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SCH3U1 summative!

Weijie Liu

on 25 April 2011

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Transcript of CRYOGENICS

CRYOGENICS The study of the properties and behaviours of materials in extremely cold temperatures OVERVIEW What is Cryogenics? Cryogens Metal Treatment Superconductivity Superfluidity Temperature and Kinetic Theory
Sub-studies Liquefied Gases Nitrogen
Oxygen Austenite
Martensite What It Is
BSC Theory
Industrial Applications What It Is
Bose-Einstein Condensation
Industrial Applications Cryogenics eh? Phase Transitions What will happen if the temperature
keeps droping? Temperature and Kinetic Theory Temperature is related to kinetic energy like this

in other words, they are proportional. Therefore, the colder something is, the less the particles move. Sub-studies Cryobiology: effects of low temp on organisms

Cryonics: preservation of humans/animals with the intent of reviving the bodies in the future.
continuing... Cryoelectronics: superconductivity at low temps

Cryotronics: practical applications of superconductivity
Cryogens Liquefied gases used as coolants are called cryogens.
They are manufactured through the cryogenic distillation process. They are stored in Dewar Flasks. Several Risks... Cold burns if handled without proper equipment.
Container could explode due to high expansion rate when gases vaporize.
Liquid Nitrogen Boils at 77K (-196C)

The most common (and cheapest) industrial coolant. Eg. used to preserve biological samples.
However, inefficient as it boils immediately upon contact. Liquid Oxygen Boils at 90K (-183C)

Part of rocket fuel in order to allow combustion to happen in outer space. Eg. NASA Centaur and Saturn V rockets. Metal Treatment Austenite Martensite An industrial cryogenic freezer.

It converts 99.8-100% of the austenite to martensite.
Regular treatment only converts 60-80% Superconductivity The phenomenal of zero electric resistivity in a metallic/ ceramic conductor as temperature decreases below the critical temperature.
Without resistance, a current can be carried forever without losing energy. However, there is no reliable method of predicting whether a material superconducts or not. Types of Superconductors Organic Compounds
(TMTSF)2X, where TMTSF is tetramethyltetraselenafulvalene and X is an inorganic ion (eg. PF6-). A15 Compounds A3B, where A is a transition metal.
Based on Niobium and arranged in this fashion: Copper-Oxide Compounds Higher critical temperature than A15 compounds.
Contains conductive "planes" of copper and oxygen atoms.
3 sub classes: Class 1:
where A is barium, strontium, or calcium

Tc= 40K (-233C) Class 2:
where δ<1.

Tc=92K (-181C) Class 3:
where n is the number of CuO planes

Tc increases proportional to n How does it work though? BSC Theory • In ordinary conductors, flowing electrons collide with the irregularities in the metal conductor, resulting in a lose of energy. However, in the super cold temperature range of superconductivity, electrons pair into Cooper Pairs and distorts the lattice of metal atoms in a way that allows the pair to pass through without bumping into anything. The theory describing how superconductors form is BCS Theory. In ordinary conductors, flowing electrons collide with the irregularities in the metal conductor, resulting in a lose of energy.
However, in a cold superconductor, electrons pair into Cooper Pairs and distorts the lattice of metal atoms in a way that allows the pair to pass through without bumping into anything.
No bumps means no loss of energy!
Cooper Pairs will only stay together in cryogenic temperatures. Industrial Applications Power transmission: large amounts of electricity can be transported across enormous distances without any loss.

Particle detectors, large currents in a superconductor generates powerful magnetic fields used to discover exotic particles Magnetic Levitation trains: trains are floating on top of the rails, allowing it to go at super fast speeds. (Meissner Effect) Superfluidity Similar to how conductors experience no resistance below a critical temperature (lambda point), the viscosity of certain liquids drops to zero , thereby becoming a superfluid.

Most common superfluid is Helium (2.172K or -271C). It exhibits rapid and frictionless flow through microscopic channels and has enormous heat capacity. Why does this happen? Bose-Einstein Condensation Bose Statistics: certain rules which dictate whether 2 photons are identicle or different
Einstein applied this idea to atoms. His equations implied that at low enough temperatures, some atoms would condense into the lowest level.
A consequence of such state is that there is no way to differeniate between the separate atoms. Industrial Application Also as a cryogen, except more effective and expensive. Eg. IRAS satellite’s telescope THE END! Works Cited BEC - What is it and where did the idea come from?. (n.d.). University of Colorado Boulder. Retrieved April 24, 2011, from http://www.colorado.edu/physics/2000/bec/what_is_it.html
Campbell, L. (n.d.). Superfluidity. AccessScience. Retrieved April 24, 2011, from http://www.accessscience.com.ezproxy.torontopubliclibrary.ca/content.aspx?searchStr=Superfluidity&id=668900
Daney, D. (n.d.). Cryogenics. AccessScience. Retrieved April 24, 2011, from http://www.accessscience.com.ezproxy.torontopubliclibrary.ca/content.aspx?searchStr=Cryogenics&id=169900
Dull, R. (n.d.). A Teacher's Guide to Superconductivity for High School Students. HowStuffWorks. Retrieved April 24, 2011, from http://www.howstuffworks.com/framed.htm?parent=superconductivity.htm&url=http://www.ornl.gov/reports/m/ornlm3063r1/contents.html
Langenberg, D. (n.d.). Superconductors. AccessScience. Retrieved April 24, 2011, from http://www.accessscience.com.ezproxy.torontopubliclibrary.ca/content.aspx?searchStr=Superconductivity&id=668700
Nave, C. (n.d.). Liquid helium, superfluidity. HyperPhysics. Retrieved April 24, 2011, from http://hyperphysics.phy-astr.gsu.edu/hbase/lhel.html#c1
Nave, C. (n.d.). Superconductivity. HyperPhysics. Retrieved April 24, 2011, from http://hyperphysics.phy-astr.gsu.edu/hbase/solids/scdis.html#c1
Using a cryogenics process to improve wear resistance in metals, extension of heat treatment cryogenic stress relief. (n.d.). Cryotron Cryogenic equipment and cryogenic services. Cryogenic treatment of metals, cryo equipment tempering stress relief freezing metal tool steel. Retrieved April 24, 2011, from http://www.cryotron.com/cryogenic-wear-solutions.htm
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