Time-stability of sintered Nd-Fe-B permanent magnet with lower oxygen content

Time-stability of sintered Nd-Fe-B magnet with lower content of oxygen at different temperatures and humidity conditions for 400 d was investigated. Results showed that the magnetic flux loss was −0.68% for the non-electroplating samples and −0.43% for the electroplating samples at room temperature and average humidity was 25% during 400 d, respectively. The magnetic flux loss of the plated samples was lower than non-plated samples under the conditions of room temperature and with the average humidity of 54%, but the magnetic flux loss of the plated samples was larger than that of the non-plated sample at 80 °C. The magnetic flux loss of electroplated and non-electroplated sintered Nd-Fe-B magnets was less than 1% for 400 d, which showed that the N40SH grade magnets have good time stability.