High-temperature wettability in hard materials: Comparison of systems with different binder/carbide phases and evaluation of C addition

Metal-ceramic wettability is a decisive parameter in the high-temperature sintering of hard materials. Wettability tests enable the study of this property with minimum material waste, especially useful in the search of alternative systems to WC-Co hardmetals. In this investigation, Fe-based binders – FeNiCr and FeCrAl – were tested on Ti(C,N) and WC substrates, aiming to assess: the high-temperature interactions, the dissolutive character of the liquid phase and the nature of the interphases generated, and the influence on sintering behaviour. As a result, FeNiCr led to excellent wetting scenarios for both ceramics, whereas FeCrAl alloys induced the formation of aluminium oxides. The effect of C addition on wettability was also evaluated, resulting in an improvement of this property by the inclusion of this element in the binder phase. Inspection of the microstructures resultant from powder metallurgy processing of the different configurations confirmed their excellent correlation with wettability results. As a consequence, the effectivity of this technique as a model of the sintering scenario could be asserted.The current investigation was supported by the Spanish Government (Agencia Estatal de Investigación) and European Union through the project AEI/10.13039/501100011033 (PID2019-106631GB-C41/C43) and grants BES-2016-077340 and Margarita Salas, as well as the Regional Government of Madrid through the program ADITIMAT, ref. S2018/NMT-4411. The authors would like to acknowledge and thank CERATIZIT Group (Mamer, Luxembourg), for their contribution to the processing of the hard materials, and Johannes Pötschke, from Fraunhofer Institute for Ceramic Technologies and Systems IKTS, for providing binderless WC substrates. Funding for APC: Universidad Carlos III de Madrid (Read & Publish Agreement CRUE-CSIC 2022)

Carbon addition effects on microstructure and small-scale hardness for Ti(C,N)-FeNi cermets

The current study investigates the influence of carbon addition on the microstructural and micromechanical properties of Ti(C,N)-FeNi cermets with different ceramic/metal phase ratios. Evaluation of small-scale hardness is conducted by using high speed nanoindentation in conjunction with statistical analysis. It allows to gather extremely large data sets (40,000 imprints per grade and condition); and thus, detailed hardness mapping at the microstructure length scale. Subsequent statistical analysis was done by considering three mechanically distinct phases: Ti(C,N) particles, the metallic binder, and one exhibiting the composite behaviour (i.e. imprints probing two-phase regions). In general, it is found that porosity amount is reduced as ceramic/metal phase ratio decreases and carbon is added. Carbon addition is also observed to rise small-scale hardness, but only for two of the defined phases: metallic binder and the composite one. Similar trends are observed regarding the influence of ceramic/metal phase ratio and carbon addition on the inverse hardness-fracture toughness correlation measured under high applied loads.This investigation was supported by the Spanish Ministerios de Economía y Competitividad MINECO through grant MAT2015-70780-C4-P. J.J. Roa acknowledges the Serra Hunter programme of the Generalitat de Catalunya.Publicad

Phase diagrams in alternative hard materials: Validation of thermodynamic simulation through high temperature x-ray diffraction, differential thermal analysis and microstructural characterization

In this investigation, Ti(C,N)-FeNiCr systems were designed using Thermo-Calc® software. Materials were processed by conventional powder metallurgy, employing different carbon additions to study a wide range of the phase diagram as well as the effect of C in the sintered samples. Specimens were extensively characterised in terms of density, magnetic and mechanical properties, and microstructural features. Simulation approach was validated by means of Differential Thermal Analysis (DTA) and High-Temperature X-Ray Diffraction (HT-XRD), from room temperature up to 1200 °C for each composition, comparing phases obtained for each temperature and composition with predicted ones. Results showed excellent consonance between Thermo-Calc® and XRD phases, except for precipitation of secondary carbides, which appeared in the simulation but not in the sintered samples. Moreover, variation of C content demonstrated to have a direct effect in the microstructural homogenization of the final specimens.The current study was supported by the Spanish Government through the projects MAT2015-70780-C4-P and PID2019-106631GB-C41/C43, and grant BES-2016-077340, and the Regional Government of Madrid through the program ADITIMAT, ref. S2018/NMT-4411. The authors would like to thank BASF for providing the iron powder used in this investigation

Identificación de bacterias marinas cultivables de la ciudad costera Comodoro Rivadavia, Argentina

