The Creep of Refractory Materials at High Temperatures and its Bearing on the Performance of Glasshouse Pots
JSGT 1939 V23 T141-T153
The mechanism of creep in refractory materials is described and comprises volume changes due to recrystallisation, slip on crystal planes, and viscous flow of the glassy matrix. Data is given on the effect of impurities, on the temperature of failure of refractory materials in tension, and experiments described on mixtures for glass melting pots. Calcined alumina was added to a good china clay in different proportions, the mixture containing 62% Al203, containing only 2% of free alumina after firing and a high proportion of glassy matrix, giving a closer texture than other mixtures of higher alumina content. This mixture has given good service in the form of small crucibles, has a refractoriness of 1700°, a low rate of creep at 1500°, and is very resistant to attack by corrosive glasses. Larger pots of the kaolin-alumina mixture have been slip-cast. The load-bearing properties of refractories are improved by the removal of impurities, by volatilisation at high temperatures. Tests on the penetration of boric oxide on the creep strength of refractories showed that B203 absorption materially decreased the creep strength of a pot material used to melt an alkali-free glass containing 7% B203. After use the walls of the pot contained 0.14% B203.
J. H. Partridge, Ph.D., B.Sc., F.S.G.T., and G. F. Adams, B.Sc.
