Characterization of Ta–Si–N coatings prepared using direct current magnetron co-sputtering

Chemical inertness of Ta–Si–N coatings in glass molding

“…A previous study [7] proposed using crystalline TaN as a protective coating for glass molding dies, because of its capability to inhibit diffusion of oxygen and cobalt at 500°C in air and at 600°C in a 50-ppm O 2 -N 2 atmosphere for 4 h; however, TaN coatings were oxidized to Ta 2 O 5 when annealed in air at 600°C. The nanohardness of Ta 48 N 52 coatings decreased from 16.5 GPa in the as-deposited state to 12.6 GPa after they were annealed in a 1% O 2 -99% Ar atmosphere for 4 h at 600°C [8]. The Ta 48 N 52 coatings were fully oxidized to Ta 2 O 5 after being annealed for 24 h, exhibiting a nondense structure, and the nanohardness was only 2.5 GPa.…”

“…Therefore, SiO 2 should form preferentially in annealing. The introduction of Si into the Ta-N matrix evidently raised oxidation resistance because it led to the formation of an amorphous silicon oxide scale on the surfaces of the Ta-Si-N coatings after annealing [8]. Grain boundaries provided fast diffusion paths for oxygen through intercolumnar voids [13]; therefore, the formation of an amorphous oxide scale may increase the oxidation resistance of the undercoating [14].…”

“…Chung et al [11] reported the oxidation resistance of amorphous Ta-Si-N films under vacuum rapid thermal annealing at 2.6 Pa at 600°C-900°C for 1 min and indicated that the Ta-Si-N films remained amorphous at 600°C, but transformed into Ta 2 O 5 phase at 900°C. In our previous study [8], Ta-Si-N coatings with an N content of N50 at.% and a high Si content (10-20 at.%) were cosputtered using cyclical gradient concentration deposition; the coatings exhibited amorphous in the as-deposited state. A Ta 27 Si 20 N 53 coating remained amorphous after being annealed at 600°C in a 1% O 2 -99% Ar atmosphere up to 100 h and retained a nanohardness of 15 GPa [8].…”

“…In our previous study [8], Ta-Si-N coatings with an N content of N50 at.% and a high Si content (10-20 at.%) were cosputtered using cyclical gradient concentration deposition; the coatings exhibited amorphous in the as-deposited state. A Ta 27 Si 20 N 53 coating remained amorphous after being annealed at 600°C in a 1% O 2 -99% Ar atmosphere up to 100 h and retained a nanohardness of 15 GPa [8]. The outward diffusion of Si formed a protective oxide layer on the coatings.…”

“…The outward diffusion of Si formed a protective oxide layer on the coatings. The 36-nm-thick amorphous oxide layer of the Ta 27 Si 20 N 53 coating annealed for 100 h comprised only Si and O according to X-ray photoelectron spectroscopy depth profiles [8]. The Gibbs free energies of the metal oxidation formation of SiO 2 and Ta 2 O 5 at 600°C were −752,535 J/(mol of O 2 ) and −663,572 J/(mol of O 2 ) [12], respectively.…”