Investigation of the effect of bath temperature on Ni-W/Al2O3 nanocomposite coatings produced by electrodeposition method

Abstract

In this study, Ni-W/Al2O3 nanocomposite coatings were applied via the direct current electrolysis method on the St-37 steel substrate using a Watts bath. Ni-W alloy coating was obtained by adding sodium tungsten dihydrate as a tungsten source to a Watts-type nickel bath, and then aluminum oxide (Al2O3) ceramic nanoparticles were added to this solution to obtain a nanocomposite coating. The effect of different temperatures (25ºC, 60ºC) on Ni-W and Ni-W/Al2O3 coatings was investigated and detailed research was carried out on the hardness, surface morphology and wear resistance of the coatings. When the raw information of this study was examined in a logical order, the changes in the hardness of the material and the changes in its mechanical properties showed the effect of temperature on the coating. In general, the surface morphologies of the nanocomposite coatings exhibited a smooth and homogeneous distribution. According to the wear analysis results, with the addition of tungsten element to the main matrix, the average friction coefficient decreased by 36.51% at 25ºC and 46.03% at 60ºC compared to pure nickel. With the addition of Al2O3 nanoparticle to Ni-W alloy, the average friction coefficient increased by 12.5% at 25ºC and 2.94% at 60ºC compared to Ni-W alloy. Microhardness results showed that the hardness values increased with the increase in bath temperature. The hardness value of the Ni-W alloy coating obtained at the bath temperature of 60ºC increased by 6.43% compared to the coating obtained at 25ºC. The hardness value of the Ni-W/Al2O3 nanocomposite coating obtained at 60ºC increased by 8.72% compared to the coating obtained at 25ºC.