Thermal conductivity is a measure of a materials ability to pass heat through it. Materials with a high thermal conductivity can effectively transfer heat and readily take up heat from their environment. Poor thermal conductors resist heat flow and obtain heat slowly from their surroundings. The thermal conductivity of a material is measured in Watts per meter per degree Kelvin (W/m•K) following the S.I (International System) guidelines.
The top 10 measured thermally conductive materials and their values are outlined below. These conductivity values are averages due to the variance in thermal conductivity depending on the equipment used and the environment where the measurements were obtained.
Diamond is the leading thermally conductive material and has conductivity values measured 5x’s higher than copper, the most manufactured metal in the United States. Diamond atoms are composed of a simple carbon backbone that is an ideal molecular structure for effective heat transfer. Often, materials with the simplest chemical compositions and molecular structures have the highest thermal conductivity values.
Diamond is an important component of many modern hand held electronic devices. Their role in electronics is to facilitate heat dispersion and protect sensitive computer parts. The high thermal conductivity of diamonds also proves useful when determining the authenticity of stones in jewelry. Incorporating small amounts of diamond into tools and technologies can have a drastic impact on the thermal conductivity properties.
Silver is a relatively inexpensive and abundant thermal conductor. Silver is a component of numerous appliances and is one of the most versatile metals due to its malleability. 35% of silver manufactured in the U.S is used for electrical tools and electronics (US Geological survey mineral community 2013). A biproduct of silver, silver paste, is increasing in demand due to its use for environmentally friendly energy alternatives. Silver paste is used in the production of photovoltaic cells that are a major component of solar energy panels.
Copper is the most commonly used metal for manufacturing conductive appliances in the United States. Copper has a high melting point and a moderate corrosion rate. It is also a very effective metal for minimalizing energy loss during heat transfer. Metal pans, hot water pipes and car radiators are all appliances that utilize the conductive properties of copper.
Gold is a rare and expensive metal that is used for specific conductive applications. Unlike silver and copper, gold rarely tarnishes and can withstand conditions that experience large amounts of corrosion.
Aluminum nitride is frequently used as a replacement for beryllium oxide. Unlike beryllium oxide, aluminum nitride does not impose a health hazard to manufacture yet still displays similar chemical and physical properties to beryllium oxide. Aluminum nitride is one of the few known materials to offer electrical insulation along with a high thermal conductivity. It has extraordinary thermal shock resistance and acts as an electrical insulator in mechanical chips.
Silicon carbide is a semiconductor that is composed of a balanced mixture of silicon and carbon atoms. When manufactured and fused together, silicon and carbon bind to form an extremely hard and durable material. This mixture is often used as a component for car brakes, turbine machines and in steel mixtures.
Aluminum is generally used as a cost-effective replacement for copper. Although not as conductive as copper, aluminum is abundant and easy to manipulate due to its low melting point. Aluminum is a crucial component of L.E.D lights (light emitting diodes). Copper aluminum mixes are gaining popularity as they can harness the properties of both copper and aluminum and can be manufactured at a lower cost.
Tungsten has a high melting point and a low vapor pressure making it an ideal material for appliances that are exposed to high levels of electricity. Tungsten’s chemical inertness enables it to be used in electrodes that are a part of electron microscopes without altering the electrical currents. It is also often used in lightbulbs and as a component of cathode ray tubes.
Graphite is an abundant, low cost and lightweight alternative compared to other carbon allotropes. It is frequently used as an addition to polymer mixtures to enhance their thermal conductivity properties. Batteries are a familiar example of an appliance that harnesses graphite’s high thermal conductivity.
Zinc is one of few metals that can easily be combined with other metals to create metal alloys (a mixture of two or more metals). 20% of zinc appliances in the U.S are composed of zinc alloys. Galvanizing uses 40% of manufactured pure zinc. Galvanizing is the process of a applying a zinc coating to steel or iron that is designed to protect to metal against weathering and rust.
Mokhena, T. C., Mochane, M. J., Sefadi, J. S., Motloung, S. V., & Andala, D. M. (2018). Thermal Conductivity of Graphite-Based Polymer Composites. Impact of Thermal Conductivity on Energy Technologies. doi:10.5772/intechopen.75676
Aluminum Nitride. (n.d.). Retrieved from https://precision-ceramics.com/materials/aluminum-nitride/
Thermtest Materials Database. https://thermtest.com/materials-database
Author: Kallista Wilson, Junior Technical Writer at Thermtest