Le 25 février 2016, 08:43 dans Humeurs • 0
Fire clay bricks are sticky soil products which refer to Al2O3 containing 30%~40% aluminum silicate material. The main mineral composition of fire clay
bricks are kaolinite(Al2O3•2SiO2•2H2O) and 6%~7% impurities(oxide of potassium, sodium, calcium, titanium and iron). Fire clay bricks adopt 50% soft
clay and 50% hard clay clinker, ingredient by a certain size, and sinter under high temperature of 1300~1400℃ after forming and drying. The sintering
process is mainly the process of decomposition of kaolinite which continuously dehydrates to mullite(3Al2O3•2SiO2). SiO2 and Al2O3 form eutectic low
melting point of silicate with impurities in the process of sintering and surround the mullite crystal around.
Fire clay bricks are the weak acid refractory products which can resist acid melting slag and the erosion of acid gas, good thermal property and resist
rapid heat and cold. The refractoriness of fire clay bricks is roughly the same with silica bricks which are up to 1690~1730℃, however, refractoriness
under load of fire clay bricks is 200℃ lower than silica bricks. Duo to the low refractoriness under load, fire clay bricks will shrink at high temperature
which lead to the lower thermal property and lower mechanical strength than silica brick, so fire clay bricks are only used in the secondary parts of coke
oven, such as regenerator seal wall, small flue lining bricks and regenerator, door lining brick, roof and riser lining brick.
As the clay brick contains not only high refractoriness mullite crystal, but also amorphous glass phase with nearly half of the low melting point. Among the
temperature of 0~1000℃, the volume of fire clay bricks expand with temperature increasing, and the linear expansion ratio is 0.6%~0.7%. However,
when the temperature reaches 1200℃, the volume will shrink from the maximum with the temperature increasing.
Zhengzhou Sunrise Refractory Co., Ltd. is mainly engaged in the research and development of refractory products.