For thermal conductivity values, see List of thermal conductivities.
Thermal conductivity
Common symbols
κ
SI unit
watt per meter-kelvin (W/(m⋅K))
In SI base units
kg⋅m⋅s−3⋅K-1
Dimension
Thermal resistivity
Common symbols
ρ
SI unit
kelvin-meter per watt (K⋅m/W)
In SI base units
kg-1⋅m-1⋅s3⋅K
Dimension
The thermal conductivity of a material is a measure of its ability to conduct heat. It is commonly denoted by , , or and is measured in W·m−1·K−1.
Heat transfer occurs at a lower rate in materials of low thermal conductivity than in materials of high thermal conductivity. For instance, metals typically have high thermal conductivity and are very efficient at conducting heat, while the opposite is true for insulating materials like mineral wool or Styrofoam. Correspondingly, materials of high thermal conductivity are widely used in heat sink applications, and materials of low thermal conductivity are used as thermal insulation. The reciprocal of thermal conductivity is called thermal resistivity.
The defining equation for thermal conductivity is , where is the heat flux, is the thermal conductivity, and is the temperature gradient. This is known as Fourier's Law for heat conduction. Although commonly expressed as a scalar, the most general form of thermal conductivity is a second-rank tensor. However, the tensorial description only becomes necessary in materials which are anisotropic.
and 25 Related for: Thermal conductivity and resistivity information
insulation. The reciprocal of thermalconductivity is called thermalresistivity. The defining equation for thermalconductivity is q = − k ∇ T {\displaystyle...
In heat transfer, the thermalconductivity of a substance, k, is an intensive property that indicates its ability to conduct heat. For most materials,...
ways to measure thermalconductivity, each of them suitable for a limited range of materials, depending on the thermal properties and the medium temperature...
flow) k {\displaystyle k} is the thermalconductivity (W/(K·m)) of the sample r {\displaystyle r} is the thermalresistivity (K·m/W) of the sample A {\displaystyle...
or how strongly it resists electric current. A low resistivity indicates a material that readily allows electric current. Resistivity is commonly represented...
object. The ability of the object to conduct heat is known as its thermalconductivity, and is denoted k. Heat spontaneously flows along a temperature gradient...
V. (28 February 2012). "Electrical resistivityandthermalconductivity of liquid Fe alloys at high P and T, and heat flux in Earth's core". Proceedings...
free path, Umklapp scattering process limits thermalconductivity (regime of diffusive thermalconductivity). When L {\displaystyle L} is comparable to...
thermal bridge, also called a cold bridge, heat bridge, or thermal bypass, is an area or component of an object which has higher thermalconductivity...
made out of a material with a high thermalconductivity, such as aluminium or copper. A heat sink transfers thermal energy from a higher-temperature device...
translated to thermal energy as electrical conductivity increases, and this is the key process parameter that affects heating uniformity and heating rate...
(NTC), which occurs when a physical property (such as thermalconductivity or electrical resistivity) of a material lowers with increasing temperature, typically...
conductor Electrical resistivityandconductivity Electrical resistance and conductance Fast ion conductor Mixed conductor, ionic and electronic Electrical...
because of their relatively high thermalconductivity which keep the filament cool and maintain uniform resistivityand electrical efficiency of the filament...
one process limiting the thermalconductivity in crystalline materials, the others being phonon scattering on crystal defects and at the surface of the sample...
systems. Copper has the highest electrical conductivity rating of all non-precious metals: the electrical resistivity of copper = 16.78 nΩ•m at 20 °C. The theory...
reports exist of superior thermalconductivity in both carbon nanotubes and graphene. Because diamond has such high thermal conductance it is already...
the homogeneous cement. Campbell-Allen and Thorne (1963) derived a formula for the theoretical thermalconductivity of concrete. In practice this formula...
between objects that are in physical contact. Thermalconductivity is the property of a material to conduct heat and evaluated primarily in terms of Fourier's...
this device is that it measures thermalconductivity only. Applicable standards are: IEEE Guide for Soil ThermalResistivity Measurements (IEEE Standard 442-1981)...
the geometry of the wire. Resistivityandconductivity are reciprocals: ρ = 1 / σ {\displaystyle \rho =1/\sigma } . Resistivity is a measure of the material's...
It usually consists of 55% copper and 45% nickel. Its main feature is the low thermal variation of its resistivity, which is constant over a wide range...
of 1012 cm−2. The corresponding resistivity of graphene sheets would be 10−8 Ω⋅m. This is less than the resistivity of silver, the lowest otherwise known...
efficiency. This is determined by the material's electrical conductivity (σ), thermalconductivity (κ), and Seebeck coefficient (S), which change with temperature...
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