Optical Glass picture, B 270
 
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B 270® - Superwite

Colorless crown glass

Special Properties

  • High transmittance in the visible wavelength range
  • Crystal clear and colorless appearance
  • High purity glass composition
  • High stability against solarization effects
  • Very low visible aging when exposed to sunlight
  • Fire-polished glass surfaces

Typical Applications

B270-Superwite is an universal, economically priced Optical window of B270 Superwitequality glass, with a high transparency for visible and near infrared light. The crown glass from SCHOTT has a colorless, crystal clear appearance. The glass is very stable in regards to solarization effects, that usually occur when a material is constantly exposed to the sun or to UV-light. When other glass materials begin to change their color, B270 stays white and clear. B 270 is available as drawn glass, fire-polished sheet glass or as unpolished raw glass ingots. The B270 sheet material is available at many different standard thicknesses. For applications where surface quality and waviness is uncritical, it can be used without further surface treatment. To meet more demanding optical surface quality requirements, B270 glass should be mechanically ground and optically polished. This facilitates B270 to be used for sophisticated optical quality applications, while keeping the cost under control. In addition to B 270®, the new B 270® i is now available. The new glass composition offers an improved chemical resistivity which particularly makes it possible to use the material for special applications in biotechnology. All other optical and physical specifications remain the same.


To request windows or substrates made of SCHOTT B 270 Superwite glass with individual dimensions, please click the button below:


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48-h Express Service partially available
(please see thickness chart)

Specifications

 
Optical Transmission
B270 optical transmission
Optical transmission of B270

UV-Transmission at 1,15mm thickness
B270 UV-transmission
UV-Transmission of B270

 

Optical Properties

  • Abbe numbers:
    • ve = 58,3 +/-0,6
    • vd = 58,5

Refractive Index (20°C)

Description

Wavelength (nm)

Refractive Index

ng
436
1,5341
nF'
480
1,5297
nF
486
1,5292
ne
546
1,5251
nd
587,5
1,5230
nD
589,3
1,5229
nC'
644
1,5207
nC
656
1,5203

Mechanical Properties

  • Density: 2,55 g/cm3
  • Young's modulus E: 71,5 kN/mm2
  • Poisson's ratio μ: 0,219
  • Torsion modulus G: 29,3 kN/mm2
  • Knoop hardness HK100: 542

Thermal Properties

  • Coefficient of mean linear thermal expansion
    (static measurement):
    • 9,4 x 10-6/K (20-300°C)
    • 9,0 x 10-6/K (20-200°C)
    • 8,2 x 10-6/K (20-100°C)
  • Viscosities:
    • Working Point (104 dPa): 1033°C
    • Softening Point (107,6 dPa): 724°C
    • Annealing Point (1013 dPa): 541°C
    • Strain Point (1014,5 dPa): 511°C
  • Transformation temperature Tg: 533°C
  • Heat conductivity (W/(m x K):
    • 0,92 (24,5°C)
    • 1,01 (89°C)
    • 1,08 (127°C)
    • 1,15 (167°C)

Chemical Properties (not for B270® i type)

  • Hydrolytic Resistance according to DIN ISO 719:
    • Hydrolytic Class HGB 3
    • Equivalent of Alkali (Na2O) per g of glass grains:
      170 μg/g
  • Acid Resistance according to DIN 12 116:
    • Acid Class 2
    • Half surface weight loss after 6h:
      1,4 mg/dm2
  • Alkali Resistance according to DIN ISO 695:
    • Alkali Class A2
    • Surface weight loss after 3h:
      140 mg/dm2

Electrical Properties

  • Dielectric constant εr: 7,0 (1Mhz)
  • Dielectric Loss tangent (tan δ): 30 x 10-4 (1 MHz)
  • Specific DC-Volume Resistivity ρD (Ω x cm):
    • 109 (250°C)
    • 1,6 x 107 (350°C)
    • 2,0 x 106 (400°C)
  • Temperature Tk 100: 301°C
    (for volume resistivity of 10Ω x cm)

Thicknesses (click on thickness for a price quote)

Thickness Tolerance 48h- Express Service icon Thickness Tolerance 48h- Express Service icon
0,90mm ±0,10     - 4,00mm ±0,20     X
1,15mm ±0,15     X 5,00mm ±0,20     -
1,65mm ±0,15     X 6,00mm ±0,30     -
2,00mm ±0,20     X 8,00mm ±0,30     -
3,00mm ±0,20     - 10,00mm ±0,40     -
Other thicknesses on request.
The thicknesses marked with X are available within 48-h Express Service

All given details and specifications are mean reference values and are not guaranteed. In addition, please consider our "Notes on technical specifications"