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1.	Sefer, Birhan, 1983-, et al. (author) Chemical Milling of Cast Ti-6Al-4V and Ti-6Al-2Sn-4Zr-2Mo Alloys in Hydrofluoric-Nitric Acid Solutions 2017 In: Corrosion. - : Association for Materials Protection and Performance (AMPP). - 0010-9312 .- 1938-159X. ; 73:4, s. 394-407 Journal article (peer-reviewed)abstract The behavior of cast Ti-6Al-4V and Ti-6Al-2Sn-4Zr-2Mo during chemical milling in hydrofluoric-nitric (HF-HNO3) acid solutions with 1:3 and 1:11 molar ratios was investigated using electrochemical and atomic force microscopy (AFM) techniques. Faster corrosion rate in 1:3 solutions was measured for Ti-6Al-4V than for Ti-6Al-2Sn-4Zr-2Mo, whereas in 1:11 solution Ti-6Al-2Sn-4Zr-2Mo exhibited higher corrosion rate. Scanning Kelvin probe force microscopy measurements revealed difference in the Volta potential between the α-laths and the β-layers in the Widmansttäten microstructure indicating operation of microgalvanic cells between the microconstituents when in contact with HF-HNO3 solution. The AFM topography measurements demonstrated faster corrosion of the α-laths compared to the β-layers, in both alloys. In 1:3 solutions, higher α/β height difference was measured in Ti-6Al-4V, whereas in 1:11 solution, the difference was higher in Ti-6Al-2Sn-4Zr-2Mo. The results revealed that the chemical milling behavior of the two investigated alloys is controlled by the microscopic corrosion behavior of the individual microconstituents.
2.	Chen, Zhe, et al. (author) Nano-scale characterization of white layer in broached Inconel 718 2017 In: Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing. - Amsterdam : Elsevier BV. - 0921-5093 .- 1873-4936. ; 684, s. 373-384 Journal article (peer-reviewed)abstract The formation mechanism of white layers during broaching and their mechanical properties are not well investigated and understood to date. In the present study, multiple advanced characterization techniques with nano-scale resolution, including transmission electron microscopy (TEM), transmission Kikuchi diffraction (TKD), atom probe tomography (APT) as well as nano-indentation, have been used to systematically examine the microstructural evolution and corresponding mechanical properties of a surface white layer formed when broaching the nickel-based superalloy Inconel 718.TEM observations showed that the broached white layer consists of nano-sized grains, mostly in the range of 20–50 nm. The crystallographic texture detected by TKD further revealed that the refined microstructure is primarily caused by strong shear deformation. Co-located Al-rich and Nb-rich fine clusters have been identified by APT, which are most likely to be γ′ and γ′′ clusters in a form of co-precipitates, where the clusters showed elongated and aligned appearance associated with the severe shearing history. The microstructural characteristics and crystallography of the broached white layer suggest that it was essentially formed by adiabatic shear localization in which the dominant metallurgical process is rotational dynamic recrystallization based on mechanically-driven subgrain rotations. The grain refinement within the white layer led to an increase of the surface nano-hardness by 14% and a reduction in elastic modulus by nearly 10% compared to that of the bulk material. This is primarily due to the greatly increased volume fraction of grain boundaries, when the grain size was reduced down to the nanoscale.
3.	Annual Transactions of the Nordic Rheology Society - Volume 23 2015 Editorial collection (peer-reviewed)
4.	Hosseini Bab Anari, Elham, 1982, et al. (author) Fluorine-free salts for aqueous lithium-ion and sodium-ion battery electrolytes 2016 In: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 6:88, s. 6, 85194-85201 Journal article (peer-reviewed)abstract A first generation of fluorine-free lithium and sodium salts based on the concept of pseudo-delocalized anions has been synthesized with both high purity and yield using water as the solvent in the reaction medium. The salts have been fully characterized by Raman and FT-IR spectroscopies, thermogravimetry, and X-ray crystallography to reveal both basic properties in terms of thermal stability and solubility as well as the local, mainly ion–ion interaction dictated, coordination details and by ionic conductivity and electrochemical stability window measurements as aqueous electrolytes. Together a picture is created of the salts' promise as components in electrolytes – primarily aiming at application in low voltage fluorinefree aqueous lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs).
5.	Ekman, Jonas, et al. (author) Projekt: Rymdforskarskolan 2015 Other publication (pop. science, debate, etc.)abstract The Graduate School of Space Technology
6.	Åkerfeldt, Pia, et al. (author) Electron backscatter diffraction characterization of fatigue crack growth in laser metal wire deposited Ti-6Al-4V 2018 In: Materials Characterization. - : Elsevier BV. - 1044-5803 .- 1873-4189. ; 135, s. 245-256 Journal article (peer-reviewed)abstract By additive manufacturing (AM) there is a feasibility of producing near net shape components in basically one step from 3D CAD model to final product. The interest for AM is high and during the past decade a lot of research has been carried out in order to understand the influence from process parameters on the microstructure and furthermore on the mechanical properties. In the present study laser metal wire deposition of Ti-6Al-4V has been studied in detail with regard to its fatigue crack propagation characteristics. Two specimen orientations, parallel and perpendicular to the deposition direction, have been evaluated at room temperature and at 250 Â°C. No difference in the fatigue crack growth rate could be confirmed for the two specimen orientations. However, in the fractographic study it was observed that the tortuosity varied between certain regions on the fracture surface. The local crack path characteristic could be related to the alpha colony size and/or the crystallographic orientation. Moreover, large areas exhibiting similar crystallographic orientation were observed along the prior beta grain boundaries, which were attributed to the wide alpha colonies frequently observed along the prior beta grain boundaries. Â© 2017 Elsevier Inc.
7.	Åkerfeldt, Maria, 1982, et al. (author) Textile piezoelectric sensors – melt spun bi-component poly(vinylidene fluoride) fibres with conductive cores and poly(3,4-ethylene dioxythiophene)-poly(styrene sulfonate) coating as the outer electrode 2014 In: Fashion and Textiles. - : Springer Science and Business Media LLC. - 2198-0802. ; 1:1 Journal article (peer-reviewed)abstract The work presented here addresses the outer electroding of a fully textile piezoelectric strain sensor, consisting of bi-component fibre yarns of β-crystalline poly(vinylidene fluoride) (PVDF) sheath and conductive high density polyethylene (HDPE)/carbon black (CB) core as insertions in a woven textile, with conductive poly(3,4-ethylene dioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS) coatings developed for textile applications. Two coatings, one with a polyurethane binder and one without, were compared for the application and evaluated as electrode material in piezoelectric testing, as well as tested for surface resistivity, tear strength, abrasion resistance and shear flexing. Both coatings served their function as the outer electrodes in the system and no difference in this regard was detected between them. Omission of the binder resulted in a surface resistivity one order of magnitude less, of 12.3 Ω/square, but the surface resistivity of these samples increased more upon abrasion than the samples coated with binder. The tear strength of the textile coated with binder decreased with one third compared to the uncoated substrate, whereas the tear strength of the coated textile without binder increased with the same amount. Surface resistivity measurements and scanning electron microscopy (SEM) images of the samples subjected to shear flexing showed that the coatings without the binder did not withstand this treatment, and that the samples with the binder managed this to a greater extent. In summary, both of the PEDOT:PSS coatings could be used as outer electrodes of the piezoelectric fibres, but inclusion of binder was found necessary for the durability of the coating.
