BOROFLOAT®

The huge number of applications BOROFLOAT® is used for is testament to its exceptional range of technical advantages. Its light transmission in the visual wavelength range is exemplary, chemical and thermal resistance extraordinarily high, and its mechanical strength provides strength and reliability.

A highly valued portfolio of properties

Outstanding thermal resistance

Thanks to an extremely low coefficient of thermal expansion, BOROFLOAT® is highly resistant to elevated temperature levels. It also handles rapid cooling from high temperatures, such as the temperature difference between a hot panel center and cold panel edge.

Exceptionally high transparency

SCHOTT’S microfloat production process and purity of component materials ensure that BOROFLOAT® enjoys excellent transparency and distortion-free light transmission in the near infrared and ultraviolet ranges. This makes it highly valued in the optics, photonics and opto-electronics fields.

High chemical durability

Acids, alkalis and other organic substances have negligible impact on the integrity of this glass, making it an extremely stable material ideal for use in the medical and analytical technology fields. Its hydrolytic resistance is also impressive, a quality demanded by laboratories across the globe.

Excellent mechanical strength

Light with high elasticity, BOROFLOAT® is strong thanks to its chemical composition, enhancing reliability and product life. The material handles high pressure and large mechanical loads, with its structural integrity matched by its bending strength. BOROFLOAT® is also abrasion- and scratch-resistant.

Thicknesses and dimensions

Standard thicknesses

Thickness (mm) Tolerance (mm)
0.70 ± 0.05
1.10 ± 0.05
1.75 ± 0.05
2.00 ± 0.05
2.25 ± 0.05
2.75 ± 0.10
3.30 ± 0.20
3.80 ± 0.20
5.00 ± 0.20
5.50 ± 0.20
6.50 ± 0.20
7.50 ± 0.30
9.00 ± 0.30
 1.00 ± 0.30
13.00 ± 0.30
15.00 ± 0.40
16.00 ± 0.50
18.00 ± 0.50
19.00 ± 0.50
20.00 ± 0.70
21.00 ± 0.70
25.40 ± 1.00

"Panel thickness is continuously measured during production using laser thickness measuring equipment. Further thicknesses and tolerances are available on request."

 

Standard sizes

Size Thickness
1,150 x 850 mm 0.7 – 25.4 mm
1,700 x 1,300 mm 16.0 – 21.0 mm
2,300 x 1,700 mm
0.7 – 15.0 mm

Standard sizes of BOROFLOAT® 33

 

Limits/Rectangularity

Limits t Nominal size H or W
± 5 mm ≤ 1.000 mm
± 10 mm > 1.000 mm

Limits and rectangularity are guaranteed to a tolerance of ± 2 mm for nominal thickness ≤ 10 mm.

 

 

Thermal

Thermal properties

  • Specific heat capacity cp (20–100 °C): 0.83 kJ/(kg·K)
  • Thermal conductivity λ (90 °C): 1.2 W/(m·K)
  • Transformation temperature Tg* (according to ISO 7884): 525 °C

Maximum Operating Temperature

  • For short-term usage (< 10 h): 500 °C
  • For long-term usage (≥ 10 h): 450 °C

 

 

Graph showing the coefficient of linear thermal expansion of BOROFLOAT® glass

The CTE of BOROFLOAT® 33 is 3 times lower than the CTE of Soda-lime glass.

 

Graph showing the viscosity of BOROFLOAT® glass

 
 

 

Optical

Optical index of refraction

Wavelength λ (nm) Refraction index n
435.8 1.48015
479.9 1.47676 (nF’)
546.1 1.47311(ne)
589.3 1.47133
643.8 1.46953 (nC’)
656.3 1.46916

Reference values, not guaranteed values.

 

Optical data

  • Abbe number (ve = (ne – 1) / (nF‘ – nC‘)): 65.41
  • Refraction index (nd587.6 nm)): 1.47140
  • Dispersion (nF – nC): 71.4 x 10-4
  • Stress-optical coefficient (K): 4.0 x 10-6 mm2 N-1

Reference values, not guaranteed values.

 

 

Graph showing the transmission of BOROFLOAT® glass

 

Graph showing the transmission of BOROFLOAT® glass in the UV range

 

Graph showing the dispersion of BOROFLOAT® glass

 

Graph showing the solarization of BOROFLOAT® glass

Inherent fluorescence

Graph showing the inherent fluorescence of BOROFLOAT® glass at 365

 

Graph showing the inherent fluorescence of BOROFLOAT® glass at 488

Chemical

Chemical durability

  • Hydrolytic resistance (according to ISO 719 / DIN 12 111): HGB 1
  • Hydrolytic resistance (according to ISO 720): HGA 1
  • Acid resistance (according to DIN 12 116): 1
  • Acid resistance (according to ISO 1776): ≤ 100 μg Na₂O per 100 cm²
  • Alkali resistance (according to ISO 695 / DIN 52 322): A 2

 

Resistance to selected chemicals

24 h at 95 °C:

Reagent Abrasion [mg/cm2] Visual observations
H20 < 0,01 Unchanged
5 Vol.% HCl < 0,01 Unchanged
0,02 n H2S04 < 0,01 Unchanged

 

6 h at 95 °C:

Reagent Abrasion [mg/cm2] Visual observations
5 % NaOH 1,1 White stains
0,02 n NaOH 0,16 White haze
0,02 n Na2CO3 0,16 Unchanged

 

20 min. at 23 °C:

Reagent Abrasion [mg/cm2] Visual observations
10 % HF 1,1 Stained white haze
10 % NH4F x HF 0,14 Unchanged

Chemical resistance of BOROFLOAT® 33 to selected reagents as a function of time and temperature.

 

 

 

Graph showing the hydrolytic resistance of BOROFLOAT® glass

Quantity of Na2O released from BOROFLOAT® 33 compared tosoda-lime glass depending on the temperature after 16 hours.

 

BOROFLOAT_chemical_graphic_IONexchange.png

Compared to soda-lime glass, BOROFLOAT® 33 has a significantly higher hydrolytic resistance, because the number of sodium ions in the glass network is significantly lower with BOROFLOAT® 33. The few sodium ions are also more strongly bound. 

Mechanical

Mechanical properties:

  • Density ρ (25° C): 2.23 g/cm3
  • Young´s Modulus E (according to DIN 13316): 64 kN/mm2
  • Poisson's Ratio μ (according to DIN 13316): 0.2
  • Knoop Hardness HK0.1/20 (according to DIN ISO 9385): 480

 

Vickers-Test

Vickers hardness test to observe BOROFLOAT® ability to resist deformation compared to standard soda-lime glass

Mechanical resistance to penetration by a pointed object – BOROFLOAT® 33 is particularly resistant due to its glass structure.

 

PEI Abrasion Test

Loose grains rotate on a glass to test the abrasion on BOROFLOAT® glass compared to standard soda-lime glass

Transition from sliding abrasion to erosion (grain fill, loose grains) – BOROFLOAT® 33 is particularly abrasion resistant.

 

Want to know more? Let’s talk

Whether you need more information, samples, a quote, or advice for a project, we would be delighted to talk to you.

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