Ti3SiC2 Interphase Coating in SiCf/SiC Composites: Effect of the Coating Fabrication Atmosphere and Temperature

The SiC fibers were coated with Ti3SiC2 interphase by dip-coating. The Ti3SiC2 coated fibers were heat-treated from 900 degrees C to 1100 degrees C in vacuum and argon atmospheres to comparatively analyze the effect of temperature and atmosphere on the microstructural evolution and mechanical strength of the fibers. The results show that the surface morphology of Ti3SiC2 coating is rough in vacuum and Ti3SiC2 is decomposed at 1100 degrees C. However, in argon atmosphere, the surface morphology is smooth and Ti3SiC2 is oxidized at 1000 degrees C and 1100 degrees C. At 1100 degrees C, Ti3SiC2 oxidized to form a thin layer of amorphous SiO2 embedded with TiO2 grains. Meanwhile, defects and pores appeared in the interphase scale. As a result, the fiber strength treated in the argon was lower than that treated in vacuum. The porous Ti3SiC2 interphase fabricated under vacuum was then employed to prepare the SiCf/SiC mini composite by chemical vapor infiltration (CVI) combined with precursor infiltration pyrolysis (PIP), and can effectively improve the toughness of SiCf/SiC mini composite. The propagating cracks can be deflected within the porous interphase layer, which promotes fiber pull-outs under the tensile strength.