Effect of CNT impregnation on the mechanical and thermal properties of C/C-SiC composites
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ORIGINAL RESEARCH
Effect of CNT impregnation on the mechanical and thermal properties of C/C-SiC composites Simge Tülbez 1 & Ziya Esen 2 & Arcan F. Dericioglu 1 Received: 1 March 2020 / Revised: 4 April 2020 / Accepted: 4 May 2020 # Springer Nature Switzerland AG 2020
Abstract The present study investigates the effect of additional carbon source, in the form of carbon nanotubes (CNTs), on mechanical and thermal properties of carbon fiber reinforced silicon carbide (C/C-SiC) ceramic matrix composites (CMC) produced by liquid silicon infiltration (LSI) technique. The CNTs used in this study were impregnated into the C/C preforms before the liquid silicon infiltration stage. The results showed that the addition of excess carbon to the C/C preforms in the form of CNTs enhanced Si infiltration efficiency significantly resulting in C/C-SiC composites with higher density and microstructural uniformity. Accordingly, the addition of CNTs improved the flexural strength of the composites by 40% with respect to no-CNTcontaining composites due to a lower amount of residual porosity and additional reinforcement effect of the unreacted CNTs. The thermal conductivity of the resulting C/C-SiC composites has been also increased by 31% and 18% parallel and perpendicular to the carbon fiber–woven fabric surface, respectively, by CNT addition. Keywords Ceramic matrix composite . Microstructure . Silicon infiltration . Carbon nanotubes . Mechanical properties
1 Introduction In recent years, as compared with monolithic ceramics and traditional metallic materials, carbon fiber reinforced silicon carbide (C/C-SiC) matrix ceramic composites come into prominence with their high-temperature material properties [1]. Their relatively low densities, superior mechanical properties at elevated temperatures, high erosion, and thermal shock resistance enable the use of these composites in high-temperature applications such as nose and leading edge thermal protection materials for the reentering and hypersonic vehicles, and thrust vector controlling parts for rocket/missile systems [2, 3]. Besides these high-temperature applications, C/C-SiC composites are also being utilized in brake pad and clutch systems as they possess high wear resistance along with high and stable coefficient of friction in addition to their low densities [4]. Among
* Arcan F. Dericioglu [email protected] 1
Department of Metallurgical and Materials Engineering, Middle East Technical University, Universiteler Mah. Dumlupinar Bulv, 06800 Ankara, Turkey
2
Materials Science and Engineering Department, Cankaya University, 06810 Ankara, Turkey
these applications, thermal shock stability of the C/C-SiC composite material is especially important for thrust vector controlling parts and leading edges of hypersonic vehicles. In these application areas, better thermal shock capacity is provided by high thermal conductivity, moderate strength, and low coefficient of thermal expansion [5, 6]. Therefore, it is important to enhance the thermal conductivity and strength values of C/CSiC
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