Influence of Heat Treatment on Crystal Structure, Microhardness and Corrosion Resistance of Hybrid Electroless Ni‑P‑Al2O3-Mo2C Coating on 90wt% Al-10wt% Mg alloy

Document Type : Original Article

Authors

1 Department of Mechanical Engineering, National Institute of Technology, Durgapur, India

2 Department of Mechanical Engineering, National Institute of Technology, Durgapur 713209, India

3 Department of Mechanical & Industrial Engineering, College of Engineering, National University of Science & Technology, P.O.Box : 2322, CPO Seeb 111, Al Hail, Sultanate of Oman

Abstract

The aim of this study was to investigate the properties of an electroless Ni-P-Al2O3-Mo2C coating on a 90wt% Al-10wt% Mg alloy. A thermal process was conducted at 400 °C for 1 hour to assess the impact of temperature on the coating properties. The structure of the bilayer coatings was analyzed using X-ray diffraction (XRD), and the surface topography of the hybrid coating was observed using a scanning electron microscope. It was found that at a concentration of 2 g/L, the Al2O3 and Mo2C distributions in the Ni-P coating bath exhibited a more uniform nodular or columnar structure. The hardness of the deposit was measured using a Vickers hardness tester, and the Ni-P-Al2O3-Mo2C coating sintered with a nanoparticle concentration of 2 g/L showed the highest hardness value of 692 VHN. This value was 19.32% higher than the unsintered Ni-P-Al2O3-Mo2C external layered coating. Furthermore, potentiodynamic polarization studies were performed in a 3.5% NaCl solution to evaluate the corrosion behavior of the hybrid coating under ambient conditions. The results indicated that the Ni-P-Al2O3-Mo2C coating formed at 2 g/L provided the highest corrosion protection, as confirmed by the highest positive Ecorr value of -0.2.4 V, attributed to the maximum particle deposition rate. Overall, the combination of NiP3, Al2O3, and Mo2C phases in the coating exhibited synergistic effects, leading to improved anti-corrosion and mechanical properties.

Keywords

Egyptian Journal of Chemistry

Articles in Press, Accepted Manuscript
Available Online from 13 February 2024

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History

  • Receive Date: 22 December 2023
  • Revise Date: 01 February 2024
  • Accept Date: 11 February 2024

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