The selection of refractory materials has directly impact on the service life of furnaces and quality of glass. Since large and middle-scale float glass furnaces are always insulated simply, the temperature of glass liquid is increased. So, the selection of bottom paving bricks and ramming mass is very important. 

In float glass furnaces, different paving bricks are used in different parts. The general paving bricks include sintered AZS, fused cast AZS block, fused cast alumina block and sintered zircon brick. 

 

For sintered bricks, since pores are open, the corrosive substances are easy to penetrate into the materials, which enhance the damage of refractory materials and may cause glass defects. Since the bottom is insulated, the temperature of the glass liquid is increased, which increases the convection of molten glass and accelerates the corrosion of refractory materials. In addition, during the manufacturing process, broken glass is added. The broken glass may contain metal contaminants which are brought into the furnace, deposited on the bottom after melted. The metal contaminants drill into the bricks and reduce the corrosion resistance of bricks. There may be tin in the broken glass. Tin has a low melting point of only 230℃ and high density and permeability, which can drill to the bottom of the outermost insulation layer and drop onto the bottom of the frunace.

 

The bottom paving brick can directly contact the glass liquid. The erosion of flowing glass liquid to the refractory materials accelerates the corrosion. According to the experiments, fused cast alumina block has the best performance with good corrosion resistance and a low potential of bubbling and stoning. The next one is fused cast AZS block 33#. 

 

α-βfused cast alumina block and fused cast AZS block have good corrosion resistance due to its low porosity and high density,