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Thermal barrier coating (TBC) system has been developed for high temperature applications along with the used of yttria stabilized zirconia (YSZ) as topcoat. Recently, developing coating material made from nanoparticles is widely explored. Thus, maerogel could become a potential candidate for this purpose because it consists of nano porous particle with low in density and low in thermal conductivity. The coating is expected to improve the formation of thermally grown oxide (TGO), thermal stability and increase the insulating capability. However, maerogel need agglomeration process before coating can be made because of it has low mass and high specific area.

Nano-structured silica aerogel, which is also known as maerogel, was synthesised from rice husk ash (RHA) by a Universiti Teknologi Malaysia (UTM) research team. This super lightweight solid (powder) material with low thermal conductivity was agglomerated into micro-size particles for use as a coating material. Sprayable maerogel coating has high potential for use in various thermal insulating applications such as in aeroengine turbine blade. The maerogel was coated on Inconel 625 via the atmospheric plasma spray (APS) method. Since the APS can deposit a wide range of coating powders and particle sizes with high deposition temperature, it has become a more suitable coating technique for maerogel coating. The coating spray distance of the APS was varied to study its effect on the maerogel coating in terms of microstructure, coating thickness, adhesion strength and thermal conductivity. The coating spray distance of 10 cm was the best spray distance, a parameter by which a homogenous microstructure with adequate coating thickness, adhesion strength and thermal conductivity was obtained.

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