Estimation of Protective Efficiency of Oil-based Compositions Containing Zinc and Graphite Powders against Steel Atmospheric Corrosion

摘要

Zinc-containing oil-based compositions containing 75 wt. % zinc powder protect carbon steel in the natural conditions of urban atmosphere for a year with the protective efficiency equal to 96 %. More expedient binding is waste motor oil. The insertion of 4 wt. % graphite dust allows to decrease a content of Zn powder in the composition to 60 wt. % without essential alteration of the protective efficiency. The corrosion potential of the steel electrode covered with the oil composition containing 75 wt. % Zn powder or 60 wt. % Zn powder and 4 wt. % graphite dust in the 3 % NaCl solution is near Zn electrode potential. The polarization curves are close to ones of metal zinc. The properties of the above oil compositions were studied by the electrochemical impedance spectroscopy method too. The values of the equivalent scheme parameters satisfactorily correlate with data of the gravimetrical corrosion tests and the results of the polarization measurements and allow to explain the peculiarities of the zinc-containing oil compositions and an influence of their modification with the graphite powder.