To form a coating layer, it is known to be crucial to match the coefficient thermal expansion (CTE) between coating material and substrate, which makes coating substrates having low CTE, such as quartz, with glass difficult. Aerosol deposition (AD) method has been studied as a technique to form a coating layer at room temperature without any additional heat treatment in vacuum. In addition, when using this method, the coating layer is dense and uniform, has a proper adhesion, quick coating time, low cost and energy consumption on the metal, ceramic and polymer substrate despite mismatch of CTE between substrate and materials.

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Fig 1. (a) Schematic diagram of aerosol deposition method (AD) equipment, (b) cross section of coating layer using glass on quartz substrate by AD.

The mechanism of AD method is not clarified but it is known to form coating layer by impact energy between substrate and accelerated powders via carrier gas. The coating film is formed densely without pore and adjusts able thickness.

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Fig 2. Coating layer using amorphous materials by AD: (a) Transmittance of coating layer and (b) plasma etching results compared with reference quartz.

The transmittance of coating layers using glass frits by AD shows high values in the visible light range. The coating layer shows a much lower etch depth in comparison with the reference material, quartz.