Silicon carbide mullite bricks are also called high alumina silicon carbide bricks. SiC mullite brick main mineral phase is SiC and mullite. It can be produced by SiC and bauxite clinker. During high temperature application 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.
Silicon Carbide Mullite Bricks Characteristics
Abrasion Resistance
SiC mullite brick’s principle phases are high rigidity SiC, mullite and corundum, meanwhile, SiC mullite bricks has 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 is significantly better than high alumina bricks and magnesia alumina spinel bricks.
Spalling Resistance And Thermal Shock Resistance
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 to 46 times(1100℃, water cooling).
Insulating Performance
Silicon carbide mullite brick’s thermal conductivity(≤2.3W·(m·K) is lower than spinel bricks, and thus have better heat preservation effect.
High Temperature Performance
SiC mullite brick’s refractoriness under load is above 1500℃, max. is 1690℃, can endure high temperature impact and won’t soften or deform.
SiC Mullite Bricks Physiochemical Index
Item
GM1650
GM1600
GM1550
GM1680
Al2O3 %
63
60
57
63
SiO2+SiC %
30
30
30
30
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
Thermal conductivity(w/m·k)
1.7
1.7
1.7
1.7
Silicon Carbide Mullite Bricks Application
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.
