Dilatometry yields powerful infomation regarding the thermal expansion and shrinkage of materials during thermal treatment. On the other hand interpretation of transitions occurring in the sample is sometimes difficult, using only thermal expansion data. The new c-DTA^® feature for the DIL 402 is an additional tool for a more detailed insight into material behavior. Differential Thermal Analysis (DTA) is a well-known tool for the characterization of transformation energetics (exo- and endothermal effects). Calculation of the c-DTA^® signal on a thermal expansion curve yields information similar to the DTA method.

c-DTA^® calculation is a mathematical routine based on the temperature measurement at the sample. Transitions connected with exo- or endothermal effect, of course, slightly influence the temperature change during dynamic heating or cooling. By comparing the measured temperature change of the sample with a theoretical one these exo- or endothermal effects can be detected. If a calibration run on a standard sample is carried out prior to the sample run, this is also considered in the calculation process.

Example: Floor Tile

The thermal expansion and sintering of a floor tile during firing can easily be studied using the DIL 402. The additional c-DTA^® feature allows more detailed insight into the thermal behavior of the material. The endothermal effect at 118¡C is due to dehydration. The exothermal peak at 316¡C is due to the burnout of organic additives. Dehydration of the clays was measured at 581¡C (peak temperature). The exothermal effect at 917¡C is due to a solid-state transition in the sample. (The c-DTA^®-curve was calculated stepwise.)