Copper Thermal Conductivity

We ask this question to gauge your fundamental understanding of material properties, which is important in many engineering disciplines. Can you tell me, what is the thermal conductivity of copper? What are the typical units used to express thermal conductivity, and how does the thermal conductivity of copper compare to other common materials like aluminum or steel?

Copper Thermal Conductivity

Let's discuss the thermal conductivity of copper. I'll approach this by first defining what thermal conductivity is, then giving a value for copper, and finally talking about factors that influence it.

Definition

Thermal conductivity is a measure of a material's ability to conduct heat. A high thermal conductivity means that the material easily transfers heat from a hotter region to a cooler region. It's defined as the quantity of heat transmitted through a unit thickness in a direction normal to a unit area due to a unit temperature gradient.

Value for Copper

Copper is known for its excellent thermal conductivity. At room temperature (approximately 25°C or 298K), pure copper has a thermal conductivity of around 401 W/(m·K). This means that for every meter of thickness, for every square meter of area, and for every degree Kelvin (or Celsius) temperature difference, 401 Watts of heat will be transferred.

Factors Influencing Thermal Conductivity

Several factors can influence the thermal conductivity of copper:

• Temperature: The thermal conductivity of copper generally decreases slightly as temperature increases. The relationship isn't linear but it's good to be aware of.
• Purity: Impurities in the copper can significantly reduce its thermal conductivity. Even small amounts of other elements can scatter electrons and phonons (the primary heat carriers), hindering heat transfer.
• Alloying: Alloying copper with other metals generally decreases its thermal conductivity. The extent of the reduction depends on the type and concentration of the alloying element.
• Cold Working/Mechanical Processing: Processes like cold rolling can introduce defects and dislocations in the copper's crystal structure, which can slightly reduce its thermal conductivity.
• Grain Size: In polycrystalline copper, grain boundaries can scatter heat carriers. Smaller grain sizes generally lead to slightly lower thermal conductivity compared to single-crystal copper (though the effect is often small).

Practical Implications

Copper's high thermal conductivity makes it ideal for a variety of applications, including:

• Heat Sinks: Used to dissipate heat from electronic components, such as CPUs and GPUs.
• Heat Exchangers: Used in HVAC systems and industrial processes to transfer heat between fluids.
• Pipes: Used to transport hot or cold water in plumbing systems.
• Electrical Wiring: While primarily used for its electrical conductivity, the thermal conductivity helps prevent overheating.

Conclusion

Copper's high thermal conductivity is a crucial property that makes it a valuable material in a wide range of thermal management applications. It's important to remember that the exact thermal conductivity can vary depending on the purity, temperature, and processing history of the copper.