Browsing by Author "Agote, Iñigo"
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Item Aluminides(Elsevier, 2017-01-01) Agote, Iñigo; Lagos, Miguel A.; EXTREMATCombustion synthesis methods can be used to obtain different aluminides starting from elemental powders. Combustion synthesis of the aluminides typically begins when the system reaches the initiation temperature, and a SHS reaction begins at the metal interface. Because of its high specific mechanical properties and corrosion resistant behavior, TiAl is one of the most attractive aluminides, however because of the low adiabatic temperature of the Ti+Al reaction (Tad=1244°C), the system needs additional activation energy to support the synthesis process in self-sustaining mode.Item Development of Beta Titanium Alloys by Spark Plasma Sintering(2017) Lagos, M.A.; Amigo, A.; Vicente, A.; Agote, Iñigo; EXTREMATBeta titanium alloys have attracted considerable attention especially for orthopedic implants applications owing to their unique combination of low elastic modulus, superior bio-corrosion resistance and excellent biocompatibility. However, the PM production of these alloys is difficult due to the significant amount of refractory metals (Ta, Mo, Zr, Nb, etc). This work presents a processing route combining mechanical mixing of elemental powders (pre-alloying) and Spark Plasma Sintering in order to obtain fully dense materials with homogeneous microstructure. Two different compositions (TiMo and TiNb) with high amount of alloying elements were developed. The alloys were sintered at temperatures between 1100 and 1250ºC. The phases were evaluated by X-ray diffraction and diffraction of backscattered electrons, appreciating its mechanical properties by micro-hardness and bending tests. A transformation to Beta Titanium is obtained predominantly with a small grain size, and micro-hardness in the order of forged materials.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 Foams(Elsevier, 2017-01-01) Agote, Iñigo; Lagos, Miguel A.; Gutiérrez, Manuel; Sargsyan, Ara; EXTREMAT; SGInorganic porous materials have been widely investigated owing to their outstanding properties, such as large surface area, low density, mechanical stability, and good permeability. Some interesting examples of foams obtained by SHS are presented. Porous NiTi shape-memory alloys (SMA) with ideal pore characteristics and high strength for hard tissue implants have been fabricated by combustion synthesis. MoSi2–Al cermet foams may be obtained under the combustion mode using PTFE as foaming agent.Item Fully dense CM247LC alloy obtained by Binder Jetting. Characterization of the processing route(European Powder Metallurgy Association (EPMA), 2020) Sainz, Shandra; Iturriza, Iñigo; Agote, Iñigo; Azurmendi, Naiara; Lores, Asier; EXTREMATThe additive manufacturing of CM247LC nickel-based superalloy, has a high development potential for applications where high temperature resistance and geometrically complex parts are required. In order to avoid the hot cracking response related to laser beam manufacturing technologies, Binder Jetting (BJ) is explored for processing the material. For this research study, a non-commercial powder was specifically produced by gas atomization and the characteristics of the different batches analysed. As a means for increasing the density of the samples printed by BJ, different sintering conditions were studied, and hot isostatic pressure was applied after sintering to fully consolidate the material. An exhaustive microstructural characterization was carried out in each step of the route that covers the entire process chain, from the production of the powder to the post processing operations. Therefore, this study sheds some light on the microstructural evolution towards the manufacturing of fully dense CM247LC parts by Binder Jetting.Item Hard Metal Production by ERS: Processing Parameter Roles in Final Properties: Processing parameter roles in final properties(2019) Gallardo, José; Agote, Iñigo; Astacio, Raquel; Schubert, Thomas; Cintas, Jesús; Montes, Juan; Torres, Yadir; Cuevas, Francisco; EXTREMATCemented carbide is a hard composite material, used widely in a variety of industries. The value of the global tungsten carbide market is expected to grow by 4.4% (compound annual growth rate) from 2017 to 2022. One of the main markets is in metal cutting and wear parts, where small pieces (or inserts), a few grams in weight, are used. Field-assisted sintering technique (FAST) technologies allow for the production of small blanks in a single step from powder, which are near final dimensions. Production cycles are very short. In this paper, one of the FAST processes, the ERS technology, is applied to obtain WC10Co parts. A