Properties of high zircon Blocks.

The mass fraction of ZrO2 in zircon products is about 65%, almost all of which are composed of zircon crystals, with only a very small amount of glass phase and free ZrO2. The true density is about 4.55g/cm3, the highest is 4.62g/cm3, the bulk density of ordinary products is 3.6-3.8g/cm3, and the apparent porosity is greater than 13%; the bulk density of dense refractory Blocks is 3.8-4.0g/cm3; the apparent porosity is 5% About; high-density products, the bulk density is greater than 4g/cm3, the apparent porosity is less than 1.0%. Since this product is almost entirely composed of zircon crystals, contains only a very small amount of glass phase, and has high viscosity at high temperature, so the refractoriness is very high, greater than 1825 degrees. The normal temperature compressive strength of the product is 100-430MPa, and the flexural strength is 17.8-76.3MPa. The softening temperature under load is greater than 1650 degrees, and increases with the decrease of mineralizer and the increase of sintering temperature, and the highest can reach 1750 degrees. Therefore, it is a refractory Block with excellent resistance to heat and heavy load at high temperature and good wear resistance. The thermal expansion of zircon is low, and it is fired at high temperature, so the volume stability of the product is high. From room temperature to 1400, the thermal expansion rate is only 0.5%. After 2 hours of reburning at 1500 degrees, the residual shrinkage rate is only 0.04%~0.20%. Some products do not have any residual shrinkage after being re-fired at 1650. High-density zircon products have poor thermal shock resistance when there are no coarse particles in them. It must be heated or cooled slowly during use. Thermal shock resistance is significantly improved when the article is composed of multi-level particles. Such products are not easily wetted and corroded by molten metal and slag, especially aluminum and its alloys. Therefore, it has good corrosion resistance to slag, molten metal and molten glass. High-density products have better performance, for example, the degree of erosion by alkaline slag is only 1/3 of that of mullite products.