8.	Guldris Leon, Lorena, 1983, et al. (author) Understanding Mineral Liberation during Crushing Using Grade-by-Size Analysis - A Case Study of the Penuota Sn-Ta Mineralization, Spain 2020 In: Minerals. - : MDPI AG. - 2075-163X. ; 10:2 Journal article (peer-reviewed)abstract Coarse comminution test-work and modeling are powerful tools in the design and optimization of mineral processing plants and provide information on energy consumption. Additional information on mineral liberation characteristics can be used for assessing the potential of pre-concentration stages or screens in the plant design. In ores of high-value metals (e.g., Ta, W), standard techniques-such as the mineralogical quantification of grain mounts by quantitative evaluation of minerals by scanning electron microscopy (QEMSCAN) or chemical analysis by X-ray fluorescence (XRF) can be challenging, due to the low relative abundance of such valuable minerals. The cost of QEMSCAN is also a limiting factor, especially considering the large number of samples required for the optimization of coarse comminution. In this study, we present an extended analytical protocol to a well-established mechanical test of interparticle breakage to improve the assessment of coarse mineral liberation characteristics. The liberation of ore minerals is a function of the rock texture and the difference in size and mechanical properties of the valuable minerals relative to gangue minerals and they may fraction in certain grain sizes if they behave differently during comminution. By analyzing the bulk-chemistry of the different grain size fractions produced after compressional testing, and by generating element by size diagrams, it is possible to understand the liberation characteristics of an ore. We show, based on a case study performed on a tantalum ore deposit, that element distribution can be used to study the influence of mechanical parameters on mineral liberation. This information can direct further mineralogical investigation and test work.
9.	Stolen, Reidar, et al. (author) Solcelleteknologi og brannsikkerhet 2018 Reports (other academic/artistic)abstract Bruken av solcelleteknologi er i stor vekst i Norge. I denne studien er branntekniske utfordringer ved bruk av solcelleteknologi undersøkt, med hensyn på brannstart, brannspredning og brannslokking. Studien danner et kunnskapsgrunnlag for å ivareta brannsikkerheten under montering, drift og under slokkeinnsats, samt for å utforme et enhetlig og tydelig regelverk. Resultatene fra studien viser:Brannstart: Solcelleinstallasjoner inneholder mange koblingspunkt, som kan være potensielle tennkilder, og en liten mengde brennbare materialer. Dermed er det som trengs til stede for å starte en brann. Det er viktig at alle kontaktpunkter i solcelleinstallasjonen er robuste og tåler den påkjenningen de blir utsatt for gjennom sin levetid uten at det oppstår dårlig kontakt som kan føre til brann.Brannspredning: For utenpåmonterte solcellemoduler er det ofte en åpen luftspalte mellom modul og bygning. Dersom det er en brann i denne luftspalten, vil varmen kunne bli akkumulert, noe som kan føre til raskere og større brannspredning enn om bygningsoverflaten ikke hadde vært tildekket. I fullskalaforsøk med solcellemoduler montert på tak spredte brannen seg under hele arealet som var dekket av moduler, men stoppet da den nærmet seg kanten av dette arealet. Dette illustrerer viktigheten av at områder med solceller utenpå en bygning blir seksjonert for å unngå brannspredning. Eventuelt kan det benyttes mindre brennbare materialer på taket under solcellemodulene for å motvirke den økte varmepåkjenningen som solcellemodulene gir. Luftspalten mellom modul og bygning kan potensielt også gi endringer i luftstrømningen langs bygget, som igjen kan påvirke brannspredningen.Brannslokking: Brannvesenet har behov for informasjon om det er solcelleinstallasjon i bygget og hvilke deler av det elektriske anlegget som kan være spenningssatt. Under slokkeinnsats må brannvesenet ta hensyn til berøringsfare, og fare for at det kan oppstå lysbuer og andre feil som kan føre til nye antennelsespunkt. Ferskvann kan brukes som slokkemiddel, dette må spyles fra minimum 1 meters avstand med spredt stråle og minimum 5 meters avstand med samlet stråle. Solcellemoduler kan komplisere brannslokking ved at de danner en fysisk barriere mellom brannvesenet og brannen, samt fordi det må tas hensyn til plassering av spenningssatte komponenter. Når disse punktene er tatt høyde for, bør ikke utenpåmonterte solcelleinstallasjoner være et problem.Videre arbeid: For utenpåmonterte solcelleinstallasjoner, er det lite forskning på vertikal montering (på fasader), og hvordan en eventuell endret branndynamikk kan påvirke brannspredning og slokking. Videre er det i dag økende bruk av bygningsintegrerte solcelleinstallasjoner, noe som gir mange mulige nye utfordringer for brannsikkerheten og for regelverk, ettersom solcellen da er en del av bygningskroppen, samtidig som den er en elektrisk komponent. Tysk statistikk tyder på at brannrisiko for slike installasjoner kan være større enn for utenpåmonterte solcelleinstallasjoner, og dette vil det derfor være viktig å undersøke nærmere.
10.	Dimitrios, Nikas, et al. (author) Effect of annealing on microstructure in railway wheel steel 2022 In: 42Nd Riso International Symposium On Materials Science. - : Institute of Physics Publishing (IOPP). ; 1249 Conference paper (peer-reviewed)abstract Railway wheels are commonly made from medium carbon steels (similar to 0.55 wt.% C), heat treated to a near pearlitic microstructure with 5-10% pro-eutectoid ferrite. During the operation of freight trains, where block brakes are used, high thermal loads occur together with the high contact stresses, which combined can affect the mechanical properties of the material. In this study, the effects of annealing on local microstructure and mechanical properties in pearlitic railway wheel steel were investigated using electron microscopy and micro-hardness. It is found that after annealing at 650 degrees C, the room temperature hardness reduces about 25%, accompanied by significant spheroidization of cementite in the pearlitic colonies, though the size and the orientation gradients of the pearlitic colonies have not changed much. The relationship between the microstructural changes and the mechanical properties are discussed.
11.	Lindberg, Siv M, et al. (author) A product semantic study of the influence of the sense of touch on the evaluation of wood-based materials 2013 In: Materials & design. - : Elsevier BV. - 0264-1275 .- 1873-4197 .- 0261-3069. ; 52, s. 300-307 Journal article (peer-reviewed)abstract Based on product semantics, this study investigated how the tactile attributes of wood and wood-based composites are perceived and interpreted semantically. The wood-based samples included ash, birch, elm, oak, pine, OSB (oriented strand board), two wood pulp-reinforced polylactide composites, Comp A and B and one wood-fiber reinforced polypropene composite, Comp C. The subjects rated the samples by the descriptive words natural, exclusive, eco-. friendly, rough, inexpensive, reliable, warm, modern, snug and solid. The most significant differences between the samples were found for roughness and for the descriptors, reliable, natural and solid. A principal component analysis yielded three attributes based on the tactile perceptions: reliable, old-. fashioned and smooth. The solid wood pieces were perceived as natural and oak was perceived as being exclusive. The composite materials presented a greater variation in terms of perceived attributes than the wood specimens.
12.	Mahade, Satyapal, 1987-, et al. (author) Incorporation of graphene nano platelets in suspension plasma sprayed alumina coatings for improved tribological properties 2021 In: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 570 Journal article (peer-reviewed)abstract Graphene possesses high fracture toughness and excellent lubrication properties, which can be exploited to enhance tribological performance of coating systems utilized to combat wear. In this work, suspension plasma spray (SPS) process was employed to deposit a composite, graphene nano-platelets (GNP) incorporated alumina coating. For comparison, monolithic alumina was also deposited utilizing identical spray conditions. The as-deposited coatings were characterized in detail for their microstructure, porosity content, hardness, fracture toughness and phase composition. Raman analysis of the as-deposited composite coating confirmed retention of GNP. The composite coating also showed good microstructural integrity, comparable porosity, higher fracture toughness and similar alumina phase composition as the monolithic alumina coating. The as-deposited coatings were subjected to dry sliding wear tests. The GNP incorporated composite coating showed lower CoF and lower specific wear rate than the pure alumina coating. Additionally, the counter surface also showed a lower wear rate in case of the composite coating. Post-wear analysis performed by SEM/EDS showed differences in the coating wear track and in the ball wear track of monolithic and composite coatings. Furthermore, Raman analysis in the wear track of composite coating confirmed the presence of GNP. The micro-indentation and wear test results indicate that the presence of GNP in the composite coating aided in improving fracture toughness, lowering CoF and specific wear rate compared to the monolithic coating. Results from this work demonstrated retention of GNP in an SPS processed coating, which can be further exploited to design superior wear-resistant coatings.
