ZINC-FILLED COATINGS FOR PROTECTING AGRICULTURAL MACHINERY FROM ATMOSPHERIC CORROSION

Application of zinc-filled coatings (ZFC) on oil base is possible for protection of agricultural machinery from atmospheric corrosion. Analysis of literature has shown that anti-corrosion efficiency of ZFC largely depends on the size of zinc particles included in their composition. Zinc powders of different sizes PCR-1 (up to 40 μm) and PC-1 (up to 9 μm) in the amount of 40-60 wt.% were used for research. Oils were used: used motor oil (MMO), industrial oil I-20A, refined rapeseed oil and drying oil were used as a binder. It was determined that the corrosion potential (Ecor) of St3 steel with ZFC in 0.5 M NaCl solution occupies an intermediate value between the Ecor of steel and the Ecor of compact zinc. The concentration of Zn in the oil film as a result of its oxidation and transition to 0.5 M NaCl solution decreases over time from 40-60%, reaching almost the minimum value after 20 days. It was found that the introduction of zinc powder into oils increases their protective efficiency (Z) the more significantly, the smaller the particle size. The introduction of 40% PCR-1 powder increases Z MMO by 5%, and zinc PC-1 - by 48% in a saline solution. These trends are also preserved during tests in the G-4 heat and moisture chamber, but the difference when using different CNP is not as significant as during tests in a saline solution. The maximum Z = 93% was obtained for drying oil with 50% PCR-1; Z = 94- 95% for compositions with 50-60 wt.% PC-1 in rapeseed oil, Z = 94-95%. Coatings with PC-1 in MMO and rapeseed oil provide Z = 91% during full-scale bench tests over 12 months.