Accession Number : ADD018302

Title :   Method of Measuring the Thermal Conductivity of Microscopic Graphite Fibers.

Descriptive Note : Patent, Filed 14 Jun 94, patented 24 Dec 96,

Corporate Author : DEPARTMENT OF THE NAVY WASHINGTON DC

Personal Author(s) : Barkyoumb, John ; Kabacoff, Lawrence T ; Land, David J

Report Date : 24 Dec 1996

Pagination or Media Count : 25

Abstract : A metal or graphite fiber is suspended in a working fluid having a high refractive index change with the temperature and a modulated laser beam heats the fiber producing a synchronous thermal wave in the fiber whose amplitude and phase are measured by passing a probe laser beam through the liquid close to the fiber and converting the probe beam deflections into an electric signal. A theoretical model of the thermal wave is used to calculate the amplitude and phase shift of a theoretical thermal wave for points along the fiber from physical characteristics of the lasers and the fiber including an estimate of the thermal conductivity of the fiber. The straight line slope of the log amplitude or of the phase shift of the theoretical wave versus distance is compare against the straight line slope of the log amplitude or the phase shift versus distance for the electrical signal and the estimated value for the thermal conductivity of the fiber is adjusted until the theoretical slope and the electrical signal slope are the same which means that the thermal conductivity of the fiber has been found.

Descriptors :   *GRAPHITE, *CARBON FIBERS, *MICROSCOPY, *MEASURING INSTRUMENTS, *THERMAL CONDUCTIVITY, THERMAL PROPERTIES, MATHEMATICAL MODELS, PROBES, PHYSICAL PROPERTIES, REFRACTIVE INDEX, DEFLECTION, LASER BEAMS, SIGNALS, ELECTRIC POWER, FLUIDS, MODULATION, AMPLITUDE, WAVES, PHASE SHIFT, PATENTS

Subject Categories : Laminates and Composite Materials
      Thermodynamics
      Lasers and Masers
      Electricity and Magnetism

Distribution Statement : APPROVED FOR PUBLIC RELEASE