Development Of Penetration-resistant Castable Used In Melting Aluminium Furnace

Penetration-resistance castable used in melting aluminum furnace was fabricated using homogenizing bauxite grog and fused bauxite-corundum as aggregates,alumina and silica micropowers as main matrix constituent,concentrated phosphoric acid and low alumina cement as binders.Effects of the type of aggregate and the content of additives on the microstructures,physical properties at room temperature and penetration-resistance of castable were investigated by means of scanning electronic microscope,optical microscope,energy spectrum analysis and penetration-resistance test.The results showed that:(1)Using fused bauxite-corundum as main aggregate,the penetration-resistant castable had lower apparent porosity,higher volume density and mechanical properties than the castable concluding homogenizing bauxite grog.(2)The addition of phosphate can greatly reduce the porosity and improve the mechanical properties of materials.However,because phosphate was very easy to clot and difficult to disperse during the shaping of castable,the properties of castable was unstable.Furthermore the price of phosphate was high,it was unsuitable to be used in castable in view of economy.(3)The penetration-resistance tests showed that the addition of penetration agent can significantly improve the penetration resistance of castable.In this experiment,when the temperature was 815?,the permeability resistance of castable No.2 was better than that of No.1.Results showed that the aluminum alloy 7075 was more prone to infiltrate into the castable without penetration-resistance agent.(4)When the temperature was 865?,according to the results of SEM and energy spectrum analysis,the penetration depth of aluminum alloy 7075 was lower than that of Al alloy 3003.The castable without penetration-resistance agent was more suitable to be used to melt aluminum alloy 3003.