期刊
CERAMICS INTERNATIONAL
卷 44, 期 5, 页码 5102-5108出版社
ELSEVIER SCI LTD
DOI: 10.1016/j.ceramint.2017.12.110
关键词
Si3N4 nanowire; SiCN ceramic; Precursor infiltration and pyrolysis (PIP); Composites; Mechanical properties; Thermophysical properties
资金
- National Natural Science Foundation of China [51702361]
- Natural Science Foundation of Hunan Province [2017JJ3353]
- Aerospace Science and Technology Foundation of China
Si-C-N ceramic composites containing well distributed silicon nitride nanowires (SNNWs) were fabricated by die pressing and precursor infiltration and pyrolysis process at a low temperature. The structure, composition, mechanical and thermophysical properties of the composites were investigated. The results show that the composites consisted of amorphous SiCN, alpha-Si3N4 and alpha-cristobaslite. The composites with different contents of SNNWs possessed a density of 2.02-2.07 g cm(-3) and open porosity of 7.9-9.9%. SNNWs can effectively restrain the contraction of matrix with a decrease by 25% in linear shrinkage. The composites with 3 wt% SNNWs owned the highest flexural strength (83.7 MPa) and elastic modulus (54.0 GPa) at room temperature, which increase by 13.2% and 62.3% respectively, compared with pure SiCN ceramics. The SNNWs displayed good reinforcement function at high temperature due to the fact that the composites with 7 wt% SNNWs had a 96.8% retention rate of bending strength at 1200 degrees C. The composites had relatively low coefficient of thermal expansion and thermal diffusivity which were less than 2.2 x 10(-6) K-1 and 0.62 mm(2) s(-1), respectively.
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