Effects of nitrogen content on microstructure and oxidation behaviors of Ti-B-N nanocomposite thin films
- Department of Manufacturing Engineering and Engineering Management, City University of Hong Kong, Kowloon, Hong Kong (China) and Department of Materials Physics, Beijing University of Science and Technology, Beijing 100083 (China)
Several different types of thin films, TiB{sub 0.65}, TiB{sub 0.62}N{sub 0.18}, TiB{sub 0.61}N{sub 1.04}, and pure TiN, were deposited on Si(100) substrates at 500 deg. C by reactive unbalanced close-field dc-magnetron sputtering using two Ti and two TiB{sub 2} targets. The oxidation experiments of these films were carried out in air at fixed temperatures in a temperature regime of 600-1000 deg. C. As-deposited and oxidized films were characterized and analyzed using x-ray diffraction, plan-view and cross-sectional scanning electron microscopies, atomic force microscopy, and x-ray photoelectron spectroscopy (XPS). It was found that the microstructure and bonding configuration of Ti-B-N thin films were strongly dependent on nitrogen flow rate during deposition. Depending upon the amount of N addition, the films showed two- or three-phase nanocomposite structure. Nitrogen-free films were amorphous compound comprising of Ti and TiB{sub 2} (Ti-TiB{sub 2} compound). At 10 at. % N addition (TiB{sub 0.62}N{sub 0.18}), the films consisted of mainly TiN and TiB{sub 2} bondings with microstructures comprising of nanocrystalline (nc)-Ti(N) embedded in an amorphous (a)-TiB{sub 2} matrix. As the N concentration increased up to 38 at. % (TiB{sub 0.61}N{sub 1.04}), the films consisted of nc-TiN in a-(TiB{sub 2}, BN) matrix. The oxidation experiment illustrated that the nanocomposite TiB{sub 0.61}N{sub 1.04} thin films exhibited a much higher high-temperature oxidation resistance than TiN, TiB{sub 0.65}, and TiB{sub 0.62}N{sub 0.18} thin films. A two-stage oxidation process took place in these nanocomposite films in the whole temperature regime. A low oxidation rate accompanied with formation of small-grained Ti oxide occurred below 800 deg. C, while above 800 deg. C a rapid oxidation process accompanied with formation of large-grained Ti oxide with rough surface took place. It is believed that the two-stage oxidation process was related to oxidation resistance of nanocrystallites and thermal stability of amorphous matrix phase. By XPS, the oxides were determined to consist mainly of various types of Ti oxides in the oxidation temperatures of 600-1000 deg. C, such as TiO, TiN{sub x}O{sub y}, Ti{sub 2}O{sub 3}, and TiO{sub 2}. It was also found that no elemental B was detected in oxide formed above 600 deg. C, which may be due to a low melting temperature of B{sub 2}O{sub 3}.
- OSTI ID:
- 20777052
- Journal Information:
- Journal of Vacuum Science and Technology. A, International Journal Devoted to Vacuum, Surfaces, and Films, Vol. 24, Issue 2; Other Information: DOI: 10.1116/1.2172949; (c) 2006 American Vacuum Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1553-1813
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ATOMIC FORCE MICROSCOPY
BORON NITRIDES
BORON OXIDES
CRYSTALS
DEPOSITION
MAGNETRONS
MELTING POINTS
MICROSTRUCTURE
NANOSTRUCTURES
NITROGEN
OXIDATION
SCANNING ELECTRON MICROSCOPY
THIN FILMS
TITANIUM BORIDES
TITANIUM NITRIDES
TITANIUM OXIDES
X-RAY DIFFRACTION
X-RAY PHOTOELECTRON SPECTROSCOPY