Low temperature synthesis of anorthite based glass-ceramics via sintering and crystallization of glass-powder compacts

Anorthite based glass-ceramics were synthesized. The investigated glass compositions are located close to the anorthite-rich corner of the fluorapatite-anorthite-diopside ternary system. Glass powder compacts with mean particle size of 2 and 10 mu m were prepared. Sintering behaviour, crystallization and the properties of glass-ceramics were investigated between 800 and 950 degrees C. In the case of specimens made from the finer particles, complete densification was achieved at a remarkably low temperature (825 degrees C) and the highest mechanical strength was obtained at 850 degrees C, but density significantly decreased at higher temperatures. The samples prepared from the larger particles exhibited higher values of density, shrinkage and bending strength within a wider temperature range (825-900 degrees C). Anorthite was predominantly crystallized between 850 and 950 degrees C, along with traces of fluorapatite. Diopside was detected only in the MgO richer compositions. (c) 2005 Elsevier Ltd. All rights reserved.