Microtribological modification of silicon carbide surface by laser irradiation

This study aims to form lubricative carbon layers on the surfaces of sintered plates and thin films of silicon carbide (SiC) by local laser irradiation. This technique is suitable for use with micro-device applications on which it is difficult to add a lubricative agent. The proposed method is based on silicon elimination from SiC, which is referred to as the carbide derived carbon process. The local modification is performed on sintered polycrystalline plates and amorphous thin films using an infrared laser with/without pre-heating, and it is found that modified layers can be obtained on both specimens. Elemental, molecular structural, and frictional analyses of the layers are then conducted, demonstrating that the layer on the sintered plate primarily consists of sp2-bonded carbon with some defects and remaining silicon. The chemical bonding continuity, purity, and thickness of the layers depend on the laser irradiation conditions. On the amorphous thin film, the modified layer is composed of amorphous carbon with a depth of several nanometers. The friction coefficients are measured using a scanning probe microscope under micro-order loads. The modified layers of both the sintered plates and thin films exhibit low friction coefficients. The friction coefficient of the modified layer is approximately half that of the as-prepared or deposited SiC.