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

    Research output: Contribution to journalArticlepeer-review

    17 Citations (Scopus)

    Abstract

    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
    Volume49
    Issue number2
    DOIs
    Publication statusPublished - Jan 2014

    All Science Journal Classification (ASJC) codes

    • Mechanics of Materials
    • Ceramics and Composites
    • Mechanical Engineering
    • Polymers and Plastics
    • General Materials Science
    • Materials Science (miscellaneous)

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