Temperature Calibration - TA Instruments TGA5500 Getting Started Manual

Temperature Calibration

Temperature calibration is required for TGA experiments in which precise transition temperatures are
essential. There is one technique for TGA temperature calibration recognized by the American Society for
Testing and Materials. This technique is described in ASTM Standard E1582 and is based on the Curie
Point of magnetic metals; it is recommended for the Discovery TGA.
In this technique, a Curie standard is heated in a sample pan in a magnetic field. The Discovery TGA IR
furnace is equipped with an electromagnet to facilitate this operation. The wire-wound and EGA furnaces
require a bar magnet (provided). As the standard goes through its Curie Point, its attraction to the magnet
changes, appearing as a weight change. The extrapolated endpoint of this weight change is adjusted to
agree with the material's known Curie Point temperature. Up to five calibration points can be entered into
the temperature calibration table. A multi-point calibration is more accurate than a one-point calibration.
If the DTA option is available (standard on the TGA 5500 and optional on the TGA 550) melt standards
may also be used to calibrate temperature. High purity melt standards must be used for calibration. The
DTA signal setup must be complete before using this option. The extrapolated onset of the melt endotherm
in the DTA signal is used as the measured value and the system is adjusted based on the known value of
that specific melt standard.
See TRIOS software Online Help for more information
Discovery TGA™ Getting Started Guide Page 58