparticles improves the adhesion and corrosion resistance of polymeric coatings. Thus, the pull & off test showed that, on a surface prepared by sandblasting, the coating with 1% TiO2 had an adhesion loss of less than 25% after 35 days of immersion, against 60% of adhesion loss observed in steel with epoxy resin only.