Factors That Affect The Thermal Conductivity Of Materials

The thermal conductivity of a material is the ability of that material to transmit heat through conduction. It is measured in units of (W/mK) and it varies widely between materials and can be an important factor when designing products that utilize heat transfer processes like heat exchangers.

The temperature of a material has an impact on its thermal conductivity. This is because the molecular movement that drives the thermal conductivity depends on temperature and will be slower at lower temperatures. Conversely, higher temperatures will allow the molecules in a material to move faster, increasing the thermal conductivity of the material.

Besides temperature, there are several other factors that can cause an increase or decrease in the thermal conductivity of a material. These include porosity, crystal structure, impurities and interface effects. Porosity refers to the presence of voids or gas pockets within a material that can reduce its overall thermal conductivity. This can be a natural occurrence or can occur as a result of poor manufacturing practices. In general, voids will have a greater effect on the thermal conductivity of a material than tightly packed solids.

Crystal structures also affect thermal conductivity by altering the way that phonons vibrate within a lattice. This can have an effect on the short and mid wavelength phonons which are responsible for conducting heat within a material, causing them to scatter more often. The scattering of these phonons can significantly decrease the thermal conductivity of a material.

Other factors that can influence thermal conductivity are the surface area of a material and its thickness. The thermal conductivity of a material can be calculated by using the formula Q = k A DT, where k is the thermal conductivity constant, A is the surface area through which the heat passes and DT is the difference in temperature between one side of the material and the other.

The direction in which heat flows is also an important consideration. This is because the thermal conductivity of a material can be different along different crystal axes. This is known as thermal anisotropy and can be a significant issue when working with materials that have complex crystal structures.

Understanding Thermal Conductivity Materials has a high or low thermal conductivity is determined by its specific application. In applications where high heat transfer rates are required, then a material with a high thermal conductivity will be preferred. Conversely, if the material is used to insulate and protect against heat, then a low thermal conductivity will be preferred. Custom Materials, Inc offers an array of prototyping and production capabilities that can help with your thermal conductivity needs. Contact us today to discuss your project or request a quote.