Fabrication and Characterization of Anodic Films onto the Type-304 Stainless Steel in Glycerol Electrolyte

Abstract

Porous films without periodic structuration were formed by direct current anodizing the surface of type-304 stainless steel in glycerol solution containing NH4F and H2O at elevated temperatures. Formed in the solutions containing both NH4F and H2O at the constant voltage mode of up to 50 V, these films are thin (∼1.0–1.2 μm) and yellow, whereas those formed at higher voltages, ca. 60–70 V, are thicker (up to 15 μm) and greenish. Note that these porous films are composed of both amorphous and crystalline species. X-ray diffraction (XRD), energy-dispersive X-ray (EDX), and X-ray photoemission spectroscopy (XPS) investigations and the detailed chemical analysis of incorporated elements revealed the complex nature of these films varied depending on the anodizing solution composition and voltage value applied. On the basis of the obtained data, the possible mechanism of formation of the glycerol anodic films on the SS304 substrate is presented. Compositional and structural transitions of as-grown films to material composed of crystalline Cr1.3Fe0.7O3 and spinel-type species were achieved via calcination procedure of anodized samples in air at 700 °C.

Corrosion Resistance of Anodic Layers Grown on 304L Stainless Steel at Different Anodizing Times and Stirring Speeds

“…From the charge density values, the theoretical thickness of the anodic layer can be estimated assuming that the entire charge is used for the formation of FeOOH, acoording to Equation (1) This compound has been previously reported as the main component of the anodic layers grown in ferrous materials [35,41,49]. Figure 3 shows the current density-time curves recorded during the anodizing treatments at 0 rpm and at 600 rpm for different anodizing times (15,30,45, 60 min).…”

“…The range of applications and properties, which can be tailored and improved by manipulating the nanostructure is wide. As the morphology and structural characteristics of the anodic layers are deeply correlated with the anodizing conditions, the control of the anodizing parameters such as potential applied, temperature, electrolyte composition and anodizing time is key to the formation of the nanoestructure of the anodic layers [18,[34][35][36].…”

“…Nevertheless, most of the existing works so far are focused on the growth and chemical/ morphological characterization of the anodic layers on these ferrous materials [29,35,[39][40][41][42], but not on their influence on the electrochemical response or corrosion resistance properties. For that reason, the objective of this work is to explore the corrosion properties in a NaCl solution of the anodic layers grown on 304L SS at different stirring speeds and anodizing times inthylene glycol with 0.1 mol L −1 NH 4 F and 0.1 mol L −1 H 2 O.…”

Magnetite thin film on mild steel formed by hydrothermal electrolysis for corrosion prevention

“…In order to improve the rate of the blackening process, the electrochemical process was employed [1,2,[27][28][29][30][31][32]. Bacsa et al [29] introduced the hydrothermal-electrochemical technique to synthesis barium titanate (BaTiO 3 ) at temperatures 80-200°C with titanium as an electrode and barium hydroxide (Ba(OH) 2 ) as an electrolyte solution.…”

“…The adherent, blue black magnetite layer that provide corrosion protection can be grown several micrometers thick on some carbon steels by selecting a narrow range of temperature, voltage and electrode spacing. Klimas et al [28] reported the formation of anodic film on the surface of the same type of stainless steel by direct current anodizing in electrolyte that comprised glycerol and NH 4 F with and without H 2 O at elevated temperatures. The formation of anodic films are composed of both amorphous and crystalline species whose composition and contents depend on the anodizing conditions and the content of H 2 O in solution.…”