Production of electrolytic nickel and nickel–phosphorous composite layers containing titanium

The influence of titanium powder content in an electroplating bath on the deposition process of Ni+Ti and Ni–P+Ti composite layers was examined. Composite Ni+Ti and Ni–P+Ti layers were prepared by simultaneous electrodeposition of nickel and titanium on a steel substrate from a Watts bath in which 4, 12, 20, 28 and 40 (g dm−3) of Ti powder were suspended. The electrodeposition was carried out under galvanostatic conditions at a temperature of 343 K and current density of jD=0.1 A cm−2 during 0.5 h. The phase composition of the layers was investigated by the X-ray diffraction method. Atomic absorption spectroscopy was used for chemical characterization of the layers. The surface morphology of the coatings was examined by means of a stereoscopic microscope with a morphometric computer system. The percentage volume fraction of Ti as a composite component was determined. Chemical and phase analysis of the Ni+Ti and Ni–P+Ti layers confirms the co-deposition of Ni and Ti. It was found that the phase structure of obtained layers depends on the phosphorous content in the layer only. It was also ascertained that the increase of the titanium powder amount in the bath causes the rise in Ti content embedded in the composite layers. The presence of NaH2PO2 in the basic bath reduces the content of embedded Ti in the layers.