Sonogels in the Preparation of Advanced Glass and Ceramic Materials
Abstract
Ultrasonic irradiation of mixtures of alkoxides and water (the sonocatalytic method) was shown to provide an interesting way of preparing matrices for ceramic-ceramic composites. The gelation speed of the sonogels can be sufficiently controlled to avoid the segregation of short Al2O3 or ZrO2 fibres used as fillers. High homogeneity dispersions were produced in this way and the density of samples increased. In the case of cordierite, 5 SiO2, Al2O3, 2MgO matrices the strength of the composite strongly depends on the type of crystallographic phase, micro-cordierite which is converted into alpha- cordierite by a thermal treatment. Hot-pressing proved necessary, however, to obtain samples with sufficient mechanical strength. A substantial increase in the resistance was obtained by the addition of optimal quantity of TiO2 nucleant in precursor form to the starting cordierite sonosol. This method enables the hot-pressing to be performed while the matrix is in a glassy form, which improves the compaction by viscous flow. A subsequent thermal treatment is used to convert the seeded glass matrix into fine-grain glass-ceramic. The mechanical strength depended on the volume fraction of the filler phase (fibres). The best results obtained were: 105 MPa for cordierite-ZrO2 fibers and 158 MPa for cordierite-Al203 fibers composites.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 20, 1992
- Accession Number
- ADA258184
Entities
People
- J. Zarzycki
Organizations
- Montpellier 2 University