| Criterion to Evaluate the StabiIity of Nd Sintered Magnets for Refrigerant Compressor Motors@@ |
| Tadashi YANAGISAWACMitsuhiro FUKUTACTadashi IIZUKACAkihiko ISHIYAMACMasami WADACYuko OHTANI@ |
This paper concerns the stability of Ndineodymiumj sintered magnets used for high|efficiency DC motors in refigerant compressorsDMany kinds of Nd sintered magnets With and without surface treatment were subjected to the aging test of 140Ž and 1440 hours under three different atmospheric conditions of refrigerantCOilCmOisture content and vacuum level.Mechanical and magnetic properties of the magnet were examinedCand chemical charaCteristics of the oil and refrigerant were also analyzedDAs a resultCmost of the tested magnets retained the satisfactory properties after the aging testCbut some magnets without surface treatment showed deteriorationin magnetic properties.The deterioration was largerunder the condition with higher moisture content Concerning the oils and refrigerantsCno remarkable change in their chemical characteristics was observed after the aging testDThe test conditions employed in@ this study become one of the evaluation criteria ofthe Nd sintered magnetsD |