Silicon Brick Is An Acid Refractory Material

Silicon brick is an acid refractory material, with good resistance to acid slag erosion ability, load softening temperature as high as 1640 ~ 1670℃, long-term use volume is relatively stable at high temperature.

The mineral phase composition of the silicon brick is mainly squamous quartz and cristobalite, and a small amount of quartz and vitreous. The thermal stability of silicon brick at low temperature is very poor because of the change of crystal type and the volume of squamite, cristobalite and residual quartz. During use, it is necessary to slowly heat and cool below 800 ° C to avoid cracks. Therefore, it is not suitable for use in kilns with rapid temperature changes below 800 ° C.
The properties and processes of silicon bricks are closely related to the crystalline transformation of SiO2, so the true specific gravity is an important quality index of silicon bricks. The general requirement is below 2.38, and the high quality silicon brick should be below 2.35. The true specific gravity is small, reflecting the quantity of squamoid quartz and cristobalite in the brick, the amount of residual quartz is small, so the residual linear expansion is small, and the strength decline in use is also small. There are seven crystalline and one amorphous variants of silica. These variants can be divided into two categories: the first type of variants are quartz, squamous quartz and cristobalite, their crystal structure is very different, and the conversion between each other is very slow; The second type of variant is the subspecies of the above variant, αβ and γ-type, which are similar in structure and convert quickly from one to another. In theory, their mutual transformation relationship is shown in the figure "Transformation Relationship of silica variants".
The raw material for making silicon bricks is silica. The higher the SiO2 content of silica raw materials, the higher the refractoriness. The most harmful impurities are Al2O3, K2O, Na2O, etc., which seriously reduce the refractoriness of refractory products. Silica brick with SiO2 content of not less than 96% silica as raw materials, adding mineralizing agents (such as iron scale, lime milk) and bonding agents (such as molasses, sulfite pulp waste liquid), through mixing, molding, drying, burning and other processes to produce.