13.	Mamontov, Eugen, 1955, et al. (author) Asymptotic trajectory matching in self-navigation of autonomous manless interceptors: Nonsearch method and a formulation of the functional optimization of the stability of random systems 2006 In: Proc. 5th MATHMOD Vienna Conf., 8-10 February, 2006 (Vienna Univ. of Technol., Vienna, Austria). - 3901608303 ; 2 Conference paper (peer-reviewed)abstract In the field of self-navigation autonomous manless robots there is a noticeable interest to the robot-based target-interception problem. The interceptor trajectory is usually determined by search-based optimization algorithms. In contrast to this, the present work treats the interception as asymptotic trajectory matching and introduces a nonsearch method for the interceptor trajectory. This method is substantially simpler than the well-known proportional navigation and requires very limited computing resources. The latter feature makes the proposed method especially suitable to the interceptors based on embedded onboard computers and civil applications. An example of the latter discussed in the work is the protection of the infrastructure components against intended or unintended attacks. In a general case when parameters of the interceptor are random, the new method leads to a formulation of a new problem in stochastic optimization, namely the functional optimization of (the so-called targetal) stability of the interceptor trajectory. Certain aspects of a practical implementation of the new systems are analyzed. The work proposes the basic physical principle and schemes for innovative sensors which can make the interceptors truly autonomous, in particular, fully GPS-free. A list of the fundamental and applied topics for future research is also suggested.
14.	Grolig, Jan Gustav, 1986 (author) Coated Ferritic Stainless Steels as Interconnects in Solid Oxide Fuel Cells - Material Development and Electrical Properties 2015 Doctoral thesis (other academic/artistic)abstract Solid oxide fuel cells (SOFCs) are attracting increasing interest as devices with potentialuses in decentralized and clean electricity and heat production. Several challengeswith respect to materials have to be overcome to achieve efficiencies and life-spansthat are sufficient for long-term applications.An important element of an SOFC stack is the interconnect component, which connectstwo adjacent fuel cell elements. Interconnects, which are commonly composedof ferritic stainless steels, have to be corrosion-resistant, mechanically stable and costoptimized.This work aimed to investigate economic solutions for interconnect materials and tounderstand the underlying mechanisms of degradation and electrical conduction ofthese materials. Mainly two substrates, a commercially available steel (AISI 441) anda ferritic stainless steel that was optimized for an SOFC application (Sandvik SanergyHT) were combined with different barrier coatings and exposed to a cathode-sideatmosphere. A method was developed that allows for the electrical characterizationof promising material systems and model alloys, thereby facilitating a fundamentalunderstanding of the dominant electrical conduction processes linked to the oxidescales that grow on interconnects. The AISI 441 steel coated with reactive elementsand cobalt showed good corrosion and chromium evaporation profiles, while AISI 441coated with cerium and cobalt also had promising electrical properties. The SanergyHT steel was examined with coatings of copper and iron and copper and manganese,respectively. The corrosion and chromium evaporation profiles of Sanergy HT wereimproved by coating with copper and iron. The copper and iron-coated Sanergy HTshowed lower area specific resistance values than cobalt-coated Sanergy HT. Chromia,which is the main constituent of oxide scales, was synthesized using differentmethods. The electrical properties of chromia were found to be sensitive to not onlyimpurities, but also heat treatment. Finally the electrical properties of cobalt- andcobalt cerium-coated Sanergy HT steels were investigated. It was revealed that theaddition of cerium improved the conductivity of the interconnect by both slowingdown chromia growth and preventing the outward diffusion of iron into the spinel.
15.	Neikter, Magnus, et al. (author) Microstructure and Defects in Additive Manufactured Titanium : a Comparison Between Microtomography and Optical Microscopy 2017 Conference paper (other academic/artistic)abstract The aim of this work has been to compare two different analysing methods; x-ray microtomography and light optical microscopy, when it comes to defects and microstructure of additively manufactured Ti-6Al-4V. The results show that both techniques have their pros and cons:microtomography is the preferred choice for defect detection by analysing the full 3D sample volume, while light optical microscopy is better for analysing finer details in 2D.
16.	Carini, Giovanni, et al. (author) Hypersonic attenuation in cesium borate glasses: Relaxation and anharmonicity 2009 In: Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing. - : Elsevier BV. - 0921-5093. ; 521-22, s. 247-250 Conference paper (peer-reviewed)abstract The internal friction and the sound velocity in a cesium borate glass (Cs(2)O)(0.14)(B(2)O(3))(0.86) were measured at ultrasonic and hypersonic frequencies by Brillouin scattering measurements over the temperature range between 15 and 300 K. The analysis of the experimental results show that, in addition to thermally activated local motions of structural defects, the vibrational anharmonicity contributes substantially to the temperatures dependences of both the hypersonic loss and velocity. It has been also proved that above 150 K the vibrational anharmonicity appears to be governed by the Akhiezer mechanism of phonon viscosity.
17.	Dochev, Dimitar Milkov, 1981, et al. (author) A Technology Demonstrator for 1.6–2.0 THz Waveguide HEB Receiver with a Novel Mixer Layout 2011 In: Journal of Infrared, Millimeter, and Terahertz Waves. - : Springer Science and Business Media LLC. - 1866-6892 .- 1866-6906. ; 32:4, s. 451-465 Journal article (peer-reviewed)abstract In this paper, we present our studies on a technology demonstrator for a balanced waveguide hot-electron bolometer (HEB) mixer operating in the 1.6–2.0 THz band. The design employs a novel layout for the HEB mixer combining several key technologies: all-metal THz waveguide micromachining, ultra-thin NbN film deposition and a micromachining of a silicon-on-insulator (SOI) substrate to manufacture the HEB mixer. In this paper, we present a novel mixer layout that greatly facilitates handling and mounting of the mixer chip via self-aligning as well as provides easy electrical interfacing. In our opinion, this opens up a real prospective for building multi-pixel waveguide THz receivers. Such receivers could be of interest for SOFIA, possible follow up of the Herschel HIFI, and even for ground based telescopes yet over limited periods of time with extremely dry weather (PWV less than 0.1 mm).
18.	Goel, Sneha, 1993-, et al. (author) Effect of post-treatments under hot isostatic pressure on microstructural characteristics of EBM-built Alloy 718 2019 In: Additive Manufacturing. - : Elsevier BV. - 2214-8604 .- 2214-7810. ; 28, s. 727-737 Journal article (peer-reviewed)abstract Electron beam melting (EBM) has emerged as an important additive manufacturing technique. In this study, Alloy 718 produced by EBM was investigated in as-built and post-treated conditions for microstructural characteristics and hardness. The post-treatments investigated were hot isostatic pressing (HIP) and combined HIP + heat treatment (HIP + HT) carried out as a single cycle inside the HIP vessel. Both the post-treatments resulted in significant decrease in defects inevitably present in the as-built material. The columnar grain structure of the as-built material was found to be maintained after post-treatment, with some sporadic localized grain coarsening noted. Although HIP led to complete dissolution of δ and γ′′ phase, stable NbC and TiN (occasionally present) particles were observed in the post-treated specimens. Significant precipitation of γ′′ phase was observed after HIP + HT, which was attributed to the two-step aging heat treatment carried out during HIP + HT. The presence of γ′′ phase or otherwise was correlated to the hardness of the material. While the HIP treatment resulted in drop in hardness, HIP + HT led to ‘recovery’ of the hardness to values exceeding those exhibited by the as-built material.
