Borosilicate glass has a very low coefficient of thermal expansion, about one third of ordinary glass. This will reduce the temperature gradient stress.

　　Therefore, it has stronger fracture resistance. Because of its very small shape deviation, it has become an indispensable material for telescopes and mirrors. It can also be used to treat highly radioactive nuclear waste.

　　Borosilicate glass began to soften at about 821 (1510). At this temperature, 7740 type high viscosity borosilicate weight 107.6.

　　Borosilicate glass is less dense than ordinary glass.

　　Although more and more resistant to thermal shock than other types of glass, borosilicate glass can still be broken by rapid or uneven temperature changes. When broken, borosilicate glass cracks tend to be larger than crushing (it will unit, not split).

　　Optically, borosilicate glass has low dispersion (about 65 Abbe number crowns) and relatively low refractive index (the whole visible light range is 1.51-1.54).

　　The linear expansion coefficient of G3.3 high borosilicate glass is 3.3 x 0.1 x 10-6/K. It is a kind of glass with sodium oxide (Na2O), boron oxide (B2O 3) and silicon dioxide (SIO 2) as its basic components. The content of borosilicate in the glass is higher, which is boron: 12.5-13.5% and silicon: 78-80%. Therefore, this kind of glass is called high borosilicate glass. It belongs to PYREX glass in borosilicate glass [1]. Acid, alkali and water resistance, excellent corrosion resistance, good thermal stability, chemical stability and electrical properties, so it has chemical erosion resistance, thermal shock resistance, good mechanical properties, high temperature and other characteristics.