Siti Hawa Mohd Salleh, Dr.
http://dspace.unimap.edu.my:80/xmlui/handle/123456789/34248
This page provides access to scholarly publications by UniMAP Faculty members and researchers.2024-03-28T18:45:59ZEffect of deposition time on properties of ZrO2 coating prepared using electrolytic method
http://dspace.unimap.edu.my:80/xmlui/handle/123456789/35056
Effect of deposition time on properties of ZrO2 coating prepared using electrolytic method
Siti Hawa, Mohamed Salleh; Terng, Lim Wuh; Mohd Nazree, Derman, Dr.; Mohd Zaidi, Omar; Salmie Suhana, Che Abdullah
AISI 440C martensitic stainless steel is one of the most widely studied engineering materials for its tribological properties. It is capable of attaining the best mechanical properties such as high strength and hardness compared to other martensitic grades. Unfortunately, the corrosion resistance of this 440C steel is the lowest among the stainless group, which results in the precipitation of carbide phases. AISI 440C were coated using electrolytic ZrO2 layer deposition method in ZrO(NO3)2 aqueous solution. In order to preserve the high mechanical properties of this steel, various heat treatment processes applied to the coated samples. After drying and annealing, the ZrO2 coated samples were evaluated using SEM, hardness tests and corrosion tests. Some mudcrack had been indicated in all samples. However, it become more homogeneously on the sample which undergoes longer deposition time. This difference resulted in a significant improved on corrosion resistance of ZrO2 coated sample.
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2013-01-01T00:00:00ZSurface morphology and corrosion behavior of electrolytic coatings in different aqueous solutions
http://dspace.unimap.edu.my:80/xmlui/handle/123456789/33600
Surface morphology and corrosion behavior of electrolytic coatings in different aqueous solutions
Siti Hawa, Mohamed Salleh; Mohd Nazree, Derman, Dr.; Mohd Zaidi, Omar; Rohaya, Abdul Malek
ZrO₃/AI₂O₃, AI₂O₃/Y₂O₃, ZrO₂/Y₂O₃ coatings were applied on SS440C steel substrates via an electrolytic double layer coating process. The effect of these different ceramic aquecous solutions on the surface morphology and corrosion protection of the coatings were studied. It was seen that ZrO₂/Y₂O₃ coating layer is adherent and subsequently facilitates significant protection again corrosion as test by Tafel Extrapolation test in form of potentiodynamic polarization. The surface morphology and hardness properties were examined by scanning electron microscopy (SEM) and Vickers hardness tester respectively. ZrO₂/Y₂O₃ double layer coating shows the best properties in morphology and hardness as compared to other aqueous solutions.
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2014-01-01T00:00:00ZDifferent concentration of Al(No₃)₃ In Zro₂/Al₂o₃ double layer coating steel prepared by electrolytic method
http://dspace.unimap.edu.my:80/xmlui/handle/123456789/33595
Different concentration of Al(No₃)₃ In Zro₂/Al₂o₃ double layer coating steel prepared by electrolytic method
Siti Hawa, Mohamed Salleh; Mohd Nazree, Derman, Dr.; Mohd Zaidi, Omar; Rohaya, Abdul Malek
Stainless steels, such as 440C steel are commonly used for engineering applications. The high carbon contents of this steel have significantly been attributed to low corrosion resistance properties. Surface modification such as electrolytic double layer coating with ZrO₂/Al₂O₃ was carried out to control the performance. Samples were deposited in ZrO(NO₃)₂ and Al (NO₃)₃ aqueous solution respectively. Potentiodynamic examination (Tafel Extrapolation test) was conducted to measure the corrosion resistance of coated steel. The results showed improvements in hardness properties and corrosion rate as the Al₂O₃ concentration had been increased.
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2014-01-01T00:00:00ZMicrostructural characterization of ZrO2 layer coating on martensitic stainless steel
http://dspace.unimap.edu.my:80/xmlui/handle/123456789/31597
Microstructural characterization of ZrO2 layer coating on martensitic stainless steel
Siti Hawa, Mohd Salleh; Mohd. Zaidi, Omar, Prof. Madya Dr.; Mohd Nazree, Derman, Dr.; Salmie Suhana, Che Abdullah
High carbon steel stainless steel such as 440C martensitic stainless steel, are commonly used for automotive components, such as ball bearings, races, gage blocks and valve. In this study, 440C steel was coated with ZrO2 by electrolytic deposition in ZrO(NO3)2 aqueous solution. After annealing, the ZrO2 coated specimens were characterized by x-ray diffraction (XRD) and scanning electron microscope (SEM). Scanning electron micrograph showed that thickness of the coated sample was approximately 0.7μm. Besides that, secondary hardening effect occurred on the annealed SS440C substrate and it might be due to the presence of secondary carbide.
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2012-01-01T00:00:00Z