Effect of Navo₃ concentration and hcl pre-treatment on corrosion behavior of anodized coated AZ91D magnesium alloys

Magnesium and its alloys have some excellent properties, such as the lowest density of industrial metals, a high strength-to-weight ratio, vibration absorbency and electromagnetic wave shield characteristics. Because of these properties, magnesium and its alloys can be applied in the manufacture...

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Main Author:	Khalid Azadi, Mat Akhir
Format:	Thesis
Language:	English
Subjects:	Alloys Magnesium Navo₃ concentration Anodizing AZ91D magnesium alloy Sodium metavanadate (NaVO₃)
Online Access:	http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/44134/1/p.1-24.pdf http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/44134/2/full%20text.pdf
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spelling	my-unimap-441342016-11-22T09:15:27Z Effect of Navo₃ concentration and hcl pre-treatment on corrosion behavior of anodized coated AZ91D magnesium alloys Khalid Azadi, Mat Akhir Magnesium and its alloys have some excellent properties, such as the lowest density of industrial metals, a high strength-to-weight ratio, vibration absorbency and electromagnetic wave shield characteristics. Because of these properties, magnesium and its alloys can be applied in the manufacture of components for motor vehicles, in housing for electronics, and in the manufacture of sporting goods. In addition, magnesium and its alloys are more easily recycled than synthetic resins, which make these materials eco-friendly. The poor resistance of magnesium and its alloys to corrosion has limited the application of these materials in corrosive environments. Anodizing coating is one of the most cost effective and simple techniques for introducing a metallic coating to a substrate. This study deals with the preparation of oxide films on AZ91D magnesium alloy by anodizing coating in a solution containing La(NO3)3 and/or Mg(NO3)2, with additive NaVO3 concentration in the solution. The anodizing coating on the AZ91D magnesium alloy has been carried out and the effect of NaVO3 concentrations and pre-treatment was investigated. A chemical compound of AlO, MgO and VO was detected from the diffraction peaks of XRD pattern confirming the formation of an oxide layer on the surface of AZ91D magnesium alloy. The corrosion resistance of AZ91D magnesium alloy increases remarkably with corrosion rate of 0.2 mm/y was obtained. A self-healing morphology could be observed from SEM images indicated the recovery of the NaVO3 rich oxide film from the severe environment of NaCl solution. This result is remained constant for further improvement by HCl pre-treatment. A rough surface was obtained after immersing in HCl solution for 20 s and followed by anodizing, has yielded the corrosion rate up to 0.19 mm/y. Two peaks assigned for VO and MgO was detected from XRD patterns. The corrosion protection of AZ91D magnesium alloy has been increased by the following ways; the formation of selfhealing morphology to recover from the severe environment by the addition of NaVO3, and formation of a passive oxide layer on the surface of AZ91D magnesium alloy by immersion in HCl solution. Based on the electrochemical experiments of potentiodynamics polarization and immersion test result, coating with NaVO3 and HCl pre-treatment successfully increased the corrosion resistance of AZ91D magnesium alloy. The result demonstrated here will strongly contribute to the broad application of magnesium alloy in the field of the automotive industry. Universiti Malaysia Perlis (UniMAP) 2014 Thesis en http://dspace.unimap.edu.my:80/xmlui/handle/123456789/44134 http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/44134/1/p.1-24.pdf aae56b807481202f94408f89d225e6b7 http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/44134/2/full%20text.pdf 55f3e8150b16fca95dc906e86cd2f66a http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/44134/3/license.txt 8a4605be74aa9ea9d79846c1fba20a33 Alloys Magnesium Navo₃ concentration Anodizing AZ91D magnesium alloy Sodium metavanadate (NaVO₃) School of Manufacturing Engineering
institution	Universiti Malaysia Perlis
collection	UniMAP Institutional Repository
language	English
