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.
In the present study, we investigated the effect of an anode temperature on current transient process during porous anodic alumina growth and morphology of the anodic layers. Alumina films were formed in a 0.4 M oxalic acid at a constant voltage mode and electrolyte temperature. The temperature of the Al anode was controlled by thermoelectric Peltier element and varied in the range of 5 °C–60 °C. Surface morphology of both sides of anodic films and their cross-sections were analyzed by scanning electron microscopy (SEM) with subsequent statistical analysis of the SEM images by ImageJ software. It was found that when anode temperature was increased from 5 °С to 50 °С the pores diameter and interpore distance has not changed, but the porous structure became more ordered. According to these results, the rate of chemical dissolution of the barrier layer and pore walls did not depend on the anode temperature. At the anode temperature of 60 °С, pores diameter has increased 1.7 times and there was a distortion of the ordering of porous cells. It was concluded that the temperature difference between the aluminum substrate and electrolyte is an important parameter affecting the formation of ordered structure of nanoporous anodic alumina.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.