Protective efficiency of oil compositions with Cortec VpCI-368D

• L.G. Knyazeva¹, L.E. Tsygankova^1,2, A.V. Dorokhov¹ and N.A. Kur’yato^1,3

¹ All-Russian Scientific Research Institute of Use of Machinery and Oil Products, Novo-Rubezhnyi per., 28, 392022 Tambov, Russian Federation
² Derzhavin State University, ul. Internatsyonalnaya, 33, 392000 Tambov, Russian Federation
³ Tambov State Technical University, ul. Sovetskaya, 106, 392000 Tambov, Russian Federation

Abstract: The protection of metals by coatings based on compositions of a number of petroleum oils with Cortec VpCI-368D has been studied by gravimetric and electrochemical methods. Cortec VpCI-368D is a blend of organic solvent with volatile inhibitor. Oil compositions with Cortec VpCI-368D are well wetted with water (contact angles less than 90°), they themselves spread over the steel surface (contact angles 1–3°), displacing water layers, and are characterized by low surface tension. The work of adhesion of the compositions studied was calculated. Wetting the coatings with water promotes the penetration of an aqueous medium through the pores in them to the metal surface and the formation of an ionic double electric layer there, as a result of which it becomes possible to carry out electrochemical measurements. The protective efficiency of the composition of industrial oil I-20A and Cortec VpCI-368D (5–10 wt%) was estimated on the basis of polarization curves at a short-term exposure of a steel electrode with coating in a 0.5 M NaCl solution (Z=97–98%). Compositions of petroleum oils with Cortec VpCI-368D (5–10 wt%) showed the high protective efficiency in relation to carbon steel in a thermal moisture chamber (97–100%) and natural conditions (80–94%). These compositions are most effective in relation to brass L-62 (Z=70–80%) in a chloride-containing neutral solution at an exposure of 456 h; their use for protecting copper is impractical, since the protective effect does not exceed 40%. Only compositions with commercial oil I-20A (Z=67%) are reasonable in these conditions in relation to carbon steel. Consumption of Cortec VCl-368D for coating deposition at 20 and 70°C was calculated.

Keywords: oil compositions, protective effectiveness, atmospheric corrosion, chloride solution, field tests, thermal moisture chamber

Int. J. Corros. Scale Inhib., 2021, 10, no. 2, 551-561 PDF (343 K)
doi: 10.17675/2305-6894-2021-10-2-4

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