19.	Goel, Sneha, 1993-, et al. (author) The Effect of Location and Post-treatment on the Microstructure of EBM-Built Alloy 718 2018 In: Proceedings of the 9th International Symposium on Superalloy 718 & Derivatives. - Cham : Springer. - 2367-1696 .- 2367-1181. - 9783319894799 - 9783319894805 ; , s. 115-129 Conference paper (peer-reviewed)abstract Additive manufacturing (AM) of Ni-based superalloys such as Alloy 718 may obviate the need for difficult machining and welding operations associated with geometrically intricate parts, thus potentially expanding design possibilities and facilitating cost-effective manufacture of complex components. However, processing AM builds completely free from defects, which may impair mechanical properties such as fatigue and ductility, is challenging. Anisotropic properties, microstructural heterogeneities and local formation of undesired phases are additional concerns that have motivated post-treatment of AM builds. This work investigates the microstructural changes associated with post-treatment of Alloy 718 specimens produced by Electron Beam Melting (EBM) for as-built microstructures at 3 build heights: near base plate, in the middle of build and near the top of the build. Two different post-treatment conditions, hot isostatic pressing (HIP) alone and a combined HIP with solutionising and two-step aging were examined and compared to the results for the as-built condition. The influence of various post-treatments on minor phase distributions (δ, γ″, carbides), overall porosity, longitudinal grain widths and Vickers microhardness was considered. The HIP treatment led to significant reduction in overall porosity and dissolution of δ phase, which led to appreciable grain growth for both post-treatment conditions. The variation in hardness noted as a function of build height for the as-built specimens was eliminated after post-treatment. Overall, the hardness was found to decrease after HIP and increase after the full HIP, solutionising and aging treatment, which was attributed to dissolution of γ″ during HIP and its re-precipitation in subsequent heat treatment steps.
20.	Velaga, Sitaram, et al. (author) Drying Kinetics of Polymeric Films : theoretical and experimental studies 2016 Conference paper (peer-reviewed)
21.	Wärmefjord, Kristina, 1976, et al. (author) Welding of non-nominal geometries : physical tests 2016 In: Procedia CIRP. - : Elsevier BV. - 2212-8271 .- 2212-8271. ; 43, s. 136-141 Journal article (peer-reviewed)abstract The geometrical quality of a welded assembly is to some extent depending part positions before welding. Here, a design of experiment is set up in order to investigate this relation using physical tests in a controlled environment. Based on the experimental results it can be concluded that the influence of part position before welding is significant for geometrical deviation after welding. Furthermore, a working procedure for a completely virtual geometry assurance process for welded assemblies is outlined. In this process, part variations, assembly fixture variations and welding induced variations are important inputs when predicting the capability of the final assembly.
22.	Dahl, Ingolf, 1950 (author) How to measure the Mueller matrix of liquid-crystal cells 2001 In: Meas. Sci. Technol.. - 0957-0233. ; 12, s. 1938-1948 Journal article (peer-reviewed)abstract The Mueller matrix is the transfer matrix in the Stokes algebra that describes the polarization of natural light. This matrix is very versatile for the task of characterizing the optical properties of liquid-crystal cells, since it can be used for comparison with theoretical calculations, the determination of material parameters and the modelling of the cell as an optical building block for technological use. We have constructed a Mueller-matrix spectrometer, with the ability to perform fast, dynamic measurements of the Mueller matrix of small areas of liquid-crystal cells throughout the visible range. To illustrate the potential of the instrument, dynamic measurements on a ferroelectric-liquid-crystal cell are presented and analysed. The optical measurements indicate that there is an asymmetry between the up and the down state, tilted smectic layers and polarization reversal initiated at the boundaries.
23.	Jeong, Seung Hee, 1978-, et al. (author) Stretchable Thermoelectric Generators Metallized with Liquid Alloy 2017 In: ACS Applied Materials & Interfaces. - : American Chemical Society (ACS). - 1944-8252 .- 1944-8244. ; 9:18, s. 15791-15797 Journal article (peer-reviewed)abstract Conventional thermoelectric generators (TEGs) are normally hard, rigid, and flat. However, most objects have curvy surfaces, which require soft and even stretchable TEGs for maximizing efficiency of thermal energy harvesting. Here, soft and stretchable TEGs using conventional rigid Bi2Te3 pellets metallized with a liquid alloy is reported. The fabrication is implemented by means of a tailored layer-by-layer fabrication process. The STEGs exhibit an output power density of 40.6 ?W/cm2 at room temperature. The STEGs are operational after being mechanically stretched-and-released more than 1000 times, thanks to the compliant contact between the liquid alloy interconnects and the rigid pellets. The demonstrated interconnect scheme will provide a new route to the development of soft and stretchable energy-harvesting avenues for a variety of emerging electronic applications.
24.	Zhang, Hanzhu, 1991-, et al. (author) A high-entropy B4(HfMo2TaTi)C and SiC ceramic composite 2019 In: Dalton Transactions. - : Royal Society of Medicine Press. - 1477-9226 .- 1477-9234. ; 48:16, s. 5161-5167 Journal article (peer-reviewed)abstract A multicomponent composite of refractory carbides, B4C, HfC, Mo2C, TaC, TiC and SiC, of rhombohedral, face-centered cubic (FCC) and hexagonal crystal structures is reported to form a single phase B4(HfMo2TaTi)C ceramic with SiC. The independent diffusion of the metal and nonmetal atoms led to a unique hexagonal lattice structure of the B4(HfMo2TaTi)C ceramic with alternating layers of metal atoms and C/B atoms. In addition, the classical differences in the crystal structures and lattice parameters among the utilized carbides were overcome. Electron microscopy, X-ray diffraction and calculations using density functional theory (DFT) confirmed the formation of a single phase B4(HfMo2TaTi)C ceramic with a hexagonal close-packed (HCP) crystal structure. The DFT based crystal structure prediction suggests that the metal atoms of Hf, Mo, Ta and Ti are distributed on the (0001) plane in the HCP lattice, while the carbon/boron atoms form hexagonal 2D grids on the (0002) plane in the HCP unit cell. The nanoindentation of the high-entropy phase showed hardness values of 35 GPa compared to the theoretical hardness value estimated based on the rule of mixtures (23 GPa). The higher hardness was contributed by the solid solution strengthening effect in the multicomponent hexagonal structure. The addition of SiC as the secondary phase in the sintered material tailored the microstructure of the composite and offered oxidation resistance to the high-entropy ceramic composite at high temperatures.
25.	Posch, Josefina (author) EP9 Starlight Reserves 2023 In: Göteborgs Botaniska Trädgård, GIBCA Extended, 2023-08-19. Artistic work (other academic/artistic)abstract The sculpture EP9 Starlight Reserves was installed in Amerikadammen in Göteborgs Botaniska Trädgård and part of GIBCA Extended 2023. This work is situated in the expanded field of sculpture, where the negotiation with a specific situation plays a central role in material investigations of environmental and sustainability concerns. The shape and title of the sculpture derive from the container of old batteries, "Exposed Pallet 9," which the International Space Station launched into space in 2021 to circulate around the Earth for 2-4 years before entering the Earth's atmosphere and hopefully burn up. [1] Commercial interests, colonization, and tourism led by rich nations and private companies contribute to the increase of space debris. The main inquiry of this research project is how artistic work, through visualization in sculptural form, can draw attention to scientific observations and advocacy in establishing international environmental space law concerning space debris. By using recycled plastic from electronic scrap for the large-scale IRBAM printing of the sculpture, the work highlights the potential for sustainable and ephemeral materials in sculptural production to promote environmental awareness and question the validity of the standard requirement for "permanence" in public sculpture. 3D printing in collaboration with Samuel Johansson and Woodrow Wiest RISE – AM center in Mölndal, Sweden with in-kind funding. Supported by Göteborgs Stad Kultur och Göteborgs Botaniska Trädgård. [1] Mike Wall, “Space station tosses 2.9-ton hunk of space junk overboard. It will stay in orbit for years.”, space.com, accessed January 3, 2024, https://www.space.com/space-station-jettisons-huge-space-junk-pallet
26.	Belitsky, Victor, 1955, et al. (author) Towards Multi-Pixel Heterodyne Terahertz Receivers 2011 In: Proceedings of the 22nd International Symposium on Space Terahertz Technology, Tucson, AZ, USA, April 26-28, 2011. ; , s. 1-3 Conference paper (peer-reviewed)abstract Terahertz multi-pixel heterodyne receivers introduce multiple challenges for their implementation, mostly due to the extremely small dimensions of all components and even smaller tolerances in terms of alignment, linear dimensions and waveguide component surface quality. In this manuscript, we present a concept of terahertz multi-pixel heterodyne receiver employing optical layout using polarization split between the LO and RF. The frontend is based on a waveguide balanced HEB mixer for the frequency band 1.6 – 2.0 THz. The balanced HEB mixer follows the layout of earlier demonstrated APEX T2 mixer. However for the mixer presented here, we implemented splitblock layout offering minimized lengths of all waveguides and thus reducing the associated RF loss. The micromachining methods employed for producing the mixer housing and the HEB mixer chip are very suitable for producing multiple structures and hence are in-line with requirements of multi-pixel receiver technology. The demonstrated relatively simple mounting of the mixer chip with self-aligning should greatly facilitate the integration of such multi-channel receiver.
