Search results for "PLASMA"
showing 10 items of 4043 documents
Numerical Reconstruction of Porous Architecture for Suspension Plasma Sprayed Coatings
2021
Abstract The porous architecture of coatings has a significant influence on the coating performances and thus should be properly designed for the intended applications. For simulating the coating properties, it is necessary to determine the numerical representation of the coating microstructure. In this study, YSZ coatings were manufactured by suspension plasma spray (SPS). Afterwards, the porous architecture of as-prepared coatings was investigated by the combination of three techniques, imaging analysis, Ultra Small Angle X-ray Scattering (USAXS), and X-ray transmission. A microstructural model for reconstructing the porous architecture of the SPS coating was subsequently computed accordi…
Powder metallurgy processing and deformation characteristics of bulk multimodal nickel
2014
cited By 7; International audience; Spark plasma sintering was used to process bulk nickel samples from a blend of three powder types. The resulting multimodal microstructure was made of coarse (average size ∼ 135 μm) spherical microcrystalline entities (the core) surrounded by a fine-grained matrix (average grain size ∼ 1.5 μm) or a thick rim (the shell) distinguishable from the matrix. Tensile tests revealed yield strength of ∼ 470 MPa that was accompanied by limited ductility (∼ 2.8% plastic strain). Microstructure observation after testing showed debonding at interfaces between the matrix and the coarse entities, but in many instances, shallow dimples within the rim were observed indica…
Core-shell PLA/Kef hybrid scaffolds for skin tissue engineering applications prepared by direct kefiran coating on PLA electrospun fibers optimized v…
2021
Abstract Over the recent years, there is a growing interest in electrospun hybrid scaffolds composed of synthetic and natural polymers that can support cell attachment and proliferation. In this work, the physical and biological properties of polylactic acid (PLA) electrospun mats coated with kefiran (Kef) were evaluated. Gravimetric, spectroscopic (FTIR-ATR) and morphological investigations via scanning electron microscopy confirmed the effective formation of a thin kefiran layer wrapped on the PLA fibers with an easy-tunable thickness. Air plasma pre-treatment carried out on PLA (P-PLA) affected both the morphology and the crystallinity of Kef coating as confirmed by differential scanning…
Microstructure and mechanical properties of plasma spraying coatings from YSZ feedstocks comprising nano-and submicron-sized particles
2015
Atmospheric plasma spraying (APS) is an attractive technique to obtain nanostructured coatings due to its versatility, simplicity and relatively low cost. However, nanoparticles cannot be fed into the plasma using conventional feeding systems, due to their low mass and poor flowability, and must be adequately reconstituted into sprayable micrometric agglomerates. In this work, nanostructured and submicron/nanostiuctured powders of yttria-stabilised zirconia (YSZ) were deposited using APS, with a view to obtaining high-performance thermal bather coatings (IBC). All powders were reconstituted by spray-drying from different solid loading suspensions, followed by a thermal treatment of the spra…
High current proton source based on ECR discharge sustained by 37.5 GHz gyrotron radiation
2012
Formation of hydrogen ion beams with high intensity and low transverse emittance is one of the key challenges in accelerator technology. Present work is devoted to experimental investigation of proton beam production from dense plasma (Ne > 1013 cm−3) of an ECR discharge sustained by 37.5 GHz, 100 kW gyrotron radiation at SMIS 37 facility at IAP RAS. The anticipated advantages of the SMIS 37 gasdynamic ion source over the current state-of-the-art proton source technology based on 2.45 GHz hydrogen discharges are described. Experimental result obtained with different extraction configurations i.e. single- and multi-aperture systems are presented. It was demonstrated that ultra bright proton …
Thermo-mechanical analyses and ways of optimization of the helium cooled DEMO First Wall under RCC-MRx rules
2017
Abstract The EUROfusion Consortium develops a design of a fusion power demonstrator plant (DEMO) in the framework of the European “Horizon 2020” innovation and research program. One of the key components in the fusion reactor is the Breeding Blanket (BB) surrounding the plasma, ensuring tritium self-sufficiency, heat removal for conversion into electricity, and neutron shielding. Among the 4 candidates for the DEMO BB, 2 of them use helium as coolant (HCPB, HCLL), and another one (DCLL) uses helium to cool down the First Wall (FW) only. Due to uncertainties regarding the plasma Heat Flux (HF) load the DEMO BB integrated FW will have to cope with, a set of sensitive thermal and stress analys…
Direct determination by portable ED-XRF of mineral profile in cocoa powder samples
2019
Abstract The present study has exploited the rapidity of the analysis and the multi-elemental capability of the energy dispersive X- ray fluorescence (ED-XRF) technique for the mineral profile determination in cocoa powder. A fast, cheap and environmental sustainable method without reagent consumption or toxic waste generation has been proposed. The samples can be prepared in the form of pellets of 13 mm in diameter and 2–3 mm thickness. The different internal calibrations used by ED-XRF equipment did not provide accurate results when comparing the mineral profile with the concentration obtained by Inductively Couple Plasma Optical Emission Spectroscopy (ICP-OES) after microwave assisted di…
Enhanced thermoelectric properties of the n-type Magnéli phase WO2.90: reduced thermal conductivity through microstructure engineering
2014
The thermoelectric properties of the Magneli phase WO2.90 were investigated, with special attention to how the thermoelectric performance can be altered by changing its microstructure. Spark plasma sintering (SPS) allowed the direct preparation of large amounts of consolidated material. Adding Ta2O5 to the reaction mixture lead to the formation of solid solutions W1−xTaxO2.90via a concurrent reaction between WO3 and Ta2O5 during the SPS treatment. In addition, micron-sized inclusions containing tungsten surrounded by WOx embedded in a WO2.90 matrix were formed, which act as additional scattering centers. As a result, the thermal conductivity of the Ta-containing samples was reduced by ≈30% …
Analysis of multipactor RF breakdown in a waveguide containing a transversely magnetized ferrite
2016
In this paper, the multipactor RF breakdown in a parallel-plate waveguide partially filled with a ferrite slab magnetized normal to the metallic plates is studied. An external magnetic field is applied along the vertical direction between the plates in order to magnetize the ferrite. Numerical simulations using an in-house 3-D code are carried out to obtain the multipactor RF voltage threshold in this kind of structures. The presented results show that the multipactor RF voltage threshold at certain frequencies becomes considerably lower than for the corresponding classical metallic parallel-plate waveguide with the same vacuum gap