Fabrication of NiTi layer via co-electrodeposition of nickel and titanium

In the present study, uniform NiTi layers were synthesized by means of co-electrodeposition of Ti particles in Ni matrix in the Watts bath and subsequent thermal treatment. The substrate was mild steel and the Ti powder was suspended in the bath by mechanical stirring during the process. The influence of the plating current density, Ti particles concentration and bath agitation on the particles distribution was investigated, as well as the coating chemical composition. The results showed that Ti content in the coating could reach to 32 at.% at the current density of 2 A/dm(2). Further increase of the current density led to the reduction of Ti in the layer and the coatings turned out to be highly porous at higher current densities. It was also observed that Ti in the deposits increased from 18 at.% to the maximum value of 49 at.% with rising the particles concentration from 1 to 5 g/dm(3), respectively. The optimized coating with the maximum amount of Ti was then heat treated at 1000 degrees C and 1150 degrees C for different times. The results indicated that thermal treatment for longer times led to the formation of a porous and non-uniform structure, while heat treatment for shorter times at higher temperatures (1150 degrees C) resulted in a dense and relatively uniform NiTi layer. (C) 2012 Elsevier B.V. All rights reserved.