Mechanical properties of brazed ultra-thin GH99 honeycomb sandwich structure

In this study, aiming at the fabrication of lightweight ultra-thin metal thermal protection structures, an ultra-thin sandwich structure was fabricated by vacuum brazing. The brazing interface of the sandwich structure and the microstructure of the base metal were characterized by optical microscope and scanning electron microscope. The interfacial peel strength and in-plane/out-plane compression properties of the sandwich structure were tested by a universal testing machine and compared with the finite element simulation results. The results showed that the grains of base metal transform from annealed twin structure to equiaxed structure before and after brazing. The brazing interface is mainly composed of the eutectic structure of Ni(s, s) and Ni₃Si, accompanied by a certain Cr(Mo, Ni) solid solution, Ni₂Si and NiSi₂ phases. The interfacial delamination failure occurred on the thin-walled panel. Both the in-plane and out-of-plane compression failures of the sandwich structure were buckling failures, and the simulation results were consistent with the experimental results.