GLASS - by Atri Sikdar

GLASS

PROPERTIES OF GLASS

Chemical Composition

 

 

component

 

 

remarks

CONTENT IN %

Soda-lime glass
for containers

Soda-lime glass
for windows

SiO2

Silica Sand

Main Component

74

73

Na2O

Soda Ash

Lowering melting point

13

14

CaO

Calcium Oxide

Making glass less soluble in water.

10.5

9

MgO

Magnesium Oxide

Making glass less soluble in water.

0.2

4

Al2O3

Aluminium Oxide

Increasing elastic modulus and hardness

1.3

0.15

Others

K2O , TiO2 , Fe2O3

0.3 , 0.01 , 0.04

0.03 , 0.02 , 0.1

 

physical and mechanical Properties :

ITEM

Soda-lime glass
for containers

Soda-lime glass
for windows

Viscosity
log(η, Pa·s) = A +B / (T in °C - To)

550-1450°C:
A = -2.309
B = 3922
To = 291

550-1450°C:
A = -2.585
B = 4215
To = 263

Glass transition
temperature, Tg, °C

573

564

Coefficient of
Thermal Expansion,
ppm/K, ~100-300°C

9

9.5

Density
at 20°C, g/cm3

2.52

2.53

Refractive index
nD at 20°C

1.518

1.520

Dispersion at 20°C,
104×(nF-nC)

86.7

87.7

Young's modulus
at 20°C, GPa

72

74

Shear modulus
at 20°C, GPa

29.8

29.8

Liquidus
temperature, °C

1040

1000

Heat
capacity at 20°C,
J/(mol·K)

49

48

Surface tension,
at ~1300°C, mJ/m2

315

 

Chemical durability,
Hydrolytic class,
after ISO 719[5]

3

3...4