Morgan
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Neodymium magnet stuck like a rock to a zinc coated iron slug
So i have this disc magnet about the diameter of a nickel and about 6.5 mm in thickness and the nickel coated neodymium magnet seems to have bonded
with the zinc coated slug which is a little larger in diameter but thinner like a coin, in just a few days. The magnet still has a mirror-like finish
from what I can see but try as I might I can't dislodge the two apart now. Have I discovered a new gluing method or what? I put the magnet on the edge
of a countertop and pressed as hard as I could to no avail. I was afraid the magnet would crack being brittle and all.
I was reading about zinc/nickel batteries but didn't find iany information pertaining to uncanny bonding properties.
The magnet was used to hold a perch for hummingbirds via a silicone bottle cap that sleeves over the bottle, the slug just to help fit the magnet
evenly and fill out the space inside the silicone cap, the perch a top of a lampshade.
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Deathunter88
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Tap it with a hammer and it will come apart.
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Sulaiman
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I'd spray a little WD40 or similar and after 30 minutes or so give it a try.
Tapping with a metal hammer has two possible problems;
the NdFeB may shatter
the steel of the hammer head will stick to the magnet
maybe using a wooden rod, or the wooden handle of a hammer etc. would be safer ?
CAUTION : Hobby Chemist, not Professional or even Amateur
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Morgan
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I guess I'll give that a try but probably the magnet will start spalling and to what end would it be worth it to separate it. Although I can't seen
any corrosion, I suspect there is where the two pieces make contact.
The magnet and slug are inside the purple cap but I don't have a photo of the magnet and slug. The aluminum Coke bottle has its own screw cap on it
and the magnet and slug sit just below the cap and the purple silicone sleeved over the cap.
[Edited on 8-9-2019 by Morgan]
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Sulaiman
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I guess ;
nickel plus zinc plus moisture = electrolytic corrosion
and/or
the compressive force would deform zinc to fill surface imperfections in the nickel, forming a fairly strong bond.
You could thoroughly dry the cap/magnet/disc then fill the cap with something waterproof such as varnish/lacquer or even epoxy resin.
(I have an iron powder toroid & enammeled copper wire transformer, embedded in epoxy resin,
for a ham antenna that has been exposed to the weather for years, with no change in performance)
CAUTION : Hobby Chemist, not Professional or even Amateur
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Morgan
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Encapsulation would probably be the way to go. I bought a few smallish neo magnets that came with colorful protective coatings. They are nice in that
you can scuff them against metal objects without surface harm down the road.
I tried again to separate the magnet without luck but if anyone wants to bond galvanized iron to a neo magnet, mere contact with moisture seems to
work astonishingly well. Maybe down the road it would eventually decay but if coated with a thin layer of epoxy to block the air, perhaps not for some
time.
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