AVS 60th International Symposium and Exhibition
    Advanced Surface Engineering Thursday Sessions
       Session SE-ThP

Paper SE-ThP4
Preferential Growth of Oxide Nanorods on Multicomponent TiAlSiN Coated Stainless Steels after Thermal Oxidation

Thursday, October 31, 2013, 6:00 pm, Room Hall B

Session: Poster Session
Presenter: Y.C. Yang, National Formosa University, Taiwan, Republic of China
Authors: Y.Y. Chang, National Formosa University, Taiwan, Republic of China
Y.C. Yang, National Formosa University, Taiwan, Republic of China
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Transition metal nitrides, such as TiN and CrN, have been used as protective hard coatings due to their excellent tribological properties. Recently, multicomponent TiAlSiN coatings have been developed in order to possess high hardness and good thermal stability at temperature exceeding 800 oC. In this study, a series of TiAlSiN coatings with different alloy contents (Ti0.67Al0.32Si0.01N, Ti Al Si N, and Ti0.85Al0.03Si0.12N) were deposited onto an SS304 substrate by using cathodic arc evaporation. Cathodes of Ti, TiAl (50 at.% of Al and 50 at.% of Si) and Ti0.8Si0.2 (80 at.% of Al and 20 at.% of Si) alloy targets were used. The as-deposited films were annealed at 800 oC for different time from 20 minutes to 100 minutes in air to analyze the different preferential oxidation behaviors of TiAlSiN coatings. The surface morphology and microstructure of the deposited and oxidized coatings was investigated by field emission scanning electron microscopy (FESEM) equipped with an energy-dispersive x-ray analysis spectrometer (EDS). X-ray diffractometry was performed using PANalytical X’pert Pro diffractometer with a high resolution ψ goniometer and Cu radiation in both glancing angle and high-angle configurations for phase identification. The correlation between the preferential growth of oxide nanorods and the deposited multicomponent TiAlSiN coatings was discussed. During the oxidation process, Ti, Al, and Si would diffuse outward to form oxidative layers of Al2O3, TiO2, and SiO2 at high temperature. The Ti0.67Al0.32Si0.01N with higher Al content ratio showed that needle-like α-Al2O3 oxides preferentially grow from the macroparticle defect sites. Oxide nanorods were uniformly found on the oxidized Ti0.8Al0.17Si0.03N with smaller content of Al. The Ti0.85Al0.03Si0.12N with the highest Si and the lowest Al contents showed only short TiO2 nanorods uniformly grow on the surface. Therefore, the kinetic oxidation behavior of TiAlSiN coatings varied with the alloy content and phase segregation via high temperature oxidation.