A few of my rare-earth magnets have broken after slaming together. I have tried superglue to put them back together but it just ain’t cutting it. Am I out of luck or is there another adhesive I should try?
If it helps, rare-earth magnets are a metalic ceramic.
There are ceramic glues, but the ceramic material RE magnets are made out of is usually pretty “crumbly” once they fracture, and tends to erode and flake away from the fracture site making it very difficult to glue properly.
I may be mistaken, but once a magnet is broken, the broken end takes up the polar opposite of the other end. You will never glue it together.
The bright side is, you now have doubled your magnet inventory!
By the way, want to buy some REALLY STRONG magnets? 
Yes, yes I do.
In fact, if anything that’ll make it easier to put back together, as long as it broke between the poles. If it broke along the poles (i.e., split each pole in half), it could be difficult, though.
Get some cheap old malfunctioning IDE hard drives for a dollar or two (or free) from small local PC fix it / service shops diassemble the drives (torx set in small bit sizes usually necessary) and remove (it might take some muscle) the drive head control magnets. Solid metal and insanely strong & stronger than almost any magnet you can buy commercially for reasonable price.
These magnets are so powerful I’ve used two small ones (glued) to close the dryer door while operating after the mechanical latch broke. When the door closes it CLOSES - “CLUNK!”. I also use them on the fridge to hold up large heavy items. They will pinch your fingers and cause blood blisters if you get some of your finger caught between the magnet & the door when affixing them.
I’ve got a stack of old hard drive magnets. They are very strong. Watch your fingers.
I’ll confirm that; with HD magnets, you can move a paperclip through a thick wooden table, or put one magnet each side of your palm and they will press together quite firmly. They are typically cemented onto a metal plate inside the drive - to remove them, don’t pry the magnet, bend the plate to crack the cement.
Oh, and don’t do what I did - absent-mindedly put one in my back pocket and erased the magstripe on all my credit/bank cards.
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In my office at work we have a 5-foot-tall steel filing cabinet and a couple of hard drive magnets. If you hold the magnet a couple of inches away from the top edge of the filing cabinet and drop it, it won’t hit the floor.
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But are hard-drive magnets more powerful than ceramic rare-earth magnets? Anyone got any numbers to answer this?
No idea, but they are usually:
1:Larger than ceramic magnets (dime/quarter to half dollar size) and thus more useful
2: Metal and thus considerably more rugged than ceramic magnets
3: Incredibly strong
4: Practically free if you have a source for old hard drives
5: Fun, fun, fun!
I believe they are the same thing.
On the other hand, if he broke one pole off without it turning into a new mini-magnet with both poles, he’s got himself a Nobel Prize and a fortune marketing the technique!