Effect of laser irradiation on failure mechanism of TiCp reinforcedtitanium composite coating produced by laser cladding

Laser cladding is an effective technique to coat a metallic substrate with a layer of a different nature.It has been widely reported that the most important combined parameters controlling the quality ofthe coating are the specific energy (E) and the powder density ( ). In the present work, clad depositsof Ti6Al4V + 60 wt.% TiC were prepared on a Ti6Al4V substrate using an optimum combination of Ec= 24 J/mm2 and c= 3 mg/mm2. These experiments were performed using a laser power of 400 and600 W, in order to study the effect of laser power on the properties of the clad. The microstructure, phasecomposition and nanohardness of the coatings were investigated by optical microscopy, scanning elec-tron microscopy and X-ray diffraction. During laser processing, TiC can be partially converted to TiCX(X = 0.5) due mainly to the TiC dissolution into the laser-generated melting pool and subsequent precipi-tation during cooling. It was observed that the lower laser power limit reduces primary TiC dissolution butit also promotes secondary carbide alignment at the interface. On the other hand, the damage mechanisminduced by high laser power is dominated by primary TiC particle cracking by the high stress concentra-tion at the particle matrix interface followed by ductile failure of the matrix. It is also remarkable thatirradiance affects the TiC/TiCxratio despite Ecand care fixed and it determines hardness distributioninside the coating.Authors thank MINECO funding in special the Training of Research Staff programme with the help BES-2009-013589 and the support of the Comision Interministerial de Ciencia y Tecnologia (CICYT), Spain, under Grant MAT2012-39124. This work was developed at the Materials Technology Unit of the Polytechnic University of Valencia associated to CSIC through the National Centre for Metallurgical Research (CENIM). Finally, thank the EU for the funding received through the FEDER help in the project UPOV08-3E-005 for the purchase of equipment and the Generalitat Valenciana for the help ACOMP/2012/094.Candel Bou, JJ.; Jiménez, J.; Franconetti Rodríguez, P.; Amigó Borrás, V. (2014). Effect of laser irradiation on failure mechanism of TiCp reinforcedtitanium composite coating produced by laser cladding. Journal of Materials Processing Technology. 214(11):2325-2332. https://doi.org/10.1016/j.jmatprotec.2014.04.035S232523322141

Preliminary Water Assessment Reports of The Test Basins of The Watch Project

This report presents the initial plans of the case studies how they link to rest of the Watch project and on which water resources they will focus. This report will function as the basis for further discussions on how to improve the integration of the case studies within the project and to develop a more general protocol for each of the case studies. Currently 5 catchments are used within the Watch project, they differ in climatic and hydro-geological features and expected climate changes: the Glomma River basin (Eastern Norway), the upper Guadiana basin (Central Spanish Plateau), the Nitra River basin (central Slovakia), the Upper-Elbe basin (part of the Elbe River) and the island of Crete. Also the water resources issues vary over these cases. Agricultural (and domestic) water use is under pressure in the Mediterranean catchments probably aggravating with the expected increase in drought frequency under future climate. The Norwegian catchment provides hydropower services under threat of precipitation increase rather than decrease. The central European catchments are threatened mainly by increased variability, i.e. increased frequencies of extremes in a densely populated environment, and river flow may need additional buffers (reservoirs) to reduce floodrisk and store water for dry period

The dynamics of quasi-isometric foliations

If the stable, center, and unstable foliations of a partially hyperbolic system are quasi-isometric, the system has Global Product Structure. This result also applies to Anosov systems and to other invariant splittings. If a partially hyperbolic system on a manifold with abelian fundamental group has quasi-isometric stable and unstable foliations, the center foliation is without holonomy. If, further, the system has Global Product Structure, then all center leaves are homeomorphic.Comment: 18 pages, 1 figur

H2O Open Ecosystem for State-of-the-art Large Language Models

Large Language Models (LLMs) represent a revolution in AI. However, they also pose many significant risks, such as the presence of biased, private, copyrighted or harmful text. For this reason we need open, transparent and safe solutions. We introduce a complete open-source ecosystem for developing and testing LLMs. The goal of this project is to boost open alternatives to closed-source approaches. We release h2oGPT, a family of fine-tuned LLMs of diverse sizes. We also introduce H2O LLM Studio, a framework and no-code GUI designed for efficient fine-tuning, evaluation, and deployment of LLMs using the most recent state-of-the-art techniques. Our code and models are fully open-source. We believe this work helps to boost AI development and make it more accessible, efficient and trustworthy. The demo is available at: https://gpt.h2o.ai/Comment: EMNLP 2023 Demo - ACL Empirical Methods in Natural Language Processin

Evaluación de las transformaciones estructurales en recubrimientos de WC10Ni depositados por laser cladding sobre acero para herramienta EN 12379

