Suggestions regarding thermal diffusivity measurements on pyrolytic graphite and pyrolytic boron nitride by the laser pulse method/sup 1/
The laser pulse method can be successfully applied to the measurement of thermal diffusivity of isotropic materials subject to some assumptions. For anisotropic materials, this method is applicable to the measurement of principal thermal diffusivity only on the condition that there is no difference in direction between the principal axis and that of the temperature gradient. After analyzing the heat conduction process in an anisotropic solid, it has been shown that large errors in the measurement of thermal diffusivity would exist if the direction of the principal axis deviates inconspicously from that of the temperature gradient. The experimental results of thermal diffusivity of highly oriented pyrolytic graphite (HOPG) samples with various deviation angles have been compared with the analytical results. The laser pulse method is not applicable to measurements on semitransparent pyrolytic boron nitride (PBN). We adopted a two-layer composite sample to measure the thermal diffusivity of PBN in the c direction and a particular graphite-PBN composite sample has been prepared which has a very low thermal resistance at the interface. The thermal diffusivity and thermal conductivity of PG (below 2300/sup 0/C) and PBN (below 1000/sup 0/C) are given.
- Research Organization:
- Institute of Metal Research, Academica Sinica, Shenyang
- OSTI ID:
- 6963163
- Report Number(s):
- CONF-850617-
- Journal Information:
- Int. J. Thermophys.; (United States), Vol. 7:4; Conference: 9. symposium on thermophysical properties, Boulder, CO, USA, 24 Jun 1985
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
BORON NITRIDES
THERMAL DIFFUSIVITY
GRAPHITE
PYROLYTIC CARBON
ACCURACY
ANISOTROPY
EQUATIONS
HEAT FLOW
LASER RADIATION
ORIENTATION
PULSE TECHNIQUES
TEMPERATURE MEASUREMENT
THERMAL CONDUCTIVITY
BORON COMPOUNDS
CARBON
ELECTROMAGNETIC RADIATION
ELEMENTAL MINERALS
ELEMENTS
MINERALS
NITRIDES
NITROGEN COMPOUNDS
NONMETALS
PHYSICAL PROPERTIES
PNICTIDES
RADIATIONS
THERMODYNAMIC PROPERTIES
360204* - Ceramics
Cermets
& Refractories- Physical Properties
360603 - Materials- Properties