THERMAL CONDUCTIVITY

Thermal conductivity is one of the basic thermophysical properties which determines the heat flux and the temperature field in a material for unit spatial configurations and boundary conditions.
Thermal conductivity is the quantity of heat transmitted, due to unit temperature gradient, in unit time under steady conditions in a direction normal to a surface of unit area, when the heat transfer is dependent only on the temperature gradient.
In practice, thermal conductivity is measured as:

K = Heat Flux / Thermal Gradient
K is defined as a phenomenological constant:

K = a. d. Cp where: a - thermal diffusivity
d - density
Cp - heat capacity



Thermal Conductivity of Various Materials

Metals
• Aluminum 2.165
• Beryllium 1.772
• Beryllium-copper 1.063
• Brass 70% copper, 30% zinc 1.220
• Copper 3.937
• Gold 2.913
• Iron .669
• Lead .343
• Magnesium 1.575
• Molybdenum 1.299
• Monel .197
• Nickel .906
• Platinum .734
• Silver 4.173
• Stainless Steel-321 .146
• Stainless Steel-410 .240
• Steel, low carbon .669
• Tin .630
• Titanium .157
• Tungsten 1.969
• Zinc 1.024

Semiconductors
• GaAs .591
• Silicon (pure) 1.457
• Silicon (.0025 ohm-cm) .984
• Silicon Dioxide (amorphous) .014
• Silicon Dioxide (quartz) c-axis .11
• Silicon Dioxide (quartz) a-axis .059
• Silicon Nitride .16 - .33
• Silicon Carbide .90

Insulators
• Air (still) .0003
• Sapphire c-axis .35
• Sapphire a-axis .32
• Alumina .276
• Alumina 85% .118
• Beryllia 99.5% 1.969
• Beryllia 97% 1.575
• Beryllia 95% 1.161
• Boron Nitride (hot pressed) .394
• Diamond (room temperature) 6.299
• Diamond (77 K) 24.
• Diamond (room temperature, isotopically pure) 50.
• Epoxy .002
• Thermally conductive epoxy .008
• Glass .008
• Heat sink compound (metal oxide loaded grease) .004
• Mica .007
• Mylar .002
• Phenolic .002
• Silicone Grease .002
• Silicone Rubber .002
• Teflon .002
• FR-4 or G-10 PC board material .003
• water .0055
• Liquid Helium (4.2K) .000307
• Liquid Nitrogen (77K) .001411
• Liquid Argon (85K) .001258

Thermally Conductive Elastomers
• Bergquist Sil-pads .009
• Tecknit Consil-C 871 .023
• Tecknit Consil-R 350 .00433 to .00732
• Saracon 2.9e-3 cal/cm-sec-K
• Chomerics XTS-274 alumina filled elastomer .002 cal/sec cm K
• Cho-seal 1224 .038
• Cho-therm .0433
• Cho-therm 1678 .018
• Cho-therm 1671 .027