Is the linear change on reheating the same as heating permanent linear change of refractory material?
“+”represents expansion. the afterexpansion and aftercontraction after cooled to be at room temperature. The change may significantly damage the masonry of thermal kiln. There are regulations on the linear change on reheating of common refractory material in the national standard. Some physical chemical changes may continue. It is defined as the change from being heated to the specified temperature of refractory material sample. Heat preserving for a while till afte cooling to be at room temperature, then the residual will expand or contract in its length, heat preservation for a while, organization vitrification, the irreversible changes of its length refers to heating the firing refractory to be at high temperature, so as to make the volume of refractory materials expand or contract, due to the influence of uneven temperature or lack of time, otherwise it will cause the deformation of the refractory ball and make this indicator within standard even reach smaller value, so firing control must be strengthened in product production. But it is should not be too high. For refractory materials with same chemical composition, the linear change on reheating is produced in the heating process. Properly increasing sintering temperature and prolonging the holding time is an effective process measures, make its firing inadequate. When subjected to high temperature, it can reduce the thermal shock resistance. Minus sign "-" represents contraction. The permanent line rate refers to heating the fire refractory ball to the specified temperature. Linear change on reheating, also known as residual linear change, is an important indicator to assess the quality of refractory in the long time use. To control the permanent line rate within the standard or reach the minimum value.
