New approaches to joining ceramics for high-temperature applications

Micro-designed multilayer interlayers have been used to join both oxide and non-oxide ceramics. The approach allows the formation of ceramic-ceramic joints with high melting point metals at temperatures that are typically several hundred degrees lower than those required for more conventional joining methods. The new joining approach employs a thin transient liquid phase (TLP) layer to allow joining by a brazing-like process. Several distinct interlayers have been used to join alumina ceramics successfully; work using Ni-based interlayers has demonstrated the potentially beneficial impact of ''reactive'' metal additions to the TLP. The method has also been applied to the joining of silicon-based ceramics, and has led to the fabrication of joints with reproducibly high strengths. (C) 1997 Published by Elsevier Science Limited.