Characterization and comparison between porous anodized aluminum colored by nickel and tin deposition (original) (raw)
Related papers
Porous Layer Characterization of Anodized and Black-Anodized Aluminium by Electrochemical Studies
Three types of black anodic coatings, namely, black dyeing (BD), inorganic colouring (IC), and electrolytic colouring (EC) were prepared by conventional type II sulphuric acid anodizing on Al6061 alloys. Electrochemical behaviour of these coatings was studied by exposure to 3.5% wt sodium chloride solution for prolonged immersion periods up to 360 hours. The porous layer characteristics of all sealed, fresh and autosealed coatings were investigated by means of electrochemical impedance spectroscopy (EIS). An equivalent circuit that reproduces the a.c. impedance results of porous aluminium oxide films is proposed. The breakpoint frequency and damage function analysis were carried out to analyse the coating’s electrochemical behaviour. Corrosion morphology was studied by scanning electron microscopy. It was observed that BD and IC behaved in a very similar manner to sulphuric acid anodising (SAA). However EC was behaving in an entirely different manner. Among all colouring methods BD was showing very less Rp values. All these findings were further confirmed by linear polarisation studies. No major evidence of localised corrosion or pitting of the black anodic coatings was observed in SEM micrographs.
Journal of Physics: Conference Series, 2019
For decoration purposes, aluminum metal has widely used metal coloring techniques to enhance the aesthetic value of the metal. Most coloring techniques of the aluminum metal use aluminum metal dipping with dye or with chrome (Cr) directly. This coating technique has the disadvantage, such as the color fade easily or the chrome layer peels off. The anodizing method becomes a potential method to improve coloring techniques because this process is able to provide a protective layer and improve surface appearance through staining and can change the aluminum surface to aluminum oxide, high hardness, and corrosion resistance. This study aims to analyze the surface condition of the aluminum after the anodizing process with several variables. In this research uses the variation of H2SO4 electrolyte solution concentration and electric current as variables to improve aluminum surface quality. Anodizing process is carried out with electrolyte concentration up to 20% and current up to 5 A. The ...
IOP Conference Series: Materials Science and Engineering, 2019
The use of aluminium metal in daily life has widely used colouring techniques to enhance the aesthetic value of the metal. Aluminium anodizing process can produce porous on the metal surface. The formed porous can be used to store and hold the colouring agent to make them more durable. The research intends to observe the colouring characteristics on the aluminium surface influenced by several parameters of the anodizing process, including electrolyte concentration and electric current. In this study the current H2SO4 concentration was used as a variable to improve the quality of staining on anodised aluminium surfaces. The anodization process was carried out on H2SO4 electrolyte solution with variations in concentrations of 10% to 20% and the current density used was 3 A to 5 A. The tests were carried out using micro Vickers to observe the hardness value. The hardness was higher at lower concentration of electrolyte solution due to thinner layer of oxide film, scanning electron micr...
Coloring the Layer Thickness of Anodized Aluminum by Integral Color Process
2013
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/dm 2 , electrolyte concentration (2-6) Normality, electrolyte temperature (15-25) C o 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.
New Trends in Anodizing and Electrolytic Coloring of Metals
Egyptian Journal of Chemistry
Development of an inexpensive, effective, and technologically simple method to occur natural self-organization of oxide nanopores would become very important in light of the ever-increasing needing. The anodization process has recently attracted a wide extent of research attraction in nanotechnology. An anodizing process is considered as effective technique for fabrication of passive layer, and synthesis of nanoporous metals with new morphology enhanced mechanical and electrochemical performances. Modern fabrication techniques involved in an anodic production of nanoporous metal focus on the variation of exterior properties during the electrochemical process. Fabricating anodic nanoporous metals are constrained by the major parameters are listed. Also, this review discusses a brief generic approach for electrolytic coloring and previous investigations for electrolytic coloring as finishing anodized surface with special metal particles affords appropriate optical properties in the anodized surface of aluminum applicable for solar absorption application. Surface mechanical attrition treatment (SMAT) is a new alternative approach that can facilitate anodization; it is a type of plastic deformation technique, used prior the anodization to convert the metal from polycrystalline into nanocrystalline. The conversion results in grain size refinement and establishment of the high density of grain boundaries. A comparison between the resulting anodic metals subject and not subjected to SMAT will be displayed. The discoveries in this review open a new pathway in the anodic fabrication of nanoporous materials. By the integration of both SMAT and anodization, this setup will be a new perspective in the future developments of nanomaterials.
Electrolytic coloring of porous aluminum oxide films in CoSO4 solution
Anodic oxide matrices have been formed in a 15 % H2SO4 solution on three types of aluminum electrodes: Al (99.5%) and two alloys (8006 and 8011). The obtained Al2O3-films (thickness 20 μm, porosity 0.15) have been colored in a CoSO4 solution using AC-polarization with different duration (2-15 min) and at frequencies in the range (20-100 Hz). A comparative study has been conducted on the spectral characteristics (in the UV-VIS-NIR region) of the colored films with two different surface pretreatments: electropolished and chemically mat. It has been found, that in all cases the increase of coloring time (the quantity of cobalt incorporated in the pores respectively) leads to an increased absorbance capability of the coatings. The optimal process frequency is determined to be 60 Hz. Furthermore, the pretreatment of the metal surface has no significant influence on the quantity of cobalt incorporated in the Al2O3matrices. The obtained results show that the colored in СоSO4 porous anodic films on aluminum and its alloys exhibit good absorbance characteristics in the visible, as well as in the UV and NIR regions. This makes them suitable to serve as decorative (black) coatings and also have a potential application as solar collector elements.
Thin Solid Films, 1989
In this work, we have investigated the effect of the thickness ofboth porous and compact films of aluminium anodized in I5/, H2SO4 on the electrocolouring process using copper sulphate and magnesium sulphate solutions. With thin layers (less than 10000 A) the colours obtained depend on the porous oxide layer thickness and they are controlled mainly by an interference phenomenon. With thicker films (60000-320000 A) the colour becomes independent of the amount of copper incorporated into the pores and an interference phenomenon is not observed.
Coloring the Layer Thickness of Anodized Aluminum.pdf
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/dm 2 , electrolyte concentration (2-6) Normality, electrolyte temperature (15-25) C o 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 Characterization of Al2O3Ni Thin Film Selective Surface on Aluminium
Solar thermal collectors represent a widely used type of system for the conversion of solar energy. In order to produce selective coatings on aluminium substrates to be used as absorber plates in high efficiency solar collectors, nickel pigmentation was applied to anodically oxidised surfaces. Electrochemical dc methods are used to study the oxidation of aluminium as functions of the following electrolysis conditions: applied current, pH, temperature and concentration of electrolyte. The properties of the oxidised aluminium surfaces are investigated by cyclic voltammetry. Nickel pigmentation of porous aluminium surfaces was also performed as a function of electrochemical pigmentation conditions by ac electrodeposition. Mechanisms contributing to selectivity in anodically oxided aluminium and electrodeposits are discussed. The optical properties of the prepared surfaces are optimised, and solar absorptance αs =0.91 and thermal emittance t,23 • C =0.17 are obtained.