Borosilicate Glass Material Properties

Borosilicate Glass (SiO2 and B2O3), has a very low coefficient of thermal expansion making it more resistant to thermal shock than any other common glass. It also has very high electrical resistivity and dielectric strength, high chemical stability, withstands high applied torque loads and is visible to near Infrared transmission.

Applications for precision balls include: valves, pumps, insulators, calibration, spacer


Borosilicate Glass

PHYSICAL PROPERTIES
composition SiO2 65-85%
B2O3 8-15%
Na2O 3-9%
Al2O3 1-5%
K2O max 2%
density 2.23 g/cm3
max working temperature 300 – 400°C
THERMAL PROPERTIES
melting point 1252°C
softening temperature 821°C
thermal conductivity 1.15 W/(m·K)
shock resistance 300°C
MECHANICAL PROPERTIES
hardness Mohs 6
Knoop 420 – 520
Poisson’s ratio 0.20
Young’s modulus 64 GPa
compressive strength 9327 kg/cm2
tensile strength 832 kg/cm2
ELECTRICAL PROPERTIES
volume resistivity >10^15 Ω·m
OPTICAL PROPERTIES
refractive index 1.471 nm
MAGNETIC PROPERTIES
relative magnetic permeability diamagnetic <-1
*values are for guidance only