TAL offers a range of dilatometry and TMA services.
Dilatometry / TMA ( ThermoMechanical Analysis)
Dilatometry is a method for characterizing dimensional changes of a material as a function of temperature. The measurement may be performed across a temperature range (e.g. from 800° to 1,600°C), or a specific controlled temperature program to mimic industrial processes, firing regimes, or a material’s operating environment. The coefficient of thermal expansion (?) is defined as the degree of expansion (?L) divided by the change in temperature (?T).
A precise understanding of thermal expansion behaviour provides crucial insight into firing processes, the influence of additives, reaction kinetics and other important aspects of how materials respond to
environmental changes. Typical applications include: the determination of the coefficient of thermal expansion, annealing studies, determination of glass transition point, softening point, densification, kinetics and sintering studies.
A sample is placed inside a retractable, tubular furnace. A spring-loaded pushrod is positioned against the sample. The opposite end of the pushrod is connected to a linear variable displacement transducer (LVDT). The dimensional change of the sample resulting from the controlled temperature program is measured as the pushod physically transmits the length change to the LVDT. The displacement is recorded in relation to the temperature recorded with a thermocouple located next to the sample. A calibration or correction curve is applied in compensating for the expansion of the sample holder and pushrod.
TMA (ThermoMechanical Analyzer)
One of the primary differences between a TMA configuration (versus traditional dilatometer) is the vertical design. With Setaram’s TMA design, the DMA probe is held by electromagnetic suspension so that virtually no force is applied to the sample. This presents a number of advantages for certain applications:
- softer materials can be more easily analyzed
- powder sintering characteristics can be better studied
Conversely, one limitation of the TMA is the sample length is typically limited to 25mm (compared to 50 mm with a traditional push-rod dilatometer).
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