Comparative investigation of oxidation resistance and thermal stability of nanostructured Ti-B-N and Ti-Si-B-N coatings

Nanostructured Ti-B-N and Ti-Si-B-N coatings were deposited on silicon substrate by ion implantation assisted magnetron sputtering technique. To evaluate the oxidation resistance and thermal stability the coatings were annealed on air and in vacuum at 700-900A degrees C. As-deposited and thermal-treated coatings were investigated by transmission electron microscope, selected area electron and x-ray diffraction, atomic force microscopy, Raman and glow discharge optical emission spectroscopy. Nanoindentaion tests were also performed. Obtained results show that Si alloying significantly improves the thermal stability of Ti-B-N coatings and increases their oxidation resistance up to 900A degrees C. It was shown that formation of protective amorphous SiO2 top-layer on the coating surface plays important role in the increasing of the oxidation resistance.