27.	Cho, Sung-Woo, et al. (author) Injection-molded nanocomposites and materials based on wheat gluten 2011 In: International Journal of Biological Macromolecules. - : Elsevier BV. - 0141-8130 .- 1879-0003. ; 48:1, s. 146-152 Journal article (peer-reviewed)abstract This is, to our knowledge, the first study of the injection molding of materials where wheat gluten (WG) is the main component. In addition to a plasticizer (glycerol), 5 wt.% natural montmorillonite clay was added. X-ray indicated intercalated clay and transmission electron microscopy indicated locally good clay platelet dispersion. Prior to feeding into the injection molder, the material was first compression molded into plates and pelletized. The filling of the circular mold via the central gate was characterized by a divergent flow yielding, in general, a stronger and stiffer material in the circumferential direction. It was observed that 20–30 wt.% glycerol yielded the best combination of processability and mechanical properties. The clay yielded improved processability, plate homogeneity and tensile stiffness. IR spectroscopy and protein solubility indicated that the injection molding process yielded a highly aggregated structure. The overall conclusion was that injection molding is a very promising method for producing WG objects.
28.	Jeong, Seung Hee, 1978- (author) Soft Intelligence : Liquids Matter in Compliant Microsystems 2016 Doctoral thesis (other academic/artistic)abstract Soft matter, here, liquids and polymers, have adaptability to a surrounding geometry. They intrinsically have advantageous characteristics from a mechanical perspective, such as flowing and wetting on surrounding surfaces, giving compliant, conformal and deformable behavior. From the behavior of soft matter for heterogeneous surfaces, compliant structures can be engineered as embedded liquid microstructures or patterned liquid microsystems for emerging compliant microsystems.Recently, skin electronics and soft robotics have been initiated as potential applications that can provide soft interfaces and interactions for a human-machine interface. To meet the design parameters, developing soft material engineering aimed at tuning material properties and smart processing techniques proper to them are to be highly encouraged. As promising candidates, Ga-based liquid alloys and silicone-based elastomers have been widely applied to proof-of-concept compliant structures.In this thesis, the liquid alloy was employed as a soft and stretchable electrical and thermal conductor (resistor), interconnect and filler in an elastomer structure. Printing-based liquid alloy patterning techniques have been developed with a batch-type, parallel processing scheme. As a simple solution, tape transfer masking was combined with a liquid alloy spraying technique, which provides robust processability. Silicone elastomers could be tunable for multi-functional building blocks by liquid or liquid-like soft solid inclusions. The liquid alloy and a polymer additive were introduced to the silicone elastomer by a simple mixing process. Heterogeneous material microstructures in elastomer networks successfully changed mechanical, thermal and surface properties.To realize a compliant microsystem, these ideas have in practice been useful in designing and fabricating soft and stretchable systems. Many different designs of the microsystems have been fabricated with the developed techniques and materials, and successfully evaluated under dynamic conditions. The compliant microsystems work as basic components to build up a whole system with soft materials and a processing technology for our emerging society.
29.	Charles Murgau, Corinne, et al. (author) Temperature and Microstructure Evolution in Gas Tungsten Arc Welding Wire Feed Additive Manufacturing of Ti-6Al-4V 2019 In: Materials. - : MDPI. - 1996-1944. ; 12:21 Journal article (peer-reviewed)abstract In the present study, the gas tungsten arc welding wire feed additive manufacturing process is simulated and its final microstructure predicted by microstructural modelling, which is validated by microstructural characterization. The Finite Element Method is used to solve the temperature field and microstructural evolution during a gas tungsten arc welding wire feed additive manufacturing process. The microstructure of titanium alloy Ti-6Al-4V is computed based on the temperature evolution in a density-based approach and coupled to a model that predicts the thickness of the α lath morphology. The work presented herein includes the first coupling of the process simulation and microstructural modelling, which have been studied separately in previous work by the authors. In addition, the results from simulations are presented and validated with qualitative and quantitative microstructural analyses. The coupling of the process simulation and microstructural modeling indicate promising results, since the microstructural analysis shows good agreement with the predicted alpha lath size.
30.	Dimitrios, Nikas, et al. (author) Evaluation of local strength via microstructural quantification in a pearlitic rail steel deformed by simultaneous compression and torsion 2018 In: Materials Science & Engineering. - : Elsevier. - 0921-5093 .- 1873-4936. ; 737, s. 341-347 Journal article (peer-reviewed)abstract Pearlitic steels are commonly used for railway rails because they combine good strength and wear properties. During service, the passage of trains results in large accumulation of shear strains in the surface layer of the rail, sometimes leading to crack initiation. Knowledge of the material properties versus the shear strain in this layer is therefore important for fatigue life predictions. In this study, fully pearlitic R260 rail steel was deformed using a bi-axial torsion-compression machine to reach different shear strains. Microstructural parameters including interlamellar spacing, thickness of ferrite and cementite lamellae and dislocation density in the ferrite lamellae, as well as hardness were quantitatively characterized at different shear strain levels. Based on the microstructural observations and the quantification of the microstructural parameters, the local flow stresses were estimated based on boundary strengthening and dislocation strengthening models. A good agreement was found between the estimated flow stresses and the flow stresses determined from microhardness measurements. d
31.	Dimitrios, Nikas, et al. (author) Mechanical properties and fatigue behavior of railway wheel steels as influenced by mechanical and thermal loadings 2015 In: CM 2015 - 10th International Conference on Contact Mechanics of Wheel / Rail Systems. - : International Conference on Contact Mechanics of Wheel / Rail Systems. ; 366:SI, s. 407-415 Conference paper (peer-reviewed)abstract In the current work the deterioration of mechanical properties of railway wheel steels (UIC ER7T and ER8T) is in focus. These are medium carbon steels (∼0.55 wt.% C) heat treated to a near pearlitic microstructure with some 5-10% pro-eutectoid ferrite. During operation of trains, high thermal loads are evolved because of recurring acceleration, braking, curving and occasional slippage. It is thus relevant to examine the high temperature performance of wheel material and evaluate the decrease in strength after thermal exposure as well as the degradation of fatigue properties. Samples were extracted from virgin wheels and pre-strained to around 6.5% strain as well as cyclically deformed, to also account for the change in properties that is induced by plastic deformation inherent in the wheel tread surface. Both un-deformed and pre-strained material was heat treated for different times in the temperature range of interest, from 250°C to 600-700°C. Hardening was observed in both conditions around 300°C followed by softening at higher temperatures. Spheroidization of the pearlite started to become visible at 450°C for the un-deformed material and at around 400°C for the pre-strained.
