Hot Dip Galvanizing Of Zn-Al-WO3 Coating On Mild Steel: Effect Of Surface Treatment
Traditionally, galvanizing has been used to protect steel from corrosion. Although galvanized layers may be able to protect steel substrate from atmospheric corrosion, they may not be able to provide a long-term corrosion protection in highly aggressive environments. The aim of this project is to de...
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| Main Author: | |
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| Format: | Monograph |
| Language: | English |
| Published: |
Universiti Sains Malaysia
2022
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| Subjects: | |
| Online Access: | http://eprints.usm.my/56533/1/Hot%20Dip%20Galvanizing%20Of%20Zn-Al-WO3%20Coating%20On%20Mild%20Steel%20Effect%20Of%20Surface%20Treatment_Devah%20Kalai%20Selvam.pdf http://eprints.usm.my/56533/ |
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| Summary: | Traditionally, galvanizing has been used to protect steel from corrosion. Although galvanized layers may be able to protect steel substrate from atmospheric corrosion, they may not be able to provide a long-term corrosion protection in highly aggressive environments. The aim of this project is to develop hydrophobic surface on the mild steel by reaction process on the surface of galvanized steel to increase the corrosion resistance. Zn-Al-WO3 was coated to the mild steel via hot dip galvanizing, followed by surface treatment containing stearic acid (STA) and silicon dioxide (SiO2). Molarity of STA
(0.002,0.005,0.008,0.01,0.02,0.05 M), solvent type (ethanol, acetone), immersion time (2,3,5 hours) and coating compositions were varied during surface treatment. Several characterizations such as thickness, phases of coating, morphology, contact angle, surface roughness as well as corrosion test were conducted. The Zn-Al-WO3 coating has an average thickness of 107 µm and is made up of an inhibition layer and an outer layer. The lowest corrosion rate of 0.7073 mm/years and hydrophobic water contact angle of 122.29° were
recorded with 0.008M of STA in ethanol solution for 2 hours. The 0.008M of STA in 2 hours surface treatment shows better distribution of feather-like lamellar structure of zinc
stearate. Agglomeration occurs more quickly with increasing molarity and immersion time, leading to non-uniform surface roughness and reduced hydrophobicity. The STA more
soluble in ethanol than acetone, thus formation of homogenous zinc stearate, increasing its hydrophobicity and anti-corrosion property. The obtained hydrophobic surface on galvanized steel yield a promising result and has potential to provide a cost effective and green solution for corrosion protection. |
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