Borosilicate glass (Pyrex)

The material. Borosilicate glass is soda lime glass with most of the lime replaced by borax, B203. It has a higher melting point than soda-lime glass and is harder to work, but it has a lower expansion coefficient and a high resistance to thermal shock, so it is used for glassware and laboratory equipment.

Composition

74% SiO2/1% Al2O3/15% B2O3/4% Na2O/6% PbO General properties

Density

2200

– 2300

kg/m3

Price

*4.15

– 6.22

USD/kg

Mechanical properties

Young’s modulus

61

– 64

GPa

Yield strength (elastic limit)

*22

– 32

MPa

Tensile strength

22

– 32

MPa

Compressive strength

*264

– 384

MPa

Elongation

0

%

Hardness—Vickers

*83.7

– 92.5

HV

Fatigue strength at 107 cycles

*26.5

– 29.3

MPa

Fracture toughness

*0.5

– 0.7

MPa. m12

Thermal properties

Glass temperature

450

– 602

°C

Maximum service temperature Thermal conductor or insulator?

230 – 460 Poor insulator

°C

Thermal conductivity

*1

– 1.3

W/m. K

Specific heat capacity

*760

– 800

J/kg. K

Thermal expansion coefficient

3.2

– 4

p, strain/°C

Electrical properties

Electrical conductor or insulator?

Good insulator

Electrical resistivity

3.16 X 1021 –

3.16 X 1022

pohm. cm

Dielectric constant

4.65 –

6

Dissipation factor

0.01 –

0.017

Dielectric strength

*12 –

14 106

V/m