| 1. |
- Chen, Zhe, et al.
(författare)
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Nano-scale characterization of white layer in broached Inconel 718
- 2017
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Ingår i: Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing. - Amsterdam : Elsevier BV. - 0921-5093 .- 1873-4936. ; 684, s. 373-384
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Tidskriftsartikel (refereegranskat)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.
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| 2. |
- Lindberg, Siv M, et al.
(författare)
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A product semantic study of the influence of the sense of touch on the evaluation of wood-based materials
- 2013
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Ingår i: Materials & design. - : Elsevier BV. - 0264-1275 .- 1873-4197 .- 0261-3069. ; 52, s. 300-307
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Tidskriftsartikel (refereegranskat)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.
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| 3. |
- Reza, Salim, 1985-, et al.
(författare)
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Non-Destructive Method to Resolve the Core and the Coating on Paperboard by Spectroscopic X-ray Imaging
- 2013
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Ingår i: Nordic Pulp & Paper Research Journal. - 0283-2631 .- 2000-0669. ; 28:3, s. 439-442
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Tidskriftsartikel (refereegranskat)abstract
- Quality control is an important issue in the paperboard industry. A typical sheet of paperboard contains a core of cellulose fibers [C6H10O5], coated on one or both sides with layers of calcium carbonate [CaCO3] or Kaolin [Al2Si2O5(OH)4]. One of the major properties of a good quality paperboard is the consistency of the expected ratio between the thickness of the core and the coating layers. A measurement system to obtain this ratio could assist the paperboard industry to monitor the quality of their products in an automatic manner. In this work, the thicknesses of the core and the coating layers on a paperboard with coating layer on only one side were measured using an X-ray imaging technique. However, the limited spectral and spatial resolution offered by the measurement system being used led to the measured thicknesses of the layers being lower than their actual thicknesses in the paperboard sample. Suggestions have been made in relation to overcoming these limitations and to enhance the performance of the method. A Monte Carlo N-particle code simulation has been used in order to verify the suggested method.
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| 4. |
- Hosseini, Seyedehsan, 1994
(författare)
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Additive-Driven Improvements in Interfacial Properties and Processing of TMP-Polymer Composites
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Efforts to address environmental concerns have resulted in new regulations designed to plan the reduction of plastic and synthetic polymer usage, necessitating the search for sustainable natural alternatives with comparable cost-effectiveness and mechanical performance. Thermomechanical pulp (TMP) fibres are one of the most affordable natural fibres that have no chemical refining in production, production have a high yield of 90-98% and TMP fibres have been demonstrated to improve the mechanical characteristics (strength, stiffness and toughness) of wood-polymer composites (WPCs) compared to the pure polymer. The integration of TMP fibres with non-polar synthetic polymers remains a challenge due to surface polarity differences. This PhD thesis aims to ease the processing of TMP fibre composites through the incorporation of additives. The hypothesis posits that incorporating magnesium stearate (MgSt), molybdenum disulfide (MoS2) and alkyl ketene dimer (AKD) as additives in TMP composites will enhance interfacial properties, resulting in improved processability and flow behaviour at high temperatures. MoS2 is known for its interaction with lignin, which exists in TMP and MgSt is recognised for its ability to improve flow in pharmaceutical processing when combined with cellulose, also a component of TMP. AKD modifies the hydrophilic properties of lignocellulosic surfaces. The experimental work explores the effect of these additives on the properties of TMP composites of ethylene acrylic acid copolymer (EAA) and polypropylene (PP) matrices. The dynamic mechanical analysis (DMA) and mechanical analysis results reveal that MoS2 exhibits superior interaction with TMP fibres, yielding enhanced interfacial properties compared to MgSt in between EAA and TMP fibres. Rheological studies elucidate the transition from a fluid-like state to a network-like structure upon the incorporation of TMP into the PP matrix. The incorporation of AKD with C18 reduces the viscosity of TMP-PP composites and PP itself, and, as determined through theoretical Hansen solubility parameter (HSP) calculations, increases compatibility between cellulose in TMP fibres and PP. The addition of AKD influences both the colour (lighter) and shape (smoother surface) of the extrudate filaments in the TMP-PP composites, indicative of improved processing. In addition, frictional analysis demonstrates the reduction of the coefficient of friction (COF) between metal and TMP fibre by MgSt and AKD treatments.
