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| urbana |
 Posted: Thu Aug 21, 2003 9:00 am |
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Do anyone here had listen something about any material having a
condition of increasing or decreasing tensile strength due a
electrical current applied to it?
Or, any material with modification of shape due a electrical current
application?
Is there knowledge of any research in these directions? |
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| Uncle Al |
| Posted: Thu Aug 21, 2003 10:30 am |
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urbana wrote:
Quote:
Do anyone here had listen something about any material having a
condition of increasing or decreasing tensile strength due a
electrical current applied to it?
Or, any material with modification of shape due a electrical current
application?
Is there knowledge of any research in these directions?
Are you hoping for a Puppeteer indestructible hull (Larry Niven's
future history)?
Piezoelectric dielectrics reversibly change shape in response to an
applied voltage. Terfenol-D is reversibly magnetostrictive. Nitinol
and aluminum bronze compositions undergo reversible shape-memory
transformations with IR heating. Light atom metals (aluminum)
electromigrate at high cumulative currents.
At any reasonable wire gauge vs. current, compare the number of
electrons injected/second with the number of atoms in the wire. Hint:
96,485 coulombs is a mole of electrons.
http://www.google.com/
Read the instructions for use.
--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
"Quis custodiet ipsos custodes?" The Net! |
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| Steve Roberts |
| Posted: Fri Aug 22, 2003 9:49 am |
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"urbana" <urbana@laser.com.br> wrote in message
news:bae12b1.0308210700.63d1e419@posting.google.com...
Quote: Do anyone here had listen something about any material having a
condition of increasing or decreasing tensile strength due a
electrical current applied to it?
Or, any material with modification of shape due a electrical current
application?
Is there knowledge of any research in these directions?
I examined a thesis a couple of year sago on work in this area - based on
some Russian work where apparently they significantly reduce the flow stress
of steel during rolling by passing massive DC currents through it. The
Russkies thought the effect might be due to electron-wind enhanced
dislocation motion - me, I reckon it's simply Joule heating. Unfortunately I
can't remember any names !
There are also well-documented effects of electric fields and currents
affecting dislocation motion and flow stress in ionic and compound
semiconductor crystals. Also Russian work, mostly. They did some pretty
esoteric stuff before the 1990's.
Steve |
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| jbuch |
| Posted: Fri Aug 22, 2003 6:12 pm |
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Guest
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Steve Roberts wrote:
Quote: "urbana" <urbana@laser.com.br> wrote in message
news:bae12b1.0308210700.63d1e419@posting.google.com...
Do anyone here had listen something about any material having a
condition of increasing or decreasing tensile strength due a
electrical current applied to it?
Or, any material with modification of shape due a electrical current
application?
Is there knowledge of any research in these directions?
I examined a thesis a couple of year sago on work in this area - based on
some Russian work where apparently they significantly reduce the flow stress
of steel during rolling by passing massive DC currents through it. The
Russkies thought the effect might be due to electron-wind enhanced
dislocation motion - me, I reckon it's simply Joule heating. Unfortunately I
can't remember any names !
There are also well-documented effects of electric fields and currents
affecting dislocation motion and flow stress in ionic and compound
semiconductor crystals. Also Russian work, mostly. They did some pretty
esoteric stuff before the 1990's.
Steve
The Russians seem to have a history of seraching for external fields
that change behavior and structure of matter.
In the mid 1960's I read early translations of this kind of work in
quite a few kinds of materials. WOnderful stuff..... that nobody else
ever seemed to manage to duplicate.
I've forgotten the details but Russian work in the 1980's suggested
major changes in the properties of polymers in high magnetic fields.
I met a government lab worker who had worked on trying to verify this
Russian work for three or four years..... and was at the ends of his
rope. Pretty testy individual.
Jim Buch
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| TTK Ciar |
| Posted: Mon Aug 25, 2003 9:06 pm |
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Guest
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Once upon a time, urbana@laser.com.br (urbana) said:
Quote: Date: 21 Aug 2003 08:00:36 -0700
Or, any material with modification of shape due a electrical current
application?
Yes .. there was work in the 90's in America on metal alloys which
acted like "muscles" by changing between two shapes depending on
whether current was applied or removed. Sometimes they were called
"memory metal".
IIRC, the most successful ones were an alloy of Ti-Ni. I don't
know the ratios. The metal was tempered in one shape, and then when
rearranged it would "remember" that shape when current was applied.
Sorry if I'm wrong about any of this .. it's outside my niche. If
not for the cool-factor, I doubt I'd have remembered it at all.
-- TTK |
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