The following Application Highlight features the use of the Modified Transient Plane Source method in the thermal conductivity testing of aerogels.
Aerogels represent a class of ultra-lightweight materials that are primarily composed of air (typically >99%). As a result, these materials have very high insulative capabilities (low thermal conductivity) and are extremely low density. Silica based aerogels are amongst the most common, however they can be made from a variety of materials. In application, aerogels can be applied for thermal insulation around critical components or in certain cases impregnated within a larger matrix to introduce better insulative performance, without sacrificing weight. Due to the novel characteristics of the material, it is important to have a way to properly characterize their performance.
Figure 1. Silica aerogel sample for MTP sensor
Thermal characterization of aerogels is often first attempted using steady-state methods such as Guarded-hot Plate (GHP) and/or Heat Flow Meter (HFM). While a powerful tool, steady-state methods add certain restrictions that can make sample preparation quite difficult. Most devices require samples ranging from 10-30 cm in length/width with thickness generally 5-10 mm or larger, in some cases an impossibility for experimental aerogels. These steady-state options are also limited in the environment state in which they can test, and measurements can take many hours to complete. These factors add some significant limitations for many groups looking to characterize their aerogels in ways that are truly representative to their application. For these reasons, C-Therm’s Modified Transient Plane Source (MTPS) method is a great alternative to traditional steady-state methods. Requiring samples only 18 mm in diameter and 1-5 mm thick, the MTPS provides users a much more realistic option for testing aerogels. The MTPS can also be placed in varying temperature, humidity, and atmospheric environments to allow for truly representative testing. Lastly, MTPS results can be collected in a matter of minutes, making it one of the fastest thermal characterization techniques available.
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