There are different parameters which can affect electrochemical reactions such as type of electrolyte, velocity, temperature, oxidizing agents, impurities, anode material type and surface treatment. It has been shown that pre-treatment of working electrode (anode) through abrasion techniques is one of the most important parameters affecting on Tafel slopes and consequently corrosion rate. Surface roughness of the metal surface is a major influence on general corrosion, nucleation of metastable pitting and pitting potential as well. In this study different surface roughnesses were created on nickel surface by SiC papers and corrosion properties were compared. Electrochemical impedance spectroscopy (EIS) and profilometry tests were carried out on all the samples and the results were compared with another sample prepared through laser ablation method. Corrosion rate values were calculated and were compared with EIS results for all the samples and a trend in the effect of roughness on corrosion protection of nickel was introduced. SEM and 3D roughness images were taken and compared for all of the samples before and after corrosion tests. Different mechanisms were distinguished for samples created through different methods. The lower the roughness values, the more the corrosion resistance. Sample with patterns created through laser ablation method showed the best protection properties compared to other samples.

The electrochemical and corrosion behaviour of a surface is extremely complicated and depends on various chemical, physical and mechanical factors. In this study the effect of different surface roughnesses on the corrosion resistance of nickel in 0.5 M sulphuric acid was investigated. Open circuit potential, corrosion current density, polarization resistance and corrosion rate were measured for surfaces polished with different grits (120, 240, 400, 600 and 1200) of silicon carbide papers. The surface roughness was measured using a profilometry method both before and after corrosion testing. SEM images were taken and compared for all of the samples before and after corrosion tests. The results showed that surface roughness and surface morphology can considerably change corrosion and corrosion rate. A higher corrosion resistance is obtained for surfaces with lower roughnesses. Finally, the results were compared with specimens where a specific surface patterning was obtained using a laser ablation method.

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Most common methods of decreasing the corrosion rate of metals use inhibitors, chemicals, coatings and surface modifiers. In this study a new method has been used to combat corrosion. This new approach is based on creating specific patterns on nickel surface. A pattern of holes with different diameters (D) and inter-hole spacings (L) were created through a laser ablation method on nickel sheet samples. Corrosion tests were carried out in a 0.5M H2SO4 solution. Scanning electron microscopy (SEM) was performed in order to compare the appearance of the samples before and after corrosion tests. Energy dispersive spectroscopy (EDS) technique showed chemical composition of materials inside and outside of the holes before and after the corrosion tests. As a result of the surface patterning a significant improvement of protective properties of nickel surface has been achieved. All patterned surfaces showed better corrosion resistance compared to the polished reference samples. In addition, it has been shown that for a few specific patterns the corrosion resistance can be increased by orders of magnitude compared to the polished reference samples.