Fatigue behaviour of GMAW welded aluminium alloy AA7020

[EN] The aim of this investigation is to evaluate the influence on fatigue behaviour of the finishing of the bulge in a welded aluminium zinc magnesium alloy AA7020. It was determined that total or partial elimination of the bulge has very little influence on its behaviour, giving a very similar result on both cases, where one is better than the other by only 3%.Bloem, C.; Salvador Moya, MD.; Amigó, V.; Vicente-Escuder, Á. (2009). Fatigue behaviour of GMAW welded aluminium alloy AA7020. Welding International. 23(10):111-116. doi:10.1080/09507110902843321S111116231

Microstructural change of the HAZ in an MIG welded bond on an AA7020 aluminium alloy: stress corrosion crack growth rate in dissimilar metal welds

[EN] Many researchers have undertaken studies into the mechanical behaviour of the welded bond,1,2 others have devoted their attentions to metallurgical phenomena, whether concerning phenomena inherent to the area immediately surrounding the weld interface or concerning models or simulations of the welded structure;3,4 in addition, there are those who have made comparisons between different welding methods2 or who have dedicated their time to post-welding treatments.5 However, very few researchers have devoted their attentions to studying microstructural change throughout the HAZ on welded test pieces.Bloem, C.; Salvador Moya, MD.; Amigó, V.; Busquets Mataix, DJ. (2004). Microstructural change of the HAZ in an MIG welded bond on an AA7020 aluminium alloy: stress corrosion crack growth rate in dissimilar metal welds. Welding International. 18(7):538-542. doi:10.1533/wint.2004.3287S53854218

Fatores Motivadores de Empresas que Estabelecem Cooperação com Institutos de Ciência e Tecnologia

Technological innovation is deemed strategic for organizations and nations to achieve and sustain competitive advantage. One of the most effective means for companies to achieve these innovations is through the relationship with universities. Thus, this study aimed to identify the main factors that motivate companies to establish this partnership. Hence, a descriptive study was elaborated, in which respondents are companies that have some level of cooperation with universities and institutes of science and technology. The results obtained show that the main reasons are, according to their importance: (1) to strengthen the technology, (2) to search for new sources of creativity, (3) to obtain expertise in market-oriented technologies, (4) to acquire new technologies; (5) to reach skilled labor, (6) to train their human resources, and (7) to develop new products. Furthermore, this study found that the less important factors are related to social reasons; this finding deserves further investigation in future studies.A inovação tecnológica é considerada estratégica para que organizações e nações alcancem e sustentem a vantagem competitiva. Um dos meios mais efetivos para que as empresas obtenham essas inovações é por meio da relação com universidades. Nesse sentido, neste estudo o objetivo foi hierarquizar os principais fatores que motivam empresas a estabelecer esse tipo de parceria. Para tanto, foi realizado um estudo descritivo cujos respondentes são empresas que mantêm algum nível de cooperação com universidades e institutos de ciência e tecnologia. Os resultados demonstraram que os principais motivos são, por ordem de importância: (1) fortalecer a tecnologia; (2) buscar novas fontes de criatividade; (3) obter expertise em tecnologias para o mercado; (4) adquirir novas tecnologias; (5) acessar mão de obra qualificada; (6) capacitar seus recursos humanos; e (7) desenvolver novos produtos. Ademais, neste estudo verificou-se que o fator de menor importância está associado às razões sociais, que merecem ser mais bem investigadas em estudos futuros

Publisher Correction: Science diplomacy for plant health

Correction to: Nature Plants https://doi.org/10.1038/s41477-020-0744-x, published online 11 August 2020.1 Pág.An amendment to this paper has been published and can be accessed via a link at the top of the paper.In the version of this Comment originally published, in the penultimate paragraph of the section “Steps towards global phytosanitary research coordination” the second sentence incorrectly defined IPPC as ‘Intergovernmental Panel on Climate Change’, though it was cor rectly defined earlier as ‘International Plant Protection Convention’; the sentence has now been corrected to read “Ideally, they should benefit from the reputation of a United Nations mandate convention, such as the IPPC…”Peer reviewe

Os primórdios da organização do espaço territorial e da vila cearense: algumas notas

This paper presents, in outline, the action taken by economic agents, representatives of the Church and the Portuguese State in organizing the space of the Captaincy of Ceará in the eighteenth century. The Portuguese State founded towns in strategic locations for better capitalization of the cattle breeder economy, where first settled sesmeiros and the Church. There was no reason or justification of geopolitical nature that demanded technical and financial investments by the Portuguese in the full adequacy of the local conditions to Portuguese urban guidelines. In the face of the late occupation, the article also discusses the late cartographic representation as expressing the lack of interests of the Portuguese administration in relation to a fuller understanding of the region

