Absolute Thermal Conductivity Methods
As reference materials are required to have the highest accuracy possible, Thermtest uses only absolute thermal conductivity methods. As absolute methods do not require calibration, the lowest uncertainty is attained. There are only three absolute methods of measuring thermal conductivity for reference materials:
- Guarded Hot Plate – This method is ideal for measuring low thermal conductivity materials.
- Transient Plane Source – This is a versatile method for testing low to high thermal conductivity materials.
- Laser Flash Apparatus – Is also a well-known method for testing medium to high thermal diffusivity. If density and specific heat is known, thermal conductivity can be calculated.
Guarded Hot Plate (GHP):
Paper: Salmon, D. (2001). Thermal conductivity of insulations using guarded hot plates, including recent developments and sources of reference materials. Measurement Science and Technology, 12(12): R89.
Available at: http://iopscience.iop.org/article/10.1088/0957-0233/12/12/201/meta
ASTM: ASTM C177-13, Standard Test Method for Steady-State Heat Flux Measurements and Thermal Transmission Properties by Means of the Guarded-Hot-Plate Apparatus, ASTM International, West Conshohocken, PA, 2013, www.astm.org
Transient Plane Source (TPS):
Paper: S. E. Gustafsson. Transient plane source techniques for thermal conductivity and thermal diffusivity measurements of solid materials. Review of Scientific Instruments, 62(3): 797-804 (1991).
Available at: http://scitation.aip.org/content/aip/journal/rsi/62/3/10.1063/1.1142087
ISO: ISO 22007-2, Plastics — Determination of thermal conductivity and thermal diffusivity — Part 2: Transient plane heat source (hot disc) method, 2015, www.iso.org
Laser Flash Apparatus:
Paper: W. J. Parker, R. J. Jenkins, C. P. Butler and G. L. Abbott. Flash Method of Determining Thermal Diffusivity, Heat Capacity, and Thermal Conductivity. Journal of Applied Physics, 32: 1679, (1961).
Available at: http://scitation.aip.org/content/aip/journal/jap/32/9/10.1063/1.1728417
T. Baba and A. Ono. Improvement of the Laser Flash Method to Reduce Uncertainty in Thermal Diffusivity Measurements. Measurement Science and Technology, 12, (2001).
Available at: http://iopscience.iop.org/article/10.1088/0957-0233/12/12/304/meta
ASTM: ASTM E1461-13, Standard Test Method for Thermal Diffusivity by the Flash Method, ASTM International, West Conshohocken, PA, 2013, www.astm.org