Glass fiber furnace refractories
Glass fiber is very thin fiber shape material made from molten glass by drawing method or other method. Glass fibers are chemically divided into alkaline free, medium alkaline, high alkaline and special glass fibers. Alkaline free glass fiber is also called E glass fiber, it is aluminum borate glass which has excellent electric insulation performance, good fireproof performance and high mechanical strength, containing 0~2% of R2O. Middle alkaline fiber is also called C glass fiber, it is boron containing soda-lime-silica glass which contains 8%~12% of R2O. high alkali fiber(A glass fiber) is soda-lime glass fiber which contains 14%~17% of R2O.
Fused AZS bricks are most important refractory products for glass kilns, they are mainly used at parts where contact with glass liquid. Fused zirconia bricks is not inclined to agglomerate, they are suitable for key parts of high quality glass production furnaces. Fused AZCS bricks are suitable for glass productions which are not sensitive to chrome coloring.
Borate containing glass has strong corrosion to refractory material. Tests suggest that chrome bricks have best corrosion resistance to E glass corrosion, secondly is dense zircon bricks, thirdly is zircon bricks and lastly alumina bricks.
Alumina materials have weak corrosion resistance, fused AZS bricks are apt to form ZrO2 lump. Glass fiber is very sensitive to lump formation, as it may block holes and cause production failure. So high corrosion part of continuous glass fiber furnace should adopt adequately sintered chromite blocks made by isostatic pressing method, medium and low corrosion parts should choose dense zircon blocks.
When producing glass wool, hole diameters are large, the possibility of blockage is low, so fused AZS bricks can be used. Throat part should select isostatic pressed chrome bricks or fused zirconia chrome bricks with 27% Cr2O3 and 27% ZrO2. Sidewall bricks are fused chromite zircon bricks or 41# AZS bricks. Bottom bricks are ordinary shrinkholes free 33# ASZ bricks.
As boron oxide greatly affects alkaline refractory material high temperature performance, regenerator checkerwork material should have very good high temperature strength, high refractoriness under load, strong creep resistance and so on. Therefore, magnesia refractory bricks can’t be used as chekerwork bricks in alkali free or medium alkali glass fiber furnaces.