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Surface Coating of Hddr Processed and Mechanically Alloyed Powder Based on RE-TM

Published online by Cambridge University Press:  21 February 2011

S. Kobe ,
S. Novak ,
P.J. Mcguiness ,
D Mandrino  and
M. Jenko
S. Kobe
Affiliation:
Jožef Stefan Institute, 1001 Ljubljana, Slovenia, [email protected]
S. Novak
Affiliation:
Jožef Stefan Institute, 1001 Ljubljana, Slovenia
P.J. Mcguiness
Affiliation:
Jožef Stefan Institute, 1001 Ljubljana, Slovenia
D Mandrino
Affiliation:
Institute of Metals and Technology
M. Jenko
Affiliation:
Institute of Metals and Technology
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Abstract

Chemical surface modification can be used as a method for corrosion protection of sensitive powders based on intermetallic alloys between rare earth and transition metals. Surface coating is used for preventing fine powders, based on Nd-Fe-B, or Sm2Fe17−xTaxN3−δ prepared by HDDR processing and mechanically alloying, from hydrolysis. Powders coated by chemisorbed organic substance, after exposing to a humid atmosphere, do not show any chemical or physical change.

Different coating agents were used and the sufficient amount of various materials was optimised with the emphasis on minimising their quantity. Simple experiment shows that the surfactant is successfully chemisorbed on the powder surface and that the coated powders are hydrophobic indefinitely. Magnetic properties were measured on samples after they were exposed to the same corrosion tests. Measurements on coated and bonded samples were compared with the measurements of non-coated and bonded samples. By using Auger electron spectroscopy the thickness of the coating was controlled. In order to distinguish the nature of the bonding between the powder surface and the surface-active substance FT-IR spectroscopy in absorbency and diffuse reflection modes was used. The protection of the fine particles is based on the formation of a covalent bond between the hydroxyl groups at the particle surface and the surface-active substance. The monomolecular layer of organic substance does not damage the magnetic properties of the powder, but successfully protect the powder against humidity.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 577: Symposium H – Advanced Hard and Soft Magnetic Materials , 1999 , 41
Copyright
Copyright © Materials Research Society 1999

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References

REFERENCES

1. Takeshita, T. and Nakayama, R.: 10th Int. Workshop on RE Magnets and their Applications, Kyoto, Japan (1989), 551 Google Scholar
2. McGuiness, P.J., Zhang, X.J., Yin, X.J. and Harris, I.R.: J. Less-Common Metals, 158 (1989), 359 Google Scholar
3. Schultz, L., Schnitzke, K., Wecker, J., Katter, M., and Kuhrt, C.: J. Appl. Phys., 70 (1991), 6339 Google Scholar
4. Sagawa, M.: Japanese Patent No. 63–38555 (1988)Google Scholar
5. Allibert, C.H.: CEAM, eds. Mitchell, I.V., Coey, J.M.D., Givord, D., Harris, I.R. and Hanitch, R., Elsevier Appl. Science, Barking (1989), 358 Google Scholar
6. Tenaud, P., Vial, F. and Sagawa, M.: J. IEEE Trans. Magn., 26, 5 (1990),1930 Google Scholar
7. Kobe-Beseničar, S., Holc, J., Dražič, G., Saje, B.: J. IEEE Trans. Magn., 30, 2 (1994), 693 Google Scholar
8. Beseničar, S., Saje, B., Dražič, G. and Holc, J.: JMMM, 104–107 (1992), 1175 Google Scholar
9. Burkhardt, C., Harris, I.R., Kobe, S., Vehovar, L. and , Steinhorst: 14th Int. Workshop on RE Magnets and their Applications, Sao Paulo, Brazil (1996), 689 Google Scholar
10. Kobe, S., Williams, A.J., Burkhardt, C., Dimc, F. and Saje, B.: 14th Int. Workshop on RE Magnets and their Applications, Sao Paulo, Brazil (1996), 213 Google Scholar
11. McGuiness, P.J., Škulj, I., Porenta, A. and Kobe, S.: Proc. Of the 15th Inter. Workshop on RE Magnets & Appl., Dresden, Germany (1998) 553–563 Google Scholar
12. Novak, S., Vidovič, K., Sajko, M., Kosmač, T.: J.Europ.Cer.Soc., 17 (1997) 217–223 Google Scholar
13. Wolfrum, S. M., Ponjee, J.J.: J.Mat.Sci.Letters, 8 (1989) 667–669 Google Scholar
14. Zhang, J.G., Edirisinghe, M.J., Evans, J.R.G.: J.Mat.Sci., 23 (1989)2115–2120 Google Scholar
15. Gorter, H., Gerretsen, J., Terpstra, R.A.: Proc. Third Euroceramics V.1, pp. 615–620 (1993) ed. Duran, P., Fernandez, J.F. Google Scholar
16. Egashira, M., Shimizu, Y., Takao, Y., Yamaguchi, R., Ishikawa, Y.: J.Am.Ceram.Soc. 77(7) (1994) 1793–98Google Scholar
17. Egashira, M., Shimizu, Y., Takatsuki, S.: J.Mat.Sci.Letters, 10 (1991) 2115–2120 Google Scholar
18. Metselaar, R., Reenis, R., Chen, M., Gorter, H., Hintzen, H.T.: J.Europ.Cer.Soc., 15 (1995) 1079–1085 Google Scholar
19. McGuiness, P.J., Škulj, I., Porenta, A. and Kobe, S., JMMM 188 (1998) 119–124 Google Scholar
20. Kobe, S., Novak, S., Škulj, I., McGuiness, P.J., Proceedings of the Fifteenth International Workshop on Rare-Earth Magnets and their Application, Ed. Schultz, L., Müller, K.-H., 1998, 897–90Google Scholar
21. Žuzek, K., McGuiness, P.J., and S. Kobe: this conferenceGoogle Scholar