A novel strategy to enhance the tribological properties of Cr/GLC films in seawater by surface texturing

In this paper, the patterns of micro-dimples with different area densities and the Cr/GLC films were fabricated by laser surface texturing and magnetron sputtering technology, respectively. The morphologies and surface chemical states of the Cr/GLC films were characterized by AFM, SEM, and XPS. The effects of dimple area density on the tribological behavior of Cr/GLC films under seawater condition were investigated by UMT-3 tribometer in a ball-on-plate reciprocating mode. The experimental results showed that the Cr/GLC film was mainly composed by Cr-C and C-C bonds. Both the friction coefficients and wear rates of the Cr/GLC films in seawater decreased with the increase of dimple area densities in the lower range, whereas, they were constant when the dimple area densities further increased. The Cr/GLC films with proper dimple area density (G3 film) were effective in enhancing the tribological properties because of the entrapment of graphitized particles and seawater in the dimples. The graphitized particles can reduce the strong adhesive interaction between contact surfaces, resulting in the low frictional shear resistance during sliding process. Furthermore, Ca2 + and Mg2 + in seawater will be deposited on the counterface in the form of Mg(OH)2 and CaCO3, which with sludge-like matters have some lubricating effects. At the same time, the Cr/GLC films with low dimple area densities exhibited low surface roughness, which could decrease the resistance in sliding process.