Transient liquid phase bonding of HfC-based ceramics

Laura Esposito, Diletta Sciti, Laura Silvestroni, Cesare Melandri, Stefano Guicciardi, Noritaka Saito, Kunihiko Nakashima, Andreas M. Glaeser

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13 Citations (Scopus)


Transient liquid phase (TLP) bonding enables joining at lower temperatures than traditional bonding techniques and preserves the potential for high-temperature applications, making it particularly attractive for joining ultra-high-temperature ceramics (UHTCs) such as carbides and borides. The feasibility of a TLP joint between "pure" carbides has been recently demonstrated. The present study examines the interactions that occur between undoped HfC or MoSi2-doped HfC and a Ni/Nb/Ni multilayer interlayer during TLP bonding. Bonding is performed at 1400 C for 30 min in a high-vacuum furnace. SEM-EDS characterization shows that the reaction layer formed at the interlayer/ceramic interface contains mixed carbides and depending upon the ceramic, Ni-Nb-Hf, or Ni-Nb-Hf-Si, or Ni-Nb-Si alloys. Nanoindentation tests traversing the reaction layer between the bulk ceramic and Nb foil midplane also show a clear transition zone across which the indentation modulus and hardness vary. Crack-free joints have been obtained with undoped HfC. The addition of 5 vol% MoSi2 introduces small (<5 μm long) isolated cracks within the reaction layer, whereas with 15 vol% MoSi2 added, cracking was pervasive within the reaction layer. When the reaction layer exceeds a critical thickness, as in the case of the bond obtained with HfC doped with 15 vol% MoSi2, residual stresses become sufficiently large to cause extensive cracking and bond failure. The results suggest a need to characterize and balance the positive role of additives on sintering with the potentially deleterious role they may have on joining.

Original languageEnglish
Pages (from-to)654-664
Number of pages11
JournalJournal of Materials Science
Issue number2
Publication statusPublished - Jan 2014

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Mechanics of Materials
  • Mechanical Engineering

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