Three-dimensional C/SiC composites with different interphase thickness were fabricated by chemical vapor infiltration method, and transverse thermal diffusivity was measured in the temperature range 20 ~ 1400 oC using a laser flash technique. The diffusivity decreases initially with interphase thickness increasing from 30 nm to 100nm, whereas an increase is observed when interphase thickness increases from 100 nm to 200 nm. Heat treatment at 1400 oC improves the diffusivity of the composites, and yet it has little effect on the relationship between the diffusivity and interphase thickness.

Keywords: C/SiC composites, Thermal diffusivity, Interphase thickness, Heat treatment.