Material reference
Mullite 3Al₂O₃·2SiO₂
Aluminosilicate ceramic stable to 1700 °C with low thermal expansion. A versatile workhorse for high-temperature service where thermal shock matters.
Used for: furnace tubes · thermocouple sheaths · insulators · kiln furniture · crucibles · heater components
At a glance
Key Properties
High thermal shock resistance
Stability at high temperature
High corrosion resistance
Good electrical resistance
Low thermal conductivity
Dense or porous material grades
Products in this material
Mullite products
More Details
This material is not limited to the products and applications illustrated above. For more information, or to find out about other products/applications, please click here.
Mullite is a material that is manufactured by combining Alumina with Silica, fused together during sintering, in various combinations to produce a family of materials. Known as Mullite for the dense materials and Porous mullite or corundum for the porous grades.
Synthetic Mullite (Al2O3–SiO2) products are available in both impervious and porous forms. Densely sintered (impervious) mullite combines high strength with good thermal shock resistance. Porous mullite have a reasonably high strength combined with low thermal expansion giving improved levels of thermal shock.
Mullite ceramics with high thermal shock and operating temperatures up to 2910F (1600C) are used in furnaces, heaters, electrical insulation, wear and corrosion resistant applications. Stock is available in rods, Mullite tubes, insulators, thermocouple protection sheaths and crucibles.
These mullite materials are also available in Special and custom shapes according to specific and discreet customer demands.
Request the Mullite datasheet
Full property data, grade comparison, machining guidance and typical applications. EN and FR versions available.
At a glance
Applications
Casting pins
Kiln furniture
Protection tubes
Molten metal processing
Furnace tubes
Furnace construction and repair
Electrical insulation
Ferrules
Metal filtration
Heat treatment support
Stopper Rods
Crucibles
At a glance
Grades
Dense Mullite - C610Dense Mullite - C61060% Alumina (Porous) - sillimanite65% Alumina (Porous)70% Alumina (Porous)80% Alumina (Porous) - corundum
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FAQs
Frequent technical questions
Why specify mullite instead of alumina?
Mullite costs less than dense alumina and tolerates thermal shock significantly better. Where the operating temperature is below 1700 °C and chemistry is benign, mullite is usually the right specification.
Is mullite the same as sillimanite?
Sillimanite is an Al₂SiO₅ mineral that converts to mullite plus silica on firing. In commercial language, porous Al₂O₃–SiO₂ bodies near 60% alumina are sold under both names; chemically and mechanically they are very similar.
Can mullite hold molten glass or metal?
Dense mullite is widely used for glass-tank components and crucibles handling oxidising melts. For aggressive non-oxide melts or alkali glasses, check chemistry with us before specifying.
Is mullite dense or porous?
Mullite can be made as both dense or porous depending on the product type, geometry, and application of the part.
How you determine the correct material grade?
You need to assess the application requirements for maximum operating temperature, mechanical strength, thermal shock, shape/geometry – speak to one of our team to find out which material grade is best for you.
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