Phase Formation, Residual Stress, and Surface Energy of Carbon-Doped TiZrN Coatings

We investigated the relationship between the surface energy, phase formation, residual stress, and wettability of carbon-doped TiZrN coatings. Carbon-doped TiZrN coatings were prepared via laser ablation by controlling the thickness of the carbon paste. The crystal structure analysis revealed that the (111) plane peak shifted to a lower angle as the paste thickness increased. Lattice expansion was confirmed through Rietveld refinement, and the lattice constant of the coating increased from 4.17 to 4.41 Å. Based on X-ray photoelectron spectroscopy, it was confirmed that the formation of carbide (TiC, ZrC) phase was 4.85% for a paste thickness of 100 μm, and 12.10% for a paste thickness of 180 μm. The TiC/ZrC ratio also increased with paste thickness. The increase in carbide formation was attributed to the initial carbon concentration, whereas the increase in the TiC/ZrC ratio was ascribed to the reduction of high-energy carbon, which was sufficient to form ZrC bonds by plasma shielding. The residual stress was calculated to increase from 4439 to 5861 MPa using the sin 2 ψ method. The contact angle of water decreased from 95.9° to 74.75° and that of diiodomethane decreased from 46.75° to 36.65° after carburization. With carburization, an improvement in wettability was observed for both polar and dispersive liquids, with the surface energy increasing from 36.42 to 46.24 mN/m.