Pe. Parris et Vm. Kenkre, THERMAL RUNAWAY IN CERAMICS ARISING FROM THE TEMPERATURE-DEPENDENCE OF THE THERMAL-CONDUCTIVITY, Physica status solidi. b, Basic research, 200(1), 1997, pp. 39-47
Thermal runaway during microwave heating in ceramic materials has been
explained recently in terms of a microscopic model involving a nonlin
ear feedback between microwave absorption and heat dissipation. We stu
dy here an alternate model of thermal runaway which is based on the te
mperature dependence of the thermal conductivity of the material being
heated. If the thermal conductivity decreases as the temperature incr
eases, a decrease could occur in the removal of heat from the central
regions of the sample which, unlike the surface, cannot cool off quick
ly through processes such as radiation. The result would be an enhance
d heating of the central regions and a further decrease of the thermal
conductivity thus providing a feedback loop, A quantitative analysis
of these concepts is provided.