Preparation and Mechanical Behavior of Glass-Ceramics from Feldspathic Frits

Glass-ceramics were produced from frits with feldspar (79.09% wt/wt), alumina, sodium carbonate, potassium carbonate, borax and cerium dioxide. Feldspathic frits obtained at 1200 A degrees C were shaped and sintered at various temperatures. Flexural strength results were analyzed by using the Weibull statistical distribution. These materials were also characterized by x-ray diffraction and scanning electron microscopy (SEM). At 600 A degrees C, an initial leucite formation occurred as a crystalline phase, but the amorphous phase still prevailed, with low flexural strength. On the other hand, when the temperature increased to 800 A degrees C, flexural strength also increased to approximately 70 MPa and Weibull modulus, . This behavior was explained by the formation of leucite crystals dispersed within the glassy matrix, which hinders, in a certain concentration, the propagation of cracks. However, for the sintering temperature of 1000 A degrees C, flexural strength decreased and may be associated with higher levels of this leucite crystal, in spite of the higher reliability m = 6.6. .