Heat-Insulating Refractory Material Based on Hollow Corundum Microspheres

Abstract

A study is made of the effect of dispersant additives on the properties of a mix and a fired material containing hollow corundum microspheres. It is shown tht the addition of CASTAMENT FS10 together with CASTAMENT FW 10 makes it possible to obtain a green product having an ultimate compressive strength of at least 2 MPa. The fired material is slightly less porous than the material without dispersant additives. Heat-insulating ceramics based on hollow corundum microspheres and having an open porosity of at least 50.7% and an ultimate compressive strength of at least 35 MPa are obtained after firing at 1600°C. The material shrinks no more than 0.2% during the firing operation, which has made it possible to make large products of complex shape and ship them to customers.

A low bulk density, low thermal conductivity permanent lining castable for tundish obtained by adding pearlescent sand

“…In order to improve the thermal insulation performance of castables and reduce their heat storage loss, lightweight porous aggregates are often used instead of traditional dense aggregates. [4][5][6][7][8] At present, the representative high-strength lightweight aggregates include hollow corundum spherical aggregates, 9,10 lightweight microporous mullite aggregates, 11 and lightweight microporous bauxite aggregates. 12 The bulk density and thermal conductivity of the castables prepared with these lightweight aggregates are extremely low, but their key properties such as strength and thermal shock are still insufficient to meet the requirements of tundish permanent linings, and the prices of high-strength lightweight aggregates are much higher than that of traditional aggregates.…”

Effect of Hollow Corundum Microspheres Additive on Physical and Mechanical Properties and Thermal Shock Resistance Behavior of Bauxite Based Refractory Castable

“…In terms of increasing the thermal shock resistance of refractories by inhibiting cracks, a certain positive effect can be achieved by using additives with particle of a spherical shape, such as hollow corundum microspheres (HCM), which, also, have a low thermal conductivity and low sintering activity [ 15 , 16 ]. Authors of [ 17 ] found that HCM improve mullite castables’ thermal shock resistance and explain this effect by the strong bonding at the microsphere and matrix interface, when the crack propagation is stopped at the corundum microsphere.…”