Glass Industry

Nano-technology Applications in the Glass Industry

The glass industry is undergoing a period of accelerated innovation as regulatory and competitive pressures, together with evolving customer expectations, provide incentives for new product development.  Nanotechnology is seen as an important source of new performance in this industry. 

The float glass process is standard for high-quality flat glass production. Molten glass, at approximately 1050 ºC, is poured continuously from the furnace onto a shallow bath of molten tin. It floats on the tin, spreads out and forms a level surface.  Thickness is controlled by the speed at which the solidifying glass ribbon is drawn off from the bath.  After annealing (controlled cooling) the glass emerges as a 'fire' polished product with virtually parallel surfaces.

Coatings that make profound changes in properties of the glass can be applied to the cooling ribbon of glass or applied to the glass after cooling. Technologies for applying coatings include on-line chemical vapour deposition, spray pyrolysis, sputtering, and sol gel coating.

 

New Glass Products Recommended by Concept Patterns

Self Cleaning Glass

Self cleaning surfaces consist of an active layer of nanocrystalline titanium dioxide (TiO2) deposited upon float glass. When the ultraviolet (UV) component of sunlight interacts with the titanium dioxide the energy of the UV light is adsorbed; if moisture is present from the atmosphere, strongly oxidizing free radicals are formed, which clean the glass surface. Glass cleaned in this way becomes super hydrophilic (literally “water loving”).  This forces water to spread across the surface, rather than beading, thereby washing away debris on the surface of the glass.

Self cleaning aquarium glass utilizing a light activated nanostructured coating has been developed by Diamond Shell, a Victorian start-up company. This animation shows how the DiamondShell product can prevent algae growth on aquarium glass.

Antireflective Glass

Antireflective Glass, an example of which is Pilkington Optiview consists of multiple layers of conductive metals and high refractive index metal oxides such as TiO2. The thickness of the layers is related to the wavelength of light resulting in destructive interference of light reflected off the surfaces and hence greatly reduced reflectivity.

Another method of producing Antireflective Glass is to deposit a single layer of nanoporous SiO2. The refractive index of the porous coating is between that of the glass surface and air, thereby reducing the reflectivity and increasing the transmission of light at the glass surface.

Conductive Glass

Transparent, conductive coatings on glass can be achieved by coating a thin layer of conductive material such as Indium doped tin oxide or fluorine doped tin oxide. Conductive glass finds application in high tech applications such as solar cells. In buildings conductive glass can be used for EMI shielding in computer rooms and office buildings where data security is critical.

Solar Heat Control

The control of heat entering and leaving a building is the most important application of coated glass. Companies coat thousands of square meters of glass per day for use in commercial buildings. The coatings act by selectively reflecting near infra red and UV radiation, while letting most visible light through. Another approach is a laminated polymer film containing solar heat adsorbing nanoparticles.

Electrochromic glazing can be reversibly changed from clear tungsten oxide (WO3) to dark blue (HxWO3) by hyrogen ion insertion. In the clear state more solar heat can enter the room in cold weather, while in warm weather the electrochromic window can be switched to the coloured state leading to significantly decreased solar gain, reducing the need for cooling.

Privacy - Switchable Glass

Switchable glass such as Pilkington Switchable consists of an emulsion of rod shaped liquid-crystals laminated between two transparent electrodes of indium doped SnO2 or fluorine doped SnO2.

Switchable Glass (Transparent) - New Product Recommended by Concept Patterns   When a voltage is applied across the electrodes, the liquid crystals in the emulsion align and light can pass through. When the voltage is off the liquid crystals become randomly oriented scattering light and making the glass opaque. The ability to select the transparency of glass at the flick of a switch has led to applications in car sun roofs, office buildings, and residential apartments. Switchable Glass (Opaque) - New Product Recommended by Concept Patterns

Thermal insulation – Aerogels

Aerogels have exceptional thermal insulation, are light weight, and translucent. These properties result from the nanoporous structure of the aerogel.  The material is 99% air and only 1% solid. In glazing units, aerogels have been laminated between two panes of glass for applications where high thermal insulation is required, while allowing light diffusion.

Source: NanoVic