Borosilicate Glass SCHOTT 8250

Alternative and trade names
SCHOTT 8250
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Description

For sealing to kovar metal and molybdenum. Electrically highly insulating and low-melting borosilicate glass.

This material data has been provided by Schott Glass Tubing.

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.

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Properties

General

PropertyTemperatureValue

Density

23.0 °C

2.28 g/cm³

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Mechanical

PropertyTemperatureValue

Elastic modulus

23.0 °C

64 GPa

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Poisson's ratio

23.0 °C

0.21 [-]

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Thermal

PropertyTemperatureValueComment

Annealing temperature

500 °C

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Viscosity 10¹³ dPa.s (ISO 7884-4)

Coefficient of thermal expansion

23.0 °C

5E-6 1/K

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mean value for 20-300 °C - ISO 7991

Glass transition temperature

490 °C

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ISO 7884-8

Softening temperature

720 °C

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Viscosity 10⁷·⁶ dPa.s (ISO 7884-3)

Specific electrical resistance temperature

375 °C

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For ρ = 10⁸ Ω·cm

Thermal conductivity

90.0 °C

1.2 W/(m·K)

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Working temperature

1055 °C

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Viscosity 10⁴ dPa.s (ISO 7884-2)

Electrical

PropertyTemperatureValue

Dielectric constant, 1MHz

23.0 °C

4.9 [-]

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Electrical resistivity

250.0 °C

1.00E+8 Ω·m

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350.0 °C

2.00E+6 Ω·m

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Loss tangent, 1MHz

23.0 °C

2.2E-3 [-]

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Optical

PropertyValueComment

Refractive index

1.49 [-]

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at λ=587.6 nm

Stress optical coefficient

3.6E-6 mm²/N

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DIN 52314

Chemical properties

PropertyValueComment

Other

0.01 %

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max., Lead, Cadmium, Mercury and Hexavalent Chromium

Technological properties

Property
Application areas

Signal intensifier, Detector and (fibre-) optics (X-ray tubes, Transmitter tubes, Image amplifier tubes, HeNe-laser capillaries, Sensor technic, Fibre optics light guide), Home (Giftware), Lighting (Flash lamps, Exhaust and plate tubing), Electreonic components (Read switches, Opto discs). Engineering (Ozon generators, Instrument / Barometers / Aerometers / Sightglasses), Endoscopy

Corrosion properties

Hydrolytic resistance Class HGB3 (ISO 719) - Acid resistance Class S4 (DIN 12116) - Alkali resistance Class A3 (ISO695)