In this investigation, particulate composites materials made of epoxy resin matrix with magnetite particles were fabricated via additive manufacturing with the direct ink writing technique. Magnetite is an inexpensive material and the direct ink writing process is not only inexpensive but also easy to adapt to any material. A total of eight formulations were investigated, from which only four were feasible for the printing process: 32.6, 33.6, 35.4 and 41 wt.% of particles. The composites were characterized by scanning electron microscopy, compressive strength, particle size distribution, density, and ductility. Results showed that composites exhibit very competitive mechanical properties even though the process was not vacuum assisted, therefore enabling them to be used in large scale and in other structural applications. Composite can be used in electromagnetic shielding.

Weldability of aluminum-steel joints has been studied mainly to avoid the formation of IMC. Nowadays, there are two ways to control the effect of FexAly in welding: 1) the elimination of IMCs or 2) the generation of a thin and homogeneous layer of these phases. In this way, the present work explores the first route, manufacturing joints aluminum-steel using solid state welding process. In order to evaluate the effect of the welding parameters, temperature measures were carried out during the process as well as the microstructural evaluation using optical microscopy and SEM. Finally, the welded joints were subject to tensile strength tests to evaluate their mechanical behavior and try to stablish the nature of the interfacial bonding between both metals. The microstructural characterization of the joints does not reveal the formation of IMCs; this is attributed to the low temperature reached during the process, lower than 545 °C. The welded joint failures in the TMAZ, in the low hardness zone, product of the over aging of the precipitates β". The nature of the bonding in the interface is not clear yet, but it is considered that the atomic diffusion trough the interface and adhesive bonding favors the joint.

No abstract

No abstract