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Silicon Carbide Bricks

Silicon carbide bricks are high grade refractory material, which’s main chemical composition is SiC. Silicon carbide bricks have both normal temperature and high temperature mechanical strength, good thermal conductivity, small linear change rate, excellent thermal shock resistance, excellent high temperature abrasion resistance and fairly good chemical corrosion resistance. Silicon carbide bricks are popularly used in steel industry, nonferrous metal industry, chemical industry, power plants, ceramics industry and so on.

Silicon Carbide Bricks Classification

Silicon carbide bricks can be divided into different categories based on SiC content, binder types and quantity. According to binder types, SiC bricks can be divided into:
Oxide bonded SiC bricks. The bonding phase is Al2O3-SiO2 series silicate, including clay bonded silicon carbide bricks, mullite bonded silicon carbide bricks and silica bonded SiC bricks.

Nitride bonded silicon carbide bricks.

The bonding phases are Si3N4, Si2N2O, Sialon and other covalance compounds.

Self bonded SiC bricks.

Including β-SiC bonded SiC bricks and re-crystallization SiC bricks, Siliconizing reaction sintered SiC bricks. SiC and free Si consisted engineering ceramics material. Normally, SiC products with less than 50% SiC are called semi SiC refractory, including clinker SiC refractory, high alumina SiC refractory, zircon SiC refractory, mullite SiC refractory and Corundum SiC refractory, etc.

Oxide Bonded Silicon Carbide Bricks

The mineral phases of oxide bonded silicon carbide bricks are quartz, mullite and silicate glass phase. Based on the difference of bonding phases, oxide bonded SiC bricks can be divided into SiO2 bonded SiC bricks, mullite bonded SiC bricks and clay bonded SiC bricks.

Clay Bonded Silicon Carbide Bricks

Clay bonded silicon carbide bricks contain 50%~90% SiC, binding material is binding clay, usually added in sillimanite, andalusite, kyanite and other mineral fine powder. The sintering temperature is between 1350~1450℃. The quantity and types of binding material can directly affect the performance of clay bonded SiC bricks. With the increase of clay content, oxidization resistance is improved, but thermal conductivity, refractoriness under load temperature, thermal shock resistance and high temperature strength will all decrease.
Clay bonded SiC refractory are mainly used as muffle boards of various kinds of industrial kilns and furnaces, ceramic kiln furniture ( refractory slab, sagger and so on). But due to the clay bonding phase in SiC refractory, Clay bonded SiC refractory high temperature performance is greatly affected.

Mullite Bonded Silicon Carbide Bricks

Mullite bonded silicon carbide bricks are developed on basis of clay bonded SiC refractory. The bonding raw material are high purity Al2O3 and SiO2 micro powder or fine powder, sometimes sillimanite, andalusite and kyanite fine powders are also added. The bonging phase are mainly mullite, with low glass phase. In mullite bonded SiC bricks, SiC content is between 65%~85%, sintering temperature is between 1350~1500℃. Mullite bonded SiC bricks have significantly better high temperature performance than clay bonded SiC bricks. Mullite bonded SiC bricks are widely used in ceramic industry, nonferrous metals industry, machinery industry and so on.

Silica Bonded Silicon Carbide Bricks

SiO2 bonded SiC bricks has far better high temperature performance than clay bonded SiC refractory, high temperature modulus of rupture is higher than mullite bonded SiC refractory. Silica bonded SiC bricks are mainly used as kiln furniture.

Oxide Bonded SiC Refractory Physiochemical Index

Item Clay bonded SiC refractory Mullite bonded SiC refractory SiO2 bonded SiC refractory SiO2 bonded SiC refractory
Bulk density g/cm3 2.5 / 2.70~2.75 2.78
Apparent porosity % 14~18 14~16 7~8 5.8
Cold crushing strength Mpa 100 / 130 150
Modulus of rupture Mpa(1400℃) 13 24~26 / 30~50
Linear expansion coefficient ℃-1 4.6*10-6 / 4.9*10-6 4.8*10-6
Thermal conductivity W·(m·K)-1(1000℃) 11 / 15.7~16.9 16.2(1000℃)
SiC % >85 >70 ≥90 89.8
SiO2 % / / / 8.9
Al2O3 % / / / 0.5
Fe2O3 % / / / 0.5


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