Keywords : Anodization

Variation of crystallinity of Cu and Cu2O nanowires arrays grown in various pores of porous alumina membrane

Yu-Min Shen; Dipti. R. Sahu;Jow-Lay Huang; Wen-Fang Chiu; Sheng-Chang Wang; Pramoda K. Nayak

Advanced Materials Letters, 2017, Volume 8, Issue 11, Pages 1046-1051
DOI: 10.5185/amlett.2017.1493

Various pore sizes of a porous alumina membrane were fabricated using H2SO4 and H2C2O4 electrolyte under different ionization voltages. Cu nanowire arrays with high aspect ratios, uniform pore size, and ordered pore arrangement were synthesized using the above porous alumina membrane (PAM). Moreover, Cu2O nanowire arrays were prepared through the oxidization of Cu metal nanowire arrays. From the microstructure and compositional analysis, it was observed that pores of different sizes, i.e. 20~30, 70~90 and 90~100 nm could be obtained by controlling various electrolytes and anodization voltage. The Cu nanowire synthesized with various pore sizes were found to be single crystal (20~90 nm) and polycrystalline (90~100nm) respectively. The single crystal Cu with (111) direction was occurred due to homogeneous current density distribution and relationship between current density (J) and nucleus radius (ro). After oxidation of Cu, the Cu2O nanowires with the pore sizes of 20~100 nm was found to be single crystal. The rearranged of Cu and O2 lattice sites promotes the enhancement of crystalline property. 

Contact Angle Measurement Studies On Porous Anodic Alumina Membranes Prepared Using Different Electrolytes

P. Ramana Reddy; Ajith K. M.;N. K. Udayashankar

Advanced Materials Letters, 2016, Volume 7, Issue 5, Pages 398-401
DOI: 10.5185/amlett.2016.6230

This paper investigates the effect of pore widening duration on the wetting properties of nanostructured porous anodic alumina (PAA) membranes fabricated using sulphuric and oxalic acid as electrolytes by two step anodization process. XRD analysis shows that prepared PAA membranes were amorphous in nature. With increasing of pore widening durations from 0 to 120 min, the contact angle of PAA membranes varied from 21 to 78Ëš. It was noticed that PAA membranes were hydrophilic in nature in the present of water medium. In the presence of acetone medium, PAA membranes prepared with 1hr pore widening time showed super hydrophilic behaviour. 

Titanium Dioxide Nanotube Arrays: A Novel Approach Into Periodontal Tissue Regeneration On The Surface Of Titanium Implants  

S. Goodarzi; F. Moztarzadeh; N. Nezafati; H. Omidvar

Advanced Materials Letters, 2016, Volume 7, Issue 3, Pages 209-215
DOI: 10.5185/amlett.2016.6014

Titanium alloys have been extensively used as promising implant materials. The anodic oxide layer on the surface of this alloy can be a compact, porous or a tubular structure, which has a direct impact on the final characteristics of the implants. In this study, nano topographic oxide arrays were synthesized on the surface of titanium substrates using an anodic oxidation technique. The anodization process was performed at a two-electrode electrochemical cell, and then the samples were annealed to obtain crystalline structures. The synthesized samples were analyzed to evaluate the compositional phase, morphology, surface hydrophilicity and corrosion resistance of the nanostructured oxide arrays in artificial saliva. Microscopic observations confirmed the formation of a nanotubular structure on the surface of titanium substrate depending on the anodization condition. After heat-treatment at 570 °C, crystallographic analyses showed that the obtained crystalline phase was a mixture of Anatase and Rutile phases. The electrochemical impedance spectroscopy (EIS) results indicated a significant improvement in the corrosion resistance and electrochemical stability of the anodized sample in artificial saliva compare to the control samples. In addition, the anodized samples showed a better hydrophilic characteristics, viability and proliferation of periodontal ligament cells in comparison with the un-anodized samples. This study demonstrated that the anodized titanium samples, with the nanotubular structure on the surfaces, could be considered as a good candidate for dental implants. 

Influence Of Anodizing Time On Porosity Of Nanopore Structures Grown On Flexible TLC Aluminium Films and Analysis Of Images Using MATLAB Software

C. C. Vidyasagar; Parashuram Bannigidad; H. B. Muralidhara

Advanced Materials Letters, 2016, Volume 7, Issue 1, Pages 71-77
DOI: 10.5185/amlett.2016.5967

The effect of time on nanopore structures formed via electrochemical anodization of high purity Al2O3 was investigated. The electrochemical bath consists of 5 % phosphoric acid electrolyte; a platinum electrode was used as the cathode electrode, and TLC (thin layer chromatography) aluminium film as anode electrode. It is found that the regularity of nanopores arrangement can be significantly improved by increasing anodizing time at constant temperature and voltage. It is observed after the anodizing process, that at every interval of time there is a significant decrease in wall thickness from 58-26nm and increase in the nanopore diameter size about 31-86 nm. According to Nielsch, self-ordering of porous alumina requires a porosity of 10 % independently of anodizing conditions. It means that the most optimum anodizing conditions always results in a porosity of 10 %. The result optimized at 30 min is well matched with 10 % porosity. The morphology and phase composition were characterized by field emission scanning electron microscope (FE-SEM), energy dispersive spectroscopy (EDX). The nanopores thin film images obtained by FESEM are used for image analysis using MATLAB software and porosity and nanowall thickness results are compared with experimental and automated methods, which demonstrate the efficacy of the proposed method.

Room Temperature Anodization Of Aluminum And The Effect Of The Electrochemical Cell In The Formation Of Porous Alumina Films From Acid And Alkaline Electrolytes 

Alaba O. Araoyinbo; Azmi Rahmat; Mohd Nazree Derman; Khairel Rafezi Ahmad

Advanced Materials Letters, 2012, Volume 3, Issue 4, Pages 273-278
DOI: 10.5185/amlett.2012.2323

Nanoporous alumina was produced by anodic oxidation of aluminum in both acidic and alkaline electrolytes. Previous reports indicate that nanoporous alumina is mainly produced from strongly acidic electrolytes, and with the use of a low freezing temperature controlled bath to control the propagation and growth of the pores. We design an in-house electrochemical cell with an electronic circuit box attached, to control the anodization of aluminum at room temperature. The electrolytes used were phosphoric acid solution and sodium hydroxide solution. The pH of the acidic electrolyte was adjusted to 1, 3 and 5 with an applied potential of 50V and anodization time of 1 and 3 hrs, respectively, while the alkaline electrolyte pH was adjusted to 9, 11 and 13 with an applied potential of 40V and the templates anodized for 5 hrs. The micrographs of the nanoporous alumina formed from these electrolytes confirm that the nucleation and growth of nanoporous alumina films is achievable with the aid of the electronic circuit box connected to the electrochemical cell.