Browsing by Author "Lopez, D."
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Item Development of electric resistance sintering process for the fabrication of hard metals: Processing, microstructure and mechanical properties: Processing, microstructure and mechanical properties(2017-08-01) Lagos, M.A.; Agote, Iñigo; Schubert, T.; Weissgaerber, T.; Gallardo, J.M.; Montes, J.M.; Prakash, L.; Andreouli, C.; Oikonomou, V.; Lopez, D.; Calero, J.A.; EXTREMATThis work presents the development of the Electrical Resistance Sintering (ERS) process for the fabrication of hard metals. The compositions of the materials produced were WC with 6 and 10 wt% of Co. In addition to the specific characteristics of the technology, the characterization of the produced parts is presented and compared to materials obtained by conventional processes. The parts produced by ERS present densities comparable to the ones obtained by conventional methods. The microstructural comparison shows a considerable grain size reduction in the ERS materials which consequently brings a hardness increase. ERS materials show similar fracture toughness to conventional ones. The very fast sintering allows performing the process without any protective atmosphere, therefore making this process very attractive for the production of materials that need to be sintered under non-oxidising environments. The total duration of the cycle, including heating, holding time and cooling is few seconds. Finally, some considerations about the scale up and possible industrialization of the technology are explained.Item Development of the ers process for the fabrication of hardmetal parts(European Powder Metallurgy Association (EPMA), 2016) Lagos, M. A.; Agote, I.; Gallardo, J. M.; Montes, J. M.; Schubert, T.; Weissgaerber, T.; Prakash, L.; Andreouli, C.; Oikonomou, V.; Lopez, D.; Calero, J. A.; EXTREMATIn the past different field assisted sintering processes like Spark Plasma Sintering (SPS) have emerged as potential alternatives to conventional sintering routes. However, the need to use a sintering chamber is the main drawback for its industrial implementation. Work carried out within the EC funded EFFIPRO project includes the development of a novel hybrid electrical sintering process, performed in air with a very short sintering time (few seconds). These features allow an easy industrialization of the process. With the new technology, cutting tools with real dimension and complex shapes were obtained. A complete characterization of the prototypes is presented including density, microstructure, hardness, toughness and magnetic properties. Energy consumption evaluation was also carried out. Density and mechanical properties present values comparable to conventional materials and for that reason this novel process appears to be an excellent candidate as an alternative to the conventional sintering process for certain tools production, specifically for short production series and customised tools.Item Fabrication of chromium carbide cermets by electric resistance sintering process: Processing, microstructure and mechanical properties: Processing, microstructure and mechanical properties(2021-02) Lagos, M.A.; Agote, I.; Leizaola, I.; Lopez, D.; Calero, J.A.; EXTREMATChromium carbide-based cermets are suitable for use in abrasive and corrosive environments. This work presents the fabrication of chromium carbide-based cermets by a very fast sintering process: Electric Resistance Sintering. The thermal cycle duration was less than 1 s and without protective atmosphere. Two different compositions were studied: Cr3C2-25NiCr (wt%) and WC-20Cr3C2-7Ni (wt%). Microstructure and crystallographic phases of the initial powders and sintered materials are presented. In addition, hardness and toughness were characterized and compared to conventional materials. One important issue of ERS is the size and homogeneity of the pieces. This work presents the also the fabrication of a mining wear piece and some aspects about scaling up.