glass possessing high chemical and thermal stability, thus making it suitable for working in a glass-forming machine; used in the manufacture of laboratory vessels and instruments and apparatus for the chemical industry. The properties of chemical glasses depend primarily on their composition. The thermal stability of such glasses, as well as the resistance to the action of water and acid, increases with increasing silica content and decreasing content of alkaline oxides. As a rule, alkali-resistant glass contains zirconium dioxide, lanthanum oxide, or stannic oxide. The glasses that are most resistant to all reagents and are the most thermally stable are the quartz glasses.
In the USSR, all chemical glasses fall into four basic categories: KhU-1, chemically resistant class 1; KhU-2, chemically resistant class 2; TU, thermally stable; and TUK, thermally stable quartz glass. Type DG-3 glasses, which are more resistant to alkalies, have also been developed.
REFERENCESDubrovo, S. K. Steklo dlia laboratornykh izdelii i khimicheskoi apparatury. Moscow-Leningrad, 1965.
Steklo: Spravochnik. Moscow, 1973.
N. P. DANILOVA