A SABOUR ROUHAGHDAM
Articles written in Bulletin of Materials Science
Volume 39 Issue 3 June 2016 pp 857-864
In this study, a Ni–Fe–Al$_2$O$_3$ nanocomposite coating was deposited on the substrate of low-carbon steel by electrodeposition from a sulphate-based bath. The effects of frequency and duty cycle were investigated to producethe functionally graded (FG) coating. For this purpose, first, the coatings with duty cycle-decreased method (DDM) were deposited in eight steps from 88 to 11%. At the second step, frequency-increased method (FIM) was utilized from 50 to 6400 Hz during eight steps. Assessing of coatings was carried out by scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), potentiodynamic test, Vickers microhardness test and wear test.Microstructure evaluations gained by SEM and EDS demonstrated that the continuous alterations of duty cycle contribute for manufacturing of FG coatings, so that the maximum particle fraction was in the free surface of the coating and its amount was gradually decreased to the interface. These investigations showed that FIM had no effect on production of graded structure. Corrosion and wear tests indicated high corrosion and wear resistance of DDM coatings in comparison to FIM coatings. Investigating the best coatings obtained from both above methods exhibited 50 and 20% reduction in corrosion current density and wear rate, respectively, for DDM specimen in comparison to FIM sample.
Volume 39 Issue 7 December 2016 pp 1691-1699
In this study, the Ni/Al$_2$O$_3$ nanocomposite multilayer coatings with six consecutive layers were electrodeposited on the mild steel by pulse electrodeposition with ultrasound agitation from nickelWatts-type bath. Thestructure and morphology of the etched coatings cross-section were characterized by scanning electron microscopy (SEM). The corrosion behaviour of these coatings was investigated in 1 M H$_2$SO$_4$ solution. All of the coatings showed the active–passive transition and the distinct difference in structure had negative influence on their corrosion resistance. Moreover, the tribological behaviour of these coatings was evaluated by pin-on-disc type. The results showed that wear resistance increased with increase in duty cycle and frequency.
Volume 43, 2020
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