Chemically resistant nanostructured protective coatings for metal surfaces

The aim of this study is to develop nanostructured protective coatings with high chemical resistance for metal surfaces. To modify paints and varnishes, compositions based on carbon nanotubes (CNTs), bismuth oxide nanoparticles, silicon dioxide, titanium dioxide, magnesium hydroxide and aluminum hydroxide were used. The introduction of nanomaterials into acrylic paint and varnish material helps to increase the adhesive strength of coatings, so the best effect was determined with the introduction of CNTs in the amount of 0.1 % – the adhesive strength increased from 2.0–2.2 MPa to 2.9–3.1 MPa with a change in the nature of the separation of the paint and varnish coating from the substrate from fully adhesive (100 %) to adhesive-cohesive. Evaluation of the chemical resistance of nanostructured paint and varnish coatings modified with CNTs showed that when the coatings were exposed to an herbicide solution, they retained their weight regardless of the concentration of the modifier, while their hardness did not change (H). Evaluation of the equilibrium swelling rate made it possible to determine that paint and varnish coatings modified with bismuth oxide nanoparticles and CNTs are resistant to solvents and acquire a more mesh structure in relation to coatings without additives. Scanning of various sections of the sample surfaces on atomic force microscope (AFM) showed that when modified with bismuth oxide and CNT nanoadditives, the surface becomes smoother, and the nanometer roughness decreases from 50–60 nm to 20–30 nm. A more significant reduction in protrusions is observed in coatings modified with CNTs, which indicates that the coating is strengthened by reducing the size of depressions and pores.