Comparative investigation of scratch resistance and tribological performance of Ni–B–TiO2 composite coatings prepared by conventional and novel processing methods

Abstract

Ni–B–TiO2 composite coatings were elaborated by conventional and novel methods. While the first one was designed using TiO2 powder, the second was prepared by adding TiO2 sol in the bath solution. A comparative study between both coatings was performed in terms of microstructure, adhesion strength and wear resistance. To achieve a systematic study, various characterization tests were carried out, including Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), microhardness test, progressive load scratch test, reciprocating sliding test and multi-pass scratch test. The results showed that the TiO2 structure (crystalline or amorphous) has extensively changed the microstructure of Ni–B matrix. Furthermore, it was proven that the novel process provided superior scratch response and better wear resistance of the Ni–B deposit since it offers a compact structure. Nevertheless, the traditional method yielded to porous one, thus leading to mediocre mechanical properties of the same coating.