32.	Duan, Shanghong, 1992, et al. (author) Determination of transverse and shear moduli of single carbon fibres 2020 In: Carbon. - : Elsevier BV. - 0008-6223 .- 1873-3891. ; 158C, s. 772-782 Journal article (peer-reviewed)abstract Carbon fibres are extensively used for their high specific mechanical properties. Exploiting their high axial stiffness and strength, they are employed to reinforce polymer matrix materials in advanced composites. However, carbon fibres are not isotropic. Data of the elastic properties in the other directions of the fibres are still largely unknown. Furthermore, standardised methods to characterise these properties are lacking. In the present work, we propose a methodology to determine the transverse and shear moduli of single carbon fibres. An experimental procedure is developed to fabricate high-quality, flat fibre cross-sections in both longitudinal and transverse directions using Focused Ion Beam, which gives full control of the specimen geometry. Indentation modulus on those surfaces are obtained using both Atomic Force Microscopy (AFM) and nanoindentation tests. Hysteresis was found to occur in the nanoindentation tests. The hysteresis response was due to nano-buckling and reversible shear deformation of the carbon crystals. For this reason, indentation tests using AFM is recommended. From the AFM indentation tests the transverse and shear moduli of three different carbon fibres (IMS65, T800 and M60J) are successfully determined.
33.	Fargas, G., et al. (author) Influence of cyclic thermal treatments on the oxidation behavior of Ti-6Al-2Sn-4Zr-2Mo alloy 2018 In: Materials Characterization. - : Elsevier BV. - 1044-5803 .- 1873-4189. ; 145, s. 218-224 Journal article (peer-reviewed)abstract Ti-6Al-2Sn-4Zr-2Mo is one of the most common titanium alloys for aerospace industry. This alloy experiences oxidation phenomenon at elevated temperatures. In the present study, cyclic thermal treatments were performed in air at 500, 593 and 700 °C, up to 500 cycles, in order to determine the oxidation kinetics and to analyze the oxide scale and alpha-case formation. Moreover, results were compared to those achieved under isothermal conditions to elucidate differences between both thermal conditions. In this sense, metallographic techniques and X-ray diffraction, together with a detailed advanced characterization of the microstructure by Field Emission Scanning Electron Microscopy and Focus Ions Beam, were used to analyze surface oxidation evolution. Results pointed out that cyclic treatments induced a strong increase of the weight gain compared to isothermal treatments. The analysis of the oxide scale revealed the formation of not only rutile, as isothermal treatments, but also anatase. Thickness of the oxide scale was higher for cyclic conditions, while alpha case did not exceed values reached by isothermal treatments and even became lower at 500 °C.
34.	Fargas, Gemma, et al. (author) Oxidation behavior of TI-6Al-4V alloy exposed to isothermal and cyclic thermal treatments 2017 In: Proceedings of the conference METAL 2017. - Ostrava : TANGER Ltd.. - 9788087294796 ; , s. 1573-1579 Conference paper (other academic/artistic)abstract One of the most common titanium alloys for aerospace industry is Ti-6Al-4V (usually designed as Ti-64) which is used for manufacturing aero-engine components, such as fan discs, compressor discs, blades andstators. The maximum service temperature for this alloy is limited partly because of degradation of mechanical properties at elevated temperatures (above 480 ºC). During the first stage of oxidation the oxidescale is protective, whereas after prolonged oxidation time it loses its protective nature and favours higher diffusion of oxygen through the oxide. In the present study, cyclic thermal treatments were performed in air at 500 and 700 ºC, up to 500 hours, and compared with similar studies carried out on isothermal oxidation conditions. The evolution of the surface oxidation was analyzed by metallographic techniques and X-ray diffraction, together with a detailed advanced characterization of the microstructure by Scanning Electron Microscopy and Focus Ions Beam. The results point out that the cyclic thermal treatments induced a strong increase of the weight gain compared to isothermal treatments. The analysis of the oxide scale revealed not only the presence of rutile, at 700 ºC, but also anatase and TiOx at 500 ºC for both isothermal and cyclic thermal treatments. At 700 ºC, thermal stress caused by cyclic thermal treatments promoted the fracture of the oxide after the first 20 hours.
35.	Hörnqvist Colliander, Magnus, 1979, et al. (author) High-temperature crack growth in a Ni-base superalloy during sustained load 2014 In: Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing. - : Elsevier BV. - 0921-5093. ; 609, s. 131-140 Journal article (peer-reviewed)abstract he high-temperature sustained load crack growth behaviour of a Ni-base superalloy was investigated using a combination of mechanical testing in controlled atmosphere, fractographical and microanalytical investigations, and finite element modelling. The results show that the local crack front geometry is un- even on two scales – jaggedness on the scale of 100 μm was observed in all specimens, whereas mm- scale waviness could occasionally be observed. The jaggedness can be explained by a percolation-type crack growth along weaker grain boundaries, whereas the large-scale waviness is presumably due to larger regions of the material having specific grain texture with high crack growth resistance. The un-even crack front is shown to potentially have considerable effects on the loading conditions at the crack tip, whereas ligaments of un-cracked material in the crack wake are deemed to have less effect on the crack tip loading due to their low area fraction. The ligaments fail intergranularly in the wake as the crack grows in the present case, as opposed to by creep fracture as previously proposed. Finally, the plastically deformed regions about the crack and crack tip are shown not to exhibit any elevated oxygen levels, implying that the damage in these regions is purely mechanical.
36.	Johansen, Marcus, 1994, et al. (author) Mapping nitrogen heteroatoms in carbon fibres using atom probe tomography and photoelectron spectroscopy 2021 In: Carbon. - : Elsevier BV. - 0008-6223. ; 179, s. 20-27 Journal article (peer-reviewed)abstract Carbon fibres show great potential as multifunctional negative electrode for novel structural battery composites – a rechargeable electrochemical cell with structural function. The electrochemical performance of carbon materials can be enhanced with nitrogen heteroatoms, which conveniently are inherent in polyacrylonitrile (PAN)-based carbon fibres. However, it is not fully understood how the electrochemical performance is governed by microstructure and composition of the carbon fibres, particularly the distribution and chemical states of nitrogen heteroatoms. Here we reveal the atom-by-atom three-dimensional spatial distribution and the chemical states of nitrogen in three PAN-carbon fibre types (M60J, T800 and IMS65), using atom probe tomography (APT) and synchrotron hard X-ray photoelectron spectroscopy (HAXPES), and correlate the results to electrochemical performance. The findings pave the way for future tailoring of carbon fibre microstructure for multifunctional applications.
37.	Johansen, Marcus, 1994 (author) Microstructure of Carbon Fibres for Multifunctional Composites: 3D Distribution and Configuration of Atoms 2021 Licentiate thesis (other academic/artistic)abstract Lightweight energy storage is a must for increased driving range of electric vehicles. “Mass-less” energy storage can be achieved by directly storing energy in structural components. In such multifunctional devices called structural composite batteries, carbon fibres carry mechanical load and simultaneously act as negative battery electrode by hosting lithium ions in its microstructure. Little is known of how the microstructure of carbon fibres is optimised for multifunctionality, and deeper understanding of the configuration and the distribution of atoms in carbon fibres is needed. Here synchrotron hard X-ray photoelectron spectroscopy and atom probe tomography are used to reveal the chemical states and three-dimensional distribution of atoms in commercial carbon fibres. This thesis presents the first ever guide for how to perform atom probe tomography on carbon fibres, and the first ever three-dimensional atomic reconstruction of a carbon fibre. The results show that the chemical states and distribution of nitrogen heteroatoms in carbon fibres affect the electrochemical performance of the fibres. Carbon fibres performed electrochemically better with higher amount of nitrogen with pyridinic and pyrrolic configurations. Additionally, the nitrogen concentration varies throughout the carbon fibre, which may suggest that the electrochemical properties also vary throughout the carbon fibre. The knowledge provided by this thesis can lead to future carbon fibre designs with enhanced electrochemical performance for multifunctional applications.
