Wetting behavior and bonding characteristics of bismuth-based glass brazes used to join Li-Ti ferrite systems

Panpan Lin, Tiesong Lin, Peng He, Dusan P. Sekulic

Research output: Contribution to journalArticlepeer-review

16 Scopus citations

Abstract

A series of bismuth-based glass brazes were used to join Li-Ti ferrite. The wetting behavior and bonding characteristics of glass brazes utilized to join Li-Ti ferrite were systematically investigated. The glass brazes feature a good CTEs match, and a favorable wetting ability over Li-Ti ferrite mating surfaces. Upon brazing, the Bi-rich phases (Bi46Fe2O72, Bi12SiO2 and Bi24B2O39) and Zn-rich phase (ZnO) were observed in the Li-Ti ferrite/Bi40 and Li-Ti ferrite/Bi35 joints. The Zn2SiO4, ZnFe2O4 and Bi5Ti3FeO15 whiskers were detected in the Li-Ti ferrite/Bi25, Li-Ti ferrite/Bi20 and Li-Ti ferrite/Bi25-BC joints, respectively. No crystalline phase was detected in the Li-Ti ferrite/Bi30-BF joint. Multiple factors impact the joint strength, such as the three-point bending strength of glass brazes, the CTE match of the glass braze and the Li-Ti ferrite, as well as the crystal phases within the seam. The joint strength has the maximum value of 86 MPa for a Li-Ti ferrite/Bi25-Ba couples. The main impact is attributed to the strengthening effect of Bi5Ti3FeO15 whiskers. The dielectric properties of Li-Ti ferrite/glass braze joints show a stronger frequency dependence than that of Li-Ti ferrite at low frequency. This is attributed to the formation of new interfaces. The glass matrix or a crystal phase with a higher dielectric constant could counteract the decrease in the dielectric constant of heat-treated Li-Ti ferrite. Therefore, the dielectric constant of joint, especially that of Li-Ti ferrite/Bi25-BC joint, would be near that of the original Li-Ti ferrite at a high frequency. Meanwhile, no increase in the dielectric loss tangent of a joint takes place.

Original languageEnglish
Pages (from-to)13530-13540
Number of pages11
JournalCeramics International
Volume43
Issue number16
DOIs
StatePublished - Nov 2017

Bibliographical note

Publisher Copyright:
© 2017

Keywords

  • Bismuth-based glass
  • Dielectric constant
  • Dielectric loss tangent
  • Joint strength
  • Li-Ti ferrite
  • Microstructure
  • Wetting ability

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Process Chemistry and Technology
  • Surfaces, Coatings and Films
  • Materials Chemistry

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