In situ passivation during high pressure gas atomization of improved MRE2Fe14B for high performance permanent magnet applications

P. K. Sokolowski, I. E. Anderson, W. Tang, Y. Q. Wu, K. W. Dennis, M. J. Kramer, R. W. McCallum

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

2 Scopus citations

Abstract

Passivation of RE-containing powder is warranted for large-scale manufacturing of bonded magnets for use in high performance applications. A modified gas atomization chamber allows for a novel approach to in situ passivation of solidified particle surfaces through injection of a reactive gas, nitrogen trifluoride (NF3). The ability to control surface chemistry during processing of fine spherical Rare Earth (RE)-Fe-B powders leads to advantages over current processing methodologies. In particular, the capability to coat particles while "in flight" may eliminate the need for post atomization treatment, otherwise a necessary step for oxidation and corrosion resistance. Formation of RE-type fluorides on the surface was evidenced through x-ray photoelectron spectroscopy (XPS). Gas fusion analysis on coated powders (dia. <45μm) indicated a reduced oxygen concentration of 580ppm. Thermogravimetric analysis (TGA) revealed a decreased rate of oxidation at elevated temperatures up to 300°C.

Original languageEnglish
Title of host publication8th Global Innovations Symposium
Subtitle of host publicationTrends in Materials and Manufacturing Technologies for Energy Production 2007 - Proceedings of Symposium held during the 2007 TMS Annual Meeting
Pages7-17
Number of pages11
StatePublished - 2007
Event136th TMS Annual Meeting, 2007 - Orlando, FL, United States
Duration: 25 Feb 20071 Mar 2007

Publication series

NameTMS Annual Meeting

Conference

Conference136th TMS Annual Meeting, 2007
Country/TerritoryUnited States
CityOrlando, FL
Period25/02/071/03/07

Keywords

  • Atomization
  • Bonded permanent magnets
  • Surface passivation
  • X-ray photoelectron spectroscopy

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