Dilatometric

Dilatometric, relating to dilatometry, refers to the study, instrumentation, and methods involved in dilatometry, the measurement of dimensional changes in a material as a function of temperature, time, or other stimuli. The term is used for linear dilatometry, which tracks length changes along a specimen, and volumetric dilatometry, which assesses changes in volume. Dilatometry is a fundamental tool in characterizing thermal expansion and related phase behavior.

A dilatometer measures the sample’s dimensional change with high precision while it is heated or cooled in a controlled furnace. In linear dilatometry, the relative change in length ΔL/L0 is recorded as a function of temperature, and the coefficient of linear thermal expansion α is obtained from the slope. In volumetric dilatometry, changes in volume or diameter are monitored, yielding the volumetric expansion coefficient β. Methods may be contact-based (push-rod, capacitance or microbalance sensors) or non-contact (optical interferometry, laser displacement sensors). Materials often exhibit temperature-dependent α, with abrupt changes signaling phase transitions such as solid-solid transformations, melting, or glass transitions.

Applications include metals, alloys, ceramics, and polymers, where dilatometry supports thermal stability assessments, material design, and phase diagram studies. Data produced by dilatometry are often compared with standards from ASTM or ISO to ensure reproducibility. Practical considerations involve calibration, sample geometry, high-temperature stability, and corrections for thermal lag or anisotropy in polycrystalline or composite materials.