D4 Thermal Analysis and Dilatometry

Topic

Monitoring the shrinkage, thermal expansion, and phase transformations of a ceramic as its temperature changes—the objective of this model—is carried out using two distinct techniques. Because each technique tracks a different aspect of this temperature-dependent change, together they cover both the ceramic's dimensional changes and its internal phase transformations.

Dilatometry experimentally tracks the ceramic's dimensional changes with temperature: both its thermal expansion—characterized by the linear thermal expansion already established in the thermal analysis model for metals—and the shrinkage it undergoes during sintering. Since dilatometry records the piece's contraction or expansion in real time as the temperature changes, the shrinkage occurring during sintering is experimentally monitored step by step.

Differential thermal analysis, on the other hand, tracks a different aspect of this same temperature-dependent change: it detects phase transformations within the ceramic via the enthalpy of transformation—also established in the thermal analysis model for metals—which is obtained by integrating the peak produced by the transformation on the thermal curve. If the phase transformation absorbs or releases more energy, the area of ​​the peak (and thus the measured enthalpy of transformation) is larger; if it absorbs or releases less energy, the peak and the enthalpy are smaller.

Therefore, this model—which reuses both the enthalpy of transformation and linear thermal expansion from the thermal analysis model for metals—also provides the experimental characterization of sintering shrinkage described by another model in this set: the real-time data captured by dilatometry ensures that the shrinkage addressed at the start of this model serves as the precise experimental input for that description.

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