Fabrication and mechanical properties of carbon short fiber reinforced barium aluminosilicate glass–ceramic matrix composites

Dense BaSi2Al2O8 (BAS) and Ba0.75Sr0.25Si2Al2O8 (BSAS) glass–ceramic matrix composites reinforced with carbon short fibers (Csf) were fabricated by hot pressing technique. The microstructure, mechanical properties and fracture behavior of the composites were investigated by X-ray diffraction, scanning and transmission electron microscopies, and three-point bend tests. The carbon fibers had a good chemical compatibility with the glass–ceramic matrices and can effectively reinforce the BAS (or BSAS) glass–ceramic because of associated toughening mechanisms such as crack deflection, fiber bridging and pullout effects. Doping of BAS with 25 mol% SrSi2Al2O8 (SAS) can accelerate the hexacelsian to celsian transformation and result in the formation of pure monoclinic celsian in Csf/BSAS composites, which can avoid the undesirable reversible hexacelsian to orthorhombic transformation at ∼300 °C and reduce the thermal expansion mismatch between the fiber and matrix.