B270 - Superwite

Special Properties

• High consistent visible transmission
• Very clear colorless appearance
• High purity glass composition
• High solarization stabilty

Typical Applications

• Laboratory and Coating Substrates
• LCD Covers
• Image Forming Optics
• Chip Masks
• Optical Windows
• Mirror coating substrates

B270-Superwite is an universal, economically priced quality glass, with a high transparency for visible and near infrared light. The crown glass from Schott has a colorless, white appearance and is particularly clear. B 270 is available as drawn, fire-polished sheet glass or as unpolished bar raw glass. The B270 sheet material is available at many different standard thicknesses and can be used without further surface treatment if surface quality is uncritical. To meet more demanding optical surface quality requirements, B270 can be mechanically ground and optically polished. This facilitates B270 to be used for sophisticated optical quality applications, while keeping the cost under control.

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

Specifications of B 270-Superwite

 

Optical Properties

• Optical Transmission spectrum of B 270
• UV-Transmission of B 270
• Abbe numbers:
  • v_e = 58,3 +/-0,6
  • v_d = 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 (10^7,6 dPa): 724°C
  • Annealing Point (10¹³ dPa): 541°C
  • Strain Point (10^14,5 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

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

Electrical Properties

• Dielectric constant ε_r: 7,0 (1Mhz)
• Dielectric Loss tangent (tan δ): 30 x 10^–4 (1 MHz)
• Specific DC-Volume Resistivity ρ_D (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 10⁸ Ω x cm)

Thicknesses
Thickness	Tol.	Thickness	Tol.
0,90mm	±0,10	4,00mm	±0,20
1,15mm	±0,15	5,00mm	±0,20
1,65mm	±0,15	6,00mm	±0,20
2,00mm	±0,20	8,00mm	±0,30
3,00mm	±0,20	10,00mm	±0,40
Other stock thicknesses on request.

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