Fabrication of fiber-reinforced celsian matrix composites

A method has been developed for the fabrication of small diameter, multifil ament tow, fiber-reinforced ceramic matrix composites. Its application has been successfully demonstrated for the Hi-Nicalon/celsian system. Strong an d tough celsian matrix composites, reinforced with BN/SiC-coated Hi-Nicalon fibers, have been fabricated by infiltrating the fiber tows with the matri x slurry, winding the rows on a drum, cutting and stacking of the prepreg t apes in the desired orientation, and hot pressing. The monoclinic celsian p hase in the matrix was produced in situ, during hot pressing, from the 0.75 BaO-0.25Sr0-Al2O3-2SiO(2) mixed precursor synthesized by solid state reacti on from metal oxides. Hot pressing resulted in almost fully dense fiber-rei nforced composites. The unidirectional composites having similar to 42 vol. % of fibers exhibited graceful failure with extensive fiber pullout in thre e-point bend tests at room temperature. Values of yield stress and strain w ere 435 +/- 35 MPa and 0.27 +/- 0.01%, respectively, and ultimate strengths of 900 +/- 60 MPa were observed. Young's modulus of the composites was mea sured to be 165 +/- 5 GPa. (C) 2001 Elsevier Science Ltd. All rights reserv ed.