Información Investigador: Bloem Irazabal, Carlos Alberto

Resumen Curricular Ingeniero Mecánico ULA 1990, Doctor Universidad Politécnica de Valencia 2000.Doctorado5493I - 2004; I - 200288 - 2005; 65 - 2003Materiales, Aluminio, Soldadura, Fatiga, Endurecimiento por precipitación.Noviembre de 2005Ingeniero Mecánico+58 274 2402933Facultad de Ingenierí[email protected]

Tribological behavior of TZ4YS-MoSi2 composites obtained by Spark Plasma Sintering

[EN] The aim of this work was to evaluate the role of MoSi2 content (5, 10, 15 wt%) in the mechanical and tribological behavior of TZ4YS-MoSi2 composites obtained by colloidal processing and spark plasma sintering (SPS) at 1500 degrees C. Firstly, the densification of TZ4YS-MoSi2 composite and the shrinkage-rate curves by SPS applying 80 MPa from 1300 degrees C to 1500 degrees C is studied. The hardness and fracture toughness values confirmed that up to 99.9% densification is gradually reached with increasing MoSi2 percentage. Secondly, pin-on-disk tribological tests at different distances (1, 5, 15 and 2000 m) with Al2O3 as counterpart were performed to record the behavior of the materials in the initial and final stages of wear. The MoSi2 content was associated to the beginning of the transition from mild to severe wear, higher the amount of MoSi2 faster is the transition. This behavior was correlated with MoSi2 content, which aids the formation of a tribolayer.The authors would like to thank the Ministry of Science, Innovation and Universities (Spain) for its financial through the projects RTI2018-099033-B-C32&C33 (MCIU/AEI/FEDER, UE) and RYC-2016-20915.Benavente Martínez, R.; Salvador Moya, MD.; Bloem, C.; Gutiérrez-González, CF.; Alcázar, C.; Moreno, R.; Borrell Tomás, MA. (2021). Tribological behavior of TZ4YS-MoSi2 composites obtained by Spark Plasma Sintering. Journal of the European Ceramic Society. 41:7155-7183. https://doi.org/10.1016/j.jeurceramsoc.2021.07.053715571834

EVALUACIÓN DEL COMPORTAMIENTO MECÁNICO DE BARRERAS TÉRMICAS MEDIANTE TÉCNICAS DE EMISIÓN ACÚSTICA

Para desarrollar turbinas más eficientes se requiere aumentar la temperatura de entrada y/o disminuir las pérdidas de temperatura dentro de esta, por eso, es necesario desarrollar materiales resistentes a mayores temperaturas y con coeficientes de transferencia de calor más bajos. Una solución tecnológica a este inconveniente es la implementación y mejoras de las barreras térmicas (TBC, Thermal Barrier Coating). La ZrO2 estabilizada con Y2O3 (Y-TZP), es una de las cerámicas que se emplea como TBCs. Sin embargo, la fatiga termomecánica a la que están sometidas estas barreras hace que se deterioren formando grietas y/o delaminaciones. El Carburo de Silicio (SiC) se ha empleado como agente autosellante, gracias a su reactividad a altas temperaturas que conduce al sellado de estos daños por oxidación, alargando la vida útil de los componentes de la turbina. Este trabajo se centra en el estudio mediante emisión acústica, (EA) en el comportamiento mecánico de las TBCs por la adición del SiC en la suspensión de Y-TZP/Al2O3. Para ello, se ha realizado un análisis microestructural, ensayos mecánicos con EA y una simulación por elementos finitos de con el fin de cotejar resultados. Los recubrimientos se realizaron por proyección térmica por plasma de suspensiones (SPS) sobre planchas metálicas de 70x12x2 mm, en éstas, se depositó un intermetálico a modo de capa de anclaje y finalmente un recubrimiento de Y-TZP/Al2O3 con y sin 15% en peso de SiC. Se realizaron ensayos a flexión a tres puntos con la finalidad evaluar la generación de grietas por EA, la cual resultó ser una herramienta fundamental en el estudio del comportamiento mecánico de las barreras térmicas. El uso de las transformadas de wavelet agiliza el estudio y análisis de los espectros de sonido registrados. Se comprobó que la generación de grietas sucede a niveles muy bajos de esfuerzo y se identificaron patrones de frecuencia asociados a los modos de fractura