Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : Anodizing


Corrosion Behavior of Anodized Pure Zinc in Sea Water

S. A. Ajeel; B. Ahmed

Engineering and Technology Journal, 2017, Volume 35, Issue 9, Pages 961-969

In the present work an electrochemical anodizations of pure Zn sheet result in the ZnO porous film structure in alkaline solution (15% ammonium florid) by using constant voltage technique at a range of (2-10) volt, for period time of 10 minutes at room temperature was studied .
Atomic force microscope (AFM) used to investigate the topography and roughness of anodic film formed on the surface, it was found that the roughness of the anodic film is mainly depended on the anodizing voltage and its increase from 0.2 (as polished) to (2.9) nm after anodizing. Coating thickness also increases with an increase in voltage from 0 to 285 μm after anodizing. The corrosion behaviors of anodized and non-anodized of zinc specimens in sea water are obtained. The corrosion current density and corrosion rate are decreased with an increase in supplying voltage which increases anodic film thickness.

Coloring the Layer Thickness of Anodized Aluminum by Integral Color Process

Talib M. Naieff Al-Bayati

Engineering and Technology Journal, 2013, Volume 31, Issue 3, Pages 450-469

The identification of the self coloring process in anodizing process is integral color. In this research specimens of pure aluminum (1000) and AA 5056 anodized by using Alternative Current (A.C) techniques were investigated under standard conditions and electrolytically colored in sulfuric acid baths solutions at different operating conditions [Alternative Current density (A.C) (2-3) Amp/dm2, electrolyte concentration (2-6) Normality, electrolyte temperature (15-25) Co and anodizing time (20-60) minutes]. The experimental work was designed according to (Box-Wilson) method by using second order polynomial model between four variables and thickness of anodic layer for the two types of materials and substituted the experimental results for anodizing process in proposed model to calculate the coefficients of the mathematical equations to find an expression for obtaining best film thickness. The coloring deposition efficiency increases with the increase of applied electrolytic coloring alternative current and the purity of aluminum.
Under standard electrolytic coloring conditions, the current efficiency for coloring deposition is low for all examined materials. However, pure aluminum has much higher coloring deposition efficiency than the alloy. The anodizing alternative current density affects the electrolytic coloring process to a lesser degree for alloy than for pure aluminum, indicating the role of the morphology of the oxide film. The increases of anodizing temperature and porous layer thickness have marginal effect on electrolytic coloring process. Understanding the effect of alloy types on electrolytic coloring process will enable us to achieve color uniformity and to expand color and shade selections.

Electrochemical Behavior of Chemical Conversion of Coated Aluminum 1100Al in a Neutral Tartrate Solution

Khalid H. Rashid

Engineering and Technology Journal, 2010, Volume 28, Issue 18, Pages 5640-5650

1100 Al specimens were anodically oxidized in different concentrations of
tartaric acid-tartrate solution (pH=7) in 1, 1.75, 3.25 and 4 wt % at temperatures of
30, 37.5, 52.5 and 60 ºC by applying a range of potentials of 30, 37.5, 52.5 and 60
V at exposure times of 40, 47.5, 62.5 and 70 min.. These four variables are
manipulated through the experimental work using Box – Wilson experimental
design where second order polynomial model was proposed to correlate the studied
variables with the thickness of anodic film of aluminum alloy (1100) to estimate
the coefficients of the proposed polynomial adopted via statistica software.
Optimum conditions for achieving the maximum film thickness are obtained from
optimizing the above correlation and are found as follows: temp. = 44ºC, acid conc.
= 2.8 wt %, voltage = 43.6 V, time = 54.6 min.. Stagnate Solutions of 3, 5, 10 and
25 wt % Nacl at 25ºC have been investigated using polarization technique at
optimum conditions for anodizing. The most important feature achieved was the
great difference in behavior between the anodic polarization curves for bare and
anodized aluminum in different concentrations of Nacl solutions. The corrosion
rates for anodized specimens are lower than those for unanodized ones. The
polarization behavior of anodizing specimens shows that the breakdown potentials
are shifted to more noble direction than bare specimens which is more pronounced
in 25 wt % Nacl solution due to anodizing.