The use of polytetrafluoroethylene in the production of high-density bonded Nd-Fe-B magnets
1994; American Institute of Physics; Volume: 76; Issue: 10 Linguagem: Inglês
10.1063/1.358145
ISSN1520-8850
AutoresC. Tattam, A. Williams, J. N. Hay, I.R. Harris, S.F. Tedstone, M.M. Ashraf,
Tópico(s)Superconducting Materials and Applications
ResumoRotary forging has been used to produce high-density bonded magnets from rapidly quenched Nd-Fe-B based ribbons [MQP-D, of nominal composition 28%Nd-56%Fe-15%Co-1%B (wt %)]. Polytetrafluoroethylene (PTFE), when used as an additive (5%–15% by volume) has been found to act as an effective binder and greatly enhances the forgeability of the MQI, allowing higher forging pressures to be used. Densities of up to 98% of the fully dense composite have been achieved. The forging process can be undertaken in air at room temperature. Magnetically, the compacts are comparable to conventional epoxy resin bonded MQI, with energy products of up to 84 kJ/m3. Equivalent volume fractions of MQI (∼83.5 vol %) have been achieved in the compacts with increased PTFE content due to the displacement of pores by the PTFE. The effect of PTFE content on the mechanical strength of the compacts has been assessed and it has been found that strength increases with increasing PTFE content, consistent with the reduction in porosity.
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