Thermal Strains During Firing of a Ceramic Body

The tendency of a ceramic body to crack in firing owing to thermal stress was examined. Use was made of the physical measurement of three factors: (1) thermal gradient as affected by firing rate and thermal reactions, (2) coefficient of thermal expansion at each temperature, and (3) maximum strain, also a function of temperature. Each factor was determined individually during the firing of appropriate samples of a body consisting of 60% kaolin and 40% grog. Plastic flow was noted during the measurement of maximum strain. The effect of all these variables on the development of firing schedules was considered.