Journal
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
Volume 37, Issue 15, Pages 4467-4474Publisher
ELSEVIER SCI LTD
DOI: 10.1016/j.jeurceramsoc.2017.07.012
Keywords
Si3N4(w)-SiC composite; Catalytic nitridation; Fe2O3 nanoparticles; DFT calculation; High-temperature mechanical property
Categories
Funding
- National Natural Science Foundation of China [51502212, 51672194, 51472184]
- Program for Innovative Teams of Outstanding Young and Middle-aged Researchers in the Higher Education Institutions of Hubei Province [T201602]
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The complete conversion from Si into Si3N4 was achieved after 2 h nitridation at 1400 degrees C by using in-situ formed Fe2O3 nano-particles (NPs) as a catalyst. Such a synthesis condition was remarkably milder than that (> 1450 degrees C for many hours) required by the conventional Si nitridation method. Density functional theory (DFT) calculations suggest that Fe2O3 catalyst accelerates the Si nitridation via weakening the bond strength of absorbed N-2 molecule. Furthermore, Si3N4(w)-SiC composites prepared by the present catalytic nitridation method showed excellent high-temperature properties including modulus of rupture (MOR of 29.9 MPa at 1400 degrees C), thermal shock resistance (residual MOR percentage of 50% at Delta T= 1300 degrees C), as well as good oxidation resistance and cryolite corrosion resistance against molten cryolite. It can be concluded that, Fe2O3 NPs not only greatly accelerated the Si nitridation and Si3N4 formation, but also facilitated the epitaxial growth of reinforcement phase of Si3N4 whisker in the Si3N4(W)-SiC composites. (c) 2017 Elsevier Ltd. All rights reserved.
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