review of the process variable effects on the final properties of the parts is accomplished. Final properties of a range of conventionally produced inserts are obtained, using 100 MPa compacting pressure, 80 MA/m2 of current density, and processing times of around 800 ms.Item Investigation of the Microstructural and Thermoelectric Properties of the (GeTe)0.95(Bi2Te3)0.05 Composition for Thermoelectric Power Generation Applications(2014) Weintraub, Lior; Davidow, Joseph; Tunbridge, Jonathan; Dixon, Richard; Reece, Michael John; Ning, Huanpo; Agote, Iñigo; Gelbstein, Yaniv; EXTREMATIn the frame of the current research, the p-type Bi2Te3 doped (GeTe)(0.95)(Bi2Te3)(0.05) alloy composed of hot pressed consolidated submicron structured powder was investigated. The influence of the process parameters (i.e., powder particles size and hot pressing conditions) on both reduction of the lattice thermal conductivity and electronic optimization is described in detail. Very high maximal ZT values of up to similar to 1.6 were obtained and correlated to the microstructural characteristics. Based on the various involved mechanisms, a potential route for further enhancement of the ZT values of the investigated composition is proposed.Item Joining of ceramic matrix composites to high temperature ceramics for thermal protection systems(2016-02-01) Jiménez, C.; Mergia, K.; Lagos, M.A.; Yialouris, P.; Agote, Iñigo; Liedtke, V.; Messoloras, S.; Panayiotatos, Y.; Padovano, E.; Badini, C.; Wilhelmi, C.; Bárcena, Jorge; EXTREMATThe current work reports a novel approach for the integration of external protective SIC multilayers with ceramic matrix composite (C-f/SiC) with the view of application in aerospace heat protection systems. The integration method is based on diffusion brazing bonding. As a joining agent the MAX-Phase Ti3SiC2, produced by self-propagating high temperature synthesis, has been employed. The pressure applied during the joining process and its effect on the microstructure of the integrated structure is discussed. Microstructural analysis of the resulting joints is conducted using scanning electron microscopy coupled with energy dispersive spectroscopy and X-ray diffraction measurements. Analysis of the joints showed that the bonds are uniform, dense, with few crack vertical to the interface which are not detrimental for the performance of the joints. Ground re-entry tests showed that the joints survive 5 re-entry cycles at 1391 and 1794 degrees C without any detectable damage. (C) 2015 Elsevier Ltd. All rights reserved.Item Master Alloys(Elsevier, 2017-01-01) Agote, Iñigo; Lagos, Miguel A.; Gutiérrez, Manuel; EXTREMAT; SGMaster alloys are formed by base metals such as aluminium, titanium, and iron combined with a relatively high percentage of one or more other elements or compounds. SHS provides an excellent route to produce the master alloys for different applications with minimum energy consumption. Heavily loaded compounds (master alloy) synthesised by SHS have obtained ample approval because of their cutting and wear-resistant properties. Aluminium-based master alloys have also been obtained by SHS.Item Physical, mechanical, and structural properties of highly efficient nanostructured n-and p-silicides for practical thermoelectric applications(2014-06) Gelbstein, Yaniv; Tunbridge, Jonathan; Dixon, Richard; Reece, Mike J.; Ning, Huanpo; Gilchrist, Robert; Summers, Richard; Agote, Iñigo; Lagos, Miguel A.; Simpson, Kevin; Rouaud, Cedric; Feulner, Peter; Rivera, Sergio; Torrecillas, Ramon; Husband, Mark; Crossley, Julian; Robinson, Ivan; EXTREMATCost-effective highly efficient nanostructured n-type Mg2Si 1-x Sn x and p-type higher manganese silicide (HMS) compositions were prepared for the development of practical waste heat generators for automotive and marine thermoelectric applications, in the frame of the European Commission (EC)-funded PowerDriver project. The physical, mechanical, and structural properties were fully characterized as part of a database-generation exercise required for the thermoelectric converter design. A combination of high maximal ZT values of ∼0.6 and ∼1.1 for the HMS and Mg2Si1-x Sn x compositions, respectively, and adequate mechanical properties was obtained.Item PM Based Titanium Matrix Composites for Aerospace Applications: Processing, Mechanical Properties and Scale Up: Processing, mechanical properties and scale up(2017) Lagos, M.A.; Agote, Iñigo; Atxaga, G.; Pambaguian, L.; EXTREMATThe reinforcement of titanium with a hard phase is an efficient way to increase the stiffness and strength of conventional titanium alloys. The high reactivity of titanium is a critical challenge in the processing of Titanium Matrix Composites (TMCs). For this