Developments in Ceramic Materials Research

Modeling of Thermal Transport in Ceramics Matrix Composites 177
ceramic, multiple infiltrations are necessary to obtain an acceptable density of the composite.
Polymeric precursors for ceramic matrices permits the usage of conventional polymer
composite fabrication technology that is readily available and capitalise on processes used to
make polymer matrix composites. Complex shape forming and fabrication are possible and
the fairly low processing and pyrolysing temperatures prevent fibre degradation and the
formation of unsolicited reaction products at the fibre/matrix interface.
Figure 1. Schematic diagram of the infiltration technique.
2.2. Thermal Behaviour of CMCs
The behaviour of composite materials is often sensitive to changes in temperature. Such
trends are displayed due to the temperature-dependent response of the matrix to an applied
load. Also, alterations in temperature can induce internal stresses because of a differential
thermal contraction and expansion. These stresses ultimately affect the thermal expansion of
the composite. Furthermore, thermal gradients are especially deleterious to CMCs as they
possess relatively lower thermal diffusivities and are inherently heterogeneous. A thermal
gradient is inversely related to thermal diffusivity (α) of a material, which is in turn related to
thermal conductivity (k), specific heat (Cp) and density (ρ) of the material [2] as:
(1)