Characteristics and application of quartz glass
2010-05-10 15:21:16 Author：admin Source： Views：0
Quartz glass is a material containing silica,such as crystal, silica., which melting from silicon tetrachloride .
Its silica content is much higher than that of ordinary glass, quartz glass silica content is generally in 99.999.
Quartz glass has excellent optical properties, not only visible light transmittance is particularly good, but also transmiting ultraviolet , infrared.
Quartz glass is a good acid-resistant material, with the exception of hydrofluoric acid and 300degrees of hot phosphoric acid , at high temperature, it ability to resist sulfuric acid, nitric acid , hydrochloric acid, aqua regia, neutral salts, carbon and sulfur, such as erosion, the chemical stability of acid-resistant is 30 times of ceramic equivalent , which is equivalent to 150 times of Ni-Cr alloy and ceramics, resistting high temperature and thermal shock, and thermal expansion coefficient is very small.
Excellent electrical properties of quartz glass, at room temperature, its resistance is equivalent to 10 times of ordinary glass, it is very small dielectric loss for all freguencies, and its insulation strength is great.
Quartz glass also has cosmic radiation resistant, and not through the nature of nuclear fission products.
Quartz glass used mainly for eletric hight sources, semiconductor, optical and other aspects of new technologies.
New type of light source areas: Making high-pressure mercury lamp, long-arc xenon lamp, iodine-tungsten lamp, thallium iodide lights, infrared lights and lamps and so on..
Semiconductor areas: It is a indispensability material in the production process of semiconductor , such as the growth germanium, the silicon crucible, boat furnace core tube and Bell.
In the field of new technologies: Using its sound, light, excellent electrical property to make the ultrasonic delay line on the radar and infrared tracking direction finder, infrared camera, communication, spectrograph, spectrophotometer prism, lens , large reflector window of telescope, high-temperature operating window, the reactor, radioactive devices;rocket,missile nose cones, nozzles and Radome; satellite radio insulation parts, radiation; thermal scales, vacuum adsorption device,precision casting and so on….
Quartz glass is also used for chemical industry,metallurgy,electrical work,as well as scientific research. and so on…
In the chemical aspects: do high-temperature combustion of acid gas, cooling and ventilation devices, acidis solution fo evaporation, absorption cooling material collection, storage devices, distilled water, hydrochloric acid, nitric acid, sulfuric acid, such as the preparation and other items of physical chemistry experiment. In the industry for high-temperature areas:optical glass can be, and crucible body into fluorescent kind, electric furnace core tube , gas burning body radiation in the optical aspects:quartz glass and quartz glass wool can be used for the rocket nozzle, spacecraft theermal cover and observation windows,short,with the development of modern science and technology, quartz glass in various fields receive more extensive applications.
First,heat areas:
The linear expansion coefficient of transparent quartz glass is 5.4 ×10, which is equivalent to an ordinary glass 1/121/20 quartz glass. Due to the low thermal expansion coefficient, the stability are particularly good. Its average specific heat is 0.2510-900℃ , heat exchange rate is 0.0035 cal/cm sec degree (20℃) transparent quartz glass deformation point, annealing point and the operating temperature. See Table2. The performance of transparent quartz glass.
Table2. The deformation point of transparent quartz glass, annealing point and the working temperaure.
The performance of transparent quartz glass
Deformation at 1075℃
Annealing at 1180℃
Softening point 1730℃
Working temperature: For a short period of time 1000℃-1100℃ 1300℃
First, chemical properties:
Quartz glass is a good acid-resistant material, its chemical stability is equivalent to 30 times the acid-resistant ceramics, which is equivalent to 150 times of Ni-Cr alloy and ceramics , especially in high-temperature applications and iconcentrated acid. It is is not eroded by other acid, in particular to high temperature acid-sulfuric acid, nitric acid, hydrochloric acid and aqua regia.
Acid processing time (hours) Temperature(℃) transparent quartz glass (g/sq m)
Sulfuric acid (specific gravity 1.82) 242,050.06
Nitric acid(specific gravity 1.40)
Sulfuric acid (specific gravity 1.19) 24660.14
Sulfuric acid (specific gravity 1.84) 240200.016
Sulfuric acid (specific gravity 1.40) 240200.06
Sulfuric acid (specific gravity 1.19) 240200.18
Second, eletrical performance:
Quartz glass is almost non-electric ion, it is a poor conductor. its dielectric loss is very small for all frequencies. for the solid insulating material, the electrochemical and mechanical properties is superior than other materials. At room temperature, its inherent resistance is 10 ohm cm, which is equivalent to the dielectric constant 3.78 of an ordinary glass . As the temperature increased, the maximum is at 550℃, the conductivity is also very small; it does not appear the of relaxation of structure and deformation at high temperature, so the dieletric loss is very small and voltage insulation is large
Table4. Withstanding Voltage
Temperature(℃) transparent quartz glass voltage (kv/mm)
2043
10037
20032
40017
50010
6005.2
Notes:
1,In the use of gum,we must clean carefully with hydronium water and scrubbed with alcohol. After washing , mustn’t touch it with your hands directly, and must prevent the dust off, or it will loss its purity , andt influence its using time directly.
2, Although the radical-thermal-resistant of quartz glass is very good, but must take into account the expansion coefficient expansion of other substances with the use of other substances, or else it will cause damage.