TMA: Thermomechanical analysis

In terms of dental materials, thermal properties are of high importance, especially when different materials are to be joined together. Dental crowns or bridges consist of metal alloy or ceramic cores covered with veneering ceramics. These materials undergo changes during heating and cooling.

Thermomechanical analysis, TMA, can provide valuable information on materials that influence on production conditions for dental restorations, which is difficult to obtain by other analytical techniques.

NIOM can perform measurements of coefficients of linear thermal expansion for dental metals, alloys and crystalline ceramics, as well as of glass transition temperatures for glass-containing ceramics. NIOM also offers accredited testing of theses parameters using a TMA 402 F3 Hyperion.

Thermomechanical analysis is also used in research projects. Glass transition is typical for amorphous materials, like glass and polymer materials. Therefore, this instrument is also suitable for determining the same parameters for polymer materials.

TMA provides valuable insight into structural changes or phase transformations. Coefficients of thermal expansion for the core material and the veneering material will always be different and stresses will build up between the two materials by repeated heating and cooling during veneering.

Metal alloys and crystalline ceramics have almost a linear thermal expansion from low temperatures up to a possible phase transformation or melting point while veneering ceramics consisting of a glass matrix filled with different crystals have a less well-defines change in the thermal expansion at the glass transition temperature (Tg).