Stress and Damage Analysis of the Innovative BrazingSeams between Al2O3 Ceramic and Nb Metal

This study employs numerical analysis to investigate the influence of seam structure on the residual stress and dam-age state in Al(2)O(3 )ceramic/Nb metal brazed structures. A block of Al(2)O(3 )ceramic and a Nb metal plate are connected with Ag-Cu-Ti filler under high temperature. Alongside the normal seam structure, three novel seam structures are proposed, including the groove-type seam structure, the hole-type seam structure, and the surrounding-cut seam structure. The residual stresses of all four Al2O3/Nb brazed structures are simulated with the finite element method(FEM). The numerical model is verified based on comparison with literature and the residual stress of the normal seam structure is checked against the experimental result. The findings demonstrate that the surrounding-cut seam structure is the most reliable since the surrounding groove can significantly reduce the harmful residual tensile stress by 29.5 % compared to the normal seam structure. Additionally, damage prediction conducted using ANSYS UPFs (User Programmable Features) confirms the reliability of the surrounding-cut seam structure. Besides, as an alternative, proper removal of the filler material from the seam edge can also reduce the harmful residual stress during the brazing process.