Silica brick quartzite as a raw material, crushed and added to the binder, the mineralizing agent mixing, forming, drying and heating up as planned firing.
Silica brick containing SiO2 is more than 93%, Department acidic refractories having good acid residue erosion effect. Silica brick thermal conductivity, refractoriness of 1690 to 1710 ° C, the softening point of the load can be up to 1640 ° C, no residual contraction. Its disadvantage is cold acute Poor ME-resistant, heat-expandable.
SiO2 (silica) at different temperatures can exist in different polymorph, crystal transformation is generated when the change in the volume and produce stress, and therefore the manufacturing, performance and use of the silica bricks and SiO2 crystal transition closely related.
The level of conversion, such changes no rearrangement of the crystal lattice, the lattice distortions or straight, so the conversion speed is fast and reversible.
Various patterns for the SiO2 conversion temperature and volume change of the type, cristobalite conversion at 180 ° C ~ 270 ° C, and the most dramatic change in volume, and 570 ° C when the quartz into smaller sizes change, the to the tridymite crystal transformation point: 117 ° C. and 163 ° C, the minimum volume change. Silica brick for coke oven in the manufacturing process, as far as possible into tridymite. But the actual production of silica brick products are always three polymorphs exist. Tridymite the minimum density due to three quartz, tridymite higher the content of silica brick, the true density is smaller.
The curve of the change in the volume of the silica brick product is a complex organization of the sum of the volume change. True density of silica brick, quartz transformation completely smooth expansion process, the residual expansion, is conducive to maintaining tight furnace. In addition, tridymite load softening temperature, good thermal conductivity, the coke oven as far as possible the true density of silica brick, generally require less than 2.38, the true density of high-quality silica brick should be in the range of 2.34 to 2.35.
