ZrO//2-free glasses and glasses containing ZrO//2 in the system Y//2O//3- Al//2O//3-SiO//2 have been investigated. Properties of compositions fired in nitrogen at 1600, 1650 and 1700 degree C have been assessed. The solubility limit of ZrO//2 in yttrium aluminosilicate liquids with a high content of Y//2O//3 at 1700 degree C was determined to be 6 wt%. The hardness and density of the ZrO//2- containing glasses were slightly increased compared to the ZrO//2-free glass; y- Y//2Si//2O//7 (at temperatures less than 1300 degree C) and beta -Y//2Si//2O//7 (at temperatures greater than 1300 degree C) monoclinic phases are the main products formed during the crystallization. An unidentified intermediate phase rich in Y, Al and Si was observed to undergo a transformation at temperatures greater than equivalent to 1200 degree C resulting in the formation of the beta -Y//2Si//2O//7 phase. (Author abstract) 31 Refs.
Vomacka, P. Babushkin, O.