This study identifies marine bacteria obtained from three sites along Comodoro Rivadavia coast, south of Argentina. Seawater and intertidal sediment samples were collected. Two of the sites were located close to the city sewage system (CR1, CR2) and the third one (CR3) was near from an oil buoy. Bacterial counts were performed on four culture media: BBR, BRN, mineral medium with crude oil and gas oil and ENDO for coliforms. The identification of bacteria was performed by using fatty acid methyl esters. The counts resulted positive to total coliforms and faecal coliforms in sites CR1 and CR2 and resulted negative in site CR3 except in autumn. We isolated 469 strains, to which a fatty acid extraction and identification were performed. The system identified 37 genera and 54 species in only 236 strains. The other strains were unidentified because they were not found in Sherlock data base. Pseudoalteromonas was the genus frequently found isolated and the enterobacteria group was conformed by Citrobacter, Enterobacter and Escherichia. The principal components analysis related the winter season to Gram positive strain, and autumn season was asociated to the biggest biodiversity of genera.Este estudio identifica bacterias marinas obtenidas de tres sitios costeros de la ciudad de Comodoro Rivadavia, sur de Argentina. Se tomaron muestras de agua de mar y sedimento del intermareal. Dos de los sitios se ubicaron cerca de desagües cloacales (CR1, CR2) y el tercero (CR3) fue cerca de una boya de carga de hidrocarburos. Se realizaron recuentos bacterianos en cuatro medios de cultivo: BBR, BRN, medio mineral con petróleo gas oil y ENDO para coliformes. Las bacterias fueron identificadas utilizando ácidos grasos metíl esteres. Los recuentos de coliformes totales y fecales fueron positivos en los sitios CR1 y CR2 y negativos para CR3 con excepción de la estación de otoño. Se aislaron 469 cepas a las que se les realizó la extracción de ácidos grasos e identificación. El sistema identificó 37 géneros y 54 especies en solo 236 cepas. Las restantes cepas no fueron identificadas debido a que no se encontraron en la base de datos Sherlock. Pseudoalteromonas fue el género que más frecuentemente se encontró aislado y el grupo de las enterobacterias estuvo integrado por Citrobacter, Enterobacter y Escherichia. El análisis de componentes principales asoció el invierno a las cepas Gram positivas y el otoño se asoció con la mayor biodiversidad de género

Ti(C,N)-Fe15Ni10Cr cermets as alternative hard materials: Influence of the processing route and composition on their microstructure and properties

Processing route is a determining factor that affects the properties of hard materials. Although processing routes are well defined for WC-Co hardmetals, a complete study is needed to understand the factors influencing the properties when alternative compositions are developed. In this investigation, Ti(C,N)-Fe15Ni10Cr cermets were produced following conventional powder metallurgy routes. Two types of milling – attritor and planetary, using different vessel/ball materials – and of sintering regimes – sinter-HIP and high-vacuum – were used to process the specimens and compare their final properties. Carbon content was also included in the study as experimental variable. Density, porosity, microstructure, mechanical and magnetic properties, and corrosion behaviour of the resulting cermets were determined by using a wide range of characterization techniques. Optimization of their production led to materials with a competitive hardness-toughness combination, comparable to those exhibited by plain WC-Co grades. Evaluation of corrosion confirmed the improved resistance when Cr is included as alloying element and also compared to cobalt, as well as the superior corrosion response of Ti(C,N) with respect to WC.The current investigation was supported by the Spanish Government (Agencia Estatal de Investigación) through the project PID2019-106631GB-C41/C43 and grant BES-2016-077340, and the Regional Government of Madrid through the program ADITIMAT, ref. S2018/NMT-4411

Lithospheric domain and deformation style mapping in the Galicia continental margin (northwestern Iberian margin)

