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crucible

 
Dictionary: cru·ci·ble   (krū'sə-bəl) pronunciation
n.
  1. A vessel made of a refractory substance such as graphite or porcelain, used for melting and calcining materials at high temperatures.
  2. A severe test, as of patience or belief; a trial. See synonyms at trial.
  3. A place, time, or situation characterized by the confluence of powerful intellectual, social, economic, or political forces: "Macroeconomics . . . was cast in the crucible of the Depression" (Peter Passell).

[Middle English crusible, from Medieval Latin crūcibulum, night-light, crucible, possibly from Old French croisuel, cresset. See cresset.]


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Chemistry Dictionary: crucible
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A dish or other vessel in which substances can be heated to a high temperature. See also Gooch crucible.



Thesaurus: crucible
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noun

    A state of pain or anguish that tests one's resiliency and character: ordeal, trial, tribulation, visitation. See easy/hard.

Dental Dictionary: crucible
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(krōō′sibəl)
n

A vessel or container that will withstand high heat and is used for melting or holding material.


Pot of clay or other refractory material, used from ancient times as a container for melting metals or other materials. Modern crucibles may be small laboratory utensils for conducting high-temperature chemical reactions and analyses, or large industrial vessels for melting and calcining metal, ore, or glass, and may be made of clay, graphite, porcelain, or a relatively infusible metal.

For more information on crucible, visit Britannica.com.


[Ar]

A small clay bowl used for re-melting smelted metal so that it can be poured into a mould.

 
Columbia Encyclopedia: crucible
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crucible, vessel in which a substance is heated to a high temperature, as for fusing or calcining. The necessary properties of a crucible are that it maintain its mechanical strength and rigidity at high temperatures and that it not react in an undesirable way with its contents. Porcelain, iron, and platinum are used in the lab; graphite is usually used in industry, but firebrick is also used, especially when vessels of large capacity are needed. The chamber at the bottom of a metal-refining furnace, where the molten metal collects to be drawn off, is known as a crucible.


Veterinary Dictionary: crucible
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A vessel for melting refractory substances.

A 54-hour training event in which Marine recruits are physically and mentally challenged by lack of sleep, minimal food, forced marches, teamwork exercises and leadership opportunities. It is the final major training event of boot camp and is designed to pull together everything they have been taught previously and survive a real challenge. Parents of recruits or potential recruits should be told that while it will be difficult for their child, it is safe and well supervised. It culminates in the Warrior Breakfast and signals a change in their drill instructors from task masters to mentors.

Wikipedia: Crucible
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A crucible is a heat-resistant container in which materials can be heated to very high temperatures. The use of crucibles to manufacture Crucible steel, introduced in England in the eighteenth century, was an important part of the Industrial Revolution.

Contents

Laboratory crucibles

Crucibles used in Czochralski method

A crucible is a cup-shaped piece of laboratory equipment used to contain chemical compounds when heated to extremely high temperatures. Crucibles are available in several sizes and typically come with a correspondingly-sized crucible cover (or lid).

Crucible materials and description

Crucibles and their covers are made of high temperature-resistant materials, usually porcelain or an inert metal. One of the earliest uses of platinum was to make crucibles. Ceramics such as alumina, zirconia, and especially magnesia will tolerate the highest temperatures. More recently, metals such as nickel and zirconium have been used. The lids are typically loose-fitting to allow gases to escape during heating of a sample inside. Crucibles and their lids can come in high form and low form shapes (see this ext. link for photos) and in various sizes, but rather small 10–15 ml size porcelain crucibles are commonly used for gravimetric chemical analysis. These small size crucibles and their covers made of porcelain are quite cheap when sold in quantity to laboratories, and the crucibles are sometimes disposed of after use in precise quantitative chemical analysis. There is usually a large mark-up when they are sold individually in hobby shops.

Crucible after being used
Melting gold in a graphite crucible
Several graphite crucibles of different sizes
Three crucibles used by Thomas Edison.

