TECHNIQUE FOR DETERMINING THERMAL-SHOCK RESISTANCE OF CARBON MATERIALS

A technique for determining the thermal shock resistance of highly inh omogeneous industrial carbon materials has been developed. The techniq ue is based on the controlled imposition of internal transient tempera ture gradients in a disk-shaped test specimen by conducting a constant direct current through the central area of the disk. The geometrical disk data, the power produced in the disk, the time-dependent radial s urface temperature, and the time period needed to build up the necessa ry stress to crack the test specimen are used to calculate the individ ual thermal shock resistance of each specimen. The technique therefore gives the thermal shock resistance for one single test specimen as an absolute quantity, rather than a threshold value of energy input or t emperature drop needed to crack the specimen, as given by other method s, Test measurements were performed on anthracite-based materials spec ially designed to show the validity of the technique, as well as on a commercial prebaked anode for aluminium production. The thermal shock resistance measured using this new method agrees qualitatively well wi th thermal shock resistance calculated from other material parameters.