IX Congreso Geológico de España, 12-14 septiembre 2016, Huelva.-- 4 pages, 3 figures[EN] The continental margin of Galicia presents a very complex structure, due to two main effects. On the one hand, it's a magma-poor rift margin, generated in the vicinity of the triple R-R-R junction, which resulted in the simultaneous opening of the Atlantic Ocean and the Bay of Biscay during the Cretaceous. On the other hand, the Cenozoic compressive stress regime led to the partial inversion of the continental margin to the north and northwest, providing a greater structural complexity. In this work we have carried out a detailed analysis of new gravity and bathymety data acquired during the ZEE Project cruises, as well as new 2D multichannel seismic reflection profiles from the ERGAP Project. We present here some the results of this joint analysis of all the geophysical and geological information available, consisting of a continuous mapping of the different lithospheric domains and of the style of deformation which affect them, from the western margin of the Iberian Peninsula to the northern one[ES] El margen continental de Galicia presenta una estructura muy compleja, debido a dos efectos principales. Por un lado, se trata de un margen de rift pobre en magma, generado en las proximidades del punto triple R-R-R que dio lugar a la apertura simultánea del Océano Atlántico y el golfo de Vizcaya durante el Cretácico. Por otra parte, el régimen de esfuerzos compresivo Cenozoico generó la inversión parcial del margen continental hacia el norte y el noroeste, aportando una mayor complejidad estructural. En este trabajo hemos realizado un análisis detallado de la nueva información gravimétrica y batimétrica obtenida durante las campañas del Proyecto ZEE, así como de nuevos perfiles de sísmica de reflexión multicanal procedentes del Proyecto ERGAP. Presentamos aquí parte de los resultados de este análisis conjunto de toda la información geofísica y geológica disponible, consistentes en una cartografía continua de los diferentes dominios litosféricos y del tipo dedeformación que los afectan, desde el margen oeste de la Península Ibérica hasta el margen nortePeer Reviewe

Deep crustal structure and continent-ocean boundary along the Galicia continental margin (NW Iberia)

Trabajo presentado en la EGU General Assembly 2016 (European Geosciences Union), celebrada en Viena del 17 al 22 de abril de 2016.The Galicia continental margin is a magma-poor rifted margin with an extremely complex structure. Its formation involves several rifting episodes during the Mesozoic in the vicinity of a ridge triple junction, which produces a change in the orientation of the main structures. In addition, there is an overimposed Cenozoic partial tectonic inversion along its northern border. Although this continental margin has been widely studied since the 70’s, most studies have focused on its western part in the transition to the Iberia Abyssal Plain, and there is a significant lack of information on the north and northwestern flanks of this margin. This fact, along with its great structural complexity, has resulted in the absence of a previous comprehensive regional geodynamic model integrating all the processes observed. In the present study we integrate a large volume of new geophysical data (gravity, swath bathymetry and 2D multichannel reflection seismic). Data come from the systematic mapping of the Spanish EEZ project which provides a dense grid of gravity data and full seafloor coverage with swath bathymetry, and from the ERGAP project which provides serially-arranged 2D seismic reflection profiles across the NW Iberia margin. The combined interpretation and modelling of this new information has arisen significant constraints on the origin, the deep crustal structure and the physiographic complexity of the margin, as well as on the characterization of the along- and across-strike variation of the ocean-continent transition along NW Iberia margin. The analysis of this information leads us to propose a conceptual model for the initiation of the tectonic inversion of a magma-poor rifted margin. Finally, a framework for the geodynamic evolution of the Galicia margin has been constructed, involving three main stages: A) an early stage from the end of rifting and oceanic drift in the Bay of Biscay (Santonian); B) an intermediate stage with the beginning of tectonic inversion in the north and northwestern Iberia margin (Campanian-Paleocene) mainly concentrated along the exhumed mantle zone; and C) a final stage of compressive deformation (Eocene-Oligocene) affecting both the continental and the oceanic crust, evidenced by large dip-slip thrustingPeer reviewe

New interpretation of the sedimentary infill of the San Pedro basin based on new seismic data (Dominican Republic offshore)

IX Congreso Geológico de España, 12-14 septiembre 2016, Huelva.-- 4 pages, 4 figures[EN] New 2D multichannel seismic reflection data recorded in the San Pedro Basin (south-eastern margin of Dominican Republic,) combined with vintage seismic reflection profiles, have allowed a detailed analysis and review of the seismic stratigraphy. New data supply new constraints on the evolution of the basin and suggest at least an Upper Eocene origin instead of Miocene. The new interpretation is based on the onshore-offshore correlation of fan deposits with the main tectonic events constrained onshore and related with the collision of the Bahamas banks with the island arc in Middle Eocene ages[ES] Los nuevos datos de sísmica de reflexión multicanal 2D adquiridos en la Cuenca de San Pedro (margen sudeste de la República Dominicana), junto con antiguos perfiles sísmicos reprocesados, han permitido llevar a cabo un detallado análisis y revisión de la estratigrafía sísmica. Los nuevos datos sísmicos aportan nuevas precisiones sobre la evolución de la cuenca sugiriendo un origen de al menos Eoceno Superior, en lugar de Mioceno. La nueva interpretación se basa en la correlación onshore-offshore de un nivel guía de abanicos bien desarrollado, con los eventos tectónicos constreñidos tierra y asociados a la colisión con los Bancos de las Bahamas con el arco isla el Eoceno MedioPeer Reviewe