reason, Powder Metallurgy is considered a very promising route for the manufacturing of TMCs. In this work, a master alloy (Ti-TiC) was developed by combustion synthesis. This alloy was further blended with conventional titanium alloy and the final consolidation was performed by Spark Plasma Sintering. In addition to the processing details, microstructural and thermomechanical characterization is presented. Materials obtained present higher Young Modulus and strength than conventional Ti-6Al-4V, with higher thermal conductivity and maintaining similar thermal expansion coefficient (CTE). The good corrosion resistance of the material makes it a candidate for possible applications in aerospace. This work presents also the scale up of the process to obtain aerospace demonstrators.Item A review on recent developments in binder jetting metal additive manufacturing: materials and process characteristics: materials and process characteristics(2019-10-20) Lores, Asier; Azurmendi, Naiara; Agote, Iñigo; Zuza, Ester; EXTREMATBinder Jetting Metal Additive Manufacturing (BJ-MAM), known also as metal 3D-printing, is a powder bed-based additive manufacturing technology. It consists of the deposition of liquid binder droplets to selectively join powder particles to enable the creation of near-net shaped parts, which subsequently are consolidated via sintering process. This technology is known for its capability to process a wide range of different materials and for its orientation towards large volume production series. Binder Jetting has recently been drawing the attention of both the research sphere as well as several industrial sectors. The present review study encompasses the various and most remarkable aspects of BJ-MAM part fabrication. The review covers the material selection and characterisation considerations, followed by the manufacturing process features and the parameter effect on different part properties. It concludes with an overview concerning the most recent case studies with regards to diverse metal alloy developments.Item SPS Co-Sintering Of Metal-Ceramic Composites For High Performance Electronic Applications(European Powder Metallurgy Association (EPMA), 2022) Lores, Asier; Lagos, Miguel Angel; Agote, Iñigo; Leizaola, Iñaki; Neubauer, Erich; Kovacova, Zuzana; Wallis, Christopher; Bringer, Charlotte; EXTREMATElectronic packages and sensors for special purpose applications demands the use of high electrical resistivity ceramics and conductive metallic materials which are sometimes difficult to be compatibilized, and whose manufacturing process involves many different processing steps. In this study, a bi-material composite consisting on a resistive SiC-Feldspar ceramic with around 109Ω.cm and a conductive Invar36 alloy has been developed in a one-step process by Spark Plasma Sintering (SPS). The SPS process permits the fast co-sintering of the composite achieving near full densities. Also, it has been observed that the joining interface of the material is stable and crack free. Both selected ceramic and metallic materials have low and similar CTE values (3.5 ppm/K), which makes them ideal for co-processing purposes and also for applications where high dimensional stability is required.Item Zero Waste Binder Jetting Process: Study Of The Reusability Of The Rejected Part Powder(2023) Lores, Asier; Azurmendi, Naiara; Leizaola, Iñaki; Agote, Iñigo; EXTREMATBinder Jetting Additive Manufacturing is renowned for its high powder reusability ratio, reaching near 100 % for certain alloys. This technology offers an advantage over thermal-based methods, such as laser or electron beams, which can degrade or sinter the surrounding powder particles, diminishing the reusability ratio. However, during the setup and production of parts, defects may occur, leading to the direct rejection of certain printed components. The objective of this work is to investigate the feasibility and impact of reusing powder from rejected parts, aiming to achieve zero waste and maximize the utilization of metallic powders. To accomplish this, the rejected parts underwent a series of processes including debinding, sieving, characterization, and subsequent mixing with virgin powder at various proportions. The goal was to identify suitable mixing ranges that would enable the production of high-quality material. The study focused specifically on the 17-4PH alloy and confirmed that employing separate debinding and sintering processes facilitates the complete recirculation of all used powder, thus achieving zero waste. This finding highlights the potential for implementing a closed-loop system that maximizes powder reusability and minimizes material waste in the Binder Jetting Additive Manufacturing process.