Comparison Between The Microstructural, Morphological, Mechanical And Tribological Characteristics Of Nanocrystalline Ni And Ni-co Electrodeposited Coatings
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Date
2017
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Oum-El-Bouaghi University
Abstract
For improving the wear resistance of steel type commonly used in industry, nanocrystalline nickel and nickel-cobalt coatings were electrodeposited on A60 steel substrate in a modified Watts bath. The observation of the coatings produced by scanning electron microscopy (SEM) showed that nickel coatings have a smooth morphology whereas Ni-Co alloy deposits have a lens-shaped morphology with a considerable increase in the grains size of Ni-Co alloy deposits. The results of XRD showed that nickel coatings having fcc phase structure while Ni-Co coatings have hcp phase structure. The study of coatings micro-hardness indicate that the latter follows Hall Petche effect where nickel deposits which have the smallest grain size show a higher micro-hardness in comparison with Ni-Co coatings. Pin on disk tribometric analysis under unlubricated conditions illustrated a great improvement of the wear resistance by the addition of cobalt on nickel coatings, where the friction coefficient and the wear rates are significantly reduced in Ni-Co coatings compared with nickel coatings.
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Keywords
Ni, Ni-Co, Coating, Microstructure, Morphology, Microhardness, Tribological behavior