The impedance of anodic processes on passive NiSi-electrode in sulfuric fluoride containing electrolyte

The mechanism and kinetics of anodic oxidation of the Ni-Si electrode in solutions of 0.5 M H2SO4 + (0,005 – 0,05)M NaF in the passive state were investigated by methods of polarization and impedance measurements. The impedance spectra are interpreted on the assumption about the formation of the bilayer oxide film on the surface of the silicide nickel, the outer layer which has a porous structure. The growth of the porous layer with the increase of the electrode potential in the investigated solutions is linearly (constant anodizing is 2.2 nm/V). The increase in NaF concentration leads to a decrease in the thickness of the porous layer. The growth of the barrier layer of the oxide film was described in the framework of the model of point defects. The diffusion coefficient of oxygen vacancies inside the barrier layer of the film is 8.5 · 10–16 cm2/s and varies weakly with the potential and the content of sodium fluoride in solution. Microscopic and profilometric studies show the development of the surface of the NiSi electrode during anodic etching.The work is executed at financial support of RFBR under research project No. 14-03-31016

Investigation of industrial compositions SONKOR as corrosion inhibitors of mild steel in neutral media containing hydrogen sulfide

Electrochemical and corrosion behavior of mild steel in neutral media containing hydrogen sulfide has been investigated by weight-loss and electrochemical methods and protective effect of industrial compositions SONKOR has been determined. It has been shown that in 3 % NaCl compositions SONKOR have weak protective effect but it increases greatly in presence of hydrogen sulfide in the solution. At concentration of H2S = 0,6 gram per liter maximal protective effect has SONKOR 9801 (85.57 %) and SONKOR 9920А (81.97 %). Inhibitors SONKOR 9021С (70.82 %), 9510А (73.11 %) и 9701 (67.87 %) show less protective effect