This work aims to better understand the type of thermoplastic binders required to produce highly loaded copper filaments that can be successfully printed via low-cost filament-based material extrusion (MEX). Compounding feedstock material with 55 vol.% of copper and three multi-component binder systems has been performed. The MEX behavior of these feedstocks was evaluated by depositing material at different speeds and appropriately selecting the extrusion temperature depending on the binder composition. The rest of the MEX parameters remained constant to evaluate the printing quality for the different feedstocks. Printable filaments were produced with low ovality and good surface quality. The filaments showed good dispersion of the powder and polymeric binder system in SEM analysis. The feedstock mechanical properties, i.e., the tensile strength of the filament, were sufficient to ensure proper feeding in the MEX machine. The viscosity of the feedstock systems at the adjusted printing temperatures lies in the range of 102–103 Pa·s at the shear rate of 100–1000 s−1, which appears to be sufficient to guarantee the correct flowability and continuous extrusion. The tensile properties vary greatly (e.g., ultimate tensile strength 3–9.8 MPa, elongation at break 1.5–40.5%), and the most fragile filament could not be reliably printed at higher speeds. Micrographs of the cross-section of printed parts revealed that as the printing speed increased, the porosity was minimized because the volumetric flow of the feedstock material increased, which can help to fill pores. This study offers new insights into the feedstock requirements needed to produce low-cost intricate copper components of high quality in a reliable and efficient manner. Such components can find many applications in the electronics, biomedical, and many other industries.

Materials with specific stiffness value above 100 [GPa/(g/cm3)] are typically fiber‑reinforced materials. These materials suffer from the fact that they have anisotropic behavior which means high specific stiffness values can only be obtained in the direction parallel to the fiber. In order to obtain materials with a specific stiffness >60 in all directions, several Titanium based composites have been screened. Fillers based on B4C particles have been identified as most promising to reinforce a Titanium or Titanium alloy matrix for this purpose. For the manufacturing of the composites a rapid hot pressing technique (similar to Spark Plasma Sintering) was used. Besides the assessment and characterization of the Young´s Modulus and the hardness the impact of processing parameters on the microstructure was also investigated.

In this work, the “4M-System” (Machine for Multi-Material-Manufacturing) has been developed by RHP Technology for the manufacturing of Titanium Metal Matrix Composites. This equipment allows the Additive Layer Manufacturing (ALM) of large structures and uses a Plasma Transferred Arc (PTA) as a heat source for depositing feedstocks (powder/wire) layer by layer onto a substrate. Test coupons, made of Titanium powders and having different concentrations of B4C particles, were deposited to form Metal Matrix Composites. Various processing parameters such as deposition rate, travel speed of the torch as well as plasma parameters (power/current/gas flow) were assessed for getting pore- and crack-free samples. After deposition, the specimens were cut and the cross-sections were analysed by optical- and scanning electron microscopy. Furthermore, the hardness, Young’s Modulus, and tensile strength were measured. Ti-Metal Matrix Composite materials resulted in higher strength and Young´s Modulus in comparison to the pure Ti-metal matrix. Using the 4M-System, B4C particle reinforced Ti-MMC’s were successfully manufactured. Thus the 4M-System proved the capability of joining multi-material concepts, which also promises to create graded concentrations of reinforcement in the material.