In a message dated 04/06/2010, gmvoeth@........... writes:

In the  past I have noticed some of these rare earth magnets are chrome 
plated
and  some are not.
ALSO,
They seem terribly sensitive to  corrosion.



Hi There,
 
    Sm/Co magnets are relatively expensive but do not  corrode at all 
easily.
 
    NdFeB magnets are quite cheap and are usually  protected by several 
layers of Nickel plate. Some are Epoxy coated. It is VERY  IMPORTANT when 
handling these magnets that the surface plating is NOT scratched  or damaged. If 
you are mounting them permanently in a seismometer, I suggest  that you 
mount them in liquid yacht varnish on the baseplate and coat them with  two more 
layers of varnish. Bare NdFeB corrodes quite quickly in damp  air.
 
    Regards,
 
    Chris Chapman






In a message dated 04/06/2010, gmvoeth@........... writes:
In the=20
  past I have noticed some of these rare earth magnets are chrome platedand=20
  some are not.
ALSO,
They seem terribly sensitive to=20
corrosion.


Hi There,
 
    Sm/Co magnets are relatively expensive but do=
 not=20
corrode at all easily.
 
    NdFeB magnets are quite cheap and are usually=
=20
protected by several layers of Nickel plate. Some are Epoxy coated. It is=
 VERY=20
IMPORTANT when handling these magnets that the surface plating is NOT scra=
tched=20
or damaged. If you are mounting them permanently in a seismometer, I sugge=
st=20
that you mount them in liquid yacht varnish on the baseplate and coat them=
 with=20
two more layers of varnish. Bare NdFeB corrodes quite quickly in damp=
=20
air.
 
    Regards,
 
    Chris Chapman