Uncertainty of Thermal Diffusivity Measurements by Laser Flash Method

Abstract

The laser-pulse method is a well-established nonsteady-state measurement technique for measuring the thermal diffusivity, a, of solid homogeneous isotropic opaque materials. BNM-LNE has developed its own bench based on the principle of this method in which the thermal diffusivity is identified according to the "partial time moments method." Uncertainties of thermal diffusivity by means of this method have been calculated according to the ISO/BIPM "Guide to the Expression of Uncertainty in Measurement." Results are presented for several cases (Armco iron, Pyroceram 9606) in the temperature range from 20 to 800 • C. The relative expanded (k = 2) uncertainty of the thermal diffusivity determination is estimated to be from ±3 to ±5%, depending on the material and the temperature.

Measurement of the In-Plane Thermal Conductivity of Long Fiber Composites by Inverse Analysis

“…Transient techniques such as hot wire [8], flash method [9] [10], transient plane source [11] [12] or periodic methods [13] [14] allow a more rapid estimation provided that the isothermal state is reached before the experiment is performed. The models describing heat transfer in these experimental tests are more complex than those of the previous methods.…”

New infrared radiation temperature measurement system applied to the Laser Flash Method

“…To verify the validity and desired features of the new temperature measurement system, it was used to measure the thermal diffusivity of two reference samples (Pure Inconel 600 and Pyroceram 9606) using the laser flash method [1][2][3][4].The system was coupled to the apparatus [4] developed by the staff of the Laboratório de Medição de Propriedades Termofísicas of Centro de Desenvolvimento da Tecnologia Nuclear ( figure 5). This apparatus is composed of sample holding device, heating furnace, laser CO 2 (of 100 W total power) working at 10.6 µm wavelength, vacuum pump, measuring control and data processing system.…”

“…The determination of thermal diffusivity by laser flash method [1][2][3][4] is based on the variation of temperature on the opposite side of a thin cylindrical sample resulting from a short pulse of radiant energy received on its front side. This thermogram is measured and the thermal diffusivity is calculated as a function of sample thickness and the time required to reach half of the maximum rate of temperature on the opposite side.…”

Novel mathematical and statistical approaches to uncertainty evaluation in the context of regression and inverse problems

“…An evaluation of measurement uncertainty according to the GUM [1] may be performed but it is not straightforward [12]. Figure 3 shows the experimental layout in which a measurement is made of the temperature rise on the back face of a thin disk sample resulting from a short energy pulse applied to the front surface.…”