Browsing by Author "Popova A."

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    CORROSION BEHAVIOR OF MILD STEEL IN SODIUM SULFATE SOLUTION IN PRESENCE OF PHOSPHATES OF DIFFERENT COMPOSITION
    (2024-01-01) Raimbekova A.; Kapralova V.; Popova A.; Kubekova S.; Dalbanbay A.; Kalenova A.; Mustahimov B.; Yermekbayeva S.; Myrzabekova S.
    Corrosion of mild steel in sodium sulfate solutions (1000 mg SO4 2- L-1) in the presence of various phosphate inhibitors was studied gravimetrically. Studies were performed under static conditions at room temperature. The known sodium polyphosphate inhibitor has been found to have low efficacy under these conditions. The inhibitor efficiency of its does not exceed 30.5 % at a concentration of 100 mg P2O5 L-1. It has been shown that a more effective inhibitor is calcium-manganese polyphosphate (Са, Mn)(PO3)2 obtained on the basis of manganese ore enrichment wastes of the Zhayrem deposit. The inhibitor efficiency of its already at a concentration of 20 mgP2O5 L-1 is 47.3 %. At a concentration of 100 mgP2O5 L-1, the inhibitor efficiency (Са, Mn)(PO3)2 is 96.2 %. Electrochemical tests confirmed the results of the gravimetric study. Infrared spectroscopic analysis showed that phosphate protective coatings were formed on the steel surface in solutions of sodium sulfate with additives of calcium-manganese polyphosphate.
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    Evaluation of the electrochemical impedance measurement of mild steel corrosion in an acidic medium, in the presence of quaternary ammonium bromides
    (2018-10-13) Popova A.; Vasilev A.; Deligeorgiev T.
    Three quaternary ammonium bromides were investigated as mild steel corrosion inhibitors in 1 M HCl. Two investigation methods were applied: electrochemical impedance spectroscopy (EIS) and polarization resistance (Rp method). The experimental impedance data showed capacitance frequency distribution, which imposed the introduction of a constant phase element, instead of a pure capacitance. Adequate structural models were advanced, to describe the interfacial processes. The models parameters values were determined. The resistance values found by impedance spectroscopy were compared to those of the polarization resistance provided by the Rp method. The inhibition efficiency of the investigated compounds was evaluated by both applied methods. The comparison of the investigated compounds’ protective properties outlined the best among them.
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    Impedance spectroscopy study of inhibitive properties of quaternary ammonium salts
    (2014-01-01) Popova A.; Christov M.; Vasilev A.; Deligeorgiev T.; Djambova A.
    Two quaternary ammonium di-bromides were investigated as corrosion inhibitors of mild steel in 1M HCl using impedance spectroscopy. Equivalent structure model of the interface metal/1M HCl+inhibitor was presented to describe the process. Independently the polarisation resistance was measured as well and compared with impedance data. Good agreement was found. Both investigated compounds show very good inhibitive properties.