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Microstructural characteristics and performance of HVAF sprayed WC- and CrC-based coatings with alternate green binders
No full textThe use of thermally sprayed coating deposited by high velocity oxy-fuel (HVOF) is a very effective way to protect various mechanical components. More specifically, thermally sprayed carbides such as Tungsten carbides and Chromium carbides are widely used by the industry due to their very good tribological properties. Carbide-based are cermet and are composed of two distinct phases, the hard carbide phase (composed of tungsten carbides or chromium carbide particles) and the ductile metallic binder phase. Despite having excellent properties some awareness is raised concerning the ecological, health, and economic aspects of using Co-based carbides. Indeed, the Co used is harmful to the environment, toxic for the people that work on it, and the reserves available are very concentred in small geographical areas. Moreover, limitations exist regarding the HVOF process that can induce some decarburization, which leads to tribological properties loss. Consequently, a newer spray process, the high-velocity air fuel (HVAF) can be used, and greener binders need to be found for tungsten carbide-based coatings. Similar issues are also observed for chromium carbide-based coatings to a lesser extent. This thesis aims to study new types of greener binders, and manufacturing routes for tungsten carbides and chromium carbides-based coatings deposited by high-velocity air fuel. To do so, a bibliographical review of tribological properties, wear, and corrosion has been done. As well as testing all these properties for different coating with greener types of binders or new manufacturing routes. The microstructural investigation was carried out using a scanning electron microscope. The wear behavior has been investigated through ball-on-disk testing, the erosion properties by air jet testing, and finally, corrosion testing with an electrochemical cell. The results have shown for tungsten carbides that the new iron-based binders have similar wear properties and coefficient of friction compared to the reference CoCr-based binder. Moreover, it was found that thinner feedstock particles for Fe-based binders exhibit better anti-wear properties compared to the coarser WC-Fe-based ones. The coefficient of friction was similar for tungsten carbide coatings. Regarding erosion performance, the iron-based binder exhibits lower erosion properties but is still very close to the reference coating. Finally, the thin particle size cut of iron-based binders has shown better anti-corrosion properties than the reference cobalt-chromium-based matrix coating. Consequently, it is possible to say that thin iron-based tungsten carbides are a promising alternative to standard WC-CoCr coatings
Tröst : Vad det är och vad det inte är
No full textVad är tröst, vad är inte tröst och är tröst är relevant för professionell vård idag? Dessa frågeställningar analyseras och utläggs i essayns form. Utgångpunkten för analysen är Roxbergs avhandling om tröst. Ricoeurs och Kristensson Ugglas etiska utläggning av ’personhood’ och av inre och yttre sanning bildar teoretiskt ramverk och förståelsehorisonten är främst från Jobs bok i Gamla testamentet. Job råkar ut för sjukdom och olyckor och Jobs vänner försöker trösta men Job blir inte tröstad. Deras tröst är en icke-tröst som inte tröstar och frågan är varför. Vännernas brist på öppenhet för Jobs lidande och låsta uppfattning om vad som är rätt tröst för Job uppfattas som att den hermeneutiska idén om tolkningarnas konflikt uteblir. På tröstens spelplan finns bara ett lag, den egna sanningen. Det saknas ett lag att spela mot, den andres sanning. Trösten blir då en ensam lagspelare utan lag att spela mot.CC BY 4.0</p
Three-dimensional Microstructure Representation and Virtual Testing of Additive Manufactured Material to Predict Homogenized Directional Elastic Properties
No full textArbetet undersöker förbättring inom produktionsteknik, med särskilt fokus på additiv tillverkning (AM) och tekniker såsom Powder Bed Fusion-Electron Beam(PBF-EB) och Powder Bed Fusion-Laser Beam (PBF-LB), för att förstå strukturegenskapsrelationer i komplexa mikrostrukturer hos nickelbaserade högpresterande superlegeringar. Det primära målet är att förstå och förutsäga de riktade elastiska egenskaperna och mikrostrukturella beteenden hos material som Inconel 718, Haynes 282 och Hastelloy X. Genom att använda 2D Electron Backscatter Diffraction (EBSD) data samt metoder för mikrostrukturkarakterisering i MTEX, och genom att generera representativa volymelement (RVE) och representativa areaelement (RAE) i NEPER, erhålls detaljerade 3D-representationer av mikrostrukturer. Forskningen använder både ideala och verkliga mikrostrukturer för att fördjupa kunskapen om riktad elasticitet hos