Principe : The dilatométrie allows access to a value of expansion or contraction (expansion or shrinkage of the sample studied), called the coefficient of linear thermal expansion, but also to the characteristics of annealing or other physical or chemical transformations leading to dimensional changes.
the methods of measurement of dilatométrie are varied, and the devices can be classified according to their principle : dilatomètre vertical, dilatomètre to push rod horizontal, dilatomètre optical, dilatomètre quenching and deformation. the set temperature of the sample is ensured by means of ovens with temperature ranges and speeds warm-up variables. in addition to solid, some systems can determine the thermal expansion of powder, liquids or pastes.
currently, the most sensitive method is the one offered by the dilatométrie optical. this method of measurement of expansion without contact of the sample is made by optical sighting using a high resolution camera. when they are equipped with modules for acquisition and analysis of data, ovens, motorized rapid response, an optical system performing the dilatomètres recent offer a measurement resolution below the micrometer.