Microstructural evolution and thermal stress relaxation of Al2O3/1Cr18Ni9Ti brazed joints with nickel foam
Abstract
Joining ceramic to metal is of great significance in both scientific and industrial areas. Al2O3 ceramic and 1Cr18Ni9Ti stainless steel were vacuum brazed using single Ag-Cu-Ti filler metal and Ag-Cu-Ti/Ni foam/Ag-Cu-Ti filler system, separately. The microstructural evolutions of the brazed joints were examined using SEM and EDS, and the mechanical property of the brazed joints was investigated through shear testing. Thermal residual stress was also simulated with ABAQUS software. Results show that the wavelike layer (Fe-Ti + Ni-Ti) in the single Ag-Cu-Ti brazed joint was corrupted due to the presence of Ni barrier and a crack-free brazed joint was achieved, when using Ag-Cu-Ti/Ni foam/Ag-Cu-Ti filler system. Shear strength was significantly improved by 292%, from 18.4 MPa to 72.1 MPa. The thermal residual stress in the joint brazed with Ag-Cu-Ti/Ni foam/Ag-Cu-Ti filler system was more evenly distributed than that of the joint brazed with single Ag-Cu-Ti filler metal, and the maximum thermal residual stress on Al2O3 ceramic substrate decreased from 449.9 MPa to 74.7 MPa.
- Publication:
-
Vacuum
- Pub Date:
- February 2018
- DOI:
- 10.1016/j.vacuum.2017.10.030
- Bibcode:
- 2018Vacuu.148...18S
- Keywords:
-
- Brazing;
- Al<SUB>2</SUB>O<SUB>3</SUB>;
- Stainless steel;
- Microstructure;
- Thermal stress relaxation