Metallic Hollow Sphere Structures Manufacturing Process

AbstractThis paper focuses on manufacturing process of regular Metallic Hollow Sphere Structures (MHSS) through brazing technique. As a large stress level is generally confined into the necks formed by brazed spheres, the influence of the filler material on mechanical behavior of cellular metal has been studied. The microstructures of joints resulting from nickel hollow spheres brazing with different commercial fillers “MBF 30” and “MBF 1006” were compared by Scanning Electron Microscopy (SEM) and microhardness testing. These studies revealed a wide boron diffusion into nickel shells through grain boundaries for “MBF 30” brazing, with the formation of borides in a fine brittle eutectic structure. Conversely it was observed that the eutectic structure concentrates at the necks for “MBF 1006” and can be completely eliminated by diffusion-brazing, despite of the shells thinness. The uniaxial compressive tests of HSP specimens have shown two different strain mechanisms depending on brazing process.