Corrosion of Ni-Al and Ni-Al-Al₂O₃ Flame Sprayed Coatings of „CastoDyn 8000" System in 0.01 M H₂SO₄ and 3.5% NaCl Solutions

Abstract

In the paper researches results of corrosion properties of Ni-Al alloy and Ni-Al-Al2O3 composite coatings were presented. Coatings were obtained by flame spraying of "Casto-Dyn 8000" torch. During coatings flame spraying of torch was used a small distance from the substrate. Instead of commonly used spray distance 150 mm, 100 mm was used. The studies in 0.01 M H2SO4 and 3.5% NaCl (artificial seawater) environments were realized. Evaluated coatings are more corrosion resistant in the 3.5% NaCl environment than in the 0.01 M H2SO4. Corrosion current density for alloy coatings in artificial seawater was 20 μA/cm2 and 223 μA/cm2 in an acidic environment. The value of corrosion potential in an environment of 3.5% NaCl is about 200 mV lower than in 0.01 M H2SO4. Composite coatings Ni-Al-Al2O3 were characterized by a lower corrosion current densities and increased resistance than Ni-Al coatings in acidic environment. The presence of alumina in the coating matrix caused increased corrosion current density in sea water environment.

Influence of Friction Stir Welding on Corrosion Properties of Aw-7020M Alloy in Sea Water

“…Used in studies three electrode system consists of the following elements: the sample, an auxiliary electrode (polarizing) of titanium and platinum reference electrode (saturated calomel electrode) [11,12]. All electrodes were placed in a tank with 3.5% water solution of NaCl.…”

Eis Research of Aw-7020 Alloy Joints Welded by Mig

“…Before the measurements the samples were exposed in the electrolyte to stabilize the corrosion potential. During measuring the electrolyte was continuously mixed using a magnetic stirrer [6][7][8][9]. The samples were degreased before the test.…”

“…Currently, one of the best research methods of resistance to this type of corrosion is electrochemical impedance spectroscopy (EIS). It allows you to not only determine the electrochemical corrosion resistance but also gives the opportunity to evaluate homogeneity of the corrosion process on the metal surface [6,7,10].…”

Corrosive Properties Distribution in Aw-7020 Alloy Joints Welded by FSW

“…Before the measurements, the samples were exposed in the electrolyte to stabilize the corrosion potential. During measuring, the electrolyte was continuously mixed using a magnetic stirrer [5,8,[10][11][12]. The samples were degreased before the test.…”

“…Currently, one of the best research methods of resistance to this type of corrosion is electrochemical impedance spectroscopy (EIS). It allows not only determine the electrochemical ISSN: 1231-4005 e-ISSN: 2354-0133 ICID: 1132702 DOI: 10.5604/12314005.1132702 corrosion resistance but also gives the opportunity to evaluate homogeneity of the corrosion process on the metal surface [5,8,[10][11][12][13].…”