Lightweight Refractory Articles

articles with a total porosity of 45 percent and higher and an apparent density of 150–1,500 kg/m³. A distinction is made among fireclay, Dinas brick, high-alumina, corundum, and zirconium oxide materials.

The main methods for the production of lightweight refractory articles are addition to the charge of materials such as sawdust, lignin, and coke, which burn out during firing and form pores, and production of porous raw material (which is later dried and fired) by mixing suspensions of fire-resistant powders with foam (foam materials) or by adding gas-forming materials to the suspensions (the chemical method). The thermal conductivity of lightweight refractory articles depends on the porosity and is usually two to five times lower than that of products of normal density.

Lightweight refractory articles are used in heating and firing furnaces and in other heating devices as effective thermal insulation in the intermediate and outer layers of the refractory lining, as well as in the exposed working layers of linings if they are not exposed to molten materials and if there is no danger of mechanical damage.