Glass-contact refractories are subjected to severe conditions in use. The high temperature and the corrosion and erosion by the molten glass cause rapid wear of these refractories. This will directly affect the quality of glass and increase costs. So the selection and quality of these refractories is important. 

 

The glass-contact refractories is required to has high resistance to corrosion and erosion and minimum contamination of the molten glass. Also, the cost of the materials used must be sufficiently low for economical production, and the materials must have certain properties for shaping, handling and firing.

For all glass-contact refractories, the most important property is corrosion resistance to molten glass. The corrosion Another very desirable improvement in these refractories is in resistance to thermal shock. When these refractories are installed or replaced because badly worn or because parts of different sizes are required, they must undergo a drastic change in temperature, namely, from room or factory temperature to the temperature of the furnace. 

 

Many glass-contact refractories have to conform to certain dimensions or shapes for proper operation, and rapid wearing away of such parts requires even more frequent replacement than is necessary with other parts. 

 

The glass-contact areas of the glass furnaces include the sidewall, the tank bottom, feeder pool, throat, the channel, the refining zone and forming zone.

 

In the sidewall, fused cast AZS block is used. The sidewall block is subjected to the wear and corrosion by molten glass and chemical corrosion by the batch materials and glass water. The sidewall block is required to have good corrosion resistance, thermal shock resistance, low thermal conductivity and cause no glass defects such as stripes, stones and bubbles. 

 

The bottom block is required to have good resistance to wear and corrosion. Now the bottom of the glass furnace usually adopts multi-layer bottom structure. The fireclay brick is used in the lower parts as the insulation layer. Over the fireclay layer is AZS ramming mass. On the top layer which is in contact with glass is fused cast AZS block. 

 

The feeder pool is subjected to the corrosion by batch materials and molten glass and wear by the liquid flow and flame. The corner block of the feeder pool suffers from more serious wear and corrosion and bigger mechanical stress and is one of the weakest parts of the glass furnace. AZS 41# WS is usually used in this part. Other parts of the feeder pool always adopts AZS 33#. 

 

Since the flowing rate of glass liquid in the throat is the largest, the wear and corrosion is very severe here. AZS 41# WS is used here. AZCS WS block is sometimes used here since it has much better wear and corrosion resistance than AZS 41# WS, but it can color the glass liquid. In the borosilicate glass furnace, fused silica brick can also be used here. 

 

In the refining zone and the forming zone is the molten and refined glass. Refractories used in those parts are required to cause no glass defects to the glass. Since the temperature is low here, the corrosion is not quite serious. Sometimes, in order to maintain the forming temperature, the molten glass is heated in the refining and forming zone. AZS 33# is used in the refining zone since it has higher exudation temperature and will not cause bubbles. In the forming zone, alpha-beta fused cast alumina block and alpha fused cast alumina block are better choices as it has a minor amount of glass phase and produce almost no pollution to glass. Under 1350℃, it has better corrosion resistance than fused cast AZS. Sillimanite brick and mullite brick can also be use in the forming zone due to their dense structure and low bubbling potential. 

 

Although glass contact refractories have been improved in recent years in their resistance to high temperature, corrosion and erosion, further improvement is highly desirable in order to reduce the costs of and to, facilitate the production of glass.