EVALUATION OF THE EFFICIENCY OF INTRODUCING A SERIES OF ADDITIVES INTO USED ENGINE OIL TO PROTECT AGRICULTURAL MACHINERY DURING OFF-SEASON STORAGE

The search for effective conservation materials to protect agricultural machinery from atmospheric corrosion during off-season storage continues to be an urgent task. Compositions based on used engine synthetic oil with emulgin and paraffin additives at a concentration of 1–10 wt. % investigated for its solution. Preservative compositions were prepared by dissolving a multifunctional additive in used oil when heated. Corrosion and electrochemical tests were carried out on samples of steel St3, a protective film of the studied composition was formed within 15 minutes. The effectiveness of anti-corrosion protection of steel with these compositions was studied by gravimetric (tests in 0.5 M NaCl and a climatic chamber) and electrochemical methods. It is shown that in 0.5 M NaCl, the composition with paraffin at a maximum additive concentration of 10% provides a protective effect of more than 70%. The addition of emulgin at the same concentration is less effective. Paraffin-containing formulations provide protective effect values of over 90% in the absence of aggressive chloride ions under climate chamber conditions. The inhibition of the corrosion process under the films of the studied compositions occurs due to the shift of the corrosion potential to the anode region. The presence of the conservation composition does not change the mechanism of the corrosion process of steel in 0.5 M NaCl, since there is no sharp change in the Tafel slope coefficients of the cathode and anode sections of the polarization curves. According to impedance spectroscopy, it was found that the presence of paraffin in the film of used motor oil at a concentration of 5, 10 wt. % causes a decrease in the capacitance of the electrical double layer, as well as an increase in the charge transfer resistance in both the cathodic and anodic reactions. In addition, there is an increase in the diffusion resistance of the depolarizer oxidizer, which may indicate the effectiveness of shielding the metal surface. The results obtained showed the prospects for the use of compositions with paraffin for further research as a conservation material for the protection of agricultural machinery.