Silicon carbide mullite bricks are also called high alumina silicon carbide bricks. SiC mullite brick’s main mineral phase is SiC and mullite. It can be produced by SiC and bauxite clinker. During high-temperature applications in kilns, silicon carbide can be oxidized and produce SiO2, which can react will Al2O3 to form mullite (3Al2O3·2SiO2). The synthesized mullite can not only enhance brick’s density and strength but also form protection film to prevent further oxidization of SiC. The un-reacted SiC can enhance thermal shock resistance, abrasion resistance, and corrosion resistance of silicon carbide mullite bricks.
SiC mullite brick’s principal phases are high rigidity SiC, mullite, and corundum, meanwhile, SiC mullite bricks have high structural density, its bulk density is between 2.7 and 3.0g/cm3. So SiC mullite bricks have good abrasion resistance. Silicon carbide mullite brick’s density, strength, and abrasion resistance are significantly better than high alumina bricks and magnesia alumina spinel bricks.
SiC in silicon carbide mullite bricks has high thermal conductivity, small thermal expansion rate, so SiC carbide mullite bricks have good thermal stability, max. thermal shock times can reach 46 times(1100℃, water cooling).
Silicon carbide mullite brick’s thermal conductivity(≤2.3W·(m·K) is lower than spinel bricks, and thus has a better heat preservation effect.
SiC mullite brick’s refractoriness under load is above 1500℃, max. is 1690℃, can endure high-temperature impact and won’t soften or deform.
|Apparent porosity %||17||17||19||17|
|Cold crushing strength Mpa||85||90||90||100|
|Refractoriness under load ℃ (0.2Mpa)||1650||1600||1550||1680|
|Thermal shock resistance(11oo℃, water cooling)||10||10||12||13|
|Bulk density g/cm3||2.65||2.60||2.55||2.65|
|Cold abrasion resistance cm3||5||5||5||5|
Due to silicon carbide mullite brick’s good abrasion resistance, high refractoriness, and thermal shock resistance, it is popularly used in rotary cement kiln sintering zone, transition zone, and so on, where material rolling friction, high-temperature thermal stress, temperature fluctuation, and material corrosion are severe.