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 (C-sf) 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 C-sf/BSAS composites, which can avoid the undesirable reversible hexacelsian to orthorhombic transformation at similar to 300 degrees C and reduce the thermal expansion mismatch between the fiber and matrix. (c) 2008 Elsevier Ltd. All rights reserved.