Composite materials with ZrO2-TiO2 matrix and ZrO2 containing ceramic fibres

The aim of the work reported in the present paper was to obtain composites consisting of a ZrO2-TiO2 matrix reinforced with ceramic fibres containing 12 wt-% ZrO2, which are resistant to temperatures higher than 1500 degreesC . The resulting ceramic matrix consisted of 95 wt-% ZrO2, partially stabili sed with CaO, and 5 wt-% rutile TiO2. A ceramic fibre content of 0.82 vol.- % was used and for the matrix, several grades of ZrO2 partially stabilised with CaO were explored, prepared by dry and wet grinding for various grindi ng periods. Composites were prepared by uniaxial die pressing at 350 MPa an d sintered at two temperatures: 1360 degreesC for 1 h and 1500 degreesC for 3 h. The resulting composites showed the following range of properties: to tal drying and firing shrinkage 0.4-3.3%: apparent density 3.51-3.96 g cm(- 3); porosity 25-34%; water absorption 6-10%; bend strength 12-43 MPa. The o ptimum ZrO2 grades were determined based on physical and mechanical propert ies, and on structural determinations carried out by thermodifferential and thermogravimetric analyses. X-ray diffraction (XRD), and scanning electron microscopy (SEM). SEM evaluation illustrated the increase in average size of crystallites typical of ZrTiO4 solid solution as a function of temperatu re, from 2 mum at 1360 up to 14 mum at 1600 degreesC, and of their tendency to sinter. BCT/437.