SURFACE MODIFICATION OF TIN HARD COATINGS WITH CONCENTRATED SOLAR-ENERGY

Physical vapour deposited TiN coatings were partially oxidized by a be am induced heat treatment using concentrated solar radiation, in a sea rch for the tailoring of the functionality of hard ceramic coatings. T he TiN coatings were heated in ambient air up to 800-degrees-C at a me an heating rate of 1.2-degrees-C/s and held at this temperature for pe riods of 10, 60, and 350 s. The solar treated samples were characteriz ed using techniques as Rutherford backscattering spectrometry, grazing incidence X-ray diffraction, and cross-sectional transmission electro n microscopy. At the surface of the heat treated TiN coatings, single oxide layers consisting of the rutile polymorph of TiO2 were identifie d. The oxide microstructure was found to be porous and non-uniform acr oss the layer thickness, in particular near the interface between oxid e 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.