Effects of interface-edge angle on the bonding strength of a ceramics/metal joint with arc-free surface of interface edges

Abstract

The focus of this study is to clarify the effects of an interface-edge shape on the bonding strength of a ceramics/metal joint. Each silicon nitride-to-nickel joint plate with an arc-shaped free-surface edge was prepared using wire-electric discharge machining after a bonding process. The interface-edge shape was characterized by defining an interface-edge angle as the configuration angle between the interface plane and tangential line at the arc edge of the bonded interface. The dependence of the bonding strength on the interface-edge angle was experimentally verified in the silicon nitride-to-nickel joint with an arc-shaped free surface of the interface edges. The result shows that enlarging or reducing the edge angle from a right angle improved the bonding strength because it reduced the residual stress near the interface edges in the ceramic side. Setting a suitable interface-edge condition using a secondary-bonding process produced the highest strength in a ceramics/metal-joint system. The free surface of the interface edges removed by the secondary-machining process was very smooth. Secondary machining can improve the surface integrity and redistribute the stress concentration because of the removal of the gap at the interface edges. This study demonstrates that secondary machining can be effective for improving the bonding strength.

Keywords

• ceramics/metal joint
• bonding strength
• residual stress
• fracture pattern
• interface-edge condition