Measurement of High Thermal Conductivity Sheets
When measuring the thermal conductivity of thin sheets with any transient thermal conductivity method, the heat from sensor must stay within the available dimensions of the sample. This becomes increasingly difficult as the thermal conductivity / thermal diffusivity of the sample increases and the thickness decreases. The limiting measurement parameter is test time, can it be reduced to keep heat within the thickness of the sheet you are testing?
To demonstrate this concept, we have selected carbon diamond, which has a thermal conductivity of 543 W/m•K and thermal diffusivity 306 mm2/sec. Using a sample thickness of 2 mm, you can see a test time of 0.1 seconds, the heat penetrates 11 mm, several times the available thickness dimension.
Feel free to vary thickness and test time to investigate the concept.
Using the Hot Disk TPS Slab module, the thickness is isolated and heat is allowed to propagate along the in-plane direction. This maximizes the largest dimensions to test for longer times.
Slab Testing Module: https://thermtest.com/tps-testing-modules/slab
Demo link: https://thermtest.com/demo-corner/videos/high-thermal-conductivity-sheets
Graphite sheet paper: https://thermtest.com/papers/thermal-conductivity-enhancement-of-epoxy-adhesive-using-graphene-sheets-as-additives