Soda-lime glass is a kind of the glass which is most widely used for various purposes. It can be processed so inexpensively that it is used for windowpanes or bottles.

Soda-lime glass can be created by melting a mixture of silicon dioxide, sodium carbonate, and either calcium carbonate or calcium oxide. Adding sodium carbonate lowers the melting point of the glass, thus lowering the energy required to heat it, but also making it soluble in water. Calcium carbonate or calcium oxide are added to counter this.

In soda-lime glass, sodium (Na⁺) and calcium (Ca²⁺) ions are inserted into the silicate ion structure such that the tetrahedrons of silicon and oxygen atoms are stretched. The glass transition temperature (T_g) is about 730°C and the melting point is about 1000°C.

Water containing powders of soda-lime glass exhibits alkalinity because Na⁺ and Ca²⁺ dissolve in it, leading to hydrolysis.

A flame test of soda-lime glass reveals colors consistent with the mixing of its constituents, intermediate between those of Na⁺ and Ca²⁺.

Soda Lime Glass is formed by drawing the glass over molten tin baths. The air side (facing up) is typically flatter and smoother than the tin side.

Principal uses

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Mirrors, microscopic slides, touch screens, filters, photomasks, glass masters, data storage disks, printed circuit substrates, photographic plates, substrates, light bulbs, wafers and optical windows.

Typical thermal/Mechanical Properties

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Thermal Conductivity: 0.937 W.m/m² °C

Density (at 20º C/68 ºF): 2.44 g/cm³

Hardness (Moh's Scale): 6 - 7

Knoop Hardness: 585 kg/mm2 + 20

Modulus of Elasticity (Young's): 7.2 x 1010 Pa

Modulus of Rigidity (Shear): 3.0 x 1010 Pa

Bulk Modulus: 4.3 x 1010 Pa

Poisson's Ratio: 0.22

Specific Gravity: 2.53

Specific Heat: 0.21

Specific Weight: 2,483 g/cm³

Thermal Coefficient of Expansion (0/300 °C): 8.6 x 10 -6/°C

Softening Point: 726°C/1340°F

Annealing Range: 546°C/1015°F

Strain Point: 514°C/957°F

Typical optical properties

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See also

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Glass

glass

ソーダ石灰ガラス