Investigations on composition and morphology of electrochemical conversion layer/titanium dioxide deposit on stainless steel

In this study, the formation and characterization of conversion coatings modified by a sol-gel TiO₂ deposit were investigated as a way to develop a new photocatalyst for water and air depollution. The conversion coating, characterised by strong interfacial adhesion, high roughness and high surface area facilitates the sol-gel deposition of titania and enhances its adhesion to the substrate. The conversion treatment is carried out in an acid solution. Observation by Scanning Electron Microscopy (SEM) reveals a rough surface with pores and cavities. According to SIMS measurements, the thickness of the initial conversion layer is evaluated at about 1.5 μm. On this pre-functionalised support, the titanium dioxide was deposited by the sol-gel method. The roughness measurements coupled with SIMS analysis allowed a precise evaluation of the surface state of the final layers. The coating consists of two layers: a TiO₂ outer layer and an inner layer containing iron chromium oxides. Characterization by X-ray diffraction (XRD) showed the existence of the TiO₂ anatase structure as the main compound.     

Benzodiazepine Derivatives as Corrosion Inhibitors of Carbon Steel in HCl Media: Electrochemical and Theoretical Studies

Protection of Metals and Physical Chemistry of Surfaces - New benzodiazepine derivatives, namely 8-Chloro-1,2,3,4,10,11-hyxahydrospiro[cyclohexane-1,11-dibenzo[1,4]diazipine] and...     

Synthesis and evaluation of the inhibitor effect of a new class of triazole compounds

In this work, a new class of triazole molecules, containing heteroatoms such as nitrogen and sulphur, is prepared. The effect of these molecules on the corrosion behaviour of iron was investigated. Electrochemical studies were performed in aerated chloride acid solution (1 M) by potentiodynamic polarisation curves. Surfaces were characterised by scanning electron microscopy.

The recorded electrochemical data showed that the corrosion resistance was greatly enhanced in the presence of inhibitor. The maximal protection efficiency exceeded 94%. The corrosion protection could be explained by the adsorption of inhibitor through the S- or N-atom and formation of a protective layer attached to the metal surface.     

Theoretical Prediction and Experimental Study of Benzimidazole Derivate as a Novel Corrosion Inhibitor for Carbon Steel in 1.0 M HCl

Protection of Metals and Physical Chemistry of Surfaces - The inhibiting effect of benzimidazole derivate (DBI) on corrosion of carbon steel (CS) at temperature range of 303–333 K was...     

Effects of copper concentration on the properties of Cu2CoSnS4 thin films co-electrodeposited on the FTO substrate

Journal of Materials Science: Materials in Electronics - The optimization of the factors influencing the co-electrodeposition method makes it extremely efficient in the production of thin films...     

Aromatic quinoxaline as corrosion inhibitor for bronze in aqueous chloride solution

A new corrosion inhibitor, viz. 3-ethyl-6-méthyl-quinoxalin-2-one, 1-benzyl-6-methyl-quinoxalin-2-one, 2-benzyloxy-3,6-dimethyl-quinoxaline, 1-benzyl-3-methyl-quinoxalin-2-one, were synthesized in the laboratory. Their influence on the inhibition on corrosion of bronze in aqueous chloride solution (3% NaCl) was studied by electrochemical polarization methods and weight-loss measurements. The impact of temperature on the effectiveness of the substances mentioned above has been determined between 20 and 60°C. The results showed that the corrosion resistance was greatly enhanced in the presence of inhibitor and that the effectiveness depends on some physicochemical properties of the molecule, related to its functional groups. These compounds act through the formation of a protective film on the surface of the alloy.     

Study of the inhibition of the corrosion of iron steel in neutral solution by electrochemical techniques and theoritical calculations

The effect of triazole organic molecules (triazole thiol and amino triazole) containing heteroatoms such as nitrogen or sulfur on the corrosion behavior of iron was investigated. Electrochemical studies of the iron samples were performed in an aerated solution of NaCl (3%) by means of electrochemical impedance spectroscopy (EIS) as well as polarisation curves. These results are completed with theoretical calculations, which allow determining the possible anchoring site suitable for bonding.     

Corrosion inhibition performance of 4-(prop-2-ynyl)- [1,4]-benzothiazin-3-one against mild steel in 1 M HCl solution: Experimental and theoretical studies

4-(prop-2-ynyl)-2H [1,4]-benzothiazin-3(4H)-one (PBO) was synthesized and evaluated on corrosion resistance for mild steel (MS) in1 M HCl environment. The molecular and crystal structure of PBO has been determined by single-crystal X-ray crystallography, Hirshfeld surface (HS) analysis was carried out by using Crystal Explorer 17.5. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) techniques were used to find corrosion rate (CR) and corrosion inhibition efficiency (η) in the presence and absence of PBO. These techniques were supported with energy dispersive X-ray (EDX) and scanning electron microscope (SEM). Molecular Dynamics Simulation (MDS) and Frontier Molecular Orbital (FMO) are realized by means of the Density Functional Theory (DFT) method. The results show that PBO could offer an inhibition efficiency of 92% at 303 K. The type of inhibition mechanism of PBO was mixed-type. The Langmuir isotherm proved the highest compliance with experimental data, representing the generation of protective mono-layer of inhibitors on the MS substrate. The SEM pictures displayed a metallic substrate covered with a highly compact protective layer covered. The theoretical findings suggested by electronic/atomic computer simulations supported the inhibitive chemicals interfacial adsorption through reactive centres.     

Influence of temperature and hydrodynamic conditions on the corrosion behavior of AISI 316L stainless steel in pure and polluted H3PO4: Application of the response surface methodology

Phosphoric acid is mainly produced by the wet acid process, where corrosion problems could be intensified due to the presence of impurities in the phosphate ores. Operating temperatures and flowing conditions aggravate the aforementioned problems. This work studies the influence of temperature (25–60 °C) and hydrodynamic conditions (Reynolds numbers from 1456 to 5066) on the corrosion of AISI 316L stainless steel in pure and polluted phosphoric acid solutions, by means of cyclic potentiodynamic polarization curves in a hydrodynamic circuit. The effect of temperature is the same as that caused by impurities, that is, higher corrosion rates and hindered passivation and repassivation resistance of the alloy. Statistical analysis by means of surface response methodology proved that the effect of temperature on the corrosion parameters of AISI 316L is more influential than the Reynolds number effect. The Reynolds number seems to have no significant influence on the corrosion behavior of stainless steel. Furthermore, the influence of temperature on the corrosion rate is much higher than on the rest of the corrosion parameters analyzed, especially in polluted phosphoric acid solutions. AISI 316L stainless steel has a clear interest for the phosphoric acid industry as a component material of some equipment due to its good corrosion properties at the different temperatures and Reynolds numbers studied even in polluted media.