Accession Number : ADA195951

Title :   Principles of the Optical Differential Thermal Analysis.

Descriptive Note : Final rept.,

Corporate Author : ARMY LAB COMMAND WATERTOWN MA MATERIAL TECHNOLOGY LAB

Personal Author(s) : Caslavsky, Jaroslav L

PDF Url : ADA195951

Report Date : Apr 1988

Pagination or Media Count : 15

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)

Descriptors :   *INFRARED RADIATION, *PYROMETERS, *RADIOMETRY, *INFRARED DETECTION, BEHAVIOR, COLORS, DETECTION, DIFFERENTIAL THERMAL ANALYSIS, EMISSIVITY, EQUILIBRIUM(GENERAL), FEASIBILITY STUDIES, GRAPHICS, HIGH SENSITIVITY, HIGH TEMPERATURE, MELTING, OPTICAL ANALYSIS, PHASE TRANSFORMATIONS, RATES, SAPPHIRE, SINGLE CRYSTALS, SOURCES, SYNCHRONISM, TEMPERATURE

Subject Categories : Optics
      Thermodynamics
      Physical Chemistry

Distribution Statement : APPROVED FOR PUBLIC RELEASE