2004 年 70 巻 1 号 p. 133-137
Precise periodic structures can be generated on the surface of various kinds of materials by linear polarized femtosecond laser of energies nearby ablation threshold. The direction of the periodic structures can be changed easily by polarization rotator. The technique was employed to create precise periodic structures of different directions with a ring pattern (radial type, concentric circles type, spiral type) on sintered tungsten carbide flats. This paper deals with effect of the periodic structures on tribological characteristics under sliding tests. Ring-on-disk tests and disk-on-disk tests revealed that the precise periodic structures take remarkable effects to reduce friction coefficient. Radial type and spiral type produced fluid film lubrication on wide sliding condition under ring-on-disk tests. Concentric circles type achieved low friction coefficient at low sliding velocity under ring-on-disk tests. Spiral type was the most suitable for reducing friction coefficient under disk-on-disk tests.