topic	Alloys Magnesium Navo₃ concentration Anodizing AZ91D magnesium alloy Sodium metavanadate (NaVO₃)
spellingShingle	Alloys Magnesium Navo₃ concentration Anodizing AZ91D magnesium alloy Sodium metavanadate (NaVO₃) Khalid Azadi, Mat Akhir Effect of Navo₃ concentration and hcl pre-treatment on corrosion behavior of anodized coated AZ91D magnesium alloys
description	Magnesium and its alloys have some excellent properties, such as the lowest density of industrial metals, a high strength-to-weight ratio, vibration absorbency and electromagnetic wave shield characteristics. Because of these properties, magnesium and its alloys can be applied in the manufacture of components for motor vehicles, in housing for electronics, and in the manufacture of sporting goods. In addition, magnesium and its alloys are more easily recycled than synthetic resins, which make these materials eco-friendly. The poor resistance of magnesium and its alloys to corrosion has limited the application of these materials in corrosive environments. Anodizing coating is one of the most cost effective and simple techniques for introducing a metallic coating to a substrate. This study deals with the preparation of oxide films on AZ91D magnesium alloy by anodizing coating in a solution containing La(NO3)3 and/or Mg(NO3)2, with additive NaVO3 concentration in the solution. The anodizing coating on the AZ91D magnesium alloy has been carried out and the effect of NaVO3 concentrations and pre-treatment was investigated. A chemical compound of AlO, MgO and VO was detected from the diffraction peaks of XRD pattern confirming the formation of an oxide layer on the surface of AZ91D magnesium alloy. The corrosion resistance of AZ91D magnesium alloy increases remarkably with corrosion rate of 0.2 mm/y was obtained. A self-healing morphology could be observed from SEM images indicated the recovery of the NaVO3 rich oxide film from the severe environment of NaCl solution. This result is remained constant for further improvement by HCl pre-treatment. A rough surface was obtained after immersing in HCl solution for 20 s and followed by anodizing, has yielded the corrosion rate up to 0.19 mm/y. Two peaks assigned for VO and MgO was detected from XRD patterns. The corrosion protection of AZ91D magnesium alloy has been increased by the following ways; the formation of selfhealing morphology to recover from the severe environment by the addition of NaVO3, and formation of a passive oxide layer on the surface of AZ91D magnesium alloy by immersion in HCl solution. Based on the electrochemical experiments of potentiodynamics polarization and immersion test result, coating with NaVO3 and HCl pre-treatment successfully increased the corrosion resistance of AZ91D magnesium alloy. The result demonstrated here will strongly contribute to the broad application of magnesium alloy in the field of the automotive industry.
format	Thesis
author	Khalid Azadi, Mat Akhir
author_facet	Khalid Azadi, Mat Akhir
author_sort	Khalid Azadi, Mat Akhir
title	Effect of Navo₃ concentration and hcl pre-treatment on corrosion behavior of anodized coated AZ91D magnesium alloys
title_short	Effect of Navo₃ concentration and hcl pre-treatment on corrosion behavior of anodized coated AZ91D magnesium alloys
title_full	Effect of Navo₃ concentration and hcl pre-treatment on corrosion behavior of anodized coated AZ91D magnesium alloys
title_fullStr	Effect of Navo₃ concentration and hcl pre-treatment on corrosion behavior of anodized coated AZ91D magnesium alloys
title_full_unstemmed	Effect of Navo₃ concentration and hcl pre-treatment on corrosion behavior of anodized coated AZ91D magnesium alloys
title_sort	effect of navo₃ concentration and hcl pre-treatment on corrosion behavior of anodized coated az91d magnesium alloys
granting_institution	Universiti Malaysia Perlis (UniMAP)
granting_department	School of Manufacturing Engineering
url	http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/44134/1/p.1-24.pdf http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/44134/2/full%20text.pdf
_version_	1747836827444707328

Effect of Navo₃ concentration and hcl pre-treatment on corrosion behavior of anodized coated AZ91D magnesium alloys

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