The Heating Microscope measurement technique, included in ELS-MDF:
○ Is able to store images of the test piece at predetermined temperature or time intervals
○ Works in the range between 25°C and 1600°C
○ Is able to identify characteristic shapes
ELS is equipped also with different kind of analysers:
○ A heating microscope that works up to 1750°C
○ A heating microscope that can analyses up to 8 samples at the same time
The applications of heating microscopes include:
- Identifications of charactristic shapes of glasses, glazes and frits
- Determination of melting point
- Comparison between different kind of samples that undergo the same thermal cycle
- The study of behaviour of mold powders for continuous casting
Identification of characteristic points typical of glasses, glazes and frits:
Comparison between the curves obtained for two different ceramic frits subjected to the same heating cycle (heating rate of 50°C/min):
Black curve represents a glassy frit: as the temperature increases, the sample assumes the characteristic points typical of glasses (Sintering, Softening, Sphere, Half Sphere and Melting). Red curve represents the result obtained for a crystallizing frit. Between 950 and 1250°C the curve shows a long plateau: this means that a crystallization takes place inside the material. This frit does not behave like a glass, but melts with the typical behaviour of a crystalline material.
Effect of different heating rates on the behaviour of mold powders for continuous casting:
The application of different heating rates (30°C/min, 80°C/min, “flash” heating) causes different effects on the melting behaviour of a material. The red curve proves that a low heating rate (30°C/min) promotes crystallization processes inside these powders. On the other hand, the blue and green ones prove that the same sample shows a different behaviour when subjected to fast heating cycles.
The fusibility of continuous casting powders strongly depends on the thermal cycle applied: here is shown the effect of the heating rate on the melting behaviour.
Fusibility test up to 1750°C
A fusibility test until 1750°C is also available with a maximum heating rate of 20°C/min. The graph above shows the fusibility curve and the fundamental shapes of a sand.