Use in chemical analysis

In the area of chemical analysis, crucibles are used in quantitative gravimetric chemical analysis (analysis by measuring mass of an analyte or its derivative). Common crucible use may be as follows. A residue or precipitate in a chemical analysis method can be collected or filtered from some sample or solution on special "ashless" filter paper. The crucible and lid to be used are pre-weighed very accurately on an analytical balance. After some possible washing and/or pre-drying of this filtrate, the residue on the filter paper can be placed in the crucible and fired (heated at very high temperature) until all the volatiles and moisture are driven out of the sample residue in the crucible. The "ashless" filter paper is completely burned up in this process. The crucible with the sample and lid is allowed to cool in a desiccator. The crucible and lid with the sample inside is weighed very accurately again only after it has completely cooled to room temperature (higher temperature would cause air currents around the balance giving inaccurate results). The mass of the empty, pre-weighed crucible and lid is subtracted from this result to yield the mass of the completely dried residue in the crucible.

A crucible with a bottom perforated with small holes which is designed specifically for use in filtration, especially for gravimetric analysis as just described, is called a Gooch crucible after its inventor, Frank Austen Gooch.

For completely accurate results, the crucible is handled with clean tongs because fingerprints can add weighable mass to the crucible. Porcelain crucibles are hygroscopic, i. e. they absorb a bit of weighable moisture from the air. For this reason, the porcelain crucible and lid is also pre-fired (pre-heating to high temperature) to constant mass before the pre-weighing. This determines the mass of the completely dry crucible and lid. At least two firings, coolings, and weighings resulting in exactly the same mass are needed to confirm constant (completely dry) mass of the crucible and lid and similarly again for the crucible, lid, and sample residue inside. Since the mass of every crucible and lid is different, the pre-firing/pre-weighing must be done for every new crucible/lid used. The desiccator contains desiccant to absorb moisture from the air inside, so the air inside will be completely dry.

Use in ash content determination

Ash is the completely unburnable inorganic salts in a sample. A crucible can be similarly used to determine the percentage of ash contained in an otherwise burnable sample of material such as coal, wood, or oil. A crucible and its lid are pre-weighed at constant mass as described above. The sample is added to the completely dry crucible and lid and together they are weighed to determine the mass of the sample by difference.

See also

External links


Translations: Crucible
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Dansk (Danish)
n. - svær prøve, smeltedigel

Nederlands (Dutch)
(smelt)kroes, vuurproef

Français (French)
n. - (lit) creuset, (fig) épreuve

Deutsch (German)
n. - Schmelztiegel

Ελληνική (Greek)
n. - χοάνη τήξης μετάλλων (κν. χωνευτήρι), (μτφ.) αποφασιστική δοκιμασία

Italiano (Italian)
crogiuolo

Português (Portuguese)
n. - crisol (m)

Русский (Russian)
тигель, горнило, суровое испытание

Español (Spanish)
n. - crisol

Svenska (Swedish)
n. - smältdegel, svårt prov (bildl.), skärseld

中文(简体)(Chinese (Simplified))
坩锅, 严酷的考验

中文(繁體)(Chinese (Traditional))
n. - 坩鍋, 嚴酷的考驗

한국어 (Korean)
n. - 도가니, 가혹한 시련

日本語 (Japanese)
n. - るつぼ, 厳しい試練

العربيه (Arabic)
‏(الاسم) بودقه الصهر, محنه, امتحان عسير‏

עברית (Hebrew)
n. - ‮כור-היתוך, מבחן רציני‬


 
 
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Dictionary. The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.  Read more
Chemistry Dictionary. A Dictionary of Chemistry. Sixth Edition. Copyright © Market House Books Ltd, 2008. All rights reserved.  Read more
Thesaurus. Roget's II: The New Thesaurus, Third Edition by the Editors of the American Heritage® Dictionary Copyright © 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.  Read more
Dental Dictionary. Mosby's Dental Dictionary. Copyright © 2004 by Elsevier, Inc. All rights reserved.  Read more
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Archaeology Dictionary. The Concise Oxford Dictionary of Archaeology. Copyright © 2002, 2003 by Oxford University Press. All rights reserved.  Read more
Columbia Encyclopedia. The Columbia Electronic Encyclopedia, Sixth Edition Copyright © 2003, Columbia University Press. Licensed from Columbia University Press. All rights reserved. www.cc.columbia.edu/cu/cup/ Read more
Veterinary Dictionary. Saunders Comprehensive Veterinary Dictionary 3rd Edition. Copyright © 2007 by D.C. Blood, V.P. Studdert and C.C. Gay, Elsevier. All rights reserved.  Read more
Marine Corps Dictionary. Copyright © 2003 "Unofficial Dictionary for Marines" compiled and edited by Glenn B. Knight  Read more
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