What are the weak points of clay bricks?
SiO2 and Al2O3 in clay bricks form eutectic, low melting point silicates with impurities during sintering, and are surrounded by mullite crystals. Clay brick belongs to weak acid refractory products, it can resist acid slag and acid gas corrosion, and its resistance to alkaline material is a little worse. The thermal performance of clay brick is good, it is fast and cold. The clay brick refractory brick and be roughly the same, up to 1690~1730 DEG C, but the load softening temperature is 200 degrees Celsius above the low brick. Because clay bricks contain crystalline Mullite with high refractoriness, they contain nearly half of the amorphous glass phase of low melting point.
In the temperature range of 0~1000 DEG C, the clay brick volume increases with temperature uniform expansion, linear expansion curve approximates a straight line, the line expansion rate is 0.6%~0.7%, about half of the brick. When the temperature reaches 1200 degrees Celsius and then continues to heat up, the volume will begin to shrink from the maximum expansion. The residual shrinkage of clay brick results in the cracking of masonry joints, which is a major drawback of clay bricks. When the temperature is above 1200 degrees, the low melting point of the clay brick gradually melts because the particles are very close to each other due to surface tension, resulting in volume shrinkage.
Clay bricks are clay products with Al2O3 content of 30%~40% aluminum silicate material. Clay brick is made of 50% soft clay and 50% hard clay clinker, according to the requirements of a certain particle size. After molding and drying, the clay brick is burnt at high temperature 1300~1400 degrees celsius. The mineral composition of clay brick is mainly kaolinite (Al2O3, 2SiO2, 2H2O) and 6%~7% impurities (potassium, sodium, calcium, titanium, iron oxides). The sintering process of clay brick is mainly the process of the continuous dehydration of kaolinite and the formation of crystallization of mullite (3Al2O3. 2SiO2).
