Preparation and microstructural characterization of TiC and Ti0.6W0.4∕TiC0.6 composite thin films obtained by activated reactive evaporation

Abstract

Titanium carbide-based coatings were deposited on W substrates at a high coating growth rate by activated reactive evaporation at 500 and 600°C in a L560 Leybold system using propene as reactive atmosphere. The crystal structure, lattice parameter, preferred orientation, and grain size of the coatings were determined by x-ray diffraction technique using CuKα. The analysis of the coating morphology was performed by scanning electron microscopy (SEM), and the composition of the films was analyzed by Auger electron spectroscopy and electron-probe microanalysis. Experimental results suggested that temperature was one of the most important parameters in the fabrication of stoichiometric TiC coatings. Thus, TiC coatings were obtained at 600°C, whereas TiC0.6 nonstoichiometric coatings codeposited with a free Ti phase were obtained at 500°C, giving rise to the formation of a composite thin film. After annealing at 1000°C, the stoichiometric films remained stable, but a crack pattern was formed over the entire coating surface. In addition, Ti0.6W0.4∕TiC0.6 composite thin coatings were obtained for the films synthesized at 500°C. The formation of a Ti0.6W0.4 ductile phase in the presence of a TiC0.6 phase was responsible to avoid the coating cracking.