Color, weight and feel are the basic ways to judge the quality of refractory bricks when purchasing refractory bricks. 

	Color	Weight	Feel
Fire clay brick	Yellow brown	General	Rough
High alumina brick	Yellow	Heavy	Rough
Corundum brick	White	Very heavy	Smooth
Silica brick	Yellow	Slightly Light	Slightly rough
Magnesia brick	Dark brown	Heavy	Slightly smooth
Magnesia chrome brick	Dark brown	Very heavy	Slightly smooth
Magnesia alumina brick	Brown	Very heavy	Slightly smooth
SiC brick	Gray black	Heavy	Slightly rough
Carbon brick	Gray black	Light	Slightly rough
Graphite brick	Black	Light	Smooth
Fire clay insulation brick	Yellow brown	Very Light	Rough

Fire clay brick is a type of aluminosilicate refractory brick containing 30-48% Al2O3. It is made of clay clinker as the aggregate material and refractory clay as the binder by firing at 1250-1350℃. It is an acid refractory material. Its softening temperature under load is lower than its refractoriness, which is its main weak point. It has good thermal shock resistance which increases with the increase of clinker and coarse particle. It is widely used in heating furnaces, heat treatment furnaces, cupola furnaces and drying furnaces. 

 

High alumina brick is a type of aluminosilicate refractory brick containing more than 48% Al2O3. It is made of bauxite and sillimanite as raw materials by sintering at 1500-1600 ℃. It has higher refractoriness and softening temperature under load than those of fire clay bricks. It belongs to acidic refractories. It has good slag resistance but low thermal shock resistance. It is mainly used in resistance furnaces, electric arc furnace lid, hot stove and blast furnaces. 

 

Corundum brick is a type of advanced refractory brick containing more than 90% Al2O3. It is made of industrial alumina as the raw material. According to manufacturing method, it can be divided into bonded corundum brick and recrystallized corundum brick. It has high refractoriness and softening temperature under load, good thermal shock resistance, high hardness, good wear resistance and good resistance to acid and alkali slags. However, if the firing temperature is low, there will be big shrinkage during use. It is used in resistance furnaces, molybdenum wire furnaces, gasifier, etc. 

 

Silica brick is a type of high quality silica refractory containing more than 93% SiO2. It is composed of silica as raw material with addition of mineralizing agents and binders by sintering at 1400-1430℃. It has high softening temperature under load, close to its refractoriness. This is its biggest advantage. It is a typical acid brick. It has poor volume stability at high temperature. When it is heated, residual expansion occurs. It is mainly used in acid electric arc furnaces, roof of the continuous furnaces, coke ovens, glass furnaces, etc.

 

Semi-silica brick is composed of 15%-30% Al2O3 and more than 65% SiO2. It is made of refractory clay containing silica sand and pyrophyllite by firing at 1250℃. It belongs to acidic refractory materials. It has a high deformation temperature under load and volume stability at high temperature, which can enhance the integrity of the masonry. It is widely used in the roof of heating furnaces, cupola furnaces, furnace hearth and flue. 

 

Magnesia brick is a type of refractory brick containing more than 87% MgO with periclase as its main crystalline phase. According to its production process, it can be divided into sintered magnesia brick and bonded magnesia brick. Sintered magnesia brick is made of magnesia sand as the raw material with addition of binders by calcining at 1550-1600℃. Its refractoriness is above 2000℃. It belongs to basic refractories. Its softening temperature under load is not high. Its softening starting temperature and softening end temperature are almost the same. It has good thermal shock resistance, high strength at room temperature and good high temperature wear resistance. It is widely used in basic electric arc furnaces, the hearth of the heating furnace, steel converter, etc.

 

Magnesia chrome brick is mainly composed of MgO (40%-60%) and Cr203 (20%-8%) with periclase and spinel as the main mineral composition. Its main raw materials are sintered magnesia and chromite. It has high refractoriness, high strength, good thermal shock resistance, fixed volume at high temperature. It belongs to basic refractories. It has good corrosion resistance to alkali slags as well as adaptability to acid slags. It is mainly used in cement kilns, electric arc furnaces, etc.

 

Magnesia alumina brick is made of sintered magnesia with low content of calcium with addition of about 8% industrial alumina powder by molding and firing at 1580℃. Compared to magnesia brick, it has good thermal shock resistance. This is the most prominent advantage. It has slightly higher temperature structural strength and good slag resistance. It is widely used in cement kilns, electric arc furnaces and the furnace hearth, etc.