Principles of the Optical Differential Thermal Analysis.

Abstract

Optical differential thermal analysis (ODTA) can operate in the 490-3600 C range, using infrared pyrometers for the temperature detection of both the Black-Body and the sample. Hence, the method is called optical. Infrared detection of any phase transition is a result of two cooperative effects: Delta H and the emissivity change. Such cooperation leads to a high sensitivity thereby permitting ODTA measurements at temperature rates as low as 0.1 C/min. Hence, phase transitions can be studied at almost equilibrium conditions. In order to detect emissivity changes, single color pyrometers have to be used. Problems associated with simultaneous use of the Black-Body as a temperature reference source and a heater are discussed. Use of the ODTA at high temperatures is demonstrated on a study of the melting behavior of a sapphire single crystal. The feasibility of computing emissivities as a function of temperature from the gathered data is indicated. Keywords: Infrared radiometry; Color graphics. (AW)

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Document Details

Document Type
Technical Report
Publication Date
Apr 01, 1988
Accession Number
ADA195951

Entities

People

  • Jaroslav L. Caslavsky

Tags

Communities of Interest

  • Energy and Power Technologies

DTIC Thesaurus Topics

  • Abstracts
  • Acquisition
  • Data Acquisition
  • Differential Thermal Analysis
  • Energy
  • Heat Transfer
  • High Temperature
  • Jet Propulsion
  • Materials
  • Measurement
  • Phase
  • Phase Transformations
  • Radiation
  • Radiometry
  • Security
  • Thermal Analysis
  • Thermophysical Properties

Fields of Study

  • Physics

Readers

  • Optical Physics and Photonics.
  • Thermal Physics or Thermal Science.