Joining Joining of silicon nitride with Al-Cu alloys

Abstract

The sessiie drop technique was used to evaluate the equilibrium contact angle and work of adhesion of molten Al-Cu alloys on Si₃N₄ at 1373 K under vacuum. The wettability of Al-Cu alloys on Si₃N₄ is improved by an addition of copper content up to 20 at%. The joining of Si₃N₄ to Si₃Ni₄ was also conducted using Al-Cu filler metal at a brazing condition of 1373 K for 3.8 ksec. The dependence of strength of the Si₃N₄ joint against the copper content in the filler corresponds to the copper content dependence of work of adhesion for molten Al-Cu alloy on Si₃N₄. The superior wettability and mechanical property of filler provide the superior strength of Si₃N₄ brazed with the filler. In particular, the Si₃N₄ joint brazed with Al-1.7 at% Cu filler exhibits the maximum fracture shear strength of 188.3 MPa at room temperature. This superior strength of Si₃N₄ brazed with Al-1.7 at% Cu filler is maintained at elevated temperatures up to 850 K.