Surface Modification by Scratching Test for Laser Cleaning WC-Co in Liquid Polymer

Tungsten carbide including cobalt, WC-Co, shows good performance for high temperature toughness and is expected when applying to a high temperature mold but it is difficult to cut into ultra-fine precision because of its brittleness. In this study, WC-Co surface is treated by a pulsed laser irradiation to softening and cleaning in a machining liquid and cutting test by Vickers indenter. Under the case of Methyl n-Nonanoic acid, the surface wetness shows same behavior for with and without laser cleaning. In this case, the surface fracture by the cutting is extended and a lot of damages are generated along the cutting track for both as polished surface and laser cleaning surface. Under the case of n-Undecyl Alcohol and Palmitic acid n-Butyl Ester, the surface wetness is improved by the laser cleaning and the surface fracture is inhibited by the laser cleaning. As results of the FT-IR measurements of Palmitic acid n-Butyl Ester on the WC-Co surface, the peak position of C-H stretching mode (2900-2950 cm-1) shifted from a lower wavenumber (on the surface of as polished) to a higher wavenumber (on the laser cleaning surface) . This result indicates that the Palmitic acid n-Butyl Ester interacts with the WC-Co surface and influences to the surface fracture of the laser cleaning WC-Co surface, where it is restrained by the surface adsorption. [Received August 1, 2006; Accepted September 21, 2006]