The most common inorganic non-metallic thermal insulation powder filler has aluminum nitride, Aluminum Oxide Flap Disc, zinc oxide, beryllium oxide, silica, silicon carbide, boron nitride and so on.
Aluminum Oxide Flap Disc not only has good insulating properties, but also its thermal conductivity is not low (at room temperature thermal conductivity of 30w/m· K), has been widely used in High-voltage, UHV switchgear field insulation products.
Heat conduction mechanism of Aluminum Oxide Flap Disc in thermal conductive silica gel
The heat energy in matter is often transmitted in the form of vibrational energy, that is, the microscopic particles in the matter collide with each other to realize the heat transfer.
For metallic materials, its heat conduction is electrically conductive by the movement of free electrons. Because the quality of free electrons is light and unfettered, this makes the metal material conductive at the same time.
The thermal conductivity of Aluminum Oxide Flap Disc filler mainly depends on the vibration of phonon, and the heat conduction is achieved through nonlinear thermal vibration of crystal.
Silica gel as a polymer material, is composed of asymmetric polar chain, the entire molecular chain can not be completely free movement, only the occurrence of atoms, groups or chain of vibration, so its thermal conductivity is very low, is a bad conductor of heat.
Aluminum Oxide Flap Disc has a wide range of sources, relatively low prices, large filler in silica gel, has a high cost-effective, therefore as the current high thermal insulation silicone material, the main thermal insulation filler.
When the amount of Aluminum Oxide Flap Disc added is less, the distribution of Aluminum Oxide Flap Disc in silica gel matrix is similar to that of isolated island, and the thermal conductivity is not improved.
With the increase of Aluminum Oxide Flap Disc addition, the distribution of silica gel is more and more dense, the particles will contact each other, in the composite materials to form a local heat conduction chain or heat conduction network;
If the amount of Aluminum Oxide Flap Disc is increased, the heat conduction chain or heat conduction network will be connected and penetrated, forming a heat conduction network through the material in the polymer matrix, so that the thermal conductivity of the filler material can be improved remarkably.
However, the amount of filler over ambassadors ' performance is worse, such as its fluidity and flexibility due to the increase of filler volume.
According to different sintering control, the crystal morphology of Aluminum Oxide Flap Disc can show a worm-like, flaky, spherical (spherical) and other morphologies, because the spherical particles of Aluminum Oxide Flap Disc surface can be small, fill in the matrix of small viscosity, more easily dispersed evenly in the matrix, and the filler relative to other shapes of large, more conducive to improve the thermal conductivity of silica gel, therefore, At present, the morphology of Aluminum Oxide Flap Disc particles filled with high thermal insulation material is spherical.