Transient Thermal Diffusivity Technique for Refractory Solids

Abstract

A new technique for the measurement of the thermal diffusivity at high temperatures is described. The diffusivity is determined from the time interval separating two radial isotherms in a cylindrical specimen. The observations are made during the transient heating (or cooling) period. Measurements are reported on Ta, ZrC, and TiC in the temperature range 1300° to 1650°C. The data are in good agreement with diffusivities calculated from specific heat and steady-state thermal conductivity measurements.

DEVELOPMENT AND TESTING OF A TEMPERATURE TRANSIENT METHOD FOR PERFORMING IN- PILE THERMAL CONDUCTANCE TESTING. Final Summary Report, March 1, 1964-November 30, 1965

“…A good summary of the older work (particularly the theoretical approach) is given by Carslaw and Jaeger. (13) A· substantial body of recent work using various time varying techniques (14)(15)(16)(17)(18)(19)(20)(21)(22) is also available.…”

“…In the work of Harmathy (22), Parker(17), Cape (19) , and Carslaw (13) and Jaeger , methods theoretically capable of measuring both thermal conductivity and diffusivity are discussed. However, of the recent work, only that of Cape gives these separate results without requiring knowledge of the absolute magnitude of the heat input.…”

Thermophysical measurements under monotonic conditions

“…A most simple test mode is usually chosen: heating the specimen in an oven already brought up to temperature or heating it in an oven while the oven is brought up to temperature, free cooling in a constant-temperature medium, monotonic heating with an internal heat source, etc. In some of these methods the computation formulas for a(t), X(t), and c(t) are derived by solving the nonlinear equation of heat conduction, taking account of the temperature dependence of a (t), X(t), and heating rate b(r, r) 59].…”

“…The method of estimating the correction proposed in [32] is not very convenient, since it requires knowledge of the time instant ~-and the use of graphieal differentiation. Cape, Lehman, and Nakata [59] have sought the solution to the analogous problem within a narrow time interval A7 in the form of a power series: N 9 ), (lo)…”