NdFeb vs. SmCO Magnets

[kitestrings]

Has anyone here used Samarium Cobalt magnets?

https://www.magnet4sale.com/comparison-between-neodymium-magnets-and-smco-magnets/

[SparWeb]

Are you looking at them for corrosion resistance?

The price of SmCo has really come down.   Maybe someday I will, but not yet.

[Adriaan Kragten]

I thought that samarium cobalt magnet are especially chosen for very hot environments.

[kitestrings]

I thought that samarium cobalt magnet are especially chosen for very hot environments.

They reportedly maintain their magnetic properties at high temps, and have better environmental resistance to corrosion.

The latter is my interest/motivation.

I did recently find a 1.5" x 3" x .75" block NdFeb that has a countersunk mounting hole, but to me that is one more place the weather and corrosion might get a start.

[SparWeb]

Before deciding what to do, I would like to know what the corrosion is like on the rotor you are taking down now.
Is it too early to blame the NdFeB material, or could you discover a way that the protection failed to protect them.

[kitestrings]

Is it too early to blame the NdFeB material

Yes, for sure.  Once I get the thing down we can get a better assessment.

On the CMS Magnets site this caught my attention:

Neodymium also has a limitation in that it does not fare well in the weather.  In a year of being outside with normal rain, cold & heat it will crumble and disintegrate. 

I know in salt air conditions there have been some issues, but I had never seen this stated quite so plainly.

[SparWeb]

Plain.  But incomplete.
What surface protection was used?
Is CMS Mags admitting that the mags they supply have ineffective surface plating?

NdFeB is made as sintered powder blocks, which is probably the most vulerable form to corrosion.  Plating is only one step to protect them.  The bonding on the rotor also matters.  So do the primer and paint layers.  Additional sealant may be used.
Each  one of these materials has a chemistry that can be chosen specifically to improve the odds of survival.