The B-H demagnetization curve maintained at a straight line at 500 ℃, the intrinsic coercivity coefficient β (25 ℃~500 ℃) was - 0.16%/℃, and the maximum operating temperature was up to 533 ℃.
Basing on the measurement results before and combined with the relationship of magnetic parameters of permanent magnet and the character of demagnetization curve, calculating formulas of the position of knee point and temperature coefficient were analyzed and given.