Measurement of Thermal Diffusivities during Self-propagating High-temperature Synthesis

Combustion synthesis (SHS) of ceramics induces strong temperature gradients in samples. The observation of relaxation of temperature gradients within a sample before or after an SHS reaction allows thermal diffusivity to be estimated. A numerical routine to optimize diffusivity and heat losses simultaneously is used to minimize the difference between a calculated temperature profile based on an earlier measured profile and the actual temperature profile measured at a given time. Temperature profiles are captured with and infrared camera. This method yielded a value close to 1.0 x 10 -6 m 2 s -1 for two porous TiC samples. For a compacted mixture of Ti and C powders, the thermal diffusivity is found to have a strong variation with temperature, and values from 4.6 x 10 -7 m 2 s -1 at 500°C to 4.5 x 10 -6 m 2 s -1 at 700°C were calculated.