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- Moberg, Christina, et al.
(författare)
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De unga gör helt rätt när de stämmer staten
- 2022
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Ingår i: Aftonbladet. - 1103-9000.
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- 1 620 forskare och lärare i forskarvärlden: Vi ställer oss bakom Auroras klimatkrav
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| 3. |
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| 4. |
- Engberg, David L. J., et al.
(författare)
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Solid Solution and Segregation Effects in Arc-Deposited Ti1-xSixN Thin Films Resolved on the nanometer scale by 15N Isotopic Substitution in AtomP robe Tomography
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Nanostructured TiSiN is an important material in wear--‐resistant coatings for extending the lifetime of cutting tools. Yet, the understanding regarding the structure, phase composition, and bonding on the detailed nanometer scale, which determines the properties of TiSiN, is lacking. This limits our understanding of the growth phenomena and eventually a larger exploitation of the material. By substituting natN2 with 15N2 during reactive arc deposition of TiSiN thin films, atom probe tomography (APT) gives elemental sensitivity and sub-nanometer resolution, a finer scale than what can be obtained by commonly employed energy dispersive electron spectroscopy in scanning transmission electron microscopy. Using a combination of analytical transmission electron microscopy and APT we show that arc-deposited Ti0.92Si0.0815N and Ti0.81Si0.1915N exhibit Si segregation on the nanometer scale in the alloy films. APT composition maps and proximity histograms from domains with higher than average Ti content show that the TiN domains contain at least ~2 at. % Si for Ti0.92Si0.08N and ~5 at. % Si for Ti0.81Si0.19N, thus confirming the formation of solid solutions. The formation of relatively pure SiNy domains in the Ti0.81Si0.19N films is tied to pockets between microstructured, columnar features in the film. Finer SiNy enrichments seen in APT possibly correspond to tissue layers around TiN crystallites, thus effectively hindering growth of TiN crystallites, causing TiN renucleation and thus explaining the featherlike nanostructure within the columns of these films. For the stoichiometry of the TiN phase, we establish a global under stoichiometry, in accordance with the tendency for SiNy films to have tetrahedral bonding coordination towards a nominal Si3N4 composition.
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| 5. |
- Eriksson, Anders, et al.
(författare)
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Arc deposition of Ti–Si–C–N thin films from binary and ternary cathodes — Comparing sources of C
- 2012
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Ingår i: Surface & Coatings Technology. - : Elsevier. - 0257-8972 .- 1879-3347. ; 213, s. 145-154
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Tidskriftsartikel (refereegranskat)abstract
- Ti–Si–C–N thin films with composition of 1–11 at.% Si and 1–20 at.% C have been deposited onto cemented carbide substrates by arcing Ti–Si cathodes in a CH4 + N2 gas mixture and, alternatively, through arcing Ti–Si–C cathodes in N2. Films of comparable compositions from the two types of cathodes have similar structure and properties. Hence, C can be supplied as either plasma ions generated from the cathode or atoms from the gas phase with small influence on the structural evolution. Over the compositional range obtained, the films were dense and cubic-phase nanocrystalline, as characterized by X-ray diffraction, ion beam analysis, and scanning and transmission electron microscopy. The films have high hardness (30–40 GPa by nanoindentation) due to hardening from low-angle grain boundaries on the nanometer scale and lattice defects such as growth-induced vacancies and alloying element interstitials.
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| 6. |
- Eriksson, Mats, 1963-, et al.
(författare)
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The water-forming reaction on thin, SiO2 supported, palladium films
- 1990
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Ingår i: Vacuum. - 0042-207X .- 1879-2715. ; 41:1-3, s. 137-138
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Tidskriftsartikel (refereegranskat)abstract
- The water-forming reaction has been studied on thin Pd films, evaporated on planar SiO2 substrates. The nominal film thickness varied between 5 and 100 Å. The studies were performed in uhv by means of mass spectrometry, UPS and work function measurements in the temperature range 323–523 K. The film structure was also studied with TEM. The results are compared with previous measurements on 1000 Å, thick, homogeneous Pd films. The structure of the thin Pd films changed dramatically during cyclic H2 and O2 exposures, from that of a continuous film with cracks to that of drop-like metal particles. These structural changes are not observed on the thick (1000 Å) Pd films. Even though there are large structural changes, the water-forming reaction looks qualitatively the same as on a thick Pd film. The total water production however, decreases with decreasing film thickness. We believe that some minor qualitative differences in the water-forming reaction for different nominal Pd film thicknesses, are due to the increasing PdSiO2 boundary as the thickness is reduced.
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| 7. |
- Falk, Lars, et al.
