Alternative mechanical pre-treatment methods of hot-dip galvanising surface to increase of the organic coatings adhesion

Abstract

The content of this contribution is an evaluation of research on various mechanical pre-treatments of inorganic coating, which is part of the so-called duplex system applied to a steel sheet. In order to coating adhesion increase, the hot-dip galvanising surface was first pre-treatment using the standard light blast technology (synthetic brown corundum F40). Furthermore, pre-treatment was also carried out using alternative methods that can be used in conditions without blasting equipment - sandpaper regrinding (P40, P60, P80 and P100) and a corrosion-resistant steel brush (wire diameter 0.30 mm). Tools are designed e.g. for cleaning metal surfaces. Samples without mechanical pretreatment and samples with blasted surface were used as a standard. The surface texture was evaluated based on the roughness height parameters Ra and Rz (according to ČSN EN ISO 4287 standard). The mechanical resistance of applied anti-corrosion protection was determined by means of a pull-of adhesion test (according to ČSN EN ISO 4624 standard). The experiment suggest results, that among the alternative methods, the use of P80 and P100 sandpapers and corrosion-resistant steel brushes seems to be the most suitable, as these tools are not as aggressive to the galvanised surface as P40 and P60 sandpapers.