Understanding Thermal Conductivity
Understanding Thermal Conductivity
The ability of a material to transmit heat, also known as Thermal Conductivity, plays a crucial role in the design and manufacture of many products. The thermal response of a material can affect everything from its machinability and tensile strength to its resistance to corrosion and fire. The way in which a material transfers heat is determined by its atomic or molecular composition, the temperature gradient over which it must travel and the specific properties of each component in the solid. Understanding this property can help you choose the best material for your application.
A thermally conductive material will transfer heat along the path of least resistance, from an area of higher temperature and high molecular energy to an area of lower temperature and low molecular energy. This occurs through molecular agitation and contact, rather than the bulk movement of the material itself. As a result,Thermal Conductivity is typically faster in solids than liquids or gases.
In general, metals have a very high Thermal Conductivity, whereas plastics and aerogels have a very low thermal Conductivity. Materials with medium thermal Conductivity fall between these two extremes and tend to be used for a variety of applications.
The characteristics that contribute to the Thermal Conductivity of a particular material include its atomic or molecular structure, the type and concentration of impurities in the material, its crystalline lattice, and its composition and arrangement with alloying elements. The temperature dependence of thermal conductivity is also important. The thermal conductivity of a pure metal decreases with increasing temperature, because the electrons that carry heat in the metal’s crystal structure become more and more scattered by vibrations of the lattice called phonons.
Because the basis of thermal Conductivity is molecular agitation, the temperature has a major influence on its value. Higher temperatures mean that more and more molecules are in motion, which leads to a greater rate of thermal conduction. The thermal conductivity of a solid also depends on the size of its cross-sectional area, its permeability, and the distance over which it must transfer heat.
In addition to the physical and chemical properties that determine thermal conductivity, there are several different methods for measuring it. The methods can be divided into two categories: steady-state and transient techniques. Steady-state techniques measure the temperature of a sample as it approaches a steady state profile, while transient techniques measure the temperature of a sample over time.
In order to obtain accurate thermal conductivity data, you need to know which factors are most relevant for the measurement method you choose. A Xometry representative can assist you in choosing the right measurement method for your needs, depending on the requirements of your specific project. Contact us today to request a quote.