High Pressure

High pressure in science and engineering is studying the effects of high pressure on materials and the design and construction of devices, such as a diamond anvil cell, which can create high pressure. By high pressure it is usually meant pressures of thousands (kilobars) or millions (megabars) of times atmospheric pressure (about 1 bar or 100,000 Pa).

Percy Williams Bridgman received a Nobel prize for advancing this area of physics by several magnitudes of pressure (400 MPa to 40,000 MPa). The list of founding fathers of this field includes also the names of Harry George Drickamer, Tracey Hall, F.P. Bundy, L.F. Vereschagin, Sergey M. Stishov.

It was by applying high pressure as well as high temperature to carbon that man-made diamonds were first produced as well as many other interesting discoveries. Almost any material when subjected to high pressure will compact itself into a denser form, for example, quartz, also called silica or silicon dioxide will first adopt a denser form known as coesite, then upon application of even higher pressure, form stishovite. These two forms of silica were first discovered by high pressure experimenters, but then found in nature at the site of a meteor impact.

Chemical bonding is likely to change under high pressure, when the P*V term in the free energy becomes comparable to the energies of typical chemical bonds - i.e. at around 100 GPa. Among the most striking changes are metallization of oxygen at 96 GPa (rendering oxygen a superconductor), and transition of sodium from a nearly-free-electron metal to a transparent insulator at ~200 GPa. At ultimately high compression, however, all materials will metallize.

High pressure experimentation has led to the discovery of the types of minerals which are believed to exist in the deep mantle of the Earth, such as silicate perovskite, which is thought to make up half of the Earth's bulk, and post-perovskite, which occurs at the core-mantle boundary and explains many anomalies inferred for that region.

Pressure "landmarks": pressure exerted by a fingernail scratching is ~0.6 GPa, typical pressures reached by large-volume presses are up to 30-40 GPa, pressures that can be generated inside diamond anvil cells are ~320 GPa, pressure in the center of the Earth is 364 GPa, and highest pressures ever achieved in shock waves are over 100,000 GPa.

Other articles related to "high, pressure, high pressure, high pressures":

Liquid Fluoride Thorium Reactor - Power Generation - Brayton Cycle
... The high-pressure working gas is expanded in a turbine to produce power ... The low-pressure warm gas is cooled in an ambient cooler ... The low-pressure cold gas is compressed to the high-pressure of the system ...
Development of The Cornish Engine
... The Cornish engine depended on the use of steam pressure above atmospheric pressure, as devised by Richard Trevithick in the 19th century ... the two principles, starting with high pressure steam but also condensing it in a separate condenser ... one at Wheal Chance (operating at 40 pounds per square inch above atmospheric pressure, which achieved a duty of nearly 50 million, but its duty then fell back ...
Scott 2.2/ 3.5/ 4.5 Air-Pak SCBA - Valve Assembly
... between the cylinder and the hose (which will send the air to a pressure reducer) ... alloy, and is angled to reduce stress of the connection made between to the high pressure female coupling of the high pressure hose ... This burst disk protects the user against situation where the pressure in the bottle would increase with exposure to heat during a fire ...
Allotropes Of Iron
... At atmospheric pressure, there are three allotropic forms of iron alpha iron (α) a.k.a ... At very high pressure, a fourth form exists, called epsilon iron (ε) hexaferrum ... experimental evidence exists for another high-pressure form that is stable at very high pressures and temperatures ...

Famous quotes containing the words pressure and/or high:

    By school age, many boys experience pressure to reveal inner feelings as humiliating. They think their mothers are saying to them, “You must be hiding something shameful.” And shucking clams is a snap compared to prying secrets out of a boy who’s decided to “clam up.”
    Ron Taffel (20th century)

    People nowadays have such high hopes of America and the political conditions obtaining there that one might say the desires, at least the secret desires, of all enlightened Europeans are deflected to the west, like our magnetic needles.
    —G.C. (Georg Christoph)