1,721,000 research outputs found
Zirconium Perowskite Coatings Obtained by Combinatorial EB-PVD Process
No full textNew coating materials for high temperature conditions have been developed by a combinatorial electron beam physical vapor deposition process (EB-PVD) on different metallic substrates. BaZrO3 and La2Zr207 nanostructured powders obtained by a hydrothermal process and hydrostatically pressed in pellets were used as starting material. The coatings were characterized by XRD, SEM and EDX. Our preliminary results show that thin films with controlled morphology could be obtained when both materials are deposited layer by layer with La2Zr207 as top coating film. İ 2018 IEEE
Antibacterial Surfaces, Thin Films, and Nanostructured Coatings
Full text linkAntibacterial surfaces can play a key role in a great number of everyday applications, spanning from biomedical purposes (medical devices, protection equipment, surgery tools, human implants, etc [...
Role of oxygen contaminant on the physical properties of sputtered AlN thin films
No full textThe paper deals with the role of the oxygen contamination, coming from residual gas atmosphere in the deposition chamber, on the physical properties of AlN thin films, sputtered in Ar + N2 working gas, at different values of nitrogen flux percentages, and without substrate heating. Contaminant concentration varies with the nitrogen partial pressure in the working gas mixture. Oxygen atoms are incorporated into the growing films due to their higher affinity towards Al atoms compared to N atoms. Oxygen inclusion produces important modifications in the structural, chemical, optical and electrical properties of the AlN thin films. Therefore, contamination can play a crucial role for the tuning of the physical characteristics of sputtered materials. © 2015 Elsevier B.V. All rights reserved
Sputtered WO3 films for water splitting applications
No full textTungsten oxide films with different thickness were grown by sputtering deposition. Analysis of sample morphology showed that the films were constituted by sub-micrometric columnar structures, with diameters in the range 100-500 nm. As-deposited films revealed an almost-amorphous crystal structure and a wide optical band-gap of about 3.28 eV. Thermal annealing at 500 °C was used to promote the formation of a monoclinic WO3 crystal structure and the reduction of the band-gap. Photo-electrochemical characterizations were used to compare the responses of the different films and to evaluate their possible use in water splitting applications. © 2015 Elsevier Ltd
Nanoindentation and scratch behaviour of Ni–P electroless coatings
No full textIn the present paper, the mechanical properties and the scratch failure mechanisms of Ni–P electroless coatings are described. The material microstructure was studied in as-deposited and annealed conditions through SEM and EDS analyses. Nanoindentation measurements on the coatings showed a remarkable hardening due to the crystallization and precipitation behaviour produced by annealing. The scratch tests, conducted by increasing the load during scratch, revealed the coating failure mechanisms in a broad range of applied stresses up to delamination
Sputter-deposited ag nanoparticles on electrospun pcl scaffolds: Morphology, wettability and antibacterial activity
Full text linkPorous scaffolds made of biocompatible and environmental-friendly polymer fibers with diameters in the nano/micro range can find applications in a wide variety of sectors, spanning from the biomedical field to textiles and so on. Their development has received a boost in the last decades thanks to advances in the production methods, such as the electrospinning technique. Conferring antimicrobial properties to these fibrous structures is a primary requirement for many of their appli-cations, but the addition of antimicrobial agents by wet methods can present a series of drawbacks. In this work, strong antibacterial action is successfully provided to electrospun polycaprolactone (PCL) scaffolds by silver (Ag) addition through a simple and flexible way, namely the sputtering deposition of silver onto the PCL fibers. SEM-EDS analyses demonstrate that the polymer fibers get coated by Ag nanoparticles without undergoing any alteration of their morphological integrity upon the deposition process. The influence on wettability is evaluated with polar (water) and non-polar (diiodomethane) liquids, evidencing that this coating method allows preserving the hydrophobic character of the PCL polymer. Excellent antibacterial action (reduction > 99.995% in 4 h) is demon-strated against Escherichia coli. The easy fabrication of these PCL-Ag mats can be applicable to the production of biomedical devices, bioremediation and antifouling systems in filtration, personal protective equipment (PPE), food packaging materials, etc
Possible alternatives to critical elements in coatings for extreme applications
No full textSurface functionalisation and protection have been used since a long time for improving specific properties of materials such as lubrication, water repellence, brightness, and for increasing durability of objects and tools. Among the different kinds of surface treatments used to achieve the required properties, the use of coatings is fundamental to guarantee substrate durability in harsh environments. Extreme working conditions of temperature, pressure, irradiation, wear and corrosion occur in several applications, thus very often requiring bulk material protection by means of coatings. In this study, three main classes of coatings used in extreme conditions are considered: i) hard and superhard coatings for application in machining tools, ii) coatings for high temperatures (thermal barrier coatings), and iii) coatings against corrosion. The presence of critical elements in such coatings (Cr, Y, W, Co, etc.) is analysed and the possibility to use CRMs-free substitutes is reviewed. The role of multilayers and nanocomposites in tailoring coating performances is also discussed for thermal barrier and superhard coatings. © Published under licence by IOP Publishing Ltd
Durability study of PVD - catalysed cathode for polymer electrolyte fuel cells
Full text linkQuesto lavoro riporta uno studio sulla comprensione delle prestazioni dei catodi per celle a combustibile a elettrolita polimerico, ottenute mediante deposizione PVD del catalizzatore di platino. Per indagare la durata di questo tipo di elettrodo, sono stati effettuati test in celle a combustibile prolungati. I risultati hanno evidenziato una diminuzione del rendimento durante il funzionamento prolungato dell'elettrodo a causa di una diminuzione della zona di reazione nello strato catalitico.This paper reports a study on the understanding of the performance of cathodes for polymer electrolyte fuel cells, obtained by means of PVD deposition of the platinum catalyst. To investigate the durability of this kind of electrode, prolonged fuel cell tests have been carried out. The results evidenced a decrease of performance during the prolonged working of the electrode due to a decrease of the reaction zone in the catalytic layer
Preface - E-MRS Fall Symposium I: Solutions for Critical Raw Materials Under Extreme Conditions
No full textWear and fretting behavior of cold sprayed in625 superalloy
No full textThe wear and fretting behaviour of IN625 cold spray coatings was analysed and the results are presented. The cold spray conditions were selected in order to obtain coatings with minimum porosity and maximum particles splat. This leads to compact and hard deposited material able to resist wear damaging and to dissipate energy during fretting. The coating’s strength was evaluated through nanoindentation that revealed an increased hardness from the surface toward the substrate. This different hardening behaviour from the coating surface toward the substrate leads to increased resistance to fretting and wear as the maximum stresses increase. This was revealed by scratch tests performed at linearly increasing loads that allowed identifying of the damage mechanisms acting on the coating as the triaxial stresses increase. The hardening behaviour of the coating also influ-enced the fretting behaviour revealed by the weight loss experienced by varying the fretting maximum load
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