Optical Glass picture, Borofloat
 
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BOROFLOAT® 33 Borosilicate Glass

Temperature- and chemically resistant glass

Special Properties

  • High temperature load capacity:
    - up to 450 °C permanent load
    - up to 500 °C temporarily (< 10 h)
  • Low thermal coefficient of expansion
  • Thermal coefficient of expansion matches the one of
    silicon wafers (anodic bonding)
  • High thermal shock resistivity
  • Clear, practically colorless appearance
  • Low self-fluorescence
  • High UV-Transmission
  • High chemical resistivity against strong acids,
    bases and organic substances
  • Low alkali content in the glass composition
  • Low specific weight
  • Good scratch and abrasion resistance
  • High elasticity and mechanical strength
  • Superior flatness obtained by micro-float process

Typical Applications

  • Flat glass substrates for dielectric coatings
  • Components for lighting applications
  • Front window for high power floodlights
  • Borosilicate glass substrates for optical filter coatings
  • Wafer substrates
  • Biotechnology
  • Photovoltaic glass
  • Sight glass windows
  • Base glass for industrial optics
  • Glass tubes
  • Components for environmental technology
  • Chemically resistant glass slides
  • Anodic bonding glass wafer applications
  • Glass for harsh environments
  • Neutron absorbers
  • Measurement and sensor technology
Borofloat borosilicate glass window
nullspacer Fig.: CNC-manufactured, temperature resistant window made of BOROFLOAT® borosilicate glass. Components like this optical window for a micro reactor can economically be made of this type of borosilicate glass.

 

BOROFLOAT® glass is a clear-transparent white borosilicate glass material that offers a superior optical quality. Resulting from a special micro-float manufacturing process developed by SCHOTT, BOROFLOAT® features a good flatness, surface quality, a low micro roughness and a good homogeneity. The glass has a low self-fluorescence over a broad light spectrum, which facilitates a wide scope of applications in the field of optics, optoelectronics, photonics and analytics.

BOROFLOAT® borosilicate glass is very resistant against water, neutral, saline and acidic solutions as well as to iodine, chlorine, bromine, and organic substances, even over long periods of time and at temperatures higher than 100 °C. BOROFLOAT® glass exceeds the chemical resistance of most metals and most other glass materials. Acids and bases dissolve only small amounts of ions from the borosilicate glass, so the test results are not impaired, as it is often the case when soda-lime glass is used. This property opens up the possibility of interesting applications in the field of medical engineering and analytics. But also the mechanical characteristics of BOROFLOAT® surpass the ones of soda-lime glass and that of most other borosilicate glass materials.

BOROFLOAT® flat glass is an ideal raw material for optical coatings, mirrors, filters, windows, glass wafers or any other kind of optics and has shown to be a good and economical choice for many technical glass applications, particularly at high operating temperatures which cannot be resisted by soda lime glass. BOROFLOAT® borosilicate glass has an almost identical coefficient of thermal expansion and nearly the same specific weight as PYREX® sheet glass and is often used to replace PYREX® which has been discontinued many years ago. BOROFLOAT® 33 is a registered trademark of the SCHOTT AG.

 

To request windows, substrates or any other optics made of original SCHOTT BOROFLOAT® borosilicate glass with individual dimensions, please use the button below:

 

Request for Quotation

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Note: Other flat borosilicate glass type materials like MEMpax®, D263 T, SUPREMAX® or DURAN® from SCHOTT are also part of the extensive manufacturing and delivery program of our company. For additional detailed information please send us your inquiry.

Specifications

  
UV-VIS-IR Transmission

SCHOTT BOROFLOAT® Glass, transmission curve UV-VIS-IR

UV-VIS-IR transmission of BOROFLOAT® borosilicate glass

 

UV-Transmission at 0,70 mm glass thickness

SCHOTT BOROFLOAT® Glass UV-transmission curve at 0,7mm thickness

UV-transmission of BOROFLOAT® at 0,70 mm thickness

 

UV-Transmission at 3,30 mm glass thickness

SCHOTT BOROFLOAT® Glass, UV-transmission curve at 3,3mm thickness

UV-transmission of BOROFLOAT® at 3,30 mm thickness

 

Optical Properties

  • Abbe Constant ve: 65,41
  • Dispersion nF - nC : 71,4 x 10-4
  • Stress Optical coefficient K: 4,0 x 10-6 mm2 N-1

