Control of the carbon content in metal hollow sphere structures by variation of the debindering conditions

The present paper highlights results from the priority program Cellular Metals of the Deutsche Forschungsgemeinschaft (DFG SPP 1075), which has been published also elsewhere. The knowledge of the mechanical properties of packed hollow spheres is essential for constructing lightweight hollow sphere structures with an adjustable strength to weight ratio. For a better understanding of the mechanics of hollow sphere structures, it is important to determine the microstructure and the mechanical properties of the cell wall. Due to the amount of organic components needed during the manufacturing of the hollow spheres, the control of carbon content in the final product is very important. At high carbon contents, the formation of carbides may lead to embrittlement and insufficient corrosion resistance. Carbothermic reduction with Fe2O3 addition in the cell walls proved to be a promising approach for the effective removal of carbon. Compression tests showed no effect of the carbon removal in the energy consumption of hollow sphere structures produced with the IFAM (Fraunhofer Institute for Manufactur ing and Advanced Materials) route.