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Propeties of magnet

  1. Aug 1, 2006 #1
    Hi friends,

    i have question will the magnet be able to stick to the steel ,when steel is at 150 degreee centigrade in same wave as it will stick to it at normail temperature.

    Please advice or give me the resourses to find magnet properties.

    Prashant Bidikar
  2. jcsd
  3. Aug 1, 2006 #2


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    This depends on the specific magnet material and the type of steel. For most common magnets (except NdFeB) and steels, there will be only a small (<20%, would be my guess) reduction in the force at 150C. Most steels have a Curie Temperature of about 500-600C, so I imagine they don't change by much until about 300C or higher. The problem is more with the magnet, and there are two points to consider here:
    (i) are we well below the Curie point of the magnetic material, and
    (ii) if the magnet is bonded, are we below the safe working temperature of the binder?

    At 150C, you can not use an NdFeB magnet, but I think most other kinds will work.

    PS: Here's a link that tells you about maximum working temperatures of different magnet types.

    Here's a better link:
    Last edited: Aug 1, 2006
  4. Aug 1, 2006 #3
    The flux density of a ferromagnet decreases with increasing temperature untill a point at which the electron configuration changes, because the molecules have sufficient energy to change configuration at high temp, and the substance becomes paramagnetic. I think its called the Curie temperature, and it varies for different metals/alloys.

    So it wont stick to it "in the same way" as in, the magnetic flux will be weaker. But it will still stick to it provided its below the curie temperature.

    i think :P
  5. Aug 2, 2006 #4


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    That's pretty close. But there's two points to consider. (i) The magnetization does not typically fall away much until you get close to the Tc, and then it decreases drastically. So, you can often heat a ferromagnet up to about 70% of Tc and see less than a 30% reduction in magnetization (from the 0K value). (ii) However, with most bonded magnets, there's a lower constraint on the working temperature due to the polymeric binder that's used to hold together the particles of the magnet.

    A typical magnetization vs temperature curve looks something like this: http://magician.ucsd.edu/sio247/lectures/html/lecture3/lecture322x.gif
  6. Aug 2, 2006 #5
    Yeah thanks, i figured it wouldnt be linear but wasnt sure.

    Intresting curve profile, does it change considerably for various materials?

    How are the electron spins distributed in the three materials (para, dia and ferro) , do any of them follow a gaussian distribution?
    Last edited: Aug 2, 2006
  7. Aug 2, 2006 #6


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    Distributed as a function of what?
  8. Aug 2, 2006 #7
    A distribution ain't a function!

    A distribution is just a record of which values of the variable in question are how probable. Now, the (random - so to say) variable itself could depend on some other parameter - say time. Then the distribution itself becomes a function of time. So at each instant, the snapshot of the distribution could look different.
  9. Aug 4, 2006 #8
    Why would a distribution not be a function? It is most definately a function - albeit it may be a non-continuous one.

    Maxwell-Boltzmann distribution, Planck distribution, radial distribution, etc...these are all functions of a variable (velocity, energy, radial seperation, respectively).

    A normalized probability distribution is a function that maps some domain to the real interval [0,1]
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