[ES] Los materiales compuestos de matriz metálica reforzados con carburos, son conocidos por su elevada resistencia a todos los tipos de desgaste, debido a la combinación de las partículas duras en una matriz metálica tenaz. Diferentes tipos de estos materiales, se han empleado en el desarrollo de nuevas herramientas de corte de altas prestaciones. La técnica de láser cladding(LC), permite obtener recubrimientos libres de defectos sobre zonas muy concretas, con un aporte de calor muy localizado. Pero en el caso de carburos de wolframio (WC), debido a la enorme absorción de energía y la diferencia de propiedades entre el metal base y la cerámica, puede producir una gran cantidad de defectos tales como grietas, poros, gran dilución de carburos, falta de adherencia, etc. El objetivo de este trabajo, es estudiar las transformaciones metalúrgicas que aparecen durante el procesado por láser de recubrimientos tipo cermet de WC10Ni, sobre acero de herramienta para trabajo en frío (EN 12379). Además se ha relacionado los parámetros de proceso con la generación de defectos. Para ello, se analiza su microestructura, composición y se obtienen perfiles de dureza en el recubrimiento y en el acero afectado por el calor. Los resultados muestran, que aunque el control de los parámetros del proceso reduce la generación de defectos, al depositar recubrimientos por solape de cordones, se produce gran cantidad de transformaciones debido a la disolución masiva de las partículas de WC y la difusión de elementos de aleación, desde el sustrato hacia el recubrimiento.[EN] Carbide metal matrix composite materials are known for a high resistance to all types of wear. It is due to a beneficial combination of properties given by hard phase particles included in a tough matrix. Different kinds of those materials have been employed in the development of new high properties cutting tools. Laser cladding (LC) technique allows obtaining an accurate defect-free coating with a low thermal affectation of the component. But in the case of WC cermet coatings due to its high laser absorption and the different mechanical and thermal properties between substrate and coating can appear a wide range of different defects as cracks, pores, massive carbide dilution and lacks of adherence. The aim of the present work is to study the metallurgical transformations during LC process of WC cermet coating on cold work tool steel substrate (EN 12379). Also it has been related process parameters with defects generation. Microstructure and composition of the coating and the heat affected zone have been analysed. Microhardness evolution profile has been obtained. Results show that although process parameters control reduce the generation of defects, in the deposition of overlapped layers appear different metallurgical transformations related with massive WC decomposition and the diffusion of alloying elements from substrate to the coating.Candel Bou, JJ.; Amigó Borrás, V.; Sampedro, J.; Bonache Bezares, V. (2011). Evaluación de las transformaciones estructurales en recubrimientos de WC10Ni depositados por laser cladding sobre acero para herramienta EN 12379. Revista de Metalurgia. 47(4):355-364. doi:10.3989/revmetalm.0964S355364474Zhang, H., Wang, G., Luo, Y., & Nakaga, T. (2001). Rapid hard tooling by plasma spraying for injection molding and sheet metal forming. Thin Solid Films, 390(1-2), 7-12. doi:10.1016/s0040-6090(01)00910-5Cadenas, P., Rodriguez, M., & Staia, M. H. (2007). Effect of the post heat treatment on the sliding wear resistance of a nickel base coating deposited by high velocity oxy-fuel (HVOF). Revista de Metalurgia, 43(1). doi:10.3989/revmetalm.2007.v43.i1.51Vilar, R. (1999). Laser cladding. Journal of Laser Applications, 11(2), 64-79. doi:10.2351/1.521888Vicario, I., Soriano, C., Sanz, C., Bayón, R., & Leunda, J. (2009). Optimización del proceso de aporte de recubrimientos anticorrosión de Stellite 6 producidos mediante plaqueado láser. Revista de Metalurgia, 45(1), 14-19. doi:10.3989/revmetalm.0708Chen, C.-C. A., & Duffie, N. A. (1996). Development of an automated surface finishing system (ASFS) with in-process surface topography inspection. Journal of Materials Processing Technology, 62(4), 427-430. doi:10.1016/s0924-0136(96)02447-8Lim, L. ., Ming, Q., & Chen, Z. . (1998). Microstructures of laser-clad nickel-based hardfacing alloys. Surface and Coatings Technology, 106(2-3), 183-192. doi:10.1016/s0257-8972(98)00525-8Wang, P.-Z., Qu, J.-X., & Shao, H.-S. (1996). Cemented carbide reinforced nickel-based alloy coating by laser cladding and the wear characteristics. Materials & Design, 17(5-6), 289-296. doi:10.1016/s0261-3069(97)00025-3Hidouci, A., Pelletier, J. M., Ducoin, F., Dezert, D., & El Guerjouma, R. (2000). Microstructural and mechanical characteristics of laser coatings. Surface and Coatings Technology, 123(1), 17-23. doi:10.1016/s0257-8972(99)00394-1Sidhu, B. S., Puri, D., & Prakash, S. (2005). Mechanical and metallurgical properties of plasma sprayed and laser remelted Ni–20Cr and Stellite-6 coatings. Journal of Materials Processing Technology, 159(3), 347-355. doi:10.1016/j.jmatprotec.2004.05.023St-Georges, L. (2007). Development and characterization of composite Ni–Cr+WC laser cladding. Wear, 263(1-6), 562-566. doi:10.1016/j.wear.2007.02.023Przybyłowicz, J., & Kusiński, J. (2001). Structure of laser cladded tungsten carbide composite coatings. Journal of Materials Processing Technology, 109(1-2), 154-160. doi:10.1016/s0924-0136(00)00790-1Wu, P., Du, H. M., Chen, X. L., Li, Z. Q., Bai, H. L., & Jiang, E. Y. (2004). Influence of WC particle behavior on the wear resistance properties of Ni–WC composite coatings. Wear, 257(1-2), 142-147. doi:10.1016/j.wear.2003.10.01

