Glass furnaces · 2026-10-23
Mullite and zircon-mullite in glass furnaces
Low-porosity mullite offers excellent thermal shock, high strength and resistance to erosion and corrosion, and is used in glass furnaces as well as in lime and non-ferrous kilns. Zircon-mullite, with corundum, mullite and ZrO₂ as its main phases, holds high-temperature, thermal-shock and corrosion resistance in the same structure.
Mullite (3Al₂O₃·2SiO₂) has a relatively low thermal expansion and good high-temperature strength, and is one of the more reliable thermal-shock-resistant phases among aluminosilicate refractories. Low-porosity mullite brick turns that phase into a dense working lining: excellent thermal shock, high strength, and resistance to erosion and corrosion, used in glass furnaces and also in lime and non-ferrous kilns. Once porosity is brought down, gas and melt find it harder to infiltrate along connected pores, and the hot face can remain intact for longer.
Zircon-mullite introduces ZrO₂ into a mullite and corundum matrix. The zirconia phase change opens microcracks in the microstructure, which absorb still more of the thermal-shock strain; ZrO₂ itself also raises corrosion resistance. With corundum, mullite and ZrO₂ present together, the brick can meet high temperature, thermal shock and corrosion in a glass furnace at the same time. Different zirconia contents allow the emphasis to shift between thermal shock and slag resistance.
If the regenerator crown is divided by fuel, chrome-corundum belongs under petroleum-coke firing, and magnesia-zirconia when the furnace is not fired with petroleum coke. Mullite and zircon-mullite do not take that crown duty against acidic flue gas; their place is in positions that ask for thermal-shock and corrosion resistance, but where the fuel chemistry is not dominated by vanadium and sulphur. The furnace type and the position decide how these families are combined.