We are working on different highly thermally conductive coatings on aluminum substrate. We want to measure in plane thermal conductivity of coating only and overall through plane thermal conductivity of substrate + coating. What is the best characterization method for this?
Also wanted to characterize / measure emissivity after coating. Please suggest the same.
I'd choose a guarded hot-plate for through plane measurement - with single-sided or double-sided apparatus (as per ASTM C177).
For in-plane?
Hmm.
I'd apply that coating to a number of substrates, measure the temperature history of a heated spot, and model the diffusion of heat assuming an infinite substrate and a thin layer atop it.
A bit like:
https://www.jstage.jst.go.jp/article/matertrans1989/32/5/32_5_429/_article/-char/en
James Garry Thanks for the answer.. Meanwhile we were interacting with thermal conductivity measurement instrument vendors. Some of them who uses methods such as Transient Plane Source (TPS) and Xenon Flash method claims in-plane thermal conductivity measurement possible. Do you have any experience with these? Please provide your valuable inputs.
I have only direct personal experience of through-plane measurement - I have a double-sided guarded hot plate apparatus (-150degC to ~90degC).
I am aware of providers of transient spot methods - and know some providers of that service in Canada - I see no obstacle to their use in this situation.
What is the temperature at which the measurements should be made?
James Garry Currently requirement is for room temperature measurement only as we are still doing research on thermal performance evaluation of different coatings. But as per the application point of view after evaluation selected coatings thermal conductivity will need to be measured at RT to approximate 250 to 300 degree Celsius.
Certainly there should be no difficulty in having room temperature in-plane measurements made by transient spot/line methods.
The elevated temperatures will pose a challenge to contact methods such as a guarded hot-plate - I can think only of this outfit: Netzsch
https://analyzing-testing.netzsch.com/en/products/thermal-conductivity/ghp-456-titan
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