Comparison of micro-hardness, corrosion resistance and hydrogen permeation of Ni-nanoTiO2 composite coating and pure Ni coating fabricated by electro-deposition

Ni-nano TiO2 composite coatings on low carbon steel have been prepared in Watts-bath using the electro deposition process. Characteristics of coatings such as micro-hardness، corrosion and hydrogen permeation were studied and compared with those of pure nickel coating. Micro-hardness results showed a noticeable increase in hardness of composite coatings in respect to the pure nickel coating. It was found that، an increase in TiO2 particle incorporation lead to the micro-hardness increment of the coatings. The corrosion study of specimens in %5 H2SO4 solution with pH=1 acquired through Tafel polarization، revealed several times reduction in the corrosion rate (CR) of composite coatings as compared to the pure nickel coating. Furthermore، hydrogen permeation test was performed on both pure nickel and Ni-TiO2 composite coating by the electrochemical approach (Devanthan-Stachursky) to compare their resistivity against hydrogen atoms through hydrogen charging by a power supply and recording permeation density versus time with a Potentiostat. Analysis of the results showed better resistivity of the composite coating against hydrogen permeation compared to the pure nickel coating.