Application of the glass-ceramic process for the fabrication of whisker reinforced celsian-composites

The glass-ceramic process has been investigated as an alternative route to the common ceramic process for the formation of whisker reinforced ceramic composites. In the BaSiAlTiO system composites have been prepared with cels ian (BaAl2Si2O8) as the matrix and hollandite (Ba1.23Al2.46Ti5.54O16) as th e reinforcement. Different starting materials have been subjected to a ther mal treatment, and the product samples have been studied with respect to th eir microstructures and the crystalline phases present. By annealing pellet s of a finely powdered, quenched melt containing Ba, Si, Al and O, to which crystalline TiO2 was added, a complete transformation of hexacelsian, form ed in a first step, into celsian was achieved at 1000 degreesC. In the cels ian matrix, needle-shaped hollandite crystals precipitate, which are distri buted homogeneously over the matrix phase. In these dense composites, typic al reinforcement mechanisms, such as crack deflection and whisker pull-out have been observed. (C) 2001 Kluwer Academic Publishers.