THERMAL-TREATMENT AND ANALYSIS - THE ART OF ADJACENT (NEAR-EQUILIBRIUM) STUDIES

Heating and/or cooling of substances is one of the oldest and basic me thods for preparing materials with defined properties. This always lea ves a definitive fingerprint of the thermal history. Beside knowing th e structure we need to specify such materials by their thermodynamic b ehaviour, i.e., stability/metastability, phase relations and transitio ns, particularly establishing corresponding characteristic points. All this can be based on ordinary thermodynamics but its validity must be approved for non-equilibrium conditions of temperature changes where equilibrium and kinetic effects overlap. The slower the phase transiti on proceeds the greater is the deviation of the system state (kinetic curve) from its equilibrium state (equilibrium background). This makes possible to locate the actual phase boundary between two states inves tigated, resulting in the so-called kinetic phase diagrams. Most of mo dern technologies are intentionally based on non-equilibrium phenomena in order to create metastable/nonstable phases of specific properties . In this sense thermal analysis is understand as the method for deter mining the sample state on the basis of the sample interactions with t he surroundings whose intensive parameters are controlled. Temperature is here considered as a basic parameter that connects all thermophysi cal measurements and thermal treatments.