THERMAL DIFFUSIVITY/CONDUCTIVITY IN SIALON CERAMICS

Thermal diffusivity and conductivity of ceramic materials in a system of Si3N4‐SiO2‐Al2O3‐AlN composed of α and β SiAlON (which is well known as duophase SiAlON ceramics) are investigated. Single‐phase β‐SiAlON ceramic has a thermal conductivity of 12.44 W/m K. The thermal conductivities of SiAlON ceramics decrease linearly with increasing content of α phase and can be best described by the following equation: K=12.46–0.043 f, where f is the weight percentage of α‐SiAlON content and K is the thermal conductivity of SiAlON ceramics. The thermal conductivity of single‐phase α‐SiAlON was then estimated to be ∼8.16 W/m K, which is in excellent agreement with the literature reported values, ∼8.4 W/m K. This estimation is also close to the value, 8.22 W/m K, obtained by using Bruggeman’s variable dispersion theory. The temperature dependence of the thermal conductivity of duophase SiAlON ceramics varies with α and β phase contents in the materials.

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