Vycor
Encyclopedia
Vycor is a glass
with high temperature
and thermal shock
resistance, made by Corning Incorporated. Vycor is 96% silica, but unlike pure fused silica it can be readily manufactured in a variety of shapes.
Vycor products are made by a multi-step process. First, a relatively soft alkali-borosilicate
glass is melted and formed by typical glassworking techniques into the desired shape. This is heat-treated, which causes the material to separate into two intermingled "phases" with distinct chemical compositions. One phase is rich in alkali and boric oxide, and can be easily dissolved in acid
. The other phase is mostly silica, which is insoluble
. The glass object is then soaked in a hot acid solution, which leaches away the soluble glass phase, leaving an object which is mostly silica. At this stage, the glass is porous
. Finally, the object is heated to more than 1200°C, which consolidates the porous structure, making the object shrink slightly and become non-porous. The finished material is classified as a "reconstructed glass".
For some applications the final step is skipped, leaving the glass porous. Such glass has a high affinity for water, and makes an excellent getter
for water vapour. It is widely used in science and engineering.
Immersing the porous glass in certain chemical solutions before the final consolidation step produces a colored glass that can withstand high temperatures without degrading. This is used for colored glass filter
s for various applications.
Corning manufactures Vycor products for high-temperature applications, such as evaporating dishes.
Glass
Glass is an amorphous solid material. Glasses are typically brittle and optically transparent.The most familiar type of glass, used for centuries in windows and drinking vessels, is soda-lime glass, composed of about 75% silica plus Na2O, CaO, and several minor additives...
with high temperature
Temperature
Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...
and thermal shock
Thermal shock
Thermal shock is the name given to cracking as a result of rapid temperature change. Glass and ceramic objects are particularly vulnerable to this form of failure, due to their low toughness, low thermal conductivity, and high thermal expansion coefficients...
resistance, made by Corning Incorporated. Vycor is 96% silica, but unlike pure fused silica it can be readily manufactured in a variety of shapes.
Vycor products are made by a multi-step process. First, a relatively soft alkali-borosilicate
glass is melted and formed by typical glassworking techniques into the desired shape. This is heat-treated, which causes the material to separate into two intermingled "phases" with distinct chemical compositions. One phase is rich in alkali and boric oxide, and can be easily dissolved in acid
Acid
An acid is a substance which reacts with a base. Commonly, acids can be identified as tasting sour, reacting with metals such as calcium, and bases like sodium carbonate. Aqueous acids have a pH of less than 7, where an acid of lower pH is typically stronger, and turn blue litmus paper red...
. The other phase is mostly silica, which is insoluble
Solubility
Solubility is the property of a solid, liquid, or gaseous chemical substance called solute to dissolve in a solid, liquid, or gaseous solvent to form a homogeneous solution of the solute in the solvent. The solubility of a substance fundamentally depends on the used solvent as well as on...
. The glass object is then soaked in a hot acid solution, which leaches away the soluble glass phase, leaving an object which is mostly silica. At this stage, the glass is porous
Porosity
Porosity or void fraction is a measure of the void spaces in a material, and is a fraction of the volume of voids over the total volume, between 0–1, or as a percentage between 0–100%...
. Finally, the object is heated to more than 1200°C, which consolidates the porous structure, making the object shrink slightly and become non-porous. The finished material is classified as a "reconstructed glass".
For some applications the final step is skipped, leaving the glass porous. Such glass has a high affinity for water, and makes an excellent getter
Getter
A getter is a deposit of reactive material that is deliberately placed inside a vacuum system, for the purpose of completing and maintaining the vacuum. When gas molecules strike the getter material, they combine with it chemically or by adsorption...
for water vapour. It is widely used in science and engineering.
Immersing the porous glass in certain chemical solutions before the final consolidation step produces a colored glass that can withstand high temperatures without degrading. This is used for colored glass filter
Filter (optics)
Optical filters are devices which selectively transmit light of different wavelengths, usually implemented as plane glass or plastic devices in the optical path which are either dyed in the mass or have interference coatings....
s for various applications.
Corning manufactures Vycor products for high-temperature applications, such as evaporating dishes.
External links
- Corning Inc. Manufacturer's website
- Momentive Performance Materials, Inc. Quartz and Low Softening Point Glass (LSPG) Manufacturer
- Phase separation in borosilicate and alkali earth silicate glasses