Search results
Results from the WOW.Com Content Network
Fused quartz, fused silica or quartz glass is a glass consisting of almost pure silica (silicon dioxide, SiO 2) in amorphous (non- crystalline) form. This differs from all other commercial glasses, such as soda-lime glass, lead glass, or borosilicate glass, in which other ingredients are added which change the glasses' optical and physical ...
Melting point: 1670 °C (β tridymite); ... Quartz is a hard, ... Lechatelierite is an amorphous silica glass SiO 2 which is formed by lightning strikes in quartz sand.
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 TiO 2, 0. ...
The glass–liquid transition, or glass transition, is the gradual and reversible transition in amorphous materials (or in amorphous regions within semicrystalline materials) from a hard and relatively brittle "glassy" state into a viscous or rubbery state as the temperature is increased. [2] An amorphous solid that exhibits a glass transition ...
1802 K. 1529 °C. 2784 °F. The Gmelin rare earths handbook lists 1522 °C and 1550 °C as two melting points given in the literature, the most recent reference [Handbook on the chemistry and physics of rare earths, vol.12 (1989)] is given with 1529 °C.
Fused quartz is used for high-temperature applications such as furnace tubes, lighting tubes, melting crucibles, etc. [74] However, its high melting temperature (1723 °C) and viscosity make it difficult to work with. Therefore, normally, other substances (fluxes) are added to lower the melting temperature and simplify glass processing. [75]
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. Such glass is subjected to less thermal ...
As other minerals are melted with silica, the principle of freezing point depression lowers the melting point of the mixture and increases fluidity. The glass transition temperature of pure SiO 2 is about 1475 K. [ 35 ] When molten silicon dioxide SiO 2 is rapidly cooled, it does not crystallize, but solidifies as a glass. [ 36 ]