Lubricated sliding performance of laser-patterned sapphire

• Published in: Wear 1999-10, Vol.232 (2), p.226-230
• Main Authors: Blatter, A, Maillat, M, Pimenov, S.M, Shafeev, G.A, Simakin, A.V, Loubnin, E.N
• Format: Article
• Language: English
• Subjects: Laser patterning; Liquid lubrication; Sapphire; Sliding life
• ISSN: 0043-1648; 1873-2577
• DOI: 10.1016/S0043-1648(99)00150-7

A laser ablation technique is applied to modify the tribological properties of a hard material by the fabrication of surface microstructures. These structures act as reservoirs for a liquid lubricant, resulting in much longer life of the lubrication. A copper-vapor laser (emitting at 510 nm wavelength) was used to produce microgrooves at the surface of sapphire plates which were then coated with an extremely thin film of an oil lubricant. The effect of the patterns on the sliding friction was examined with a pin-on-disk tribometer against a steel ball. Comparing the lubricated sliding of the laser-patterned samples with the nonpatterned one revealed that the life of lubricated sliding increased considerably for the laser-patterned sapphire, but that the patterned surface was more abrasive than the original highly polished surface. For a particular pattern of grooves of a few microns in width and depth, a steady-state sliding behaviour was observed, characterized by the absence of wear and a friction coefficient of 0.02 without any degradation of the lubricant. The observed correlations between the parameters of the surface microrelief and the sliding performance of the tribosystem are discussed to determine an optimal surface structure for achieving such steady-state conditions with apparently no wear and unlimited sliding.