| Author |
Message |
west
Guest
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 Posted:
Tue Sep 13, 2005 6:20 pm Post subject:
Amorphous |
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Hi Rodents,
Amorphous is something without shape, not well organized. In pure metal the
atoms are in a repeatable crystal lattice. I believe that amorphous metal
has atoms that may be randomly (if there truly is randomness) inserted
(impurities?), disrupting that military formation. Please pardon the crude
analogies, but I think that if someone could come up with a better
definition and more importantly tell us why amorphous metal is something
desirable in output transformers, it may possibly enlighten many. Thanks
bunches.
west
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Fabio Berutti
Guest
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| Posted:
Tue Sep 13, 2005 7:33 pm Post subject:
Re: Amorphous |
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All solid metals I know of have a micro-cristalline structure, ie. they're
composed by zillions of small "perfect" crystals separated by borders where
impurities concentrate and the crystal lattice is grossly distorted. These
areas are the reason of the relatively low strength of metals (a single,
perfect crystal holds a traction of some thousands kg per square mm, plain
carbon steel about 40).
When steel is allowed to cool slowly, crystallization occurs in time, while
the mold is still relatively fluid, and crystals grow bigger; in quenched or
tempered steel crystals are smaller.
In GOSS (grain oriented silicon steel, where "grain" means crystal), a
fine-grained steel having a high degree of Si impurities to reduce its
electric conductivity is laminated and "pulled" strongly along the
lamination train; this forces the crystals to rotate until they dispose
(predominantly) in the lamination plane and in the direction of pull. This
way, the crystal lattice axes are oriented the same way (one, say Y, along
the pulling direction and the other 2 randomly), therefore magnetic
permeability is vastly increased in one direction (which will be exploited
for making transformer laminations) and reduced in the other two.
Incidentally, it can be noticed that only C-core transformers will actually
exploit GOSS to the maximum, 'cos the magnetic flux is always in the same
plane AND direction with respect to the laminations. In IE lams, only a
part of the flux will flow in the favorite direction, and then it will be
forced to "cross" it at 90° thus loosing what we gained in terms of core
saturation -> lams pack dimension. I suppose plain IE trannys are best made
out of plain, thin, un-oriented silicon steel lams.
"Amorphous" is not applicable, strictly, to any metal. There are alloys
which form micro-cristalline conglomerates if they're suddenly quenched, or
metal oxides that are easily transformed in ceramics (ie, really amorphous),
but I never heard of a really amorphous metal (in mass, I mean: if You cut a
steel sheet with a laser the cut's edge will be amorphous, but for a
thickness of say 20 atomic layers only).
I suppose that the so-called amorphous core transformers use non-oriented,
microcrystalline metals in non-oriented lams or powder form in order NOT to
have ANY preferential path for the magnetic flow, thus avoiding "local"
saturation or other "orientation-dependent" phenomena to occur.
This can be beneficial in terms of frequency response: radio coils are wound
on laminated cores for very low frequences, on iron powder cores for higher
frequencies and in air for real RFs.
These cores show much lower saturation capability, but it is much less
frequency-dependent: a lam core simply cannot "switch" @ 1MHz due to
magnetic hysteresis.
Is it worth the pain to use "amorphous" cores up to 20-30KHz? I doubt,
particularly if the extra cost is more than say 20-25% of the price of a
similar transformer made out of "plain" steel.
Ciao
Fabio
"west" <westley@Tampabay.rr.com> ha scritto nel messaggio
news:ZmAVe.65783$p_1.49201@tornado.tampabay.rr.com...
| Quote: | Hi Rodents,
Amorphous is something without shape, not well organized. In pure metal
the
atoms are in a repeatable crystal lattice. I believe that amorphous metal
has atoms that may be randomly (if there truly is randomness) inserted
(impurities?), disrupting that military formation. Please pardon the crude
analogies, but I think that if someone could come up with a better
definition and more importantly tell us why amorphous metal is something
desirable in output transformers, it may possibly enlighten many. Thanks
bunches.
west
|
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Phil Allison
Guest
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| Posted:
Wed Sep 14, 2005 4:47 am Post subject:
Re: Amorphous |
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"Fabio Berutti"
| Quote: |
"Amorphous" is not applicable, strictly, to any metal. There are alloys
which form micro-cristalline conglomerates if they're suddenly quenched,
or metal oxides that are easily transformed in ceramics (ie, really
amorphous), but I never heard of a really amorphous metal (in mass, I
mean: if You cut a steel sheet with a laser the cut's edge will be
amorphous, but for a thickness of say 20 atomic layers only).
|
** Amorphous material ( metal strip) is created in a rotating machine that
operates in vacuo.