38.	Kuzmenko, Volodymyr, 1987, et al. (author) FREESTANDING CARBON NANOFIBERS/GRAPHENE COMPOSITE ELECTRODES FOR SUPERCAPACITORS 2016 In: The World Conference on Carbon - Carbon 2016, July 10-15, State College, PA, USA. Conference paper (peer-reviewed)
39.	Maimaitiyili, Tuerdi, et al. (author) Residual Lattice Strain and Phase Distribution in Ti-6Al-4V Produced by Electron Beam Melting 2019 In: Materials. - : MDPI. - 1996-1944. ; 12:4 Journal article (peer-reviewed)abstract Residual stress/strain and microstructure used in additively manufactured material are strongly dependent on process parameter combination. With the aim to better understand and correlate process parameters used in electron beam melting (EBM) of Ti-6Al-4V with resulting phase distributions and residual stress/strains, extensive experimental work has been performed. A large number of polycrystalline Ti-6Al-4V specimens were produced with different optimized EBM process parameter combinations. These specimens were post-sequentially studied by using high-energy X-ray and neutron diffraction. In addition, visible light microscopy, scanning electron microscopy (SEM) and electron backscattered diffraction (EBSD) studies were performed and linked to the other findings. Results show that the influence of scan speed and offset focus on resulting residual strain in a fully dense sample was not significant. In contrast to some previous literature, a uniform α- and β-Ti phase distribution was found in all investigated specimens. Furthermore, no strong strain variations along the build direction with respect to the deposition were found. The magnitude of strain in α and β phase show some variations both in the build plane and along the build direction, which seemed to correlate with the size of the primary β grains. However, no relation was found between measured residual strains in α and β phase. Large primary β grains and texture appear to have a strong effect on X-ray based stress results with relatively small beam size, therefore it is suggested to use a large beam for representative bulk measurements and also to consider the prior β grain size in experimental planning, as well as for mathematical modelling.
40.	Neikter, Magnus, 1988-, et al. (author) Alpha texture variations in additive manufactured Ti-6Al-4V investigated with neutron diffraction 2018 In: Additive Manufacturing. - : Elsevier. - 2214-8604 .- 2214-7810. ; 23, s. 225-234 Journal article (peer-reviewed)abstract Variation of texture in Ti-6Al-4V samples produced by three different additive manufacturing (AM) processes has been studied by neutron time-of-flight (TOF) diffraction. The investigated AM processes were electron beam melting (EBM), selective laser melting (SLM) and laser metal wire deposition (LMwD). Additionally, for the LMwD material separate measurements were done on samples from the top and bottom pieces in order to detect potential texture variations between areas close to and distant from the supporting substrate in the manufacturing process. Electron backscattered diffraction (EBSD) was also performed on material parallel and perpendicular to the build direction to characterize the microstructure. Understanding the context of texture for AM processes is of significant relevance as texture can be linked to anisotropic mechanical behavior. It was found that LMwD had the strongest texture while the two powder bed fusion (PBF) processes EBM and SLM displayed comparatively weaker texture. The texture of EBM and SLM was of the same order of magnitude. These results correlate well with previous microstructural studies. Additionally, texture variations were found in the LMwD sample, where the part closest to the substrate featured stronger texture than the corresponding top part. The crystal direction of the Î± phase with the strongest texture component was [112¯3]. © 2018 Elsevier B.V.
41.	Saarimäki, Jonas, et al. (author) Anisotropy effects during dwell-fatigue caused by δ-phase orientation in forged Inconel 718 2017 In: Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing. - : Elsevier BV. - 0921-5093 .- 1873-4936. ; 692, s. 174-181 Journal article (peer-reviewed)abstract Inconel 718 is a commonly used superalloy for turbine discs in the gas turbine industry. Turbine discs are often subjected to dwell-fatigue as a result of long constant load cycles. The effect of anisotropy on dwell-fatigue cracking in forged turbine discs have not yet been thoroughly investigated. Crack propagation behaviour was characterised using compact tension (CT) samples cut in different orientations from a real turbine disc forging. Samples were also cut in two different thicknesses in order to investigate the influence of plane strain and plane stress condition on the crack propagation rates. The samples were subjected to dwell-fatigue tests at 550 °C with 90 s or 2160 s dwell-times at maximum load. Microstructure characterisation was done using scanning electron microscopy (SEM) techniques such as electron channelling contrast imaging (ECCI), electron backscatter diffraction (EBSD), and light optical microscopy (LOM). The forged alloy exhibits strong anisotropic behaviour caused by the non-random δ-phase orientation. When δ-phases were oriented perpendicular compared to parallel to the loading direction, the crack growth rates were approximately ten times faster. Crack growth occurred preferably in the interface between the γ-matrix and the δ-phase.
42.	Åkerfeldt, Pia, et al. (author) The effect of crystallographic orientation on solid metal induced embrittlement of Ti-6Al-1Mo-1V in contact with copper 2013 In: IOP Conference Series: Materials Science and Engineering. - : IOP Publishing Ltd. - 1757-8981 .- 1757-899X. ; 48:1, s. 012011- Conference paper (peer-reviewed)abstract Solid metal induced embrittlement (SMIE) occurs when a metal experiences tensilestress and is in contact with another metal with lower melting temperature. SMIE is believed tobe a combined action of surface self-diffusion of the embrittling species to the crack tip andadsorption of the embrittling species at the crack tip, which weakens the crack tip region. In thepresent study, both SMIE of the near alpha alloy Ti-8Al-1Mo-1V in contact with copper and itsinfluence by crystallographic orientation have been studied. U-bend specimens coated withcopper were heat treated at 480°C for 8 hours. One of the cracks was examined in detail usingelectron backscatter diffraction technique. A preferable crack path was found along high anglegrain boundaries with grains oriented close to [0001] in the crack direction; this indicates thatthere is a connection between the SMIE crack characteristics and the crystallographicorientation.
43.	Elbadawi, Mohammed, 1987-, et al. (author) Pressure-assisted microsyringe 3D printing of oral films based on pullulan and hydroxypropyl methylcellulose 2021 In: International Journal of Pharmaceutics. - : Elsevier. - 0378-5173 .- 1873-3476. ; 595 Journal article (peer-reviewed)abstract Oral films (OFs) continue to attract attention as drug delivery systems, particularly for pedatric and geriatric needs. However, immiscibility between different polymers limits the full potential of OFs from being explored. One example is pullulan (PUL), a novel biopolymer which often has to be blended with other polymers to reduce cost and alter its mechanical properties. In this study, the state-of-the-art in fabrication techniques, three-dimensional (3D) printing was used to produce hybrid film structures of PUL and hydroxypropyl methylcellulose (HPMC), which were loaded with caffeine as a model drug. 3D printing was used to control the spatial deposition of films. HPMC was found to increase the mean mechanical properties of PUL films, where the tensile strength, elastic modulus and elongation break increased from 8.9 to 14.5 MPa, 1.17 to 1.56 GPa and from 1.48% to 1.77%, respectively. In addition, the spatial orientation of the hybrid films was also explored to determine which orientation could maximize the mechanical properties of the hybrid films. The results revealed that 3D printing could modify the mechanical properties of PUL whilst circumventing the issues associated with immiscibility.
