| Polymeric monolithic doped zirconia and zirconia-alumina stiff
gels (via stable zirconia and zirconia-alumina sols respectively),
derived from Zr-n-propoxide, acetyl acetone, aluminium chloride,
di-methyl formamide etc with judicious time-temperaturepH
selection, have been prepared by controlled hydrolysis and
polycondensation, and subsequently subjected to heat treatment
at 1300°C. The crystallization behaviour of the gels was studied
by X-ray powder diffraction and differential thermal analysis. For
the dried (252C) composite gels pore size distributions were estimated.
FTIR spectra (at 25° and 200°C) and scanning electron
microscopy (at 25° and 1300°C) of both types of gels revealed
that low temperature sintering is influenced by the addition of
alumina sol in doped zirconia sol matrix to result in a better
monolithicity. The microhardness of the fired composite gel was
also deteFmined. |
