General High Borate Borosilicate Glass



High Borate Borosilicate Glass exhibit excellent sealability to metals in the expansion range of tungsten and molybdenum. In general, high borate borosilicates are less chemically resistant than non alkaline earth and alkaline earth borosilicate glasses.

Ashby charts

See where falls on the material property chart for Density against Elastic modulus in your materials selection and design process.



Density ρ

2.2 - 2.3 g/cm³ at 20 °C


Elastic modulus E

50 - 70 GPa at 20 °C

Poisson's ratio ν

0.2 - 0.22 [-] at 20 °C


Annealing temperature Tanneal

465 - 560 °C

Coefficient of thermal expansion α

3.9E-6 - 5.1E-6 1/K at 300 °C

Glass transition temperature Tg

440 - 530 °C

Thermal conductivity λ

1 - 1.2 W/(m·K) at 20 °C

Vicat softening temperature Tsoft

705 - 775 °C


Dielectric constant εr

4.7 - 5.7 [-] at 20 °C

at 1MHz

Loss tangent tanδ

2.2E-3 - 8E-3 [-] at 20 °C

at 1MHz


Refractive index nd

1.48 - 1.49 [-]

This material data has been provided by Matmatch.

All metrics apply to room temperature unless otherwise stated. SI units used unless otherwise stated.
Equivalent standards are similar to one or more standards provided by the supplier. Some equivalent standards may be stricter whereas others may be outside the bounds of the original standard.