question about magnetic shielding

[helloha]

saw a demo on magnetic shielding on youtube
https://www.youtube.com/watch?v=XVcB3mVyZWw
so trying to find out more about magnet and shield for my future model implementation.

my english suck so pls bear with it, thks

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is it possible to almost 100%, maybe 99.5%, isolate metal object from magnet?

will the shielding material get attract/pull to the magnet?

normally how heavy does a shielding material weight?

what's the life-span of a shielding material before it loses the ability to isolate (or reduce) the influence of the magnetic field?

what's the life-span of a shielding material before it became magnetized by magnet (it's possible, right?) after being continuously exposed to magnet?
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it's even better if u guys can also come out with your own questions regarding magnetic shielding.

[charly2]

Search on google about bismuth and its diamagnetic properties.

[jim_mich]

You need to learn about Mu-metal shielding.

Mu-metal is a range of nickel-iron alloys that are notable for their high magnetic permeability, composed of approximately 77% nickel, 16% iron, 5% copper and 2% chromium or molybdenum.

Basically it conducts magnetism very well. If a box is made from Mu-metal then magnetic forces flow along the metal wall of the box and do not pass through the metal wall into the box. Another similar material is Metglas, which I think is mostly cobalt.

[rlortie]

I purchased and paid dearly for some Mu-metal back in the days when Bill Muller and Bruce Depalma were the popular every day names seeking over-unity.

Yes it does shield to some degree and retains that property, but I was not impressed with the efficiency it gave for the price.

Muller used Metglas, an amorphous metal with unique physical and magnetic properties that combine high permeability in his motor/generator. Not for its shielding properties but for its ability to be magnetized and de-magnetized quickly and effectively with very low core losses. it is not noted as a shielding material.

I would look into Bismuth, it has properties closer to lead and in a lot of manufacturing it is used to replace lead. Its even in your Pesto-Bismal

Ralph

[jim_mich]

Bismuth is contraband in the USA, much like lead. Maybe it's a conspiracy to prevent discovery of some OU property?

[helloha]

Bismuth is contraband in the USA, much like lead. Maybe it's a conspiracy to prevent discovery of some OU property?

Control oil and you control nations; control food and you control the people; control space and you control the world

^o^

http://www.youtube.com/watch?v=qFcz4vm2KPQ
judging from the video, shielding material is still very much highly attracted to the magnet, not something i hoped for.

Magnetic Shielding Foil, that's soooo flexible
http://www.lessemf.com/mag-shld.html#276

[Bill_Mothershead]

somewhat reminds me of these:

http://www.youtube.com/watch?NR=1&v=vUc ... =endscreen

http://www.youtube.com/watch?v=z-vYOXm5 ... ure=fvwrel

[murilo]

Your attention, gentlemen!
There are 2 kinds of known 'magnetic shield', as in below:
- one the that shield one use to block outside/external magnetic interferences against electro/electronic devices and/or parts
- other, a chimera, is the so desired material that WOULD block fields of magnets.
TC!
M

[rlortie]

"jim_mich"]Bismuth is contraband in the USA, much like lead. Maybe it's a conspiracy to prevent discovery of some OU property?

Jim, where did you get the information that Bismuth is contraband in the USA?

I can order it from Wonder magnet.com, it is used to replace lead in shotgun shells which can be bought over the counter at any sporting goods store.

The only "contraband" usage that I am aware of is it is used in airport security detection for detecting guns ammunition and explosives. It does not detect, it is used in the detector.

Bismuth Germanate: a high-Z gamma-ray and charged particle detector
"... A position sensitive detector for 9 MeV gamma rays has been developed as part of a contraband detection system for airports. The system images contraband, such as explosives or drugs, in a geometry similar to medical x-ray computed tomography. A point source of gamma rays shines through an unknown o ..."

Bismuth contraband regarding facial makeup:

http://realizebeauty.wordpress.com/2009 ... l-make-up/

Bismuth is available in the USA, you can purchase in ingot form here:

https://www.google.com/search?q=buy+bis ... =firefox-a

[Rafael Ti]

Bismuth is contraband in the USA, much like lead. Maybe it's a conspiracy to prevent discovery of some OU property?

What?? Strange. I have some experience with Bismuth, can say that 5mm thick plate of Bismuth decreases force between magnets about 20%, maybe 30%. Just filling... Two round neodymium magnets fi16mm/40mm were set N to N /or S to S/ at distance of 20mm. Then I inserted the plate in between. I could fill that the force is less after that. As I said.. 20 to 30%. Also there was no interaction between magnets and Bismuth, at least I couldn't fill it.

[rlortie]

Rafael Ti,

"strange" if it is considered contraband. I await Jim's response as to where he received such information. A Google search brings up 10 pages for sources of Bismuth in all forms, shape and sizes.

Ralph

[jim_mich]

Starting back around 1985, there was a push to ban bismuth, which, like lead, is toxic at certain levels and with certain individuals, but less so than lead. At one time bismuth was used in cosmetic face powder, but then it was found to cause problems, and was banned in cosmetics in France.

About 15 years ago, it was my understanding that the EPA had banned bismuth because it was thought to be toxic like lead, but I can find no documentation to back up my understanding. So I'm probably wrong concerning banning of bismuth.

Please accept my apology. Usually I check my statements before posting, but I was without electric for 36 hours after high winds took down power lines and I was running my wimpy laptop by re-charging it from my pickup, and I didn't have the computer power to double-check before posting. I was going purely on memory.

[rlortie]

Helloha,

suggest you start your search for magnetic shielding or ways to deter it here:

http://www.wondermagnet.com/experiments.html

Check their other links also to learn more about Halbach Magnet Arrays which may hold the answer to that which you seek.

Ralph

[Jon J Hutton]

There is another way to shield a magnet. It is cheating but recently there has been some buzz about the idea for perpetual motion application. Two like poles of a magnet passing between a thin metal, plate will give the effect of attracting and repelling as some of the force of repulsion gets mixed with its attraction to the ferromagnetic material. This is one way. The only other way is to use a superconductor. There is another material that is anamagnetic without super cooling that is more stable, much cheaper but not sure of its ability to repel. It is impossible to shield because there are no monopoles. You can only hope to reroute through mu or one way is to use magnetic pots with a strong spring to cap them. This keeps the flux lines tight, or close to the magnet. In all my research the only way I have found is with a superconductor, but the material cracks so so easy that it can not be made very large and so it is not useful.

This is one of the best videos I have ever seen on magnatisim of different effects of elements

http://www.youtube.com/watch?v=62dez4tD5Ok

[murilo]

Jon,
great link!
Thanx!
M