Midwives\u27 knowledge, attitudes and learning needs regarding antenatal vaccination

Objective: To determine the knowledge, attitudes and learning needs of midwives regarding antenatal vaccination. Design & Setting: A cross-sectional, paper-based survey of midwives employed at the only public tertiary maternity hospital in the Australian state of XX between November 2015 and July 2016. Participants: 252 midwives providing care in antepartum, intrapartum, and/or postpartum settings. Measurements: Self-reported responses to a 41-item survey. Findings: The vast majority of midwives supported influenza and pertussis vaccination for pregnant women, with 90.0% and 71.7% reporting they would recommend pertussis and influenza vaccine, respectively, to a pregnant friend or family member, and almost all stating that midwives should administer vaccines to pregnant patients (94.8%). Seven out of ten midwives (68.1%) responded correctly to all knowledge items regarding vaccines recommended during pregnancy; 52.8% demonstrated correct knowledge regarding vaccine administration despite only 36.6% having attended an education session on antenatal vaccination in the previous two years. Nearly all midwives (97.3%) expressed a need for more education on vaccine administration. The most commonly reported barrier to administering influenza (61.3%) and pertussis (59.0%) vaccination was having staff available with the certification required to administer vaccines. Key Conclusions: Midwives view antenatal vaccination as their responsibility and are interested and receptive to education. Implications for Practice: There is an unmet need and demand among midwives for professional development that would enable them to recommend and administer vaccines to pregnant women in accordance with national immunisation guidelines and integrate vaccination into routine antenatal care

Polar Smectic Films

We report on a new experimental procedure for forming and studying polar smectic liquid crystal films. A free standing smectic film is put in contact with a liquid drop, so that the film has one liquid crystal/liquid interface and one liquid crystal/air interface. This polar environment results in changes in the textures observed in the film, including a boojum texture and a previously unobserved spiral texture in which the winding direction of the spiral reverses at a finite radius from its center. Some aspects of these textures are explained by the presence of a Ksb term in the bulk elastic free energy density that favors a combination of splay and bend deformations.Comment: 4 pages, REVTeX, 3 figures, submitted to PR

Evaluation of superficial oxidation layer of Ti6Al4V laser cladding coatings

[ES] Se ha estudiado la in¿uencia de los parámetros de procesado sobre la oxidación super¿cial y propiedades mecánicas de diferentes recubrimientos de Ti6Al4V. La gran reactividad química del polvo de titanio junto a la elevada temperatura que se alcanza producen gran variedad de colores en los óxidos formados. Esta oxidación puede tener un efecto perjudicial sobre el comportamiento en servicio, por lo que su evaluación es fundamental. Aunque la in¿uencia del procesado en el color de los óxidos formados es clara, no existe una relación sencilla que explique sus propiedades mecánicas. Por ese motivo se ha seguido una metodología basada en la microscopia, microanálisis por espectroscopia de longitud de onda (WDS) y nanoindentación. Los resultados indican que no hay diferencias importantes en la dureza y módulo elástico entre dos recubrimientos que presentan diferentes colores de oxidación[EN] It has been studied the in¿uence of processing parameters on the super¿cial oxidation and mechanical properties of different coatings of Ti6Al4V. The high chemical reactivity of titanium powder, and the high temperature reached during laser processing, produces a great variety of colors in the oxides formed. This oxidation can have a detrimental effect on the behavior in service so that its evaluation is essential. Although the in¿uence of processing on the color of the oxides formed is clear, there is no simple relationship to explain its mechanical properties. For this reason it has been applied a methodology based on microscopy, microanalysis wavelength spectroscopy (WDS) and nanoindentation. The results indicate no signi¿cant differences in hardness and elastic modulus between two coatings with different colors of oxidation.Los autores agradecen al Ministerio de Ciencia e Innovación por la financiación de esta investigación a través de los proyectos MAT2008-06882-C04-03/04 enmarcados en el Programa de Materiales del Plan Nacional.Amigó Borrás, V.; Candel Bou, JJ.; Amado, J.; Yañez, A. (2010). Evaluación de la oxidación superficial de recubrimientos de Ti6Al4V obtenidos por recubrimiento por láser. Revista de Metalurgia. 46(Extraordinario):13-18. https://doi.org/10.3989/revmetalm.02XIIPMSS131846Extraordinari