Permeability and Some Other Properties of a Variety of Refractory Materials: I

Flatwise, edgewise, and endwise permeabilities, bulk densities, moduli of elasticity, and porosities were determined for the following types of refractory brick as received from the manufacturers: fire‐clay, insulating, mullite, silica, kaolin, high‐alumina, acidproof, magnesite, unburned magnesite‐chrome, and unburned chrome‐magnesite. These properties were determined also for specimens (1) of the unburned brands of the chrome‐magnesite and magnesite‐chrome brick after heat‐treating at 925° and at 1600°C., (2) from the side wall of a clay pot after heat‐treating at several temperatures, and (3) from the side walls of two other pots and the bottom of one after heat‐treating at 1400°C. only. For refractory brick, flatwise permeability was least and edgewise greatest; permeability was not closely related to the other determined properties. Sintering caused larger increases in the permeability than the (partial) decomposition of the chemical binder of unburned basic brick. Of the determined properties of specimens cut from the pots, permeability was the most sensitive to heat‐treatment and was the best criterion of resistance to molten glass. Permeability, modulus of elasticity, and bulk density increased whereas bulk volume and porosity decreased with successively higher heat‐treatments for the pots.