Surface characterization and formation mechanism of the ceramic TiO2 xNx spherical powder induced by annealing in air
Abstract Mechanism for the formation of titanium oxynitride (TiO2 xNx) on the surfaces of spherical Ti powder particles upon heat treatment in air at 500, 600, 700 and 800 degC was investigated. The results showed that the first at 500 degC a hexagonal closed packed (HCP) TiOx film was formed while aTiO2 film was observed after annealing at 600 degC and eventually a TiO2 x Nx layer coated the spherical Ti particles at 700 and 800 degC due to N diffusion within the TiO2 crystal lattice. The resulting surface structure was studied by means of x ray diffraction (XRD) while the surface morphology of the powders was characterized using the scanning electron microscope (SEM) attached with energy dispersive x ray spectroscopy (EDS) detector. The AFM images confirmed that when the N content increases (800 degC heat treated sample) the powder loses its triangular grains (700 degC annealed sample) to irregular shaped grains.
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