MULLITE Chemical Properties
- Melting point:1750℃ [JAN85]
- Density 3.16 g/cm3
- form powder
- color White
- Water Solubility Insoluble in water.
- EPA Substance Registry SystemMullite (Al6O5(SiO4)2) (1302-93-8)
- Safety Statements 22-24/25
- WGK Germany 3
- RTECS BD1450000
- TSCA Yes
MULLITE Usage And Synthesis
- Chemical Propertiescolorless; rhomb, a=0.7557nm, b=0.76876 nm, c=0.28842 nm; hardness: hot pressed 13.6GPa, sintered 12.7GPa; indentation microfracture 2.02MPa ·m1/2; submicrometer powder(s) can be prepared by hydrolysis of mixed alkoxides, followed by drying and calcining up to 1600°C; sinter, microstructure [SOM91]; phases equilibria in mullite [PAS88]; other data in [HIR89] [ROB67] [MIZ89]
- Industrial usesArtificial mullite, or synthetic mullite, a ceramic material made by a prolonged fusing in the electric furnace of a mixture of silica sand or diasphoric clay and bauxite, has the composition 3Al2O3·2SiO2, has a melting point of 1810 C, and softens at 1650 C.
Mullite occurs in nearly all ceramic products containing alumina and silica but, with the exception of refractories, is seldom introduced as such except as calcined kyanite.
The bricks are resistant to flame and to molten ash, and have a low, uniform coefficient of thermal expansion and a heat conductivity only slightly above that of fireclays. Normally, mullite has very fine crystals that change form and become enlarged after prolonged heating, making the product porous and permeable. For stable high-temperature refractories the mullite is prefused to produce larger crystals. At very high temperatures mullite tends to decompose to form corundum and alkali-silicate minerals of lower heat resistance. Mullite is also used for making spark plugs, chemical crucibles, and extruding dies, and a foamed mullite is used as a uniformly latticed honeycomb structure for lightweight, heat-resistant structural parts.
- Company Name:Meryer (Shanghai) Chemical Technology Co., Ltd.
- Company Name:Alfa Aesar
- Tel:400-610-6006; 021-67582000
- Company Name:BeiJing Hwrk Chemicals Limted
- Company Name:Energy Chemical
- Company Name:Secco work (Beijing) chemical technology co., LTD