Synthesis and property characterization of precursor-derived ceramics
reinforced by functionalized single-wall carbon nanotubes
PD Dr. Joachim Bill
University of Stuttgart
Institute for Non-metallic
Dr. Marko Burghard
Solid State Research
Nanoscale Science Dept.
This project aims at the synthesis and investigation of novel precursor-derived ceramic matrix composites with single-wall carbon nanotubes (SWCNTs) as reinforcement of ultimate mechanical strength and resilience. The central goal is to confer high mechanical, electrical and thermal performance to composites composed of SiCN or SiBCN as ceramic matrix. To this end, high purity SWCNTs shall be chemically functionalized in order to obtain well-separated tubes as well as to control the interfacial bonding between the ceramic and the nanotubes to ensure efficient tube dispersion and load transfer. The devised chemical functionalization encompasses the fluorination, as well as the silylation of SWCNTs, which should enable covalent anchoring of the nanotubes on the precursor molecules through diverse strategies. For investigating the mechanical properties and fracture mechanism of the composites at the micro/nanoscale, measurements based upon a thermal load method will be complemented by biaxial flexure tests, nanoindentation testing, specifically addressing hardness, Young's modulus and fracture toughness as a function of the synthesis and processing conditions, as well as the nanotube content and functionalization degree. In particular, the comparison between the composites comprising unmodified SWCNTs and those containing functionalised tubes shall reveal the extent to which the envisioned interfacial coupling leads to enhanced material performance. Along the same line, the electrical and thermal conductivity of the nanotube-reinforced composites will be studied. Finally, detailed microscopic investigations shall be performed with the aim of correlating major structural features of the SWCNT/ceramic nanocomposites − such as the structural integrity and distribution of the nanotubes − with their mechanical, electrical and thermal properties, thus aiding to identify the optimal fabrication parameters and composition of these materials.