Testing samples with direction-dependent properties
The Anisotropic Measurement Module furnishes the unique ability to measure the different thermal transport properties along and perpendicular to the main axis of uniaxial materials (referred to as the in-plane and through-plane directions, respectively), using our Hot Disk® sensor. It has also been updated to test the thermal transport properties of biaxial materials (in which the thermal conductivity, thermal diffusivity, and thermal effusivity are 3D tensors) using our Hot Strip® sensors. Both single-sided and double-sided sample testing are supported, where the former enables rapid QC testing while the latter maximizes measurement accuracy.
Testing the 2D or 3D anisotropic behavior of thermal transport properties is crucial for many applications. Ascertaining this property is vital in any context where heating or cooling is involved, such as batteries, electronics, and building materials. Other hot topics where measurements of the anisotropic thermal transport properties are particularly interesting include 3D printing, carbon fibers, and graphite laminates used in robotics, automotive, and aerospace industries.
The Anisotropic Measurement Module relies on the sample’s known Specific Heat Capacity. Suppose this capacity is not found tabulated in scientific papers, etc., or known from previous testing of similar materials. In that case, it can readily and accurately be tested via our dedicated Hot Disk® instrument add-on Specific Heat Capacity Measurement Module.
For 2D-anisotropic samples, the Hot Disk® sensor is applied and placed perpendicular to the main axis of the sample. A single transient temperature reading is performed, which yields the geometrical average of the in-plane and through-plane Thermal Conductivity and the in-plane Thermal Diffusivity of the probed sample volume. With the sample’s Specific Heat Capacity as input parameter, the in-plane and out-of-plane Thermal Conductivity and Thermal Diffusivity can all be extracted.
For 3D-anisotropic samples, the Hot Strip® sensor is applied and oriented along two different orthogonal axes of the sample. Two transient temperature readings are performed for the two respective sensor orientations. With the sample’s Specific Heat Capacity as the input parameter, the Thermal Conductivity and Thermal Diffusivity along the three orthogonal axes can be extracted. Note that using our Hot Strip® sensor requires that the sample be cut to match the length of the Hot Strip® sensor geometrically.
We invented and patented the 2D-anisotropic measurement technique in 20001, and the theory behind it is presented in our paper published in Thermal Conductivity in 20012. The 2D-anisotropy testing technique, using Hot Disk® sensors, meets ISO standard 22007-2. Hot Disk AB contributed to the development of this standard.
Thermal Conductivity Range:
Instruments | Range |
---|---|
TPS 3500, TPS 2500 S | 0.005 to 1500 W/m/K |
TPS 2200, TPS 1000 | 0.01 to 500 W/m/K |
TPS 1500 | 0.01 to 50 W/m/K |