1,721,118 research outputs found
A journey into mCBEEs training, the European training network on corrosion problems at micro- and nanoscale
No full textTraining and establishing networks for the future researchers in our field of surface engineering and metal finishing has been a key focus of EAST (European Academy for Surface Technology). Here the authors briefly describe the mCBEE training network, and how it operates
Effect of pulse current on wear behavior of Ni matrix micro-and nano-SiC composite coatings at room and elevated temperature
No full textThis work presents the effect of the pulse-current on the wear behavior of Ni/nSiC and Ni/μSiC electrodeposits.
The deposits microstructure and SiC content were investigated by means of microstructural, crystallographic e chemical analysis. The mechanical properties were evaluated through microhardness measurements. Ball-on-disc tests were performed at both room temperature and 300 °C. Wear rate and mechanisms were determined by morphological and microscopical characterization.
The composite-coatings produced under pulse current present enhanced hardness and wear resistance, at both temperatures, linked to microstructural refinement and SiC content. The main wear mechanism observed was triboxidation, accompanied by abrasive wear mainly on the micro-composite coatings
The synergistic effect of cerium acetate and sodium sulphate on corrosion inhibition of AA2024-T3 at various temperatures
No full textThe present work examines the corrosion inhibition of aluminium alloy 2024-T3 immersed in NaCl+Ce(OAc)3 and NaCl+Ce(OAc)3+Na2SO4 solutions to evaluate the synergetic effect between cerium and sulphate ions at various temperatures (5 °C, 25 °C and 50 °C). The electrochemical properties were studied using short-term potentiodynamic measurements and long-term electrochemical impedance measurements. The surface topography, morphology and composition of cerium deposits formed on the alloy surface after two days of immersion were evaluated using scanning electron microscopy combined with energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. The results revealed an efficient long-term (up to 8 weeks) corrosion inhibition in NaCl+Ce(OAc)3 that was superior in the NaCl+Ce(OAc)3+Na2SO4 solution, especially at lower temperatures (5 °C > 25 °C > 50 °C). The composition of the Ce-based film varied with the temperature and the presence of Na2SO4, resulting in different mixtures of Ce(III) and Ce(IV) species. The synergistic effect of cerium and sulphate ions on corrosion inhibition was reflected by a higher degree of cerium oxidation from Ce3+ to Ce4+ at a low temperature and the incorporation of sulphates into the formed film, which protected the surface from the corrosion medium more efficiently
Effect of the plating parameters on the electrodeposition of Ni matrix coatings containing Ti nanoparticles
No full textThe effect of copolymerisation on the performance of acrylate-based hybrid sol-gel coating for corrosion protection of AA2024-T3
No full textThe study was focused on the optimisation of the copolymerisation process of acrylate-based hybrid sol-gel coating to obtain long-lasting corrosion protection of AA2024-T3. The coating was synthesised using the radical copolymerisation process of methyl methacrylate (MMA) and 3-methacryloxypropyl trimethoxysilane (MAPTMS) performed under air and nitrogen (oxygen-free) atmospheres, followed by acidic hydrolysis and polycondensation in the presence of silica prepared from tetraethyl orthosilicate (TEOS). The sol synthesis was evaluated at various stages using real-time infrared spectroscopy, multinuclear liquid- and solid-state magnetic resonance spectroscopy and gel permeation chromatography. After deposition on AA2024-T3 substrate and curing, the coating properties were further evaluated by contact profilometer and focused ion beam/scanning electron microscopy coupled with energy-dispersive X-ray spectrometry. The corrosion performance was evaluated in 0.1 M NaCl solution using electrochemical impedance spectroscopy and salt spray chamber testing. The results indicated that the reaction performed in the nitrogen atmosphere increases the degree of the copolymerisation of acrylates groups, resulting in a larger molecular weight of the formed copolymer. After curing, both sol-gels formed continuous, smooth, ∼4 μm thick coatings that provided excellent barrier properties. However, when coating synthesised under nitrogen atmosphere, the coating provided better long-term corrosion resistance reaching almost 1 GΩ cm2 after 6 months immersion in 0.1 M NaCl solution. Superior corrosion resistance was also confirmed in the salt spray chamber where the coating prepared under N2 atmosphere remained unchanged more than 500 hours
Electronic properties and surface potential evaluations at the protein nano-biofilm/oxide interface: Impact on corrosion and biodegradation
Full text linkThe formation of a protein nano-biofilm, which exhibits a special electronic behavior, on the surface of metals or oxide biomaterials considerably influences the crucial subsequent interactions, particularly the corrosion and biodegradation processes. This study discusses the impact of electrical surface potential (ESP) of a single or nano-biofilm of albumin protein on the electrochemical interactions and electronic property evolutions (e.g., charge carriers, space charge capacitance (SCC), and band bending) occurring on the surface oxide of CoCrMo implants. Scanning Kelvin probe force microscopy (SKPFM) results indicated that ESP or surface charge distribution on a single or nano-biofilm of the albumin protein is lower than that of a CoCrMo complex oxide layer, which hinders the charge transfer at the protein/electrolyte interface. Using a complementary approach, which involved performing Mott-Schottky analysis at the electrolyte/protein/oxide interface, it was revealed that the albumin protein significantly increases the SCC magnitude and number of n-type charge carrier owing to increased band bending at the SCC/protein interface; this facilitated the acceleration of metal ion release and metal-protein complex formation. The nanoscale SKPFM and electrochemical analyses performed in this study provide a better understanding of the role of protein molecules in corrosion/biodegradation of metallic biomaterials at the protein nano-biofilm/oxide interface
Microstructural and local electrochemical characterisation of Gr. 91 steel-welded joints as function of post-weld heat treatments
No full textWelded gr. 91 steel is widely used for structural components in the energy production field, where it suffers from
selective corrosion near welded joints. In this work, Gr. 91 plates were welded using a gas tungsten arc welding
technique and subjected to two different post-welding heat treatments (tempering or normalising plus tempering).
Localised corrosion measurements performed with a microcell, coupled with microstructural characterisations, showed that corrosion was very active in the heat-affected zone (HAZ) in the as-welded condition and was
worsened by the tempering treatment. In contrast, after a normalising treatment, the electrochemical behaviour
of the welded joint was uniform
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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