Congress contributions

The first time metallic foams were mentioned was in 1926 by Alexandre Meller. Since then the understanding of the behavior has developed so the material can be used for special applications. Nevertheless the mechanical properties are bad compared to solid material. Because of the mean variation of the pore size the strength underlays a variation too. A solution can be to reinforce the matrix with fibers so the mechanical properties can be improved and the variation can be reduced. In a first attempt the aluminum powder is mixed with 2 weight percent cleaned glass fibers and a blowing agent (TiH2) and were compacted with a heated compressing tool. After that the preform can be foamed by an alloy adapted heat-treatment. The preform expands to about 500 percent of the primary volume while the fibers are orientated randomly in the metal matrix so the composite keeps its isotropic behavior. Referring to compression tests the mechanical properties improved. The composite is 20% stiffer and 8% stronger than the non-reinforced foam having the same density. Analyzing the failure behavior, all of the fibers got pulled out of the matrix. To reach higher strength and stiffness the adhesion of the matrix and fibers must be improved. A solution can be to use e.g. carbon fibers or other fibers which can build a compound with the matrix material. Combined with a higher share and longer fibers the reinforced foam can be stiffer stronger and level out the influences of the mean variation of the pore size.

Functionalization by adding conductive fibers into thermoplastic matrices offers a transfer of electrical charge through a plastic component. A percolation network can be generated using contacting particles that create conductive paths through insulating thermoplastic. Injection molding parameters influences the generation of this network, thus electrical conductivity. Especially, the particle orientation and distribution result in obtaining a percolation path. To identify the main influences, a processing parameter study was carried out and verified by FEM flow simulation. A comparison of calculated and measured results shows differences resulting from interactions between individual fibers and variant cooling as a result of altered thermal conductivity. The predictability of flow orientation leads to suitable processing conditions to effect electrical conductivity patterns.