Electrodeposition and Characterization of Mn-Cu-Zn Alloys for Corrosion Protection Coating

World Multidisciplinary Earth Sciences Symposium 2017

Tsurtsumia, Gigla^1 ; Gogoli, David^1 ; Koiava, Nana^1 ; Kakhniashvili, Izolda^1,2 ; Jokhadze, Nunu^1 ; Lezhava, Tinatin^1 ; Nioradze, Nikoloz^1 ; Tatishvili, Dimitri^3

TSU, Rafael Agladze Institute of Inorganic Chemistry and Electrochemistry, 11 Mindeli Str., Tbilisi

0186, Georgia^1

Georgian Technical University, 69 Kostava Str., Tbilisi

0176, Georgia^2

G. Tsulukidze Mining Institute, 7 Mindeli Str., Tbilisi

0186, Georgia^3

关键词: Carbon steel substrates;    Coating compositions;    Corrosion current densities;    Corrosion measurements;    Corrosion potentials;    Deposition Parameters;    Electrodeposited alloys;    Tafel polarization curves;   

Others  :  https://iopscience.iop.org/article/10.1088/1755-1315/95/4/042035/pdf
DOI  :  10.1088/1755-1315/95/4/042035

来源: IOP

【 摘 要 】

Mn-Cu-Zn alloys were electrodeposited from sulphate bath, containing citrate or EDTA and their mixtures as complexing ligands. The influence of bath composition and deposition parameters on alloys composition, cathodic current efficiency and structural and electrochemical properties were studied. At a higher current density (≥ 37.5 A dm-2) a uniform surface deposit of Mn-Cu-Zn was obtained. Optimal pH of electrolyte (0.3 mol/dm3Mn2++ 0.6 mol/dm3(NH4)2SO4+0.1 mol/dm3Zn2++0.005 mol/dm3Cu2++ 0.05mol/dm3Na3Cit + 0.15mol/dm3EDTA; t=300C; τ=20 min) for silvery, nonporous coating of Mn-Cu-Zn alloy was within 6.5-7.5; coating composition: 71-83% Mn, 6-7.8% Cu, 11.5-20% Zn, current efficiency up to 40%. XRD patterns revealed BCT (body centred tetragonal) γ-Mn solid phase solution (lattice constants a=2.68 Å c=3.59 Å). Corrosion measurements of deposited alloys were performed in aerated 3.5% NaCl solution. The corrosion current density (icorr) of the electrodeposited alloys on carbon steel was 10 times lower than corrosion rate of pure zinc and manganese coatings. Triple alloy coatings corrosion potential (Ecorr= -1140 mV vs. Ag/AgCl) preserved negative potential value longer (more than three months) compared to carbon steel substrate (Ecorr= -670 mV vs. Ag/AgCl). Tafel polarization curves taken on Mn-Cu-Zn alloy coating in aerated 3.5% NaCl solution did not show a typical passivation behaviour which can be explained by formation oflow solubility of adherent corrosion products on the alloy surface. Corrosion test of Mn-Cu-Zn electrocoating in chlorine environment shows that it is the best cathodic protective coating for a steel product.