Morphological, mechanical, corrosion and hydrogen permeation characteristics of Ni-nano-TiO2 composite coating compared to Ni electrodeposited on low carbon steel

Abstract

Ni and Ni-nano-TiO2 composite coatings with various amounts of TiO2 in electrolyte, on low carbon steel, have been prepared from Watts-bath using electrodeposition process. The morphological, mechanical, corrosion and hydrogen permeation characteristics of Ni and Ni-nano-TiO2 coatings were studied and compared with each other. The results revealed that, existence of nano-TiO2 particles in Ni matrix improved the microstructure as well as microhardness, whereas increasing particle incorporation from 4.33 to 7.62 vol % concluded to microhardness enhancement. The corrosion behavior of Ni and Ni-nano-TiO2 composite coatings with various amount of particle content was studied by the anodic polarization curves in 5% H2SO4 solution at room temperature. It was seen Ni-nano-TiO2 composite coatings exhibited higher corrosion resistances comparing to pure Ni coating and corrosion protection improved with increasing nano-TiO2 in coatings. In addition to the corrosion and engineering properties, comparison of hydrogen permeation characteristics of the Ni coating was made with Ni-nano-TiO2 composite coating through Devanthan-Stachurski hydrogen permeation test. From the resulting data analysis, Ni-nano-TiO2 composite coating was seen not only to provide longer life under corroding media, but also reduces greatly the risk of the substrate being exposed to hydrogen permeation when compared to electrodeposited Ni coating.