High-temperature hydrogenation behaviour of bulk titanium silicon carbide

Abstract

Thermal stability of Ti₃SiC₂ was investigated at 1200–1400°C in hydrogen atmosphere for 3 hours. The hydrogenation mechanism was clarified by a combination of X-ray diffraction, scanning electron microscope, Raman spectroscopy and first principles calculation. At 1200°C, a dense and uniform TiSi₂ layer formed on the sample surface, which originated from both the preferable lose of silicon from the Ti₃SiC₂ substrate and the dissociation of Ti₃SiC₂. As temperature increased to 1300°C, TiSi₂ layer began to scale off and presented laminated Ti₃SiC₂ grains beneath this layer, which indicated preferential hydrogenation occurred along the basal planes. This phenomenon was ascribed to the fact that the introduction of H interstitial atom weakened the combination between titanium and silicon interface layer, which was confirmed by first principles calculations. In addition, the formation of TiSi₂ owing to the dissociation of Ti₃SiC₂ caused the volume expansion after hydrogenation, resulting in that majority of TiSi₂ layer spelled off at 1400°C.

Keywords:

• Ti₃SiC₂
• Hydrogenation
• Thermal stability

Acknowledgements

H.-B.Z. is grateful to the foundation by the Recruitment Program of Global Youth Experts and the Youth Hundred Talents Project of Sichuan Province. This work is also supported by the National Natural Science Foundation of China (Grant No. 91326102), the Science and Technology Development Foundation of China Academy of Engineering Physics (Grant No. 2013A0301012), the Presidential Foundation of China Academy of Engineering Physics (Grant No. 201402094), and Science and Technology Innovation Research Foundation of Institute of Nuclear Physics and Chemistry.