Laser texturing of zirconia surface with presence of TiC and B₄C: Surface hydrophobicity, metallurgical, and mechanical characteristics

Laser surface texturing of zirconia tile is carried out. A mixture of 3% TiC and 3% B4C particles was placed in a carbon film formed at the workpiece surface prior to the laser treatment process. Since laser intensity variation is Gaussian at the irradiated spot, it results in combination of evaporation and melting at the workpiece surface during the laser scanning. Morphological and metallurgical changes in the laser treated region are analyzed using electron scanning microscopy, energy dispersive spectroscopy, and X-ray diffraction. Microhardness and fracture toughness of the treated surface are determined from the indentation data. Residual stress formed in the treated layer is determined using the X-ray diffraction technique. Friction coefficient and scratch resistance of the workpiece are obtained incorporating the micro-tribology facility. Surface hydrophobicity is assessed incorporating the contact angle measurements. It is found that surface texture comprising of micro/nanopoles and cavities is formed after the laser ablation/melting process. Laser treated surface has a hydrophobic characteristic, which results in averaged contact angle of 130^o. Laser treatment improves microhardness and lowers fracture toughness at the surface. Friction coefficient is lower for the laser textured surface than that of untreated surface. Residual stress formed is compressive, which is in the order of -1.4 GPa.