International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395-0056
Volume: 04 Issue: 07 | July -2017
p-ISSN: 2395-0072
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A Review on Studies of Mechanical Properties of Anodized Alumina Oxide Rajesh Beri 1, Manoj Kumar Kushwaha 2, Neelkanth Grover 3 1 Research
Scholar, I. K. Gujral Punjab Technical University, Kapurthala-144603, Punjab, India of Mechanical Engineering, Shaheed Bhagat Singh State Technical Campus, Ferozepur-152001, Punjab, India 3 Department of Mechanical Engineering, I. K. Gujral Punjab Technical University, Kapurthala-144603, Punjab, India ---------------------------------------------------------------------***--------------------------------------------------------------------2 Department
Abstract - This review paper is an overview of the current state of research on AAO (anodized alumina oxide). Due to applications in electronics, optoelectronics, energy storage, photo catalysis, photonics and biosensors/biomaterials, interest in one dimensional nanostructures has grown significantly during the last decade. Anodization is done on alumina electrochemically resulting in to formation of anodic oxide layer. Nanostructures thus formed are an array of closely packed hexagonal oxide cells, in the centre of each of which there is a vertical hollow channel. These honeycomb shaped structures thus formed have been well exploited in traditional engineering applications for their unique mechanical properties including large strength-to-weight ratio, high anisotropy, extended plastic plateau corresponding to strain localization, and so on. Mechanical properties like young’s modulus, hardness, and fracture toughness of the Nano porous alumina are measured by Nano indentation. This method makes use of very low loads in the milli newton range for application on AA0. Studies show that the pores greatly improve toughness of the porous alumina. When the pore diameters of AAO structures are investigated using Nano indentation, the smallest pore diameter produces the highest hardness value. The analysis of the hardness–contact depth data reveals that the indentation hardness decreases in inverse proportion to the indenter penetration depth. Furthermore, the corresponding hardness remains constant despite the increase in indenter depth. When the specimen is subjected to heat treatment at 650°C, it causes the hardness to increase from 5.2 to 6.36 GPa and the fracture toughness sharply decreases. The study of the structural and magnetic properties of ferromagnetic nanotubes in aluminium oxide templates with different diameters, wall thicknesses, and lengths shows that magnetization processes of nanotubes is influenced by the wall thickness. In wear study, in sliding contact situations, aluminum has poor wear resistance and high friction. The naturally occurring oxide layer that forms will protect the base substrate from corrosion but is not effective for wear resistance due to inadequate thickness in its natural state. The sulfuric anodizing process found to be an economical and effective way to improve the wear characteristics of this oxide layer. Hard anodizing, at lower electrolyte temperatures, allows for thicker, denser build up of the oxide due to smaller pore size. This greater dense © 2017, IRJET
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formation of the nanotubes with small pore diameter results in higher micro hardness of the oxide layer as compared to the base substrate. Hard anodizing is an effective method to improve the friction and wear characteristics of aluminum by increasing the thickness of oxide formation on alumina surface. Key Words: Anodization, nonporous, Nano-indentation, young’s modulus, toughness. 1. INTRODUCTION The anodization process has been used by industry to protect metal components from corrosion for approximately 90 years. By using an electro-chemical process the surface chemistry of the metal is changed, via oxidation, to produce an anodic oxide layer that is thick enough to stifle further oxidation. Aluminum metal (Al), because of its high strength to weight ratio, numerous engineering applications [1, 2] is a widely used metal and is also easily available. For nanostructures Al is generally used in form of AAO. Two types of anodic Al oxide exist; the first is a non-porous barrier layer that is thin, hard, and wear resistant and behaves as an electrical insulator. The second, a thicker porous oxide structure, is called AAO layer [1]. This layer structure has a high aspect ratio and consists of a porous structure. The structure of AAO, is very stable at high temperature and in organic solvents, and exhibits uniform pore density, and the pores are parallel and perpendicular to the surface, having an ideal cylindrical shape. Thus anodization is increasingly becoming the subject of many investigations in several fields. The most recent advancement in application of AAO is the fabrication of capacitive humidity sensors because the nano sized pores provides a large surface area for absorbing water vapor. A thick porous layer i.e. structure having large pore diameter results an increase in sensitivity because of an increase in contact surface area [8]. Furthermore, the porous AAO membrane itself is employed for filtration, gas separation or as photonic crystals [3].AAO membrane itself is employed for filtration, gas separation or as photonic crystals [3].
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