polykristaller, samt spännings- och töjningsfördelningar inom heterogena och icke-homogena kornstrukturer. Beräkningsmässig homogenisering (CH), implementerad via ABAQUS, inkluderar Crystal Finite Element (CEFE) metoden, vilken är avgörande för att generera styvhetsmatriser och förutsäga riktade elastiska egenskaper. Genom att integrera dessa metoder möjliggörs en omfattande analys av isotropt och anisotropt beteende, särskilt inom ekviaxiella, kolumnära och kombinerade (ekviaxiella och kolumnära) kornstrukturer. Genom experimentell validering ger de viktigaste resultaten betydande insikter i hur olika mikrostrukturer påverkar mekaniska egenskaper, vilket förbättrar prediktiva möjligheter och noggrannhet i analysen av AMmaterialprestanda. Simuleringsresultaten betonar vikten av en noggrann representation av mikrostrukturen, med hänsyn till både kristallografisk textur och faktisk kornmorfologi. De bifogade publikationerna stöder dessa resultat och erbjuder detaljerade diskussioner om virtuell testning av mikrostrukturrepresentation. Arbetet visar sammantaget potentialen hos avancerade PBF-teknologier för att utveckla nästa generations superlegeringar med skräddarsydda egenskaper för industriella tillämpningar där komponenter utsätts för höga påfrestningar.This work investigates advancements in Production Technology, specifically focusing on Additive Manufacturing (AM) techniques such as Powder Bed Fusion-Electron Beam (PBF-EB) and Powder Bed Fusion-Laser Beam (PBF-LB), to understand the structure-property relationships of complex microstructures in high-performance Ni-based superalloys. The primary objective is to comprehend and predict the directional elastic properties and microstructural behaviour of materials such as Inconel 718, Haynes 282, and Hastelloy X. Utilizing 2D Electron Backscatter Diffraction (EBSD) data, methods such as microstructure characterization in MTEX, Representative Volume Element (RVE) and Representative Area Element (RAE) generation in NEPER, detailed 3D microstructure representations are obtained. The research employs both idealand real microstructures to advance knowledge about directional elasticity of polycrystals, stress, and strain distributions within heterogeneous and nonhomogeneous grain structures. The Computational Homogenization (CH) approach, implemented via ABAQUS, includes the Crystal Elasticity Finite Element (CEFE) method, essential for generating stiffness matrices and predicting directional elastic properties. Integrated methodologies facilitate a comprehensive analysis of isotropic and anisotropic behaviour, particularly within equiaxed, columnar, and combined (equiaxed and columnar) grain structures. Through experimental validation, the key findings provide significant insights into the influence of different microstructures on mechanical properties, enhancing predictive capabilities and accuracy in AM material performance analysis. The simulation results emphasize the importance of accurate microstructure representation, considering both crystallographic texture and actual grain morphology. The appended publications support these findings, offering detailed discussions on virtual testing of ideal microstructure predictions and real microstructure representation. This work collectively demonstrates the potential of advanced PBF technologies in developing next-generation superalloys with tailored properties for high-stress industrial applications.Paper C is to be accepted and not included in this licentiate.</p
Negotiating care in organizational borderlands : a grounded theory of inter-organizational collaboration in coordination of care.
No full textBACKGROUND: Although coordination of care and integrated care models aim to enhance patient satisfaction and perceived care quality, evidence regarding their practical implementation remains scarce. Understanding the nuances of collaboration across care providers to achieve effective coordination of care is imperative for seamless care integration. The aim of this study was to construct a grounded theory of how inter-organizational collaboration is performed to support coordination of care for patients with complex care needs. METHODS: A qualitative design with a constructivist grounded theory approach was applied. In total, 86 participants with diverse backgrounds were recruited across multiple care settings, including hospitals, ambulance services, primary care centers, municipal home healthcare and home care services. The grounded theory was developed iteratively, based on a combination of observations and interviews, and using constant comparative analysis. RESULTS: Coordination of care, a complex process that occurs across interconnected healthcare organizations, is manifested as "Negotiating care in organizational borderlands." Care coordination evolves through a spectrum of inter-organizational collaboration, ranging from "Dividing care by disease-