Index of Refraction of Borofloat glass

Title

Wavelength (nm)

Refractive Index

ng
435,8
1,48015
nF'
479,9
1,47676
ne
546,1
1,47311
nd
587,6
1,47140
nD
589,3
1,47133
nC'
643,8
1,46953
nC
656,3
1,46916

Mechanical Properties

  • Density: 2,2 g/cm3 (25 °C)
  • Young's modulus E: 64 kN/mm2
    (according to DIN 13 316)
  • Poisson's ratio μ: 0,2 (according to DIN 13 316)
  • Shear modulus σ: 25 Mpa
    (according to DIN 52 292 T 1)
  • Knoop hardness HK0,1/20: 480
    (according to ISO 9385)

Thermal Properties

  • Coefficient of thermal expansion:
    3,25 x 10-6/K (20-300 °C) (according to ISO 7991)
  • Specific heat capacity cP: 0,83 kJ (kg x K)-1
  • Specific heat conductivity:
    1,2 W (m x K)-1 (90 °C)
  • Transformation temperature Tg: 525 °C
  • Viscosities of Borofloat borosilicate glass:
    • Working Point (104 dPa): 1270 °C
    • Softening Point (107,6 dPa): 820 °C
    • Annealing Point (1013 dPa): 560 °C
    • Strain Point (1014,5 dPa): 518 °C
  • Maximum operating temperatures σmax :
    (only valid if the following RTG and RTS values
    are considered)
    • for short term load 500 °C (< 10 h)
    • for long term load 450 °C (≥ 10 h)
  • Resistance to thermal gradients (RTG):
    • 110 K (< 1 h)
    • 90 K (1-100 h)
    • 80 K (> 100 h)
      (Testing method description on request)
  • Resistance to thermal shock (RTS):
    • 175 K (at thickness ≤ 3,8 mm)
    • 160 K (at thickness = 5,0-5,5 mm)
    • 150 K (at thickness = 6,5-15,0 mm)
    • 125 K (at thickness > 15,0 mm)
      (Testing method description on request)

Chemical Properties

  • Hydrolytic Resistance:
    • Class HGB 1
      (according to. ISO 719 / DIN 12 111)
    • Class HGA 1
      (according to. ISO 720)
  • Acid Resistance:
    • Class 1 (according to. ISO 1776 / DIN 12 116)
  • Alkali Resistance:
    • Class A2 (according to. ISO 695 / DIN 52 322)

Chemical Glass Composition

  • 81 % SiO2
  • 13 % B2O3
  • 4 % Na20 / K2O
  • 2 % Al2O3

Chemical Durability of Borofloat

Solution

Reaction time/
Temperature

Weight loss
(mg/cm2)

5 Vol.% HCl
24 h at 95 °C
<0,01
0,02 n H2SO4
24 h at 95 °C
<0,01
H20
24 h at 95 °C
<0,01
5% NaOH
6 h at 95 °C
1,1
0,02 n NaOH
6 h at 95 °C
0,16
0,02 n Na2CO3
6 h at 95 °C
0,16
10% HF
20 min at 23 °C
1,1
10% NH4F x HF
20 min at 23 °C
0,14

Electrical Properties

  • Dielectric Constant εr: 4,6 (1 Mhz ; 25 °C)
  • Loss Tangent (tan δ):
    37 x 10-4 (1 Mhz ; 25 °C)
  • Logarithm of the electrical Volume Resistivity lgρ:
    • 8,0 Ω x cm (250 °C)
    • 6,5 Ω x cm (350 °C)

Standard Glass Thicknesses

(For a quotation, click desired thickness)

Thicknes
(mm)

Tolerance

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0,70 ±0,07
1,10 ±0,10
1,75 ±0,20
2,00 ±0,20 -
2,25 ±0,20
2,75 ±0,20
3,30 ±0,20
5,00 ±0,20
5,50 ±0,20 -
6,50 ±0,20 -
7,50 ±0,30 -
8,00 ±0,30 -
9,00 ±0,30 -
11,0 ±0,30 -
13,0 ±0,50 -
15,0 ±0,50 -
16,0 ±0,50 -
17,0 ±0,50 -
18,0 ±0,50 -
19,0 ±0,50 -
21,0 ±0,70 -
25,4 ±1,00 -

The marked thicknesses () are available within our 48h–Express Service.

 

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