Advanced Ni–W coatings obtained by the combination of pulse plating and chemometric techniques

Abstract

The electroplating of Ni–W alloys could represent one of the most promising environmentally friendly alternatives to replace hard chromium. However, the Ni–W process and coatings still show some limitations such as lower hardness than hard chromium and limited corrosion resistance that need to be overcome in order to be considered a real solution. In this work, a Ni–W electrolyte was proposed and optimised. A chemometric approach was used in order to design pulse plating experiments and study the effect of experimental parameters on the properties of pulse plated Ni–W coatings. In addition, multivariate analysis was proposed to establish a relation among structural and physical characteristics of Ni–W deposits, and the optimum values of the process parameters required to improve their properties were determined. Results indicate that by the combination of pulse plating and chemometric techniques, Ni–W coatings with improved uniformity, efficiency and hardness compared to those obtained by direct current could be obtained, achieving hardness and corrosion resistance values similar to those of hard chromium coatings.

Keywords:

• Nickel
• Tungsten
• Alloy deposit
• Pulse plating
• Chemometric

Acknowledgements

The authors would like to thank the MINECO of the Spanish government (MAT2011-27380-C02) for their financial support. This paper is based on a presentation given at the 6th European Pulse Plating Seminar, Baden, Austria, 7th March 2014.