What is the most reliable way to measure thermal conductivity of metals?

2 Transient methods

Transient methods are based on the principle that when a metal sample is exposed to a sudden change in temperature, such as a heat pulse or a cooling shock, the temperature response of the sample depends on its thermal conductivity. By measuring the temperature change over time, the thermal conductivity can be derived. Some examples of transient methods are the laser flash, the hot wire, and the transient plane source. These methods are fast, versatile, and suitable for small and heterogeneous samples. However, they require complex instrumentation, sophisticated data analysis, and accurate heat transfer models.

3 Comparative methods

Comparative methods are based on the principle that when a metal sample is placed in contact with a reference material with a known thermal conductivity, the heat transfer between them depends on the ratio of their thermal conductivities. By measuring the temperature distribution along the contact surface, the thermal conductivity of the sample can be estimated. Some examples of comparative methods are the parallel thermal conductance, the transient hot strip, and the comparative cut-bar. These methods are simple, economical, and suitable for irregular and composite samples. However, they require high-quality reference materials, good contact conditions, and correction factors.

4 Non-destructive methods

Non-destructive methods are based on the principle that the thermal conductivity of a metal sample can be correlated with some other physical property that can be measured without damaging the sample. For example, the thermal conductivity can be related to the electrical conductivity, the thermal diffusivity, or the ultrasound velocity. Some examples of non-destructive methods are the eddy current, the photothermal, and the ultrasonic methods. These methods are convenient, fast, and suitable for in-situ and online measurements. However, they require empirical calibration, reliable correlations, and minimal interference.

As you can see, there is no single method that can measure the thermal conductivity of metals in all situations. Each method has its own strengths and weaknesses, and the choice depends on factors such as the material type, the sample size, the temperature range, the accuracy required, and the cost involved. Therefore, it is important to understand the principles, assumptions, and limitations of each method before applying it to your manufacturing operations.

5 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?