Alumina is available in many crystal phases (α, β, etc.). According to the crystal phases of fused cast alumina block, it can be divided into α-β fused cast alumina block, α fused cast alumina block and β fused cast alumina block.
Fused cast alumina block is made of pure alumina powder(>95%) and a small amount of additions (soda sand and quartz sand). The mixed materials are melt in the three-phase industrial arc furnace at 2300℃. Thereafter the melt liquid is cast into the mold. After cooling and annealing, the cast product is cut is processed into the final product.
α-β fused cast alumina block is formed by the compact structure of α alumina and β alumina crystals in a most ideal proportion which is approximately 50% and 50% respectively, where intertwined crystals of both materials result in a very dense structure. Below 1350 ℃, it has excellent corrosion resistance against molten glass and great performance against contamination to molten glass. When in contact with molten glass, it barely produces any blistering or stones. It also presents good corrosion resistance to alkali vapor. α-β fused cast alumina block may be widely used in working tank, feeder channels, superstructures and lipstone, etc.
α fused cast alumina block comprises of a majority of α alumina crystals and a slight portion of β alumina crystals in compact structure. It has good corrosion resistance to molten glass and good wear resistance, but it is sensitive to thermal shock. It is an ideal product for the lower temperature zones of the glass melting furnaces due to its high density, superior corrosion resistance and low blister potential. It is also an ideal material for Metallurgical Titanium Furnace because the superior thermal stability.
β fused cast alumina block comprises of a majority of β alumina crystals and a slight portion of α alumina crystals in compact structure. Moreover, the intersected texture of large β-alumina ensures great dimensional stability and great resistance against spalling. Its property of base saturation enables a higher resistance to alkali vapor, thus it has excellent thermal shock resistance and does not form molten droplets. However, it is easy to form Nepheline(Na2O·Al2O3·2SiO2) with SiO2. It can be transformed into α alumina under reducing atmosphere and is easy to crack due to volume expansion. It has better corrosion resistance to molten glass than α fused cast alumina block under oxidizing atmosphere. It is the best material for molter crown, port crown, feeder channel, ect.
Sunrise offers high quality α-β fused cast alumina block, α fused cast alumina block and β fused cast alumina block available in different shapes and sizes.