Surface nanocrystallization by sandblasting and annealing for improved mechanical and tribological properties

A sandblasting and annealing process was utilized to modify the surface structure of aluminium. The modified surface structure was examined by x-ray diffraction (XRD) profile analysis and transmission electron microscopy (TEM). It was demonstrated that the grain size of the sandblast–annealed surface layer was in the range 50–70 nm. Mechanical and tribological properties of the nanocrystalline surface were investigated using micro-indentation, nano/micro-scratch, scanning Kelvin probe (SKP), and atomic force microscope (AFM) techniques. It was observed that the micro-hardness and wear resistance of the surface were considerably increased due to the formation of a nanocrystalline layer. In addition, a close correlation between the electron work function (EWF) and the adhesive force was observed; higher EWF corresponded to lower adhesive force and thus lower friction under light loads.