Interfacial Reactions between Cu-Zr filler metal and alumina and kinetics of reaction layer growth

Abstract

The interracial reactions and kinetics of the reaction layer growth in Cu-Zr/AlzO3 system were investigated and compared with those in Cu-Ti/A1203 system. Thermodynamic analysis showed that the interfacial reaction can proceed until the activity of aluminum in the Cu-5 at.% Zr filler metal reaches about 0.27 at 1373 K. Growth of reaction layer, ZrO2, was controlled by the diffusion of oxygen through ZrO: layer. The activation energy for ZrO2 growth was 126 kJ/mol. Instead of using a complex redox reaction, a simple oxidation model between reactive metal and oxygen was found to adequately describe the reaction layers growth in ceramic/metal systems. The parabolic rate constant could be expressed in terms of oxygen vacancy concentration at the reactive metal/reactive metal oxide interface. The slower growth of TiO, in comparison with ZrO2, can be rationalized using the parabolic rate constant. The lower diffusion coefficient of oxygen vacancy and a less negative free energy change of TiO formation have a dominant effect over the higher oxygen vacancy concentration at the Ti/TiO interface which resulted in slower TiO growth.

Study on properties of AgCuInTi filler metal for active bonding of alumina ceramic

“…EDS point analysis of the brazed joint was done to determine the chemical composition and identi cation of individual phases (Table 3). According to previous research [17][18][19][20] , active Ti element would react with the Al 2 O 3 matrix and form TiO and TiO 2 during brazing, as given in Eq. ( 1).…”

Formation of Interfacial Reaction Layers in Al2O3/SS 430 Brazed Joints Using Cu-7Al-3.5Zr Alloys

“…This parabolic relationship infers that the growth of the layer was followed by diffusion. Previous studies have suggested that the growth of ZrO 2 was controlled by the diffusion of oxygen through the ZrO 2 layer [25]. This phenomenon can be supported in that, as shown in Figure 6, the reaction front between Zr and α-Al 2 O 3 has moved to inside of the α-Al 2 O 3 , which infers that Al 2 O 3 was decomposed into Al and O ions through the following reaction: Al 2 O 3 → 2Al + 3O.…”