CARBON-FIBER REINFORCEMENT OF NITROGEN GLASS

A Y-Si-Al-O-N glass was prepared by conventional glass melting techniq ues. Continuous carbon fibre unidirectionally reinforced composites wi th this glass as the matrix were produced by slurry infiltration follo wed by hot-pressing. Investigation of the sintering behaviour revealed that whereas glass samples could be hot pressed to full density at a temperature slightly higher than the glass transition temperature, hig her temperatures were needed for the composite. Measurements of mechan ical properties showed that significant strengthening and toughening o f the glass matrix took place with bending strength (sigma) increasing from 162 to 323 MPa and fracture toughness (K-IC) from 1.8 to 12 MPA m(1/2). These properties are expected to be improved further if cracki ng perpendicular to the fibre direction in the composites caused by th ermal mismatch between fibres and matrix can be eliminated. Examinatio n of the fracture surface of the composites hot-pressed at temperature s below 1450 degrees C showed massive fibre pullout, but higher hot-pr essing temperatures or longer hot-pressing times at the same temperatu re resulted in reaction between the fibres and the matrix. (C) 1997 El sevier Science Limited.