Metal to ceramic joining via a metallic interlayer bonding technique

The lack of suitable joining techniques for dissimilar materials such as metal and ceramic for high-temperature applications and devices is a major hindrance to the utilization of their outstanding properties and lower costs. This paper presents the results of joining between the high-temperature and corrosion resistant iron-chromium-aluminium alloy (Fecralloy) with silicon nitride by use of metallic interlayer. The primary objectives were to produce joints for high-temperature applications (above 500 degreesC) and to observe the effects of processing parameters with regards to joint strength. Joining by use of a thin (12.5 mum) and non-remaining copper foil produced joints with an average maximum shear strength of 67.5 MPa (+/-5) at 1100 degreesC, 30 min dwell time at 9.5 MPa, under vacuum. The processing conditions were found to play a very important role in the joining process and effected joint strength. The results suggest that a thin aluminium nitride, AIN, reaction product layer was present on the silicon nitride interface in the joined samples. This is an indication that reactive wetting was occurring. Iron, chromium, aluminium and copper were found to infiltrate the silicon nitride, whilst silicon and nitrogen diffused into the Fecralloy. Joining was also attempted using a Ti/Cu/Ti multilayer and its variations. Joining was not possible due to the formation of a brittle reaction product layer, highlighting that wetting and joining are not synonymous. (C) 2003 Elsevier B.V. All rights reserved.