The composition of the fused cast AZS block: baddeleyite, corundum, a small amount of mullite, glass phase and porosity. In order to reduce and eliminate the residual thermal stress, in the products, need to have a certain amount of glass phase, as absorber to buffer thermal stress. However, fused cast AZS block resistance to erosion in glass phase is the weak link, in the process of erosion, the first is the seepage of glass phase, and with high temperature glass melt replacement, and then to crystal phase accelerated erosion.
Glass phase in high temperature conditions will happen leakage and send out air bubbles, and then pollute the glass melt. The segregation phenomenon of fused cast AZS block also reflected in the glass phase. In fused cast AZS block content of 33 #, 36 #, 41 # series products, the glass phase content is 20 ℅ - 14 ℅, so their effects on the quality of fused cast AZS block can not be ignored.
AZS three elements of alumina oxide, zirconia oxide, silicon oxide do not exist glass phase in theory, even if there is a small amount of impurities, when not adding alkaline oxides, glass phase is rarely. In production due to introduction of alkaline oxide (sodium oxide) and prompted most silicon oxide into the glass phase.
Sodium oxide (parcel potassium oxide) and silica oxide and alumina oxide constitute the backbone of the glass phase. Sodium oxide content in the raw material reduced from 1.37 ℅ to 0.65%, significantly reduce the number of the glass phase, reduced from the original 21.5 ℅ to 12 ℅. Increase of sodium content obviously reduced viscosity of glass phase. Sodium content is less than 1 ℅, is an ideal range.
Iron oxide, titanium, calcium, magnesium and other impurities from raising glass phase performance and reducing the pollution perspective to soluble glass, the quantity is the less, the better. An increase in the number of these will add to the amount of glass phase, at the same time reduce the glass phase viscosity, not only pollute the glass products and affect the service life of the products. Control the ferric oxide and titanium content is less than 0.2 ℅.
In the production process of fused cast AZS block, control iron and titanium content is less than 0.2 ℅. Sodium content is less than 1 ℅.