Mullite (3Al₂O₃·2SiO₂) is a refractory aluminosilicate that forms the backbone of kiln furniture, furnace linings and high-temperature fixtures across the ceramics and glass industries.
Its value lies in a rare combination: very low thermal expansion (4.0–5.5×10^−6/K), good creep resistance up to 1500 °C, and excellent thermal-shock survival in cycling furnaces. Unlike dense structural ceramics, porous mullite grades are intentionally lightweight and thermally insulating, making them ideal for saggers, setters and pusher-bar components.