ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
In the manufacturing of injection molded magnets made from NdFeB (MQ) powder and nylon-12, coupling agents are normally added to prevent NdFeB powders from oxidation in the period of injection processes. The reheological behavior of NdFeB pellets related to the quantities and kinds of coupling agents. The effects of coupling agents on the NdFeB injection molded magnets are seldom presented in literature1 and will be the sub-seldom presented in the literature1 and will be the subject of this work. Five coupling agents (two belong to silane series, two belong to titanate series, and one belongs to the zircoaluminate series) have been investigated and evaluated. Differential scanning calorimetry (DSC) data show that 0.5 wt. % of isopropyle tri(dioctyl)-pyrophosphate titanate has the best result for oxidation resistance. On the other hand, the compression strength and reheological behavior of the bonded magnets are dependent on the kinds of coupling agents. The zircoaluminate coupling agent induces 30% enhancement of compression strength better than other coupling agents. Titanate coupling agents have a lower injection temperature. It demonstrated that the titanate coupling agent can effectively reduce the relative viscosity of the compounds. In the meantime, we did a 100-h environmental test at 80 °C, 90% RH. Experimental results also show that the titanate coupling agents have best anticorrosion ability. Magnetic properties of bonded magnet Br=5.7 kG, Hc=4.5 kOe, iHc=8.4 kOe, and (BH)max=6.7 mGOe can be obtained. Results suggested the titanate coupling agent is the best choice in this study.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.347992
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