Thermal Conductivity of Materials: Metals, Ceramics and Insulators

Material Properties Guide

Thermal conductivity describes how readily heat flows through a material. It is central to heat exchangers, electronics cooling, insulation, furnaces, building envelopes and thermal-management systems.

What thermal conductivity means

Thermal conductivity is usually represented by k and expressed in W/(m·K). A high value means heat is conducted readily; a low value indicates stronger resistance to conductive heat flow.

Metals

Copper and aluminum are widely used when heat must be spread or transferred efficiently. Alloying often reduces conductivity compared with high-purity base metals because solute atoms and defects scatter heat-carrying electrons.

Ceramics and polymers

Many ceramics and polymers are much less thermally conductive than metals, which makes them useful as insulators. Important exceptions exist: some advanced ceramics have relatively high thermal conductivity while retaining electrical insulation, making them valuable in electronics packaging.

Temperature and microstructure

Thermal conductivity changes with temperature and can be strongly affected by porosity, moisture, phase composition, grain boundaries and fiber orientation in composites.

Design context

Conduction is only one heat-transfer mode. Convection, radiation, interface resistance and contact pressure may dominate the thermal performance of a real assembly.

Key takeaways

• This guide is written for practical engineering and technical understanding.
• Property values can vary with purity, processing route, temperature, microstructure and test method.
• For design or procurement decisions, verify values against the applicable material specification and current standard.

Frequently asked questions

Which common metal conducts heat best?

Silver has extremely high thermal conductivity, while copper is more widely used because it combines high conductivity with lower cost.

Why are thermal interface materials used?

They fill microscopic gaps between contacting surfaces and reduce thermal contact resistance.

Can an electrical insulator conduct heat well?

Yes. Materials such as selected aluminum nitride and other engineered ceramics can combine electrical insulation with useful thermal conductivity.

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