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Quartz Tube Properties

Technical Data and Reference

Properties of Fused Quartz

Silica is found almost everywhere in nature, it represents almost 1/3 the mass of the earthhhs crust. Vitreous Silica is the generic term used to describe all types of silica glass, with manufacturers referring to the material as either Fused Quartz or Fused Silica.

Manufactured by fusing naturally occuring crystalline silica, either sand or rock crystal, a wide range of products are available. After this process, their appearance wil be wither opaque, translucent or transparent. If the silicon dioxide is synthetically derived, the material produced is commonly called Synthetic Fused Silica.

Vitreous Silica, in all its forms, offers a variety of properties such as:

  • Permeability
  • Extreme Hardness
  • Very Low Coefficient of Thermal Expansion
  • Resistance to High Temperature
  • High Chemical Purity
  • High Corrosion Resistance
  • Extensive Optical Transmission from Ultra-Violet to Infra-Red
  • Excellent Electrical Insulation Qualities
  • Remarkable Stability Under Atomic Bombardment
PROPERTY
ENGLISH & METRIC
SYSTEM VALUE
INTERNATIONAL SYSTEM
OF UNITS (SI) VALUE
Density 2.2 gm/cm3 2.2 x 103 kg/m3
Hardness

 		5.5556.5 Mohsss Scale
570KHN100
Design Tensile Strength 7,000 psi 4.8 x 107 Pa (N/m2)
Design Compressive Strength Greater than 160,000 psi Greater than 1.1 x 109 Pa
Bulk Modulus 5.3 x 106 psi 3.7 x 1010 Pa
Rigidity Modulus 4.5 x 106 psi 7.2 x 1010 Pa
Younghhs Modulus 10.5 x 106 psi 7.2 x 1010 Pa
Poissonhhs Ratio .17 .17
Coefficient of Thermal Expansion

 		5.5 x 10-7 cm/cm °C
(20°C 320°C) 		5.5 x 10-7 m/m °K
(293°K 593°K)
Thermal Conductivity (20° C) 3.3 x 10-3 gm cal cm/cm2 °C 1.4 W/m °K
Specific Heat (20°) .16gm cal/gm 670 J/kg °K
Softening Point 1683°C 1956°
Annealing Point 1215°C 1488°
Strain Point 1120°C 1393°
Electrical Resistivity

 		7(107) ohm cm
(350°C) 		7(107)ohm-m
Dielectric Properties (20°C and 1 MHz) (293°K and 1 MHz)
Constant 3.75 3.75
Strength 5 x 107 volts/mil 5 x 107 V/m
Loss Factor Less than 4 x 10-4 Less than 4 x 10-4
Dissipation Factor Less than 1 x 10-4 Less than 1 x 10-4
Index of Refraction 1.4585 1.4585
Constrigence (Nu value)
Fused Quartz
67.56
67.56
Velocity of Sound-Shear Wave 3.75 x 105 cm/sec 3.75 x 103 m/s
Velocity of Sound-Compression Wave 5.90 x 105 cm/sec 5.90 x 103 m/s
Sonic Attenuation Less than 11 db/m MHz Less than 11 db/m MHz
Permeability Constants (cm mm/cm sec cm of Hg 700°C/973°K)
Helium 210 x 10-10
Hydrogen 21 x 10-10
Deutrium 17 x 10-10
Neon 905 x 10-10
PRESSURE CALCULATIONS
INTERNAL PRESSURE CALCULATIONS
RUPTURE FORMULA FOR TUBING
Because fused quartz is used in applications involving internal pressures, it is helpful to know the maximum pressure that can be applied to a selected fused quartz tube. The formula at right can approximate this information at room temperature.
S = pr/t
Where: S = Hoop Stress in Pa
p = Working Pressure (Pa)
r0 = Inside Radius (mm)
t = Wall Thickness (mm)

This formula can not be used when internal pressure exceeds 100 psi.