Possible criteria for the effectiveness of inhibitor protection of agricultural machinery and equipment: integral and differential; quantitative, semi-quantitative, qualitative; a generalized quantitative assessment based on the weightiness of each type of destruction; mass, deep, volumetric; technical and economic; environmental and toxicological, etc. were considered. It was noted that each of the criteria taken separately is not always unambiguous in specific conditions, which can lead to a subjective assessment of the appropriateness of using certain corrosion inhibitors (CI). Electrochemical methods for assessing the effectiveness of inhibitor protection are highlighted as promising, which is associated with the desire of researchers to reduce the time of corrosion testing. As an example, a study of the metal-protective coating-electrolyte system by the method of polarization resistance with an assessment of the contribution of each component is considered. Compositions based on trans-former TKp, industrial I-20A, motor M10G2k, fresh and used (MMO), and combined IR CortecVpCI-368 and Cortec VpCI-369 were studied. Coatings on steel were preliminarily formed during the day. Comparison of the results on the protective effectiveness of compositions in I-20A with those also obtained by the method of polarization curves and gravimetric methods in a 0.5 M NaCl solution and in a thermal moisture chamber G-4 showed qualitatively similar results, which indicates the reliability of the results obtained by the method of polarization resistance. The maximum protective efficiency is observed for compositions based on MMO with an IC concentration of 3 -10 wt. % in MMO.

The use of cheap, environmentally friendly natural products is especially important for the anti-corrosion protection of agricultural machinery and equipment. The studies were carried out on samples of carbon steel St3.Coatings from sunflower and rapeseed oils and their sediments; birch tar and its emulsion prepared with a homogenizer; decoctions of bifungin, black and green tea, coffee, oak bark, potato and beet peels, orange and banana peel, bay leaf, onion peel, field honey, sugar, currant berries, dried garlic, tobacco, black and red pepper, seasonings hops-suneli, celandine were studied. Gravimetric studies in a G-4 thermal moisture chamber, in a 0.5 M NaCl solution, in decoctions of natural products were used to assess the protective properties of natural products. in 0.5 M NaCl solution and 5-9% - in thermomoisture chamber G-4. The application of vegetable oils on a wet surface practically does not affect their protective effectiveness, and application on a rusty one (preliminarily oxidized for 1 month) leads to a significant decrease in the protective effectiveness of coatings: by 33 and 42% for sunflower and rapeseed oils, by 23 and 40% for their sludge, respectively. Sediments of vegetable oils completely protect the steel surface when tested in a saline solution for 3 months, in a G-4 thermal moisture chamber for 40 days, and in full-scale bench tests for a year. The tar emulsion protects the steel surface well enough in a saline solution. Ecologically safe decoctions of common natural products, such as bay leaf, black coffee, orange peel, dried garlic, ground black pepper can be recommended for effective protection of carbon steel from atmospheric corrosion for a short period.