The effect of different surface topographies on the corrosion behaviour of nickel

Abstract

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.

Simultaneous effect of surface roughness and passivity on corrosion resistance of metals

“…In contrast, as can be seen in Figure 2(b), a different corrosion behaviour and a reverse trend was observed in the case of nickel Figure 2: Dependence of i corr on surface finish of (a) mild steel and (b) nickel. in 0.5 M H 2 SO 4 solution on surfaces with different unidirectional roughnesses [6]. As can be seen in previous work done by the authors, by increasing the roughness of nickel surface from sample G1200 to G60, the polarization curves shifted toward higher corrosion current densities which mean higher corrosion rates [12].…”

“…The same effect was also observed for the effect of roughness on corrosion rate for AE44 Mg alloy before [7]. In both cases the metal has no ability to form a passive layer but in the case of other metals which form a passive layer, a reverse trend was observed [1][2][3][4][5][6]. As it is shown in Figure 1, polarization curves rise to parallel and it is clear that both cathodic and anodic branches show a lower current density indicating that the hydrogen evolution reaction is activation controlled [10,11].…”

“…This is a general trend seen for corrosion of metals with no ability to form a passive layer [7,8]. This trend is in opposite direction compared to nickel (Figure 4(b)) and aluminum with ability to form a protective passive film [3,6]. A reverse trend was also reported by Li and Li [2] for Cu in a 3.5% NaCl solution which was expected.…”

“…Last column in this table is a list of SiC particle size on grinding papers. Nickel also showed an increase in roughness parameters after corrosion which is an indication of the formation of deeper grooves (on rougher surfaces where there is more corrosion) and passive layer (on all surfaces especially smoother surfaces) [6,12]. …”

“…Such a trend was observed for copper, nickel, aluminium, stainless steel, magnesium and titanium alloys [1][2][3][4][5][6]. In all cases the effect of creating different roughnesses were investigated on both localized and general corrosion performance of the alloys.…”