Showing 3 results for Anodizing
A. Afshar and M.r. Vaezi,
Volume 22, Issue 2 (1-2004)
Abstract
Titanium is a highly reactive metal so that a thin layer of oxide forms on its surface whenever exposed to the air or other environments containing oxygen. This layer increases the corrosion resistance of titanium. The oxide film is electrochemically formed through anodizing. In this study, anodizing of titanium was performed in phosphate-base solutions such as H3Po4, NaH2Po4, and Na2Hpo4 at 9.75Ma/cm2 and 35ºC under galvanostatic conditions. The Potential-Time curves in the above solutions show that the anodic films formed on titanium are compact and their thickness depends on the solution type and concentration. The SEM and XRD techniques show that these layers are amorphous. In this paper, the effect of electrolyte concentration, composition and resistivity on breakdown voltage have been discussed in terms of Ikonopisov electron avalanche
breakdown model. This model shows that the major factor contributing to the decrease in breakdown voltage is the increased electrolyte concentration leading to increased primary electronic current.
F. Ebrahimi, F. Ashrafizade, S. R. Bakhshi,
Volume 36, Issue 3 (11-2017)
Abstract
In this research, ordered porous anodic templates with 30 nm diameter and 15 µm thickness were prepared by using double anodization process. Dip coating method was employed to synthesize strontium ferrite in the form of nanowires in sol dilution. Ferrite nanopowders were also synthesized using sol gel method. The characterization of the nanostructures were examined by X-Ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersive Spectroscopy (EDS). Hysteresis loops of nanopowders and nanowires, parallel and perpendicular to the wires axes, were measured by Superconducting Quantom Interference Device (SQUID). The results showed that double anodization in 0.3 M oxalic acid at 4 oC with a single anodization for 12 hours could produce ordered template. Dip coating in 80 oC for two hours could form fine and uniform strontium ferrite nanowires. The produced material showed parallel anisotropy.
S. H. Hashemi Rizi , A. Nourmohammadi Abadchi,
Volume 40, Issue 4 (3-2022)
Abstract
Development of materials with the ideal black body absorption spectrum are of great interest. Such materials could improve the efficiency of solar cells, and passive cooling and heat transfer systems as well as the protective and decorative coatings. Fabricating black anodizing coatings is promising for this purpose because they exhibit low light reflection from the surface. Such coatings can be produced through successive anodizing and black coating of aluminum alloys. In this study, the effect of anodizing repetition on the absorption coefficient of the black anodizing coatings on 2024 aluminum alloy was investigated, as model. All the parameters were fixed in the black coloring stage to evaluate the influence of the anodizing steps. After a one-step anodizing, the black coatings showed an absorption coefficient of 0.956 in the visible region and 0.911 in the of 220 to 2200 nm wavelength range, while their absorption coefficient increased after a three-step anodizing up to 0.982 in the visible region and up to 0.966 in the 220 to 2200 nm wavelength range. This indicates that anodizing repetition helps the optical absorption of black anodizing coatings to approach the optical absorption of an ideal black body.
