Aerogel Thermal Conductivity Compared: Why One λ Number Misleads
The thermal conductivity figure on an aerogel datasheet is the first thing buyers compare and the easiest to misread. One blanket lists 17 mW/m·K, another lists 70, and the 17 looks like the clear winner. Often it is the same class of material measured at a different temperature. Read the number wrong and you shortlist on a spreadsheet artifact.
Across the AerogelHub directory, nine suppliers publish a thermal conductivity value, and they span 13 to 70 mW/m·K. Ningbo Surnano lists the lowest at 13 to 20. Here is what that spread means and how to compare two products without fooling yourself.
One number, measured at one temperature
Aerogel conductivity climbs with heat. As temperature rises, radiation and gas conduction inside the pores pick up, and λ goes with them. A blanket that reads 17 mW/m·K at room temperature can read 40 or more at 400°C.
That is why some suppliers publish a wide band rather than a single figure. Shanghai Aerogelzone lists 20 to 67, Zhengzhou Exceed lists 17 to 70. Those are not loose numbers. On the datasheets they are typically one product measured across its rated temperature span, cold end to hot end. Compare two blankets at the same temperature, or you are comparing nothing.
So the first question about any λ figure is what temperature it was measured at. The value comes second. A supplier that tags the number to a temperature, or publishes a curve, is handing you more than one that prints a single hero figure with no conditions.
The material is not the product
Pure silica aerogel runs about 3 mW/m·K as a solid, the lowest of any solid material. You cannot buy that. The blankets and panels in the directory sit near 13 to 21 at room temperature because the aerogel is held in a fiber batting that gives it strength and lets it bend around a pipe. The reinforcement is what makes the product usable, and it is part of what raises the number above the textbook value.
Treat a quoted 3 or 4 mW/m·K as a description of the science, not of the roll arriving on your dock.
How to compare without getting fooled
Do not shortlist on the headline number. The lowest λ on a page wins a cell in your spreadsheet and little else. Three checks matter more:
- Read λ at your operating temperature, not at 25°C, unless 25°C is where your line runs. Filter the directory to suppliers that publish thermal conductivity, then sort by the λ column and read your finalists’ values side by side.
- Check the test standard. A number measured to a stated method (ASTM C177, EN 12667) is one you can hold a supplier to. A number with no method behind it is marketing.
- Treat a blank as a question, not a verdict. Nine suppliers publish λ in our directory today. Others, Aspen and Cabot among them, publish theirs in datasheets we have not yet pulled in. An empty cell means we have not sourced it, not that the number does not exist. Ask for it before you rule anyone in or out.
The supplier worth your time gives you the conditions behind the number: the temperature, the test method, and the range. Those are what let you check the claim against your own line.
Ready to compare? Filter to suppliers that publish thermal conductivity in the directory, then line up your finalists in the table.