(författare)
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Severe Lung Dysfunction and Pulmonary Blood Flow during Extracorporeal Membrane Oxygenation
- 2024
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Ingår i: Journal of Clinical Medicine. - 2077-0383. ; 13:4
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Tidskriftsartikel (refereegranskat)abstract
- Background: Extracorporeal membrane oxygenation (ECMO) is indicated for patients with severe respiratory and/or circulatory failure. The standard technique to visualize the extent of pulmonary damage during ECMO is computed tomography (CT). Purpose: This single-center, retrospective study investigated whether pulmonary blood flow (PBF) measured with echocardiography can assist in assessing the extent of pulmonary damage and whether echocardiography and CT findings are associated with patient outcomes. Methods: All patients (>15 years) commenced on ECMO between 2011 and 2017 with septic shock of pulmonary origin and a treatment time >28 days were screened. Of 277 eligible patients, 9 were identified where both CT and echocardiography had been consecutively performed. Results: CT failed to indicate any differences in viable lung parenchyma within or between survivors and non-survivors at any time during ECMO treatment. Upon initiation of ECMO, the survivors (n = 5) and non-survivors (n = 4) had similar PBF. During a full course of ECMO support, survivors showed no change in PBF (3.8 ± 2.1 at ECMO start vs. 7.9 ± 4.3 L/min, p = 0.12), whereas non-survivors significantly deteriorated in PBF from 3.5 ± 1.0 to 1.0 ± 1.1 L/min (p = 0.029). Tidal volumes were significantly lower over time among the non-survivors, p = 0.047. Conclusions: In prolonged ECMO for pulmonary septic shock, CT was not found to be effective for the evaluation of pulmonary viability or recovery. This hypothesis-generating investigation supports echocardiography as a tool to predict pulmonary recovery via the assessment of PBF at the early to later stages of ECMO support.
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| 9. |
- Frodelius, Jenny, 1978-
(författare)
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Thick and Thin Ti2AlC Coatings
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This Thesis explores the deposition techniques of magnetron sputtering and high velocity oxy-fuel (HVOF) spraying for Ti2AlC as a promising high-temperature material. Magnetron sputtering aims at producing thin (≤1 μm) Ti2AlC films of high crystal quality for use as a model system in understanding the material’s basic properties. HVOF is a new method for deposition of thick (≥200 μm) coatings by spraying Ti2AlC powder, with the aim of transferring the good bulk properties to coatings. The oxidation behavior of Ti2AlC coatings has been investigated for temperatures up to 1200 °C in air. As-deposited Ti2AlC(0001) thin films decompose into TiC during vacuum annealing at 700 °C by out-diffusion of Al as shown by x-ray diffraction analysis. The release of Al starts already at 500 °C in ambient air as driven by aluminum oxide formation on the film surface where the oxide initially forms clusters as observed by electron microscopy. While sputtering from a Ti2AlC target is simpler than by using different elemental targets, the resulting film composition differs from the target stoichiometry. This is due to differences in energy and angular distribution of the sputtered species and evaporation of Al at substrate temperatures above 700 °C. The composition can be compensated for by adding Ti to bind the Al and obtain phase-pure Ti2AlC coatings. For HVOF, I demonstrate how the total gas flow of a H2/O2 mixture (441-953 liter/min) and the powder grain size (30-56 μm) determine the thickness, density, and microstructure of the coatings. High gas flow and small grain size yield thick coatings of 210 μm with a low porosity of 2-8 % and a tensile stress of ≥80 MPa. A fraction of the Ti2AlC powder decomposes during spraying into TiC, Ti3AlC2, and Ti-Al alloys. The coatings also contain as much as 25 at.% O since the powder partly oxidizes during the spraying process. Increasing the powder size and decreasing the total gas flow yield a higher amount of Ti2AlC, but produces thinner coatings with lower cohesion. Post-annealing of the coatings at 900 °C in vacuum increases the Ti2AlC content due to a reversible phase transformation of the as-sprayed material. The high oxygen content, however, hinders the coating to completely transform into Ti2AlC and deteriorates its oxidation resistance. The work thus offers insights to the key parameters for optimizing Ti2AlC coating processing.
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| 10. |
- Ghafoor, Naureen, et al.
(författare)
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Nanolabyrinthine ZrAlN thin films by self-organization of interwoven single-crystal cubic and hexagonal phases
- 2013
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Ingår i: APL Materials. - New York, USA : American Institute of Physics (AIP). - 2166-532X. ; 1:2, s. 022105-1-022105-6
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Tidskriftsartikel (refereegranskat)abstract
- Self-organization on the nanometer scale is a trend in materials research. Thermodynamic driving forces may, for example, yield chessboard patterns in metal alloys[Y. Ni and A. G. Khachaturyan, Nature Mater. 8, 410–414 (2009)] or nitrides [P. H.Mayrhofer, A. Horling, L. Karlsson, J. Sj ¨ ol¨ en, T. Larsson, and C. Mitterer, Appl. ´Phys. Lett. 83, 2049 (2003)] during spinodal decomposition. Here, we explore theZrN-AlN system, which has one of the largest positive enthalpies of mixing amongthe transition metal aluminum nitrides [D. Holec, R. Rachbauer, L. Chen, L. Wang,D. Luefa, and P. H. Mayrhofer, Surf. Coat. Technol. 206, 1698–1704 (2011); B.Alling, A. Karimi, and I. Abrikosov, Surf. Coat. Technol. 203, 883–886 (2008)].Surprisingly, a highly regular superhard (36 GPa) two-dimensional nanolabyrinthinestructure of two intergrown single crystal phases evolves during magnetron sputter thin film synthesis of Zr0.64Al0.36N/MgO(001). The self-organization is surfacedriven and the synergistic result of kinetic limitations, where the enthalpy reductionbalances both investments in interfacial and elastic energies.
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