Horace Heffner wrote: > > On May 13, 2009, at 8:32 AM, Stephen A. Lawrence wrote: > > >> >> Also per Wikipedia, the Curie point for iron is 768 C. That's over 500 >> C margin between the hot melt temp and the Curie point, so one would >> guess that hot gluing the magnets is probably harmless. > > The Curie point of iron is irrelevant. However, I am quite surprised to > see the Curie point of Nd-Fe-B magnets is 320 degrees C.
Oops! I didn't look hard enough. Margin between 320 and 195, just 125 C, seems a bit thin, if, as I believe is the case, the magnets become less permanent as one _approaches_ the Curie point. Granted the Curie point represents an abrupt phase transition, none the less that doesn't mean they emerge entirely unscathed from heating to any temperature below that. Gluing to an aluminum disk, AKA a big heat sink, one might also wonder if the magnets might get hotter than usual during the operation as one struggles to get everything hot enough so the glue sticks to the disk rather than just freezing solid as soon as it touches down. > I thought it > was much lower. I've destroyed magnets with heat, but I don't recall > what kind, or how. Maybe soldering. > > > Best regards, > > Horace Heffner > http://www.mtaonline.net/~hheffner/ > > > >
