Thermophysical properties of SiC multilayer prepared by tape casting and pressureless sintering
In present work, SiC multilayer samples for thermal conductivity test in X (along tape casting direction), Y (perpendicular to tape casting direction and thickness direction) and Z (through thickness direction) directions were successively prepared by tape casting and pressureless sintering. Effect of oxidation treatment on the thermal diffusivity and conductivity was investigated. Elongated SiC grains were observed in three directions, especially in Y direction. The specific heat capacity of SiC multilayer increased with temperature, which could be well fitted. The relative length change of SiC multilayer increased with variation of temperature in X, Y and Z directions, and no significant difference among the thermal expansion behavior in three directions was observed. Regardless of testing directions and oxidation treatment, the thermal diffusivities and conductivities of SiC multilayer in three directions decreased with the increase of temperature. SiC multilayer demonstrated the lowest thermal diffusivity and conductivity in Z direction mainly due to the presence of interface between SiC layers. Because of the formation of silica with low thermal conductivity, the oxidation treatment could slightly decrease the thermal diffusivity and conductivity in all directions.