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| 5. |
- Granberg, Hjalmar, et al.
(författare)
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It’s a bird! It’s a plane! It’s a super multimaterial!
- 2015
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Ingår i: Paper Conference and Trade Show (PaperCon 2015). - : TAPPI Press. - 9781510818873 ; , s. 492-504
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Konferensbidrag (refereegranskat)abstract
- Matching market demands and technological solutions is not always straightforward. In this article, we report on one material, a cellulose-PLA multimaterial, which was made on a full-scale pilot paper machine and adapted to five different market applications having specialized and often conflicting demands. The material can be injection molded, 3D-printed, hot pressed, treated as a textile, used in a laminate, or converted as a paper board, giving it a wide range of possible properties depending on how it is processed.The five application areas presented here were identified as gaps in the marketplace where seemingly conflicting needs were desired: opacity and transparency; compact for transport but having an expanded size during use; stiffness and flexibility; strength and light-weight; and durability and degradability. These properties are exemplified in a number of material and product demonstrators, illustrating how tailored solutions can give products with distinctly different personalities. The material can be made flexible and given movement as graceful as the wing of a bird or be processed to be strong and light-weight enough to be used in vehicles like airplanes. By having one material that is produced on a large scale, but then processed according to specific market demands and expectations, the gap between needing scale and needing scope is bridged.
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| 6. |
- Kihlstedt, Annika, et al.
(författare)
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Material identity in a packaging context
- 2014
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Konferensbidrag (refereegranskat)abstract
- Package design includes a number of considerations ranging from protecting the content to conveying the brand image. The aim of this study was to gain a deeper understanding on how Swedish consumes perceive product packaging attributes, with a special emphasis on in which way packaging material (carton, paper plastic), and structural design (folding carton, paper bag, standing pouch and plastic bag), have an emotional impact on consumers' evaluation of the product and packaging. Assessing the appearance and effectiveness of a packaging system is often confounded by branding, why it is important to separate the brand influence from the attributes of the packaging system. Thus, in the experimental part, packaging prototypes of different structural design and materials were manufactured in order to present commercial cereal brands in different types of packaging. The research involved a combination of qualitative and quantitative methods, comprising (i) focus groups on cereal (muesli) packaging; (ii) a mock-up study of four muesli packaging types: transparent plastic bag, carton box, paper bag, and a resalable stand-up plastic pouch; and (iii) a questionnaire on environmental attitudes to packaging materials. Fourteen respondents participated in the focus groups and 20 in the mock-up study. Result show that the paper bag and the carton box were perceived to be the most environmentally friendly packaging material. Heavy ink usage on paper bags and carton boxes can however raise concern regarding the environmental impact. Introducing functionality and good print quality can cause preferences to divert to an alternative packaging material. In the mock-up study the standing pouch was the most liked package type regardless of brands. Functional reasons (protect, re-closable etc.) and appearance reasons (nice print, nice colours) was claimed for giving this package high ratings.
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| 7. |
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| 8. |
- Duan, Shanghong, 1992, et al.
(författare)
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Determination of transverse and shear moduli of single carbon fibres
- 2020
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Ingår i: Carbon. - : Elsevier BV. - 0008-6223 .- 1873-3891. ; 158C, s. 772-782
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Tidskriftsartikel (refereegranskat)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.
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| 9. |
- Johansen, Marcus, 1994, et al.
(författare)
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Mapping nitrogen heteroatoms in carbon fibres using atom probe tomography and photoelectron spectroscopy
- 2021
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Ingår i: Carbon. - : Elsevier BV. - 0008-6223. ; 179, s. 20-27
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Tidskriftsartikel (refereegranskat)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.
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| 10. |
- Johansen, Marcus, 1994
(författare)
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Microstructure of Carbon Fibres for Multifunctional Composites: 3D Distribution and Configuration of Atoms
- 2021
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)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.
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