Title: Impact of chemical composition of the substrate on the synthesis and behaviour of nano hard anodised layers

Authors: Zeinab Abdel Hamid; Malak Taher Abou El-khair; Mona Hassan Gomaa; Fatma A. Morsy; Nevien Abdel Atty Khalifa

Addresses: Corrosion Control and Surface Protection Lab., Central Metallurgical Research and Development Institute (CMRDI), P.O. 8, 7 Helwan, Cairo, Egypt ' Composite Lab., Central Metallurgical Research and Development Institute (CMRDI), Cairo, Egypt ' Corrosion Control and Surface Protection Lab., Central Metallurgical Research and Development Institute (CMRDI), P.O. 8, 7 Helwan, Cairo, Egypt ' Faculty of Science, Chemistry Department, Helwan University, Helwan, Egypt ' Faculty of Science, Chemistry Department, Helwan University, Helwan, Egypt

Abstract: The purpose of this article is to focus on the effect of chemical composition of aluminium substrate on the formation of nano hard anodised aluminium oxide layer (NHAAO) from sulphuric acid bath. The effect of operating conditions (temperature, time and current density) and chemical composition of the substrate on the thickness, pore diameter, morphology, microhardness, abrasion resistance and corrosion resistance of the anodised layers have been investigated. The optimum conditions for the formation of NHAAO films were studied by field emission-scanning electron microscope (FE-SEM) and X-ray photoelectron spectroscopy (XPS). The results demonstrated that the substrate composition, temperature and current density have been effected on the thickness and the pore diameters of the anodic film. XPS analysis illustrated that, the anodised layer consists mainly of oxide. Additionally, the formation of NHAAO on Al or 3004 Al alloy improves the hardness, abrasion resistance and corrosion resistance comparing with unanodised substrates.

Keywords: anodising process; sulphuric acid electrolyte; nanoporous materials; anodic aluminium oxide; AAO; films; hard coat; nanohardness; nanotechnology; chemical composition; aluminium substrate; layer thickness; pore diameter; morphology; microhardness abrasion resistance; corrosion resistance; substrate composition; temperature; current density.

DOI: 10.1504/IJNP.2014.067611

International Journal of Nanoparticles, 2014 Vol.7 No.3/4, pp.231 - 250

Available online: 17 Feb 2015 *

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