Development and performance of a magnetic ionic liquid for use in vacuum-compatible non-contact seals

Takao Okabe, Daichi Moritaka, Masaaki Miyatake, Yukishige Kondo, Shinya Sasaki, Shigeka Yoshimoto

Research output: Contribution to journalArticle

6 Citations (Scopus)


For the electron-beam machining of optical media, a very low rotational speed is required to enable the precise fabrication of grooves of various depths and widths. In addition, a lubricant with a very low vapour pressure, such as an ionic liquid, and a vacuum chamber are needed to avoid contamination of workpieces. Accordingly, the development of a vacuum-compatible hydrostatic bearing using an ionic liquid is required to satisfy these rotational conditions and nanometre-order machining accuracy. To use a hydrostatic bearing in a vacuum environment, a non-contact vacuum seal is needed to avoid leakage of the ionic liquid used as the lubricant. Furthermore, making a non-contact seal using an ionic liquid requires the development of a new type of magnetic ionic liquid. Therefore, this paper describes the development of such a magnetic ionic liquid, which consists of magnetite (Fe3O4) particles, a newly synthesized dispersant, and a pyridinium-based ionic liquid. The outgassed products from this magnetic ionic liquid were measured when it was applied to a non-contact seal in a vacuum of about 10−6 Pa. In addition, its mechanical properties, such as viscosity and burst pressure as a non-contact seal, were measured. From these investigations, it was found that the developed magnetic ionic liquid would meet the requirements for non-contact seals to be used in vacuum-compatible hydrostatic bearings.

Original languageEnglish
Pages (from-to)97-103
Number of pages7
JournalPrecision Engineering
Publication statusPublished - 1 Jan 2017



  • Hydrostatic bearings
  • Magnetic ionic liquid
  • Magnetic liquid
  • Non-contact seal
  • Vacuum-compatible

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