Fireclay Refractory Brick Introduction
Fireclay refractory brick refers to the clay products made of aluminum silicate with Al2O3 content of 30% ~ 40%.Fireclay brick belongs to weak acid refractory products, which can resist the erosion of acid slag and acid gas, and its resistance to alkaline substances is slightly poor. Clay brick has good thermal performance and can resist rapid cooling and heating.
Fireclay Refractory Brick Component
The mineral composition of fireclay brick is mainly kaolinite (Al2O3 · 2SiO2 · 2H2O) and 6% ~ 7% impurities (oxides of potassium, sodium, calcium, titanium and iron).The firing process of clay brick is mainly the process of continuous dehydration and decomposition of kaolinite to form mullite (3Al2O3 · 2SiO2) crystal. SiO2 and Al2O3 in fireclay brick form eutectic low melting point silicate with impurities during firing, which is surrounded by mullite crystallization.
Fireclay Refractory Brick Characteristic and Performance
The fire resistance of fireclay brick is equal to that of silica brick, up to 1690 ~ 1730 ℃, but the load softening temperature is more than 200 ℃ lower than that of silica brick. Because the fireclay brick not only contains mullite crystals with high fire resistance, but also contains nearly half of the low melting point amorphous glass phase.In the temperature range of 0 ~ 1000 ℃, the volume of fireclay brick expands uniformly with the increase of temperature. The linear expansion curve is similar to a straight line, and the linear expansion rate is 0.6% ~ 0.7%, which is only about half of that of silicon brick.When the temperature reaches 1200 ℃ and then continues to rise, its volume will shrink from the maximum expansion. The residual shrinkage of clay brick leads to the loose crack of masonry mortar joint, which is a major disadvantage of clay brick. When the temperature exceeds 1200 ℃, the low melting point materials in the clay brick gradually melt, and the particles are close to each other due to surface tension, resulting in volume shrinkage.
Fireclay Refractory Brick Classification
According to the purpose, fireclay refractory brick is mainly divided into fireclay refractory brick for blast furnace, fireclay refractory brick for hot blast stove and large fireclay refractory brick for glass kiln.Fireclay refractory bricks for blast furnace are used for the throat, shaft, hearth, bottom and shaft of small blast furnace lining.Fireclay bricks for hot blast stove are used for hot blast stove, regenerator and partition wall. Fireclay bricks for hot blast stove shall have good thermal shock resistance, high load softening temperature and low creep.Large fireclay refractory bricks for glass kilns are fireclay refractory bricks with a unit weight of no less than 50kg used for building glass kilns.
