Table of Contents
Journal of Coatings
Volume 2014, Article ID 841619, 10 pages
http://dx.doi.org/10.1155/2014/841619
Research Article

Effects of Hard Surface Grinding and Activation on Electroless-Nickel Plating on Cast Aluminium Alloy Substrates

1Metallurgical and Materials Engineering Department, Federal University of Technology, Akure, Akure 340252, Nigeria
2Materials and Metallurgical Engineering Department, Federal University Oye Ekiti, Oye Ekiti 371104, Nigeria

Received 30 May 2014; Revised 19 August 2014; Accepted 4 September 2014; Published 21 September 2014

Academic Editor: Mariana Braic

Copyright © 2014 Olawale Olarewaju Ajibola et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

This work examined effects of hard surface polishing grits and activation on electroless-nickel (EN) plating on cast aluminium alloy substrates in sodium hypophosphite baths. As-received aluminium alloy sample sourced from automobile hydraulic brake master cylinder piston was melted in electric furnace and sand cast into rod. The cast samples were polished using different grits (60 μm–1200 μm) before plating. The effects on adhesion, appearance, and quantity of EN deposits on substrates were studied. Observation shows that the quantity of EN deposit is partly dependent on the alloy type and roughness of the surface of the substrates, whereas the adhesion and brightness are not solely controlled by the degree of surface polishing. The best yield in terms of adhesion and appearance was obtained from the activation in zincate and palladium chloride solutions. Higher plating rates (g/mm2/min) of , , and were obtained from chromate, zincate, and chloride than , , and as obtained from HCl etched, NaOH, and H2O activated surfaces, respectively.