heat conducting metal

Best Metals for Conducting Heat

Thermal conductivity is the term that describes how quickly a material absorbs heat from areas of high temperature and moves it toward areas of lower temperature. The best heat-conducting metals have high thermal conductivity and are useful for many applications, such as cookware, heat exchangers, and heat sinks. On the other hand, metals with a lower rate of heat transfer are also useful where they can act as a heat shield in applications that generate large amounts of heat, such as airplane engines.

Here’s a ranking of heat conducting metals and metal alloys from lowest to highest average thermal conductivity, in Watts/meter-K at room temperature:

  1. Stainless Steel (16)
  2. Lead (35)
  3. Carbon steel (51)
  4. Wrought iron (59)
  5. Iron (73)
  6. Aluminum Bronze (76)
  7. Copper brass (111)
  8. Aluminum (237)
  9. Copper (401)
  10. Silver (429)

Stainless Steel

With one of the lowest thermal conductivities for a metal alloy, stainless takes much longer to conduct heat away from a source than, say, copper. This means that a pot made of stainless would take much longer to heat up food than a copper-bottom pot (though stainless has other benefits). Steam and gas turbines in power plants use stainless steel because of its heat resistance, among other properties. In architecture, stainless steel cladding can resist high temperatures longer, keeping buildings cooler in sunlight.

Aluminum

While aluminum has a slightly lower thermal conductivity than copper, it is lighter in weight, cheaper, and easier to work with, making it a better choice for many applications. For example, microelectronics such as LEDs and laser diodes use tiny heat sinks with aluminum fins that project into the air. Heat generated by the electronics transfers from the chip to the aluminum and then to the air, either passively or with the help of forced airflow convection or a thermoelectric cooler.

Copper

Copper has a very high thermal conductivity and is much cheaper and more available than silver, which is the best metal of all for conducting heat. Copper is corrosion resistant and resists biofouling, which makes it a good material for solar water heaters, gas water heaters, and industrial heat exchangers, refrigerators, air conditioners, and heat pumps.

Other factors affecting heat conduction

When considering the best metals for heat conduction, you must also take into account other factors in addition to thermal conductivity, which affect the rate of heat flow. For example, the initial temperature of the metal can make a huge difference to its heat transfer rate. At room temperature, iron has a thermal conductivity of 73, but at 1832°F, its conductivity drops to 35. Other influences include the temperature difference across the metal, the thickness of the metal, and the surface area of the metal.

For the largest selection of metals in the Southwest, contact Industrial Metal Supply.

Data taken from Engineering Toolbox.


corrosion resistant metals

4 Types of Metal That Are Corrosion Resistant or Don’t Rust

We usually think of rust as the orange-brown flakes that form on an exposed steel surface when iron molecules in the metal react with oxygen in the presence of water to produce iron oxides. Metals may also react in the presence of acids or harsh industrial chemicals. If nothing stops the corrosion, flakes of rust will continue to break off, exposing the metal to further corrosion until it disintegrates.

Not all metals contain iron, but they can corrode or tarnish in other oxidizing reactions. To prevent oxidation and breakdown of metal products, such as handrails, tanks, appliances, roofing or siding, you can choose metals that are “rust-proof” or more accurately, “corrosion-proof.” Four basic types of metals fall into this category:

  • Stainless steel
  • Aluminum metal
  • Copper, bronze or brass
  • Galvanized steel

Stainless Steel

Stainless steel types, such as 304 or 316, are a mix of elements, and most contain some amount of iron, which easily oxidizes to form rust. But many stainless steel alloys also contain a high percentage of chromium – at least 18 percent – which is even more reactive than iron. The chromium oxidizes quickly to form a protective layer of chromium oxide on the metal surface. This oxide layer resists corrosion, while at the same time prevents oxygen from reaching the underlying steel. Other elements in the alloy, such as nickel and molybdenum, add to its rust-resistance.

Aluminum metal

Many aircraft are made from aluminum, as are car and bike parts. This is due to its light weight, but also to its resistance to corrosion. Aluminum alloys contain almost no iron and without iron, the metal can’t actually rust, but it does oxidize. When the alloy is exposed to water, a film of aluminum oxide forms quickly on the surface. The hard oxide layer is quite resistant to further corrosion and protects the underlying metal.

Copper, Bronze and Brass

These three metals contain little or no iron, and so do not rust, but they can react with oxygen. Copper oxidizes over time to form a green patina, which actually protects the metal from further corrosion. Bronze is a mixture of copper and tin, along with small amounts of other elements, and is naturally much more resistant to corrosion than copper. Brass is an alloy of copper, zinc, and other elements, which also resists corrosion.

Galvanized Steel

Galvanized steel takes a long time to rust, but it will eventually rust. This type is carbon steel that has been galvanized, or coated, with a thin layer of zinc. The zinc acts as a barrier preventing oxygen and water from reaching the steel, so that it is corrosion protected. Even if the zinc coating is scratched off, it continues to protect nearby areas of the underlying steel through cathodic protection, as well as by forming a protective coating of zinc oxide. Like aluminum, zinc is highly reactive to oxygen in the presence of moisture, and the coating prevents the iron in the steel from further oxidation.

Industrial Metal Supply carries a wide range of rust-resistant metals for a variety of applications.