Mechanical Properties of Fused Quartz

Mechanical properties of fused quartz are much the same as those of other glasses. The material is extremely strong in compression, with design compressive strength of better than 1.1 x 109 Pa (160,000 psi).

Surface flaws can drastically reduce the inherent strength of any glass, so tensile properties are greatly influenced by these defects. The design tensile strength for fused quartz with good surface quality is in excess of 4.8 x 107 Pa (7,000 psi). In practice, a design stress of  0.68 x 107 Pa (1,000 psi) is generally recommended. 

Typical Physical Properties of Fused Quartz 

PropertyValue
Density2.2 x 103 kg/m3
Hardness5.5 – 6.5 Mohs’ Scale
570 KHN 100
Design Tensile Strength4.8 x 107 Pa (N/m2) (7,000 psi)
Design Compressive StrengthGreater than 1.1 x 109 Pa (160,000 psi)
Bulk Modulus3.7 x 1010 Pa (5.3 x 106 psi)
Rigidity Modulus3.1 x 1010 Pa (4.5 x 106 psi)
Young’s Modulus7.2 x 1010 Pa (10.5 x 106 psi)
Poisson’s Ratio 0.17
Coefficient of Thermal Expansion (20 °C – 320 °C)5.5 x 10-7 cm/cm • °C
Thermal Conductivity at 20°C1.4 W/m • °C
Specific Heat at 20 °C670 J/kg • °C
Softening Point1683 °C
Annealing Point1215 °C
Strain Point1120 °C
Electrical Resistivity  at 350 °C7 x 107 Ω • cm
Dielectric Properties at 20 °C and 1 MHz
Constant 3.75
Strength 5 x 107 V/m
Loss Factor Less than 4 x 10-4
Dissipation Factor Less than 1 x 10-4
Index of Refraction1.4585
Constringence (Nu value)67.56
Velocity of Sound-Shear Wave3.75 x 103 m/s
Velocity of Sound/Compression Wave5.90 x 103 m/s
Sonic AttentuationLess than 11 db/m MHz
Permeability Constants at 700 °C(cm3 mm/cm2 sec. cm of Hg)
Helium 210 x 10-10
Hydrogen 21 x 10-10
Deuterium 17 x 10-10
Neon 9.5 x 10-10

Typical properties are average data and should not be used as or to develop product specifications.

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