Chemical Properties
BOROFLOAT® is very resistant to attack from water, alkalis, acids and organic substances. This chemically resistant type of borosilicate glass contains a high percentage of silica and a considerable amount of boric oxide. Exposure of BOROFLOAT® to water and acids results in only small amounts of monovalent ions leaching out of the glass. This creates a thin pore-free silica coating on the outer surface of the glass making it near impermeable to further attack. Even over long periods of time at temperatures above 100°C, BOROFLOAT® exceeds the chemical resistance of most materials. BOROFLOAT’s high chemical resistance makes it suitable for use in critical medical and scientific applications, such as electrophoresis, slides, cover plates and scintillators.
| Common Reactants | Weight Loss mg/cm2 |
| 5% HCl, 24 hr @ 95° C | < 0.01 |
| 0.02 n H2SO4, 24 hr @ 95° C | < 0.01 |
| H2O, 24 hr @ 95° C | < 0.01 |
| 5% NaOH, 6 hr @ 95° C | 1.1 |
| 0.02 n NaOH, 6 hr @ 95° C | 0.16 |
| 0.02 Na2CO3, 6 hr @ 95° C | 0.16 |
| 10% HF, 20 min @ 23° C | 1.1 |
| 10% NH4F*HF, 20 min @ 23° C | 0.14 |
Electrical Properties
Glass tends to be a good electrical insulator. The ability to carry an electrical charge in glass is a function of the alkali concentration (Sodium & Potassium) in the glass. The migratory effect of alkali ions in glass combined with increased mobility at higher temperatures can result in the glass carrying or passing a charge. The low alkali content of BOROFLOAT® compared to nearly all other glasses makes it a superior insulator. This makes it suitable for many electrical applications requiring good insulating capabilities at elevated temperatures.
| Dielectric Constant (κ) | 1 Mhz @ 25°C | 4.6 |
| Dielectric Loss Factor (tan δ) | 1 Mhz @ 25°C | 37 x 10-4 |
| Dieletric Strength (Em) |
23°C 149°C 160°C |
16kV/mm 7kV/mm 1.8kV/mm |
| Volume Resistivity (log ρ) |
250°C 350°C |
8.0 6.5 |
Optical Properties
The visual clarity of BOROFLOAT® is a result of the float process with stringent quality control that minimizes defects such as bubbles, seeds and striae. The low amount of iron oxide in BOROFLOAT®, results in improved transmission of ultra-violet, visible and infra-red light over soda-lime glass. In comparison to many glasses, BOROFLOAT® has a very low dispersion. These advantages make BOROFLOAT® a good choice for beam splitters, dichroics, hot and cold mirrors, photolithography masks and lens blanks.
| n | ni | nh | ng | nF' | ne | nd | nC' | nr | nt |
| wavelength | 365.0 | 404.7 | 435.8 | 480.0 | 546.1 | 587.6 | 643.8 | 706.5 | 1014.0 |
| index | 1.489 | 1.484 | 1.481 | 1.477 | 1.473 | 1.472 | 1.470 | 1.468 | 1.463 |
| . | UV Hg | Violet Hg | Blue Hg | Blue Cd | Green Hg | Yellow He | Red Cd | Red He | IR Hg |
| Dispersion (nF- nC) 71.94 x10-4 | Optical Stress Constant (K) 4.0x10-6 mm2/N |
Physical Properties
The density of BOROFLOAT® is one of the lowest for silicate-based glasses. BOROFLOAT® has extremely good abrasion and scratch resistance. As with all glass the bending strength of BOROFLOAT® is influenced by the surface condition of the glass part, the rate at which the load is applied and the area on the glass part placed under load.
| Density(ρ) | @25°C | 2.22 g/cm3 |
| Young's Modulus (E) | @25°C | 63 GPa |
| Knoop Hardness (HK 0.1/2.0) | per ISO 9385 | 480 |
| Poisson's Ratio (μ) | 0.20 | |
| Bending Strength | per DIN 52292 | 25 N/mm2 |
Thermal Properties
BOROFLOAT® has one of the lowest coefficients of thermal expansion for conventional glass materials, this provides BOROFLOAT® with good thermal shock resistance. Combined with a maximum long term use temperature of 450°C, which makes BOROFLOAT® a good choice for applications requiring good thermal stability.
| Coefficient of Thermal Expansion | (α 20 - 300° C ) | 3.25 x 10-6/K |
| Thermal Conductivity(λ) |
10°C 50°C 90°C 190° C |
1.11 W/m K 1.17 W/m K 1.22 W/m K 1.31 W/m K |
| Heat Capacity(Cp) | 20 - 100°C | 0.83 kJ/kg K |
| Maximum Operating Temperature |
Short-term Long-term |
500°C 450°C |
| Resistance to Thermal Gradients |
< 1 hour 1 - 100 hours > 100 hours |
110K 90K 80K |
| Resistance to Thermal Shock |
< 4 mm 4-6 mm 6-15 mm > 15 mm |
175K 160K 150K 140K |
WHILE EVERY ATTEMPT HAS BEEN MADE TO VERIFY THE SOURCE OF THE INFORMATION, NO RESPONSIBILITY IS ACCEPTED FOR ACCURACY OF DATA.
