Thermal Shock Resistance of a Special Mullite Based Refractory for Molten Metal Handling Application

Abstract

Mullite is a strong material for advanced structural and functional applications owing to its low thermal expansion, low thermal conductivity, excellent creep resistance, good chemical stability and high temperature resistance. The material occurs very rarely in nature and hence synthetic mullite is a promising candidate for most of the advanced refractory applications.The main requirement of the product is high thermal shock resistance and high temperature slag resistance in presence of molten metal. A typical range of porosity and sufficiently high strength are the parameters required to achieve the above properties.In this work, a special mullite composition has been developed and characterized by measuring density, porosity, thermal expansion, modulus of rupture and modulus of elasticity. A quench test in conjunction with strength measurement has been done on uniaxially pressed test pieces to check the thermal shock resistance of the material which is a prime requirement of the material for its use in molten metal applications. It has been observed that the thermal shock resistance of the material is excellent as analyzed from the strength data after each quench. The paper analyzes these data in conjunction with other mechanical properties such as bend strength and modulus of elasticity.