is a synthetic refractory material with the primary crystal phase of 3Al₂O₃·2SiO₂, densified via high-temperature sintering (typically 1500–1750°C). Due to the scarcity of natural mullite, industrial production relies on processing aluminosilicate raw materials (e.g., bauxite, kaolin) through grinding, homogenization, and sintering.  

Key Properties  

1. High-Temperature Performance

   - Melting point ＞1850°C, service temperature ＞1700°C, low thermal expansion (5.3×10⁻⁶/K), minimal creep deformation, and exceptional thermal shock resistance.  

2. Physical Stability

   - Density 2.6–2.9 g/cm³, Mohs hardness 6–7, compressive strength 70–260 MPa, with high corrosion resistance to acids/alkaline slags.  

3. Composition Flexibility

   - Classified by alumina content into three grades:  

     | Grade  | Al₂O₃ Content | Phase Composition          |  

     | Low-Alumina  | 42%~47%    | Mullite + Glass + Cristobalite |  

  | Medium-Alumina  | 58%~65% | Mullite + Minor Corundum/Glass |  

 | High-Alumina  | 68%~75%  | Mullite (>85%) + Trace Corundum|   

Production Process

Raw Materials: Natural bauxite or Al₂O₃/SiO₂ mixtures, purified via washing and magnetic separation.  

Procedure: Wet grinding (325 mesh) → Filter pressing → Extrusion → Sintering in tunnel kiln (1500–1750°C, grade-dependent) → Controlled cooling.  

-Critical Step: Adding TiO₂, Y₂O₃ as sintering aids to reduce temperature and suppress grain-boundary phases.