Borosilicate Windows

Silicon Content

>80%

Strain Point Temperature

520°C

Annealing Point Temperature

560°C

Softening Point Temperature

820°C

Refractive Index

1.47

Transmittance

≥90%

Elastic Modulus E

67 kN·mm⁻²

Tensile Strength

40–120 N·mm⁻²

Processing Temperature (10⁴ dPa·s)

1220°C

Coefficient of Thermal Expansion (20–300°C)

3.3×10⁻⁶ K⁻¹

Poisson’s Ratio μ

0.2

Density (at 20°C)

2.23 g·cm⁻³

Specific Heat Capacity

0.9 J·g⁻¹·K⁻¹

Thermal Conductivity

1.2 W·m⁻¹·K⁻¹

Water Resistance (per ISO 719)

Class 1

Acid Resistance (per ISO 195)

Class 1

Alkali Resistance (per ISO 695)

Class 2

Heat Shock Resistance (6×30 mm Rod)

300°C