Anti-corrosion properties of oil compositions based on combined corrosion inhibitor M-531

• L.G. Knyazeva¹, L.E. Tsygankova², A.V. Dorokhov¹, N.A. Kur’yato¹ and I.V. Zarapina³

¹ All-Russian Scientific Research Institute of Use of Machinery and Oil Products in Agriculture, 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 anticorrosive properties of coatings on steel containing conservation materials based on industrial (I-20A), commercial motor (M10G2(k)) and waste motor (WMO) oils modified with combined corrosion inhibitor M-531 containing a VCI were studied. The compositions based on petroleum oils with the M-531 additive well wet a surface of steel with a contact angle θ<30°, they themselves are wetted by water with θ<48° and are characterized by low surface tension σ<27 mN/m. The temperature dependence of the kinematic viscosity of the oil compositions studied in the range of 20–60°C is described by the Reynolds–Filonov formula. The protective effect (Z) of the coatings upon short-term exposure to a 0.5 M NaCl solution, calculated on the basis of polarization curves, is 99% at 7–10 wt.% M-531 in the I-20A and WMO oils. The same high value of Z was obtained in corrosion tests performed in a thermal moisture chamber for 960 hours. The protective effect of the coatings does not exceed 70% in long-term corrosion tests (336 hours) in 0.5 M NaCl solution, and a particularly low value is typical of compositions based on I-20A oil (<25%). Salt spray chamber tests of steel samples covered with the oil coatings containing 20% M-531 showed that the best protection was characteristic of a composition based on WMO. The same composition turned out to be ineffective under natural conditions: already after 3 months, the samples protected by it were completely covered with corrosion products, indicating the inexpediency of using an additive with volatile inhibitors in protective compositions in an open atmosphere. They can be used for short-term inter-operational storage of metal products.

Keywords: oil composition, combined corrosion inhibitor, protective efficiency, atmospheric corrosion, wetting, polarization, gravimetry

Int. J. Corros. Scale Inhib., 2023, 12, no. 1, 309-323
doi: 10.17675/2305-6894-2023-12-1-18

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