Functionally graded nickel–cobalt coatings with/without alumina nanoparticles were pulse electrodeposited on a carbon steel substrate by a continuous decrease in duty cycle from 95 to 10% at different frequencies of 100, 500and 1000 Hz. The effect of pulse parameters on the nanoparticle content, chemical composition, microstructure, corrosion properties and tribological behaviour of coatings was studied. Energy-dispersive X-ray spectroscopy analysis showed that the amount of cobalt is gradually reduced and the content of alumina nanoparticles is increased from the substrate/coating interface to the surface. Based on the electrochemical studies in 3.5 wt% NaCl, the nanocomposite coatings gain the highest corrosion resistance at the lowest frequency. Also, the hardness of coatings gradually increased. Evaluation of the tribological behaviour of coatings by a pin-on-disk wear test showed that the nanoparticles have a positive effect on wear resistance and improve it by increasing frequency.
Volume 43, 2020
Continuous Article Publishing mode
Prof. Subi Jacob George — Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru
Chemical Sciences 2020
Prof. Surajit Dhara — School of Physics, University of Hyderabad, Hyderabad
Physical Sciences 2020
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