Float-Glass

FIGURE 26.9 Schematic diagram of the float glass process. 

There are three interfacial energy (y) terms between the different phases glass (G), air (v), and tin (t) g is the acceleration due to gravity, which has a value of 9.806 m/s, Pg and p, are the density of the glass and tin, respectively. 

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Flint glasses Flints Float glass Flocculants... 

Additional improvements have been incorporated since 1966 with the availabihty of thinner float glass. Glass thickness and interlayer thickness have been studied to optimize the product for occupant retention, occupant injury, and damage to the windshield from external sources (30,31). The thinner float glass windshields are more resistant to stone impacts than the early plate glass windshields. The majority of laminated windshields are made of two pieces of 2—2.5 mm aimealed glass and 0.76 mm of controlled adhesion interlayer. 

In the float-glass process, adopted by all leading plate-glass manufacturers, the molten glass is allowed to float and soHdify on the surface of a pool of molten tin which provides an ideally flat surface. The endless glass ribbon has a surface so smooth that cosdy grinding and polishing are unnecessary. 

The float glass manufacturing process was developed by PHkington Brothers Ltd. of England in 1959. It starts with a large continuous tank furnace... 

Other specialized uses of Sn and its alloys are as type metal, as the molten-metal bath in the manufacture of float glass and as the alloy NbsSn in superconducting magnets. The many industrial and domestic uses of tin compounds are discussed in later sections these compounds account for about 15% of the tin produced worldwide. 

About two-thirds of the N2 produced industrially is supplied as a gas, mainly in pipes but also in cylinders under pressure. The remaining one-third is supplied as liquid N2 since this is also a very convenient source of the dry gas. The main use is as an inert atmosphere in the iron and steel industry and in many other metallurgical and chemical processes where the presence of air would involve fire or explosion hazards or unacceptable oxidation of products. Thus, it is extensively used as a purge in petrochemical reactors and other chemical equipment, as an inert diluent for chemicals, and in the float glass process to prevent oxidation of the molten tin (p. 370). It is also used as a blanketing gas in the electronics industry, in the packaging of processed foods and pharmaceuticals, and to pressurize electric cables, telephone wires, and inflatable rubber tyres, etc. 

Two processes, referred to as sputtered and pyrolitic, were developed to produce large volumes of quality, low-e coated glass. Pyrolitic coatings are incorporated into float glass production and tend to be more durable. Sputtered systems use a stand-alone vacuum deposition process to produce coatings that are have lower emissivities but that are softer and need more protection than pyrolitic coatings. 

Fig. 8. X-ray reflection diagram of a thin polystyrene film on float glass [160]. The reflectivity R is plotted against the glancing angle . The film is spin coated from solution. A model fit (dashed line) to the reflectivity data is also shown where the following parameters are obtained film thickness = 59.1 0.1 nm, interface roughness glass-polymer = 0.4 0.1 nm, surface roughness polymer-air = 0.6+1 nm, mean polymer density = 1.05 + 0.01 g/cm-3. The X-ray wavelength is 0.154nm...

These films are deposited at atmospheric pressure on the hot glass in a continuous operation (float-glass process). The CVD reactions are described in Ch. 11. 

A conventional optical test rig is shown in Fig. 2 [13]. A superfinished steel ball is loaded against the flat surface of a float-glass disk. Both surfaces can be independently driven. Nominally a pure rolling is used as shown in Fig. 2 that the disk is driven by a shaft and the ball is driven by the disk. 

A wide range of problems have been studied, including chemical stability, the strengthening of glass, and the distribution of tin in the surface of float glass. 

Tin has many uses, including coating (tins/cans for food), alloys such as bronze, organ pipes, solder, and the float glass process. It is also important in laboratory syntheses, in spite of the well-known toxicity problems. 

Special metals Sinter processes Silicon chemistry Float glass... 

The efficiency of reactant utilization in CVD on float glass can be as low as 10%, necessitating the installation of expensive chemical scrubbing units or incinerators and requiring landfill of more than one million kg/year of waste. 

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