SEM images taken in Regions I and II are shown in Fig. 9. Any effect of BSA was difficult to find in the optical photo of Region I shown in Fig. 8(a). However, from the SEM photo of the same region shown in Fig. 9(a), evidence of BSA adsorption could be observed. Comparing Fig. 9(a) with (b), BSA adsorption on the two regions of the slider surface occurred through two different forms: discrete protein aggregation and continuous adsorption layer. Protein aggregates adsorbed on surfaces have been reported previously [9]. In this study, the protein aggregates with sizes ranging from several microns to more than 20 microns were dispersed in a continuous layer. The continuous layer of Region II was blue, as shown in Fig. 8, which results from the release of Fe ions during the corrosion process. Initially, the adsorption layer was in a gel-like form, but when it dried, cracks were generated due to dehydration as shown in Fig. 9(b). Moreover, the adsorption layer in Region II was more extensive than that in Region I as shown in Fig. 9, which could be attributed to the metal ions released and topography changed as a result of the corrosion. Similar gel-like films in a ball-on-disc contact were also reported [17], [18] and [21].