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Fabrication of silicon nitride - multi-walled nanotube composites by direct in-situ growth of nanotubes on silicon nitride particles

 
: Datye, A.; Wu, K.-H.; Kulkarni, S.; Lin, H.T.; Schmidt, J.; Hunn, D.; Li, W.-Z.; Kumari, L.

Singh, D. ; American Ceramic Society -ACerS-, Westerville/Ohio:
Mechanical properties and performance of engineering ceramics and composites IV : A collection of papers presented at the 33rd International Conference on Advanced Ceramics and Composites, January 18 - 23, 2009, Daytona Beach, Florida. This volume is a compilation of papers presented in the Mechanical Behavior and Performance of Ceramics & Composites and Geopolymers and Other Inorganic Polymers Symposia
Hoboken, NJ: Wiley, 2010 (Ceramic engineering & science proceedings 30,2)
ISBN: 0-470-45752-X
ISBN: 978-0-470-45752-8
pp.23-37
International Conference on Advanced Ceramics and Composites (ICACC) <33, 2009, Daytona Beach/Fla.>
Mechanical Behavior and Performance of Ceramics and Composites Symposium <2009, Daytona Beach/Fla.>
Geopolymers and Other Inorganic Polymers Symposium <2009, Daytona Beach/Fla.>
English
Conference Paper
Fraunhofer IFAM, Institutsteil Pulvermetallurgie und Verbundwerkstoffe Dresden ()

Abstract
In this research, Si3N4 (Silicon Nitride)-CNT (Carbon Nanotube) composites were fabricated by direct in-situ growth of CNTs on the Si3N4 mixtures using CVD (Chemical Vapor Depositon) followed by SPS (Spark Plasma Sintering). The SPS technique used to sinter these powders is characterized by high heating and cooling rates coupled with pressure which prevents grain coarsening and also allows for densification in a very short period of time compared to the conventional sintering methods. The CVD techniques for in-situ CNT growth ensures a more uniform dispersion in the matrix than traditional ex-situ CNT mixing methods. The sintered samples were analyzed using FEGSEM (Field Emission Scanning Electron Microscopy), XRD (X-Ray Diffraction), Raman Spectroscopy and HRTEM (High Resolution Transmission Electron Microscopy). FEGSEM analysis of the Si3N4-CNT powders show uniform distribution of MWNTs (multi-walled nanotubes) in the matrix without the formation of bundles seen with traditional ex-situ mixing of CNTs in ceramic compositions. FEGSEM analysis of the fractured surface shows a uniform distribution of CNTs in the ceramic matrix. The presence of CNTs in the matrix is confirmed by Raman Spectroscopy and HRTEM. The Si3N4-MWNT composite thus fabricated shows a more uniform distribution of CNTs in the matrix and excellent CNT retention after sintering at 1850 deg C. FEGSEM analysis shows a finer grain size due to the presence of CNTs at grain boundaries which inhibit the diffusion related grain growth.

: http://publica.fraunhofer.de/documents/N-139122.html