Annealing of niobium coatings deposited on graphite

Niobium coatings 8-12 μm thick were deposited by magnetron sputtering on ATJ graphite substrate. The kinetic growth of carbide layers into niobium coatings and the properties of the Nb2C and NbC phases obtained after annealing in the temperature range of 1073-1773 K were studied. It was found that the carbide layer growth displayed parabolic behavior patterns establishing the growth rate constants (K) of Nb2C and NbC layers, as follows:KNb2C=3.7×10-8exp(-190kJRT)m2s;KNbC=4.5×10-9exp(-164kJRT)m2s.