Joining technologies and mechanical properties for a new kind of 3D wire structures

The present study shows that it is possible to join 3D wire structure by brazing. It is proved that the cross points are filled with molten soldering metal by exploitation of the capillary force. To compare these modifications, the 3D wire structure specimens of two different metals with non-joined and joined nodes have been analyzed with regard to their mechanical performances under compressive loading. The results show that the joining leads to increased strength and stiffness of such structures. Highest stiffness and yield strength was achieved with brazing paste Ni102 (of Umicore AG & Co. KG) but the realized dip coating process is not as reproducible as e.g. the deposition processes. For future prospects a good ductility under load is requested to obtain high energy absorption of such structures. Therefore ductile copper or copper-alloys seem to be promising brazing solders because no brittle phases in the joint were observed. The gained results are an important step within the ongoing research project to create sandwich panels with 3D wire structures as core-layer were the metal coating can be used as bonding material to braze the structure itself and also the cover plates in one step. The present study serves for better evaluation which joining technology to choose for a good compromise between reproducibility, mechanical performance and economic processing.