The base alloy is "atomised" and spattered onto the insides of a spinning
drum - thereby preventing the formation of crystals.
Bit like a " fairy floss " maker at a fair - I imagine.
.......... Phil |
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Fabio Berutti
Guest
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| Posted:
Wed Sep 14, 2005 2:33 pm Post subject:
Re: Amorphous |
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Interesting. Curiously, a similar process of high-vacuum spraying is used
to grow perfect crystals ("epitaxial" technology), under supposedly
different parameters. I wonder how much such a space-age "amorphous metal"
will cost...
Ciao
FB
"Phil Allison" <philallison@tpg.com.au> ha scritto nel messaggio
news:3opd01F6t6dcU1@individual.net...
| Quote: |
"Fabio Berutti"
"Amorphous" is not applicable, strictly, to any metal. There are alloys
which form micro-cristalline conglomerates if they're suddenly quenched,
or metal oxides that are easily transformed in ceramics (ie, really
amorphous), but I never heard of a really amorphous metal (in mass, I
mean: if You cut a steel sheet with a laser the cut's edge will be
amorphous, but for a thickness of say 20 atomic layers only).
** Amorphous material ( metal strip) is created in a rotating machine
that operates in vacuo.
The base alloy is "atomised" and spattered onto the insides of a spinning
drum - thereby preventing the formation of crystals.
Bit like a " fairy floss " maker at a fair - I imagine.
......... Phil
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Patrick Turner
Guest
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| Posted:
Wed Sep 14, 2005 7:48 pm Post subject:
Re: Amorphous |
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Fabio Berutti wrote:
| Quote: | Interesting. Curiously, a similar process of high-vacuum spraying is used
to grow perfect crystals ("epitaxial" technology), under supposedly
different parameters. I wonder how much such a space-age "amorphous metal"
will cost...
Ciao
|
Amorphous transformer cores offer some advantages it is claimed.
But cost is greater, the permissible Bmax is lower, so Fsat is higher for a
given
equal design.
Amorphous cores are brittle like glass, and shatter. They are expensive,
so hardly anyone uses them.
Lundahll are offering them though, you should check them at their site.
Many favourable claims are made about amorphous cored audio trannies,
and I have no advice on which is best.
The amorphous core is made by spinning a mould and spraying molten metal out
where
a very very thin layer rapidly cools to make a thin strip of metal
without the crystaline stucture found in regular grain oriented silicon steels.
This spiral of metal makes a nice low loss tranny at HF.
Buy, try, and listen....
I am over simplifying the industrial process and what goes on; I suggest
you research it to fully understand it.
Patrick Turner.
| Quote: |
FB
"Phil Allison" <philallison@tpg.com.au> ha scritto nel messaggio
news:3opd01F6t6dcU1@individual.net...
"Fabio Berutti"
"Amorphous" is not applicable, strictly, to any metal. There are alloys
which form micro-cristalline conglomerates if they're suddenly quenched,
or metal oxides that are easily transformed in ceramics (ie, really
amorphous), but I never heard of a really amorphous metal (in mass, I
mean: if You cut a steel sheet with a laser the cut's edge will be
amorphous, but for a thickness of say 20 atomic layers only).
** Amorphous material ( metal strip) is created in a rotating machine
that operates in vacuo.
The base alloy is "atomised" and spattered onto the insides of a spinning
drum - thereby preventing the formation of crystals.
Bit like a " fairy floss " maker at a fair - I imagine.
......... Phil
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west
Guest
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| Posted:
Thu Sep 15, 2005 4:08 am Post subject:
Re: Amorphous |
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"Patrick Turner" <info@turneraudio.com.au> wrote in message
news:43283743.7326A066@turneraudio.com.au...
| Quote: |
Fabio Berutti wrote:
Interesting. Curiously, a similar process of high-vacuum spraying is
used
to grow perfect crystals ("epitaxial" technology), under supposedly
different parameters. I wonder how much such a space-age "amorphous
metal"
will cost...
Ciao
Amorphous transformer cores offer some advantages it is claimed.
But cost is greater, the permissible Bmax is lower, so Fsat is higher for
a
given
equal design.
Amorphous cores are brittle like glass, and shatter. They are expensive,
so hardly anyone uses them.
Lundahll are offering them though, you should check them at their site.
Many favourable claims are made about amorphous cored audio trannies,
and I have no advice on which is best.
The amorphous core is made by spinning a mould and spraying molten metal
out
where
a very very thin layer rapidly cools to make a thin strip of metal
without the crystaline stucture found in regular grain oriented silicon
steels.
