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Effect of P codeposition on the structure and microhardness of Co-W coatings electrodeposited from gluconate bath

Seenivasan, H and Bera, Parthasarathi (2017) Effect of P codeposition on the structure and microhardness of Co-W coatings electrodeposited from gluconate bath. In: SURFACE AND INTERFACE ANALYSIS, 49 (6). pp. 554-569.

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Official URL: http://dx.doi.org/10.1002/sia.6193


Effects of addition of P to Co-W coatings from gluconate bath using direct current (DC) and pulse current (PC) methods have been investigated in this study. Co-W-P coatings with different P concentrations are prepared by varying hypophosphite concentration in the bath. Current efficiency of the Co-W-P electrodeposition is lower than that for Co-W coatings. Increase in NaH2PO2 concentration increases the cobalt content significantly and decreases the tungsten content drastically. Co-W-P coatings display `cauliflower-like' morphology and roughness of the coatings increases with increasing P content. As-deposited Co-W-P deposits are amorphous while heat treatment at different temperatures has rendered them crystalline with the precipitation of stable species like, Co3W, Co2P, etc. Unlike Co-Wcoatings, Co-W-P shows two-step crystallization in differential scanning calorimetry (DSC) and on heat treatment, which is similar to the behavior of Co-P electrodeposited from gluconate baths. Moreover, inclusion of phosphorous and heat treatment have led to significant increase in microhardness of the Co-W-P coatings. X-ray photoelectron spectroscopy (XPS) studies provide a detailed insight into the nature of Co, W and P species in as-deposited and sputtered coatings. Microhardness of the heat-treated coatings is higher than the as-deposited counterparts and is comparable with that of hard chromium. Copyright (C) 2016 John Wiley & Sons, Ltd.

Item Type: Journal Article
Additional Information: Copy right for this article belongs to the WILEY, 111 RIVER ST, HOBOKEN 07030-5774, NJ USA
Department/Centre: Division of Mechanical Sciences > Aerospace Engineering(Formerly Aeronautical Engineering)
Date Deposited: 10 Jun 2017 04:37
Last Modified: 17 Oct 2018 07:29
URI: http://eprints.iisc.ac.in/id/eprint/57143

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