The influence of nano scaled additions on the Young's modulus of carbon-bonded alumina at temperatures up to 1450 °C

Within this investigation the combination of the addition of doped silicon and nano additives (multi-walled carbon nanotubes and alumina nanosheets) on the Young's modulus E of carbon-bonded alumina was investigated. The addition of nano particles resulted in an increase of E at room temperature independent of the graphite level. An interaction between the graphite content and the additive effect was found, complicating the analysis of the main effect. At elevated temperature the nano particle addition resulted in remarkably lower E values at Tmax, whereas the effect of doped silicon was an increase of E at Tmax. Furthermore, a correlation between the pore size (d90) and the normalized Young's modulus at the temperature of the former pyrolysis (Ei⟶1000°C) was found. That correlation is a confirmation of the gap opening and closing theory of Franklin and Tucker [1]. Thus, a reduction of the graphite content is possible without reducing the elasticity of the material and its high temperature elasticity by using multi-walled carbon nanotubes and alumina nanosheets as additives.