The cordierite-mullite products have a reasonably high resistance, with a low thermal expansion, allowing better levels of thermal shock and operating / working temperatures up to 1400º C.
Advisable to use in furnaces, heaters / heating devices, as electrical insulator, in wear out applications, corrosion resistant areas, trays, supports, etc.
Cordierite and mullite are naturally occurring minerals that are commonly used to make kiln shelves and related kiln furniture items. Of the two, cordierite is the most common; mullite is rarely found in nature and is usually made synthetically and sold as a white powder.
Most often, kiln shelves are made from a mixture of cordierite and mullite powder, which is mixed with clay and other ceramic materials, shaped, then heated to form kiln shelves. Mullite shelves are sturdy, rigid, and long lasting, but they can break if dropped and may crack or cause air bubbles if heated when not dried thoroughly.