SYNTHESIS OF Ni-Cr COATING THROUGH ELECTRO DEPOSITION AND ITS CHARACTERIZATION

Abstract

Ni and Cr coatings have been worked upon and also practically used for the various advantageous properties they provide, both, individually as well as when coated in form of various alloys for various applications such as tribological applications, high temperature applications, corrosion resistance and even for mere decorative purposes. Here, electrodeposition has been employed as a technique to obtain Ni-Cr coating, using divalent Ni salt and trivalent Cr salt. The distinctive feature of the coating is that the composition within the coating varies from the base to the surface wherein the Ni content decreases and simultaneously Cr increases. Also, correspondingly, it is expected that the grain size is increasing from near to the substrate-coating interface to the surface. For achieving this, a technique has been developed using the Pulsed Galvanostatic mode of electrodeposition. The coating has been characterized using SEM/FESEM, EDS, AFM, XRD. The wear test — Adhesion Wear Test was carried out, the frictional coefficient was found to be lower than the base material and the individual pure metallic coating. Corrosion behavior was studied using the Salt Spray Test, even the corrosion properties were found to be comparable to that of the individual elemental coatings. Thus, a comparison has been made between the deposits of pure Ni, Pure Cr, and the alloy coating obtained using pulsed electrodeposition, and the bare Mild steel substrate.