Abstract：The corrosion resistance of metals is closely related to their surface microstructure. This work focuses on the surfaces of gold plates which were prepared through a polishing process with different sizes of α-Al2O3. With SEM and AFM characterizations, the surface microstructures of the gold plates are distinct, indicating that the polished gold plates have surface microstructures similar to those of real work-pieces. The effects of the gold surface scratches on surface enhanced Raman scattering (SERS) and corrosion resistance were investigated. SERS on the gold surface scratches with different average feature sizes were tested using Rhodamine B (RhB) as a probe molecule. A relationship between the SERS intensity of the adsorbed Rhodamine B and the average feature size of surface scratch was obtained. By changing the angle between the polarization direction of Raman laser and the direction of scratches, it is found that the SERS signals are mainly ascribed to the transverse plasmon generated from interaction between incident light and scratches. The transverse plasmon intensity reached the maximum when the average feature size of the surface scratches is close to 50 nm. With the increase of the average feature sizes, the transverse plasmon intensity shows a gradual decrease. On the other hand, electrochemical polarization tests of the gold plates with different sizes scratches were measured. The free corrosion potential of samples is obtained. The free corrosion potential of gold plates decrease with increasing the average feature sizes. It is found that, when the average feature size of the surface scratch is more than 50 nm, a ideal coherence exists between the SERS intensity and the free corrosion potential for the gold plates. These results suggest that SERS technique could be applied for the corrosion resistance analysis of the work-pieces. By the means of smearing probe molecules and using a handheld Raman spectrometer, quick analysis of the work-pieces corrosion resistance is proven to be promising.
Key words：Surface enhanced Raman spectroscopy; Metal corrosion; Polishing; Electrochemical polarization
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