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Borosilicate glass is a type of glass with silica and boron trioxide as the main glass-forming constituents. Borosilicate glasses are known for having very low coefficients of thermal expansion (≈3 × 10 −6 K −1 at 20 °C), making them more resistant to thermal shock than any other common glass.
Properties Soda–lime glass (for containers) [2] Borosilicate (low expansion, similar to Pyrex, Duran) Glass wool (for thermal insulation) Special optical glass (similar to Lead crystal) Fused silica Germania glass Germanium selenide glass Chemical composition, wt% 74 SiO 2, 13 Na 2 O, 10.5 CaO, 1.3 Al 2 O 3, 0.3 K 2 O, 0.2 SO 3, 0.2 MgO, 0.01 ...
Imperfections of the glass, such as bubbles, and in particular surface flaws, such as scratches, have a great effect on the strength of glass and decrease it even more than for other brittle materials. [2] [1] The chemical composition of the glass also impacts its tensile strength. [3]
A Pyrex borosilicate glass measuring cup. Borosilicate glasses (e.g. Pyrex, Duran) typically contain 5–13% boron trioxide (B 2 O 3). [75] Borosilicate glasses have fairly low coefficients of thermal expansion (7740 Pyrex CTE is 3.25 × 10 −6 /°C [78] as compared to about 9 × 10 −6 /°C for a typical soda–lime glass [79]).
Glass databases are a collection of glass compositions, glass properties, glass models, associated trademark names, patents etc. These data were collected from publications in scientific papers and patents, from personal communication with scientists and engineers, and other relevant sources.
Several glasses are used in transparent armor, such as normal plate glass (soda-lime-silica), borosilicate glass, and fused silica. Plate glass has been the most common glass used due to its low cost. But greater requirements for the optical properties and ballistic performance have necessitated the development of new materials.
Macor is the trademark for a machinable glass-ceramic developed and sold by Corning Inc. It is a white material that looks somewhat like porcelain. Macor is a good thermal insulator and is stable up to temperatures of 1000 °C, with very little thermal expansion or outgassing. It can be machined using standard metalworking tools. [1]
The borosilicate glass Schott BK7 (glass code 517642) is an extremely common crown glass, used in precision lenses. Borosilicates contain about 10% boric oxide, have good optical and mechanical characteristics, and are resistant to chemical and environmental damage.