Thermal analysis

The Thermal Analysis Laboratory forms the basis for all high-temperature experimentation on natural and synthetic materials. Thermal analyses are a standard procedure in material science as they provide a fundamental characterisation of the material properties, a matter which is of great importance in geosciences.

Differential Scanning Calorimetry

Enlarge

Differential Scanning calorimetry is a frequently used method in geosciences. Here, we measure the thermodynamic properties of an unknown sample compared to a reference material as a function of temperature. It is thereby possible to study the thermal history of geomaterials, i.e. volcanic glasses.

This Differential Scanning Calorimeter (DSC) coupled to a ThermoGravimetric Analyser (TGA) can be used to determine 1) the heat capacity of material, 2) the glass transition, 3) phase changes (e.g., melting, crystallisation, crystal structure transitions), 4) weight gain/loss (e.g., hydration, dehydration, gas exolution, oxidation, decarbonation), and 5) sintering conditions. This system is coupled to a water vapour supplier to allow measurements in water vapour atmosphere as well as in traditional Ar or N atmospheres. Four furnaces are available to allow determination with a range of conditions:

Pt furnace: up to 1500 °C and heating up to 25 °C/min.
High-speed Pt furnace: up to 1250 °C and heating up to 3500 °C/min (linear heating rate up to 1500 °C/min).
Water-vapour atmosphere furnace: up to 1250 °C and heating up to 25 °C/min.
Si-C furnace: up to 1550 °C and heating up to 40 °C/min.

Enlarge

Fast Differential Scanning calorimetry is a frequently used method in geosciences. Here, we measure the thermodynamic properties of an unknown sample compared to a reference material as a function of temperature. It is thereby possible to study the thermal history of geomaterials, i.e. volcanic glasses. The sample size is here smaller than 80 micrometers, which allow to apply heating rates of up to 10000 K/s.

Thermomechanical analyser

Enlarge

.

Quadrupole mass spectrometer

This apparatus can be used to determine 1) the expansion coefficient, 2) the expansion strain rate, 3) the viscosity of liquids (via the micropenetration technique), and 4) to assess the rheological/mechanical properties of magma and rocks a) in compression, b) in tension, and c) during oscillation. Measurements are traditionally run in Ar or N atmospheres. This high-accuracy dilatometric system is equipped with double furnace hoist to accommodate several furnaces simultaneously, currently:

• Pt furnace: up to 1500 °C and heating up to 25 °C/min.

• Si-C furnace: up to 1550 °C and heating up to 40 °C/min.

Simultaneous Thermal Analyser

Enlarge

The STA is a combination of a DSC and a thermogravimetric instrument. Besides heat capacity measurements one is able to study mass changes of a sample material, as a function of temperature with time, and additionally of pressure and gas composition.

Enlarge

The STA is a combination of a DSC and a thermogravimetric instrument. Besides heat capacity measurements one can study mass changes of a sample material, as a function of temperature with time, and additionally gas composition by a gas mass spectrometer.

Optical Dilatometry

Enlarge

Through optical dilatometry, the heating and cooling behavior of solid materials (drill cores, powders, chips, etc.) can be investigated based on 2D-images. Questions of interest can be related to thermal expansion, sintering, melting and spreading, softening, foaming and contact angle analysis of the sample.

Both available instruments consist of a light source, a horizontally mounted tube furnace and a camera. Samples of interest need to be placed on an inert substrate (e.g. alumina plate) and loaded from the side (see below for possible sample sizes). Data reduction (shape analysis) can be done through specific software. All data can be exported in ACSII-format for further evaluation.

Dilatometry

Enlarge

.