Diffusion bonding of ZrB₂-SiC and Nb using dynamic compressed Ni foam interlayer

The ZrB₂-SiC ceramics were diffusion bonded to Nb using different thicknesses of Ni foam interlayer. The bonding experiments were performed at 750°C, with a pressure of 20MPa and for a bonding time of 60min. A solid state intergranular penetration of Ni was found in ZrB₂-SiC bonding region. The microstructures and chemical compositions of the joint interfaces were investigated by scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. It was found that the Ni foam compression involving extensive ligaments merging and discontinuous interfacial bonding was beneficial for stiffness improvement and stress release. The asynchronous cracking along bonding interface resulted in a ductile failure mode. The maximum shear strength of the joints was 155.6MPa when using 4mm thickness Ni foam as interlayer.