Principle of the LFA Method
The laser or light flash method is used for measurement of the thermal diffusivity of a variety of different materials. The front surface of a plane-parallel sample is heated by a light pulse and the resulting temperature rise at the sample’s rear face is recorded as a function of time. The higher the thermal diffusivity, the faster the temperature rise reaches the rear face.
In a one-dimensional, the thermal diffusivity rise is calculated from this temperature rise as follows:
a = 0.1388 ⋅ d² / t0.5 with
a – Thermal diffusivity in cm²/s
d – Thickness of the sample in cm
t0.5 – Time to half minimum in s
With all NETZSCH laser flash apparatuses (LFAs), the thermal diffusivity and specific heat capacity can be determined. This data is then used for calculation of the thermal conductivity.
