Thermography and Simulation of Advanced Nonlinear ElectroCeramic Components

Abstract

In usage active nonlinear electroceramic PTC components are heated by Joule selfheating. The heating rate is accelerated by a positive feedback effect and leads to large temperature differences in the components, which cause large mechanical stresses and may even cause a catastrophic failure of the component. Amplitude and shape of these fields sensitively depend on material parameters, geometry, initial and boundary conditions. Even very small geometry changes can shift the region of maximum temperatures from the centre to the edge of the component. Thermography turned out to be an excellent method to determine local and transient temperature fields, is used to evaluate results of model calculations and to determine local materials properties (e.g. the electric resistance).