There are three main drivers of changes and developments in refractory materials. The first is the glass manufacturer's need to improve the quality of the glass, at least for the most part. The second is the economic requirements of glass furnaces to make kilns run longer, and the third is the impact and impact of pure oxygen combustion systems. These three requirements often determine the use of improved refractory materials when repairing a kiln. These impetuses have also prompted glass manufacturers to choose improved refractory products for furnace maintenance and to adopt new technologies for extensive overhaul in their operating cycles.
Melt-cast alumina bricks have established their use in the top of the melting tank, primarily in pure oxygen fired furnaces melting high-quality glass. Before the advent of pure oxygen combustion technology, only β ˉ alumina bricks were used to melt the superstructure of the cell and alumina-free bricks without melt-casting were applied to the top of the melting cell. Today, both molten cast products of β-alumina and α-β-alumina are used in the production of some or all of the roofs of pure oxygen combustion furnaces for color television sets (screens and cones), float glass and borosilicate glass on. Melt-cast AZS bricks can typically be used at 1600 ° C or 1650 ° C (depending on the glazing), while furnace tops made of fused alumina brick can be successfully run at 1700 ° C. This creates better conditions and greater flexibility for glass manufacturers in the production of refractory glass.
For many years, melt-cast AZS furnace roofs have successfully undergone the test of cooling and reheating to enable them to use multiple operating cycles. There is now a bit of experience in successfully implementing the top cooling and reheating of fused-alumina roofs, which represent an economically viable life when they use two or more cycles of operation. The results of the observation of the fused alumina roof in service (thermal observation and shutdown observation) show that these materials are both chemically and mechanically stable. This is the first observational study of such masonry because there was neither a reference to fused alumina at the time nor the empirical basis for its application to the roof.