“Hexacelsian slurry development for 2D woven alumina fiber impregnation in CMC fabrication”

The rheological properties of BAS (BaAl₂Si₂O₈) slurries are investigated in order to optimize the impregnation of an alumina preform to manufacture oxide/oxide composite materials. The fiber preform morphology has been deeply investigated, especially the fiber to fiber gap within tows and compared to the grain size of the matrix powder. The slurry viscosity is measured as a function of powder and organic additives concentration to find the best combination. The optimal combination is evaluated by different measurements including: zeta potential, sedimentation and wettability to verify the slurry behavior for the fibers infiltration. An aqueous slurry containing 20–25 vol% of BAS with 1 wt% of dispersing agent (Darvan 821-A™) improved the rheological properties for fibers infiltration. Finally, characterizations of the composite show a good infiltration in the fiber tows spaces and indicate a mean porosity of 37 vol%, including 9 vol% of macroporosity.