Borofloat Glass, Borosilicate Glass, Schott Borofloat

Borofloat®

Borofloat® by SCHOTT is a borosilicate glass with exceptionally high transparency, outstanding thermal resistance, high chemical durability, and excellent mechanical strength. The unique properties of Borofloat® make it applicable to numerous applications. Borofloat® offers the same mechanical properties as Corning Pyrex® with far superior optical qualities and flatness. Borofloat® has been used for high-temperature lighting applications, beds for 3D printers, micro slides, additive manufacturing processes and numerous other applications. Borofloat® is even being is used for space exploration as a key component in telescopes.

Very few glass types offer the same versatility of Borofloat® by SCHOTT.

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Features

Optical

Borofloat® offers superior transmission properties.
- High transparency in the visible, IR & UV range.
- Low inherent fluorescence and solarization tendency.
Borofloat® offers exceptional visual quality and optical clarity.

Thermal

A low coefficient of thermal expansion makes Borofloat® by SCHOTT very resistant to high temperature levels.
Borofloat® is proven to stand up to thermal shock from fluctuating temperatures

Chemical

Borofloat® offers high hydrolytic resistance and excellent resistance to acids.
Borofloat® offers high resistance to alkalis and low alkali diffusion

Mechanical

Borofloat® offers abrasion and scratch resistance in combination with bending strength.
The low inherent weight of Borofloat® by SCHOTT makes it ideal for numerous applications.

Available Forms

JNS stocks SCHOTT Borofloat® in numerous thicknesses and sizes.
Thickness Range: 0.70mm – 25.4mm
Sizes: Up to 90” x 67”

JNS also offers borosilicate and pyrex glass.

JNS can fabricate Borofloat® to your specific needs
JNS regularly applies thin film coatings such as anti-reflective or oelophobic coatings to Borofloat®

Borofloat® | Borosilicate Applications:
High Temperature Lighting
3D Printer Beds
Optical Windows
Sight Glass / View Ports
Filters
Micro Slides
Chemically Resistant Windows
Appliance (oven) Windows
Robotics
Film Projectors
Optics
Photonics

PHYSICAL PROPERTIES

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’)

OPTICAL DATA
Abbe number (ve = (ne – 1) / (nF‘ – nC‘))	65,41
Refraction index (nd (λ587,6 nm))	1,47140
Dispersion (nF – nC)	71,4 x 10-4
Stress-optical coefficient (K)	4,0 x 10-6 mm2 N-1

THERMAL PROPERTIES
Coefficient of Linear Thermal Expansion (C.T.E.) α (20 – 300 °C)	3.25 x 10-6 K-1 *
Specific heat capacity cp (20 – 100 °C)	0.83 kJ/(kg·K)
Thermal conductivity λ (90 °C)	1.2 W/(m·K)-1
* According to ISO 7991.
MAXIMUM OPERATING TERMPERATURES
For short-term usage (< 10 h)	500 °C
For long-term usage (≥ 10 h)	450 °C

VISCOSITY OF BOROFLOAT® 33
Working Point (104 dPas)	1270 °C
LITTLETON temperature / Softening Point (107,6 dPas)	820 °C
Annealing Point (1013 dPas)	560 °C
Strain Point (1014,5 dPas)	518 °C
Transformation temperature (Tg)	525 °C

CHEMICAL RESISTANCE
Water resistance	(according to ISO 719 / DIN 12 111) (according to ISO 720)	HGB 1 HGA 1
Acid resistance	(according to ISO 1776 / DIN 12 116)	1
Alkali resistance	(according to ISO 695 / DIN 52 322)	A 2
CORROSION TEST FOR DISPLAY GLASS
Reagent 24 h at 95 °C	Abrasion [mg/cm2]	Visual observations
5 Vol.% HCl	< 0.01	Unchanged
0.02 n H2S04	< 0.01	Unchanged
H20	< 0.01	Unchanged
6 h at 95 °C
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
10 % HF	1.1	Stained white haze
10 % NH4F x HF	0.14	Unchanged

MECHANICAL PROPERTIES
Density ρ (25 °C)		2.23 g/cm3
Young’s Modulus Ε (according to DIN 13316)		64 kN/mm2
Poisson’s Ratio μ (according to DIN 13316)		0.2
Knoop Hardness HK 0.1/20 (according to ISO 9385)		480
Bending Strength σ (according to DIN 52292 T 1)		25 MPa
Impact resistance The impact resistance of BOROFLOAT® 33 depends on the way it is fitted, the size and thickness of the panel, the type of impact involed, presence of drill holes and their arrangement as well as other parameters.
Reference values, not guaranteed values.
CRITICAL FORCES
Material	Mean value FC [mN]	*Stadev. [mN]**
BOROFLOAT® 33	363.8	4.3
Other borosilicate glass	271.2	1.9
Soda-lime flat glass	214.4	4.6