Principal Uses
Filter lenses, wafers and substrates, tubing, labware, consumer glass products, heat shields, electrical insulators, first surface mirrors
Mechanical Properties
Density (at 20 °C/68 °F): 2.23 g/cm3
Knoop Hardness: 418 kg/mm2
Young’s Modulus: 64 GPa
Flexural Strength: 69 MPa @R.T.
Poisson’s Ratio: 0.20
Shear Modulus: 2.67 x 103 kg/mm2
Thermal Properties
Thermal Coefficient of Expansion (0/300 °C): 32.5 x 10-7/°C
Thermal Conductivity: 1.1 W/mK @R.T.
Specific Heat: 0.18 cal/g-°C @R.T.
Strain Point: 510°C/950°F
Annealing Point: 560°C/1040°F
Softening Point: 821°C/1509.8°F
Optical Properties
Refractive Index (l=589.3nm): 1.473
Optical Transmission
Chemical Properties
Hydrolytic resistance: class 1
Acid resistance: class 1
Alkali resistance: class 2
Electrical Properties
Dielectric Constant: E=4.6 1MHz @R.T.
Dielectric Strength: 0.5 kV/mm
Resistivity: 8 x 1010 ohm/cm @R.T.