44.	Fredriksson, Hans, 1974 (author) Nanostructured carbon materials prepared by hole-mask colloidal lithography 2007 Licentiate thesis (other academic/artistic)abstract Research and development of nanofabrication methods can be motivated both formanufacturing of commercially available products like micro electronic componentsand for development of model systems for fundamental and applied science. Thefabrication process developed during this work, hole-mask colloidal lithography(HCL), is primarily oriented towards the latter two, specifically for research in thefields of catalysis, nanoparticle plasmons, and bio- and fundamental physics. Designof structured samples with precise control over size and shape of the nanostructuresare crucial components in all of these fields.The thesis describes the hole-mask colloidal lithography (HCL) technique, the generalprinciples of HCL and the technical and functional differences from standard colloidallithograpy (CL). The technique is illustrated with examples giving details on how tofabricate features with diameters from ~40 to 400 nm and with different shapes andmutual orientations. Some of the demonstrated geometries are discs, ellipses, cones,particle pairs and particles buried into a TiO2 surface.The nanostructuring of carbon materials using the HCL technique is described indetail. Nanostructured carbon surfaces are relevant as model systems to study theoptical properties of naturally occurring nanocarbon structures like aerosols andinterstellar dust. The applied fabrication process utilizes oxygen plasma to etch thepart of the carbon surfaces, not protected by the HCL mask. Analysis of the structuresize and shape resulting from the applied process parameters gives information aboutthe materials durability in reactive oxygen atmospheres, which is valuable forapplications where carbon materials are exposed to similar environments.The HCL technique is used to create etch-masks subsequently used to nanostructurecarbon surfaces via oxygen RIE. HOPG and GC surfaces are patterned in parallelusing identical fabrication processes. Careful characterization of the resulting size andshape of the carbon nanostructures, using SEM and AFM, revealed a significantdifference in response to oxygen plasma treatments for the two materials. On HOPGlateral etching under the etch mask is effectively suppressed thus resulting inpractically no undercut while GC is subject to severe etching under the masks. Theetch rate in the forward direction was found to be more than three times higher for GCthan HOPG (0.65 and 0.19 nm/s respectively). The HOPG nanostructuring processwas also followed with spectrophotometry, revealing decreased reflectance as a resultof the evolution of nanostructures. Part of the change in reflectance is due to thepresence of the etch mask, which consists of gold nanodiscs, but the major part isattributed to the carbon nanostructures.
45.	Fredriksson, Hans, 1974, et al. (author) Resonant optical absorption in graphite nanostructures 2009 In: Journal of Optics A: Pure and Applied Optics. - 1361-6617 .- 1464-4258. ; 11:11 Journal article (peer-reviewed)abstract A systematic investigation of the correlation between optical absorption and the size of graphitenanostructures is presented. Five different samples with structure diameters ranging from ∼160to 330 nm and heights from ∼60 to 190 nm were prepared. The disk-like nanostructures wereetched out of the basal plane surface of highly oriented pyrolytic graphite, using hole-maskcolloidal lithography and oxygen reactive ion etching. Optical absorption spectra forwavelengths between 200 and 2500 nm were then measured. Furthermore, electrodynamicscalculations were conducted to model the optical properties of graphite nanostructures ofsimilar sizes. Both the experimental and the theoretical work revealed resonant absorptioncorrelated to the nanostructure diameters and heights. These absorption peaks are red-shifted,from the visible for the smallest structures to near infrared for the largest. Simultaneously, theintensity of the absorption peaks increases for increasing structure heights, while increasingdiameters results in decreased absorption.
46.	Komitov, Lachezar, 1944, et al. (author) Electrically commanded surfaces for nematic liquid crystal displays 2005 In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 86 Journal article (peer-reviewed)abstract Electrically commanded surfaces (ECS) is a liquid crystal display concept whereby the switching of the alignment layer, which is driven by an electric field applied across the layer, is further transferred to the bulk liquid crystal material via elastic forces. This work presents the electro-optic response of a sandwich cell with alignment layer made of siloxane-based ferroelectric liquid crystal polymer, representing the ECS. The bulk liquid crystal material of choice was an in-house nematic mixture comprising fluorinated liquid crystalline compounds with negative dielectric anisotropy (Delta-epsilon < 0). We report a distinct linear electro-optic response, arising from the field-induced in-plane switching of the nematic which in turn is mediated by the ECS. © 2005 American Institute of Physics. [DOI: 10.1063/1.1849844]
47.	Škarabot, Miha, et al. (author) Direct evidence of the molecular switching in electrically commanded surfaces for liquid crystal displays 2005 In: Journal of Applied Physics. - 0021-8979 .- 1089-7550. ; 98 Journal article (peer-reviewed)abstract This work, performed by means of time-resolved high-resolution birefringence measurements, establishes the switching mechanism of electrically commanded surfaces _ECS_ for liquid-crystal displays. A distinct polar electro-optic response, due to the field-induced in-plane switching of the molecules of the 200-nm ferroelectric liquid crystalline polysiloxane alignment layer representing ECS, was detected in a cell filled with isotropic liquid _hexadecane_. The similarity between this response and the one reported recently in cells containing the same ECS but with a nematic liquid-crystal bulk with negative dielectric anisotropy (Delta-epsilon < 0) and field-free planar alignment provides direct and unambiguous proof that the switching in these cells is indeed mediated by the ECS. © 2005 American Institute of Physics. _DOI: 10.1063/1.2009071_
48.	Shiu, Jin-Yu, 1978, et al. (author) Oxygen Ion Implantation Isolation Planar Process for AlGaN/GaN HEMTs 2007 In: IEEE Electron Device Letters. ; 28:6, s. 476-478 Journal article (peer-reviewed)abstract A multienergy oxygen ion implantation process wasdemonstrated to be compatible with the processing of highpower microwave AlGaN/GaN high electron mobility transistors (HEMTs). HEMTs that are isolated by this process exhibited gate-lag- and drain-lag-free operation. A maximum output power density of 5.3 W/mm at Vgs = −4 V and Vds = 50 V and a maximum power added efficiency of 51.5% at Vgs = −4 V and Vds = 30 V at 3 GHz were demonstrated on HEMTs withoutfield plates on sapphire substrate. This isolation process results in planar HEMTs, circumventing potential problems with enhancedgate leakage due to the gate contacting the 2-D electron gas at themesa sidewall.
49.	Johansen, Marcus, 1994 (author) Atoms in Lithiated Carbon Fibres 2023 Doctoral thesis (other academic/artistic)abstract Carbon fibres are key constituents of structural batteries, in which electrochemical energy storage and mechanical load bearing are merged in one multifunctional device. Here carbon fibres simultaneously act as structural reinforcement by carrying load and as battery electrode by hosting lithium (Li)-ions in its microstructure. However, conventional carbon fibres are not designed to be multifunctional. To enable carbon fibres with optimised multifunctional capabilities, a fundamental understanding of their microstructure, chemical information and interaction with Li is required. In this thesis, mass spectrometry and electron spectroscopy techniques are developed and used to elucidate the atomic distribution, configuration, and interaction in commercial carbon fibres used in structural batteries. Here the methodology of analysing Li in carbon fibres with atom probe tomography (APT) and Auger electron spectroscopy (AES) is demonstrated. Synchrotron-based hard X-ray photoelectron spectroscopy (HAXPES) reveals that certain chemical states of N heteroatoms, pyridinic and pyrrolic, are connected to enhanced electrochemical performance of carbon fibres. AES shows that: Li distributes throughout the entire carbon fibre; the amount of trapped Li is higher and concentrated towards the centre of the fibre at increased discharge rates; Li is initially inserted in amorphous domains and with increased states of lithiation in crystalline domains; and Li plating can occur on individual fibres without spreading to adjacent fibres. APT on lithiated carbon fibres shows that: the distribution of Li is independent of the distribution of N heteroatoms; trapped Li is distributed uniformly in all domains; and Li agglomerates at elevated states of lithiation. The work presented in this thesis paves the way for analysis of carbon-based battery materials with APT and AES. Furthermore, the work unveils much of the interplay between carbon fibre and Li and deepens the understanding of the design parameters for tailoring multifunctional carbon fibres used in improved structural batteries.
50.	Desmaris, Vincent, 1977, et al. (author) All-metal micromachining for the fabrication of sub-millimetre and THz waveguide components and circuits 2008 In: Journal of Micromechanics and Microengineering. ; 18, s. 095004- Journal article (peer-reviewed)abstract A novel technology for the manufacturing of micromachined all-metal waveguide circuits and structures for frequency bands ranging from 200 up to 7000 GHz (sub-millimetre and THz) is presented. The waveguide circuits are formed by using metal electroplating with preceding sputtering of a thin metal film seed layer over a photo-lithographically patterned thick SU-8 photoresist. The process provides the possibility of making three-dimensional structures via facilitating multi-level (layered) designs. The surface roughness of the THz waveguide structure was demonstrated to be as low as 30 nm. This technology was used to build astate-of-the-art waveguide balanced 1.3 THz hot electron bolometer mixer and other applications for radio astronomy instrumentation.

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