Lubricating layer formed on porous anodic alumina template due to pore effect at water lubricated sliding and its properties

A porous anodic alumina (PAA) template was manufactured to investigate the pore effect on the formation of lubricating layers. A PAA template with 260 nm pores was manufactured by two-step anodization using phosphoric acid. A sliding wear test was carried out using a ball-on-disk tester. Due to the pore effect, an aluminum hydroxide film; i.e., the lubricating layer, was formed at a specific condition. The PAA template has a low friction regime because of the aluminum hydroxide film. The adhesion and friction forces of the aluminum hydroxide film were measured using atomic force microscopy (AFM), and the adhesion and friction forces of the lubricating layer were lower than that of a typical oxide layer. Using AFM analysis, the existence of a lubricating layer can be verified.