Effect of silicon carbide whisker reinforcement on CaO-ZrO2-SiO2 glass-ceramic system

An industrial frit formulated in the new CaO-ZrO2--SiO2 glass-ceramic system was studied as a matrix for whisker reinforced composites. The frit was ball milled in acetone and wt ultrasonically mixed with 5, 10, 20 and 30 vol.-% SiC whiskers in order to overcome whisker agglomeration and obtain intimate mixing of the two phases. The samples were hot pressed at 14 MPa in graphite dies, using a N-2 atmosphere, for 2 h at 1280 degreesC. In order to investigate the effect of whiskers as a reinforcement, flexural strength as well as crack configuration and propagation were taken into consideration. Whisker orientation perpendicular to the hot pressing direction was found by SEM observation, and no carbon layer at the whisker/matrix interface was detected by EPMA. Further characterisation of the specimens involved physical (density, elastic modulus) and microstructural properties (XRD, SEM, TEM). The result of glass devitrification was inter-locked wollastonite crystals. BCT/436.