Thermal conductivity tester for testing the thermal conductivity of graphite materials

Graphite materials exhibit high intrinsic thermal conductivity due to their unique layered crystal structure, and are widely used in fields such as electronic device heat dissipation, thermal management materials, and new energy batteries. Accurately measuring the thermal conductivity of graphite materials, especially their anisotropic properties, is crucial for optimizing their performance and designing applications.

The traditional steady-state thermal conductivity testing methods (such as laser flash method and hot wire method) require the establishment of a temperature gradient through steady-state heat flux, which is time-consuming and has high requirements for sample shape and environmental stability; The transient planar heat source method, as a non steady state testing technique, can quickly invert the thermal conductivity, thermal diffusivity, and volumetric heat capacity of materials by measuring the temperature response of the sample after the probe releases heat in a short period of time. It is particularly suitable for efficient testing of anisotropic materials.

1、 Experimental steps

1. Experimental samples

Electrode graphite material

2. Testing equipment

DZDR-AS Thermal Conductivity Tester

3. Sample pretreatment

Sample size: Both pieces are 30 * 30 * 7.5mm, with a uniform, smooth and flat surface.

Surface treatment: Polish the surface of the sample with 600 # -2000 # sandpaper to remove scratches and improve the contact thermal conductivity between the probe and the sample.

4. Operation process

Sample placement: Place the probe in the center of two samples, ensuring that both probes cover the central area of the sample;

Parameter setting: Based on the estimated thermal diffusivity of the sample, select a test power of 5W;

Data acquisition: Start the heating pulse and record the curve of the probe temperature changing with time (sampling interval of 0.1ms, total testing time of 10s);

5. Experimental results and analysis

The purity of electrode graphite is usually lower than that of high-purity graphite, and the ash content of industrial grade electrode graphite is generally between 0.1% and 1% (some low-end products can reach more than 2%). Impurities can scatter phonons, significantly reducing thermal conductivity. For example, for every 0.5% increase in ash content, the thermal conductivity may decrease by about 5% -10%.

The in-plane thermal conductivity of electrode graphite at room temperature is usually 50-200W/(m · K), and the out of plane thermal conductivity is 10-50W/(m · K), with specific values depending on purity, density, and porosity; It has a low degree of anisotropy and is a cost-effective thermal and conductive functional material in industrial settings.