This spiral of metal makes a nice low loss tranny at HF.
Buy, try, and listen....
I am over simplifying the industrial process and what goes on; I suggest
you research it to fully understand it.
Patrick Turner.
|
| Quote: | FB
"Phil Allison" <philallison@tpg.com.au> ha scritto nel messaggio
news:3opd01F6t6dcU1@individual.net...
"Fabio Berutti"
"Amorphous" is not applicable, strictly, to any metal. There are
alloys
which form micro-cristalline conglomerates if they're suddenly
quenched,
or metal oxides that are easily transformed in ceramics (ie, really
amorphous), but I never heard of a really amorphous metal (in mass, I
mean: if You cut a steel sheet with a laser the cut's edge will be
amorphous, but for a thickness of say 20 atomic layers only).
** Amorphous material ( metal strip) is created in a rotating machine
that operates in vacuo.
The base alloy is "atomised" and spattered onto the insides of a
spinning
drum - thereby preventing the formation of crystals.
Bit like a " fairy floss " maker at a fair - I imagine.
......... Phil
|
Hi Professor,
I would love to research it further. My RDH4E makes no mention. So if you
know a site or 2, please share. Thanks.
west |
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Doug Bannard
Guest
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| Posted:
Thu Sep 15, 2005 4:35 am Post subject:
Re: Amorphous |
|
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west wrote:
| Quote: |
"Patrick Turner" <info@turneraudio.com.au> wrote in message
news:43283743.7326A066@turneraudio.com.au...
Fabio Berutti wrote:
Interesting. Curiously, a similar process of high-vacuum spraying is
used
to grow perfect crystals ("epitaxial" technology), under supposedly
different parameters. I wonder how much such a space-age "amorphous
metal"
will cost...
Ciao
Amorphous transformer cores offer some advantages it is claimed.
But cost is greater, the permissible Bmax is lower, so Fsat is higher for
a
given
equal design.
Amorphous cores are brittle like glass, and shatter. They are expensive,
so hardly anyone uses them.
Lundahll are offering them though, you should check them at their site.
Many favourable claims are made about amorphous cored audio trannies,
and I have no advice on which is best.
The amorphous core is made by spinning a mould and spraying molten metal
out
where
a very very thin layer rapidly cools to make a thin strip of metal
without the crystaline stucture found in regular grain oriented silicon
steels.
This spiral of metal makes a nice low loss tranny at HF.
Buy, try, and listen....
I am over simplifying the industrial process and what goes on; I suggest
you research it to fully understand it.
Patrick Turner.
FB
"Phil Allison" <philallison@tpg.com.au> ha scritto nel messaggio
news:3opd01F6t6dcU1@individual.net...
"Fabio Berutti"
"Amorphous" is not applicable, strictly, to any metal. There are
alloys
which form micro-cristalline conglomerates if they're suddenly
quenched,
or metal oxides that are easily transformed in ceramics (ie, really
amorphous), but I never heard of a really amorphous metal (in mass, I
mean: if You cut a steel sheet with a laser the cut's edge will be
amorphous, but for a thickness of say 20 atomic layers only).
** Amorphous material ( metal strip) is created in a rotating machine
that operates in vacuo.
The base alloy is "atomised" and spattered onto the insides of a
spinning
drum - thereby preventing the formation of crystals.
Bit like a " fairy floss " maker at a fair - I imagine.
......... Phil
Hi Professor,
I would love to research it further. My RDH4E makes no mention. So if you
know a site or 2, please share. Thanks.
west
|
Amorphous magnetic materials were not even dreamed of at the time that
RDH was written. Do a google search on "Amorphous Cores" and you will
get lots of hits. To view the website of one of the largest suppliers,
see http://www.metglas.com
Regards: Doug Bannard |
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Phil Allison
Guest
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| Posted:
Thu Sep 15, 2005 4:47 am Post subject:
Re: Amorphous |
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"Patrick Turner"
| Quote: |
Amorphous cores are brittle like glass, and shatter.
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** Unlikely for a core wound from a very thin, ductile metal tape.
That sounds more like a problem with ferrite cores.
........... Phil |
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Patrick Turner
Guest
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| Posted:
Thu Sep 15, 2005 4:47 am Post subject:
Re: Amorphous |
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west wrote:
Hi Professor,
| Quote: |
I would love to research it further. My RDH4E makes no mention. So if you
know a site or 2, please share. Thanks.
west
|
I don't know any sites explaining amorphous core production.
This time you folks are on your own.
About 4 years ago I raised the subject about amorphous cores on this group.
Maybe the archives have the results, some guys reckoned they were OK to use.
Patrick Turner. |
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