A. Zoikis - Karathanasis, E.A. Pavlatou, N. Spyrellis
Proceedings of the 6th International Conference “THE Coatings'' (2007), Hannover, Germany, October 25-27, p.257-265 (oral)
In the present work nickel-phosphorous (NiP) and NiP composite coatings with tungsten carbide (WC) nanoparticles (mean diameter 200 nm) as a reinforcing mean have been produced from a modified, organic free, Watts bath, under direct, as well as pulse current conditions. The effect of the electrolysis parameters, like type of current and frequency of imposed pulses on the structure, the morphology, the mechanical properties and the mechanism of WC particles embedment was studied. Furthermore, the impact of heat treatment at 400°C on the above mentioned properties was investigated. The composite coatings that have been produced were compact and the pulse plating conditions led to deposits with higher percentage of embedded nanoparticles, better distribution of nanoparticles in the matrix and enhanced mechanical properties than those prepared under direct plating conditions. Moreover the coatings demonstrated significantly high micro-hardness values, especially after specific thermal treatment.