Fabrication and characterization of Ni-TiO2 and Ni-V2O5 single-layer and double-layer coatings with the approach of improving the wear and corrosion properties

Abstract

The main purpose of this study is to investigate the metallurgical behavior of Ni-TiO2 and Ni-V2O5 single-layer coatings and compare them with Ni-TiO2/Ni-V2O5 and Ni-V2O5/Ni-TiO2 double-layer coatings. The general attitude is the optimal choice of coatings in terms of wear and corrosion properties. The dimensions of TiO2 and V2O5 ceramic powders were 20 nm and 500 nm, respectively, and their morphology was also different. The presence of the submicron V2O5 particles was more than the TiO2 nanoparticles in the nickel matrix deposit. Also, with double layering the coatings (Ni-TiO2/Ni-V2O5 and Ni-V2O5/Ni-TiO2), the presence of ceramic particles in the upper layer had increased compared to the same single-layer coatings. Therefore, the increase in the hardness of the deposits was directly related to the percentage of ceramic powders in the coating. The surface morphology of the Ni-TiO2 layers was formed as a cauliflower shape while the Ni-V2O5 deposits had a smooth morphology. Increasing participation of TiO2 particles in the Ni-TiO2 layer had made the morphology rougher. Also, by applying the Ni-TiO2 layer under the Ni-V2O5 deposit, the surface morphology of the Ni-V2O5 layer became smooth, which can be due to the increase in the V2O5 content in this layer. The lowest amount of fluctuation appeared in the roughness profiles related to the Ni-V2O5 layers, and the large fluctuation range in the Ni-TiO2 layers was due to the smooth and cauliflower structure, respectively. The crystallite size in double-layer coatings was smaller than the single-layer coatings due to the higher nucleation and growth rate of nickel deposition in the nickel matrix upper layers. According to the presented results, the Ni-V2O5 and Ni-V2O5/Ni-TiO2 coatings were the most wear resistant coatings. Also, the Ni-V2O5/Ni-TiO2 and Ni-TiO2/Ni-V2O5 double-layer coatings were suitable candidates for corrosion resistance and to consider both properties, Ni-V2O5/Ni-TiO2 was very suitable. Hardness, surface morphology, roughness, preferred planar texture, and ceramics powder participation were important parameters in determining the wear and corrosion properties of coatings. Also, it seems that the effect of the double layering of nickel matrix deposits on the metallurgical properties was greater than the dimensions of the ceramic particles participating in the coating.