SURFACE MODIFICATION OF TIN HARD COATINGS WITH CONCENTRATED SOLAR-ENERGY

Physical vapour deposited TiN coatings were partially oxidized by a beam induced heat treatment using concentrated solar radiation, in a search for the tailoring of the functionality of hard ceramic coatings. The TiN coatings were heated in ambient air up to 800-degrees-C at a mean heating rate of 1.2-degrees-C/s and held at this temperature for periods of 10, 60, and 350 s. The solar treated samples were characterized using techniques as Rutherford backscattering spectrometry, grazing incidence X-ray diffraction, and cross-sectional transmission electron microscopy. At the surface of the heat treated TiN coatings, single oxide layers consisting of the rutile polymorph of TiO2 were identified. The oxide microstructure was found to be porous and non-uniform across the layer thickness, in particular near the interface between oxide and nitride. The growth of a dense recrystallized oxide layer at the outer surface was observed after a prolonged solar beam treatment of 350 s.