ECOLOGICAL POSSIBILITIES OF INCREASING CORROSION RESISTANCE OF STRUC TURAL MATERIALS USED FOR SUGAR BEET HARVESTERS

Sugar beet harvesting machines are subject not only to degradation through wear, but also to significant corrosion stress due to the environment. Due to the abrasive wear of the functional parts, unprotected steel components are very quickly attacked by corrosion. However, when choosing suitable corrosion protection, increasing emphasis is being placed on the ecology and health safety of corrosion protection systems. This is due to the abrasion residues of corrosion protection systems with heavy hydrocarbons (VOC), which are not only released into the air but also into the soil. The aim of this paper is to evaluate the corrosion-mechanical resistance of three different types of coatings suitable for application on agricultural machinery operating in environments with increased corrosion aggressiveness. These include a synthetic coating that represents the standard anti-corrosion systems used, a waterborne coating with a minimum content of heavy hydrocarbons, and a waterborne primer enriched with zinc pigment with a grain size of 5 - 10 mu m. A single coat of primer was always applied with a thickness of 25 - 30 mu m. The topcoat was always applied in two layers with a total thickness of 35-40 mu m. The mechanical resistance of the applied corrosion protection was determined by means of the pull-off adhesion test according to CSN EN ISO 4624 and further to the cupping test according to CSN EN ISO 1520. The corrosion tests were carried out in a salt spray environment according to CSN EN ISO 9227. The experimental results indicate the suitability of metallic pigment application despite the lower initial mechanical resistance of the coating. This initial disadvantage in turn supports the resistance of the coating in corrosion tests. For this reason, the coating containing the metallic pigment shows more stable corrosion-mechanical properties that are almost comparable to synthetic coating.