Nitrogen‐containing steels have become an attractive material in industrial fields due to their excellent mechanical properties. Nevertheless, the current manufacturing methods to produce nitrogen steels are linked to technologies with high working pressures. Alloying elements such as Cr, Mn, and Mo enhance the solubility of nitrogen in the melt, which allows the production at atmospheric pressure. Herein, carbon–nitrogen martensitic steels are produced at low pressure (7 × 105 Pa). The composition is designed through the CALPHAD method using two carbon contents (0.7 and 1.3 wt%). The alloy is produced in an induction furnace under N2 atmosphere to mitigate desorption. Thermomechanical and heat treatments are performed. The alloys are analyzed using optical emission spectroscopy, X‐ray diffraction, optical microscopy, and scanning electron microscopy (SEM) with energy‐dispersive spectroscopy (EDS). The mechanical evaluation is conducted using hardness analysis. The steel presents a nitrogen content of 0.15 wt%, in agreement with the thermodynamic calculations. SEM and EDS results show the presence of Cr and Nb precipitates in a martensitic structure. The highest hardness values are obtained in specimens heat treated by tempering at 400 °C for 2 h and air cooling, achieving 57.4 and 59.7 Hardness Rockwell C for samples with 0.7 and 1.3 wt% C, respectively.
The effect of speed and time of stirring for AA6063 matrix manufactured by Electric Induction Furnace and reinforced 0.75wt.% and 1.5wt.% of Al2O3 nanoparticles is studied. The Specimens produced were subjected to tensile, microhardness, and tribology tests. It is observed that an increase in the speed and agitation time for AA6063 samples reinforced with 0.75%, favors an increase in the grain size, while an opposite effect is observed with the pieces produced with 1.5%, where a grain refining effect is favored, affecting the mechanical properties of the reinforced alloy.
The process of recovering metals from electronic waste has become an important topic in recent years. In this work, the recovery of electrolytic copper from the ashes produced during the pyrolysis process of waste electrical and electronic equipment (WEEE) was sought. Three gravimetric separation equipment were used: Wilfley table, JIG screen, and mechanical screen. This last method was used with and without previous grinding processes. The ashes were initially characterized by XRD to determine the phases present. The initial concentration of the ashes was carried out by physicochemical classification. The results obtained show that the JIG sieve separation processes obtained the best performance, reaching a percentage of about 87% of recovery of the metal present within the WEEE ashes during 16 minutes. The application of a vertical gravimetric separation system on material samples with a fairly wide density difference allowed an optimal separation system for the metallic material and the produced ash. On the other hand, the application of screens in the recovery of the metal obtains values much lower than those obtained by JIG sieve.
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