Soda-boric oxide glass

BS (1957) BS2649 Part 2 Recommended Procedures for the Analysis of Soda-Boric Oxide-Silica Glass with High Silica and Boric Acid Content. 

This type, made by the General Electric Co., is resistant to sodium vapour and is used in sodiiun vapour discharge lamps. It has a very high boric oxide content, a low softening temperature, and a low electrical resistance. It is used as an internal layer in soda glass tubing X.8. ... 

I il a soda-lime-silica glass, containing magnesia and boric oxide 1 than 1 per cent), made by the General Electric Co. It is often ibed as GEC X.8. or simply as X.8. The linear coefficient of Jial expansion between 20 and 350°C is 9-65 0-10 x 10-. This I il available as tubing and rod in a wide range of sizes. 

Borosilicate glass contains about 80% silica, 13% boric oxide, 4% alkali, and 2% alumina. It is more heat-shock-resistant than most glasses due to its unusually small coefficient of thermal expansion (typically between 2 and 5 x 10 cm /°C for soda-lime glass it is 8 to 9 X 10 cm /°C). It is better known by such trade names as Kim ax and Pyrex. Bakeware and glass pipelines are often borosilicate glass. 

Borosilicate glass is soda-lime glass to which boric oxide has been added. It is known under the brand names of Pyrex and Kimax . The addition of boron to the glass produces a product with superior durability, chemical, and heat resistance. 

Definition A soda-lime glass contg. approx. 5% boric oxide heat-resistant glass... 

Chemical Characteristics. The most common type of glass is known as soda-lime glass and is made primarily of silica (60 to 75 percent). Sodium carbonate, or soda ash, is added to the silica to lower its melting point. Because the presence of soda ash makes it possible for water to dissolve glass, a third compound such as calcium carbonate, or limestone, must be added to increase insolubility and hardness. For some types of glass, compounds such as lead oxide or boric oxide are added to enhance properties such as brilliance and resistance to heat. 

There are a number of other glass recipe variations that may be used to yield desired properties. Most likely, these formulations were discovered by accident or in a trial-and-error manner, using materials from their locale and measuring the resultant properties. For instance, the Europeans were the first to discover that K2O, obtained locally from plant ash, could also be combined with lime and quartz to yield a potash-lime glass, later exploited for stained-glass windows. Another popular variation substitutes boric oxide (B2O3) for lime and soda to yield... 

In order to produce the various glasses, soda ash, salt cake, and limestone or lime are required to flux the silica. In addition, there is a contribution of lead oxide, pearl (as potassium carbonate), saltpeter, borax, boric acid, arsenic trioxide, feldspar, and fluorspar, together with a great variety of metallic oxides, carbonates, and the other salts required for colored glass. 

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