热分析

Thermal Analysis Techniques
Thermal Analysis Techniques
Thermal analysis comprises a group of techniques in which a physical property of a substance is measured as a function of temperature, while the substance is subjected to a controlled temperature programme. In dierential thermal analysis, the temperature di®erence that develops between a sample and an inert reference material is measured, when both are subjected to identical heat{treatments. The related technique of di®erential scanning calorimetry relies on dierences in energy required to maintain the sample and reference at an identical temperature. Length or volume changes that occur on subjecting materials to heat treatment are detected in dilatometry; X{ray or neutron di®raction can also be used to measure dimensional changes. Both thermogravimetry and evolved{gas analysis are techniques which rely on samples which decompose at elevated temperatures. The former monitors changes in the mass of the specimen on heating, whereas the latter is based on the gases evolved on heating the sample. Electrical conductivity measurements can be related to changes in the defect density of materials or to study phase transitions.

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