ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Effect of limiting current density on corrosion performance of Ni–Mo, Ni–Cd and Ni–Mo–Cd alloy coatings

Akshatha R. Shetty and A. Chitharanjan Hegde

Department of Chemistry, Manipal Institute of Technology, Manipal Academy of Higher Education, Manipal, India

E-mail: Shetty.akshatha@manipal.edu

Received: 2 January 2023  Accepted: 13 March 2023

Abstract:

In this article an attempt was made to increase the corrosion resistance of Ni– Mo alloy coatings with the addition of small quantity of CdCl₂ into its bath. The limiting of limiting current density (i_L) of Ni in both Ni–Mo and Ni–Cd baths due to inherent induced and normal type of codeposition has been successfully alleviated by addition of 1 g/L of CdCl_2. The advent of induced and normal type of codeposition of individual binary baths has been used to optimize the Ni content of the ternary deposit for better corrosion stability. The composition vs. current density plots of all coatings have been studied, and thereby optimal i_L of Ni in all baths were assessed. The content of Mo was found to be decreased with the small addition of Cd to the bath. Results revealed that (Ni–Mo–Cd)_{6.0 Adm}⁻² coating showed better corrosion resistance by reducing i_L of Ni, on addition of Cd⁺² ions into the bath and was explained in the light of diffusion limited deposition of Ni⁺² ions. The results were supported by SEM (scanning electron microscopy), XRD (X-ray diffraction) and AFM (atomic force microscopy) study of Ni–Mo, Ni–Cd and Ni–Mo–Cd coatings at optimal current densities.

Keywords: Ni–Mo; Ni–Cd; Ni–Mo–Cd; Corrosion study

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-023-02790-8

Chemical Papers 77 (8) 4399–4407 (2023)