Optical Glass picture, Borofloat
 
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BOROFLOAT® 33
Borosilicate Glass

Special Properties

  • High temperature load capacity:
    - up to 450°C permanent load
    - up to 500°C temporarily (< 10h)
  • Low thermal coefficient of expansion
  • Thermal coefficient matches silicon
    (anodic bonding)
  • High thermal shock resistance
  • Clear practically colorless appearance
  • Low fluorescence
  • High UV-Transmission
  • High chemical resistance against acids,
    bases and organic substances
  • Low alkali content in the glass composition
  • Low specific weight

Typical Applications

  • Substrates for dielectric coatings
  • Lighting applications
  • Optical filter coating substrates
  • Wafer substrates
  • Biotechnology
  • Photovoltaics
  • Environmental Technology
  • Harsh Environments
  • Neutron absorbers
  • Measurement and Sensor-Technology
Borofloat window
Fig.: CNC-manufactured, temperature resistant window made of BOROFLOAT glass. Parts like this optical window for a micro reactor are economically made of borosilicate glass.

BOROFLOAT® glass has an excellent optical quality. Resulting from a special micro-float manufacturing process, BOROFLOAT offers a good flatness and surface quality. BOROFLOAT 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 exceeds the chemical resistance of most metals and many other materials. The borosilicate glass is an ideal substrate for dielectric coatings and has shown to be a good choice for many different technical glass applications, particularly at high operating temperatures. BOROFLOAT® 33 is a registered trademark of SCHOTT.


Specifications of BOROFLOAT®*

 
Show transmission curve of BOROFLOAT

Refractive Index

  • nd = 1,472 (588nm)

Density

  • 2,20 g/cm3

Coefficient of Thermal Expansion (20-300°C)

  • 32,5 x 10-7/K

Viscosity at different temperatures

Description

Viscosity


(dPas)

Temp.

(°C)
Working Point 104 1270
Softening Point 107,6 820
Annealing point 1013 560
Strain point 1014,5 518
Transformation Temp. Tg - 525

Chemical Properties

  • Hydrolytic Resistance (ISO 719-HGB) Class 1
    (ISO 720-HGA) Class 1
  • Alkali Resistance (ISO 695-A) Class 2
  • Acid Resistance (ISO 1776) Class 1

Electrical Properties

  • Dielectric Constant 4,6
  • Loss Factor tan d = 37 x 10-4

Standard Thicknesses

Tk.

Tol.

Tk.

Tol.
0,70mm ±0,1 7,5mm ±0,3
1,10mm ±0,1 8,0mm ±0,3
1,75mm ±0,2 9,0mm ±0,3
2,00mm ±0,2 13,0mm ±0,3
2,25mm ±0,2 15,0mm ±0,3
2,75mm ±0,2 16,0mm ±0,5
3,30mm ±0,2 17,0mm ±0,5
5,00mm ±0,2 18,0mm
±0,5
5,50mm ±0,2 19,0mm ±0,5
6,50mm ±0,2 21,0mm ±0,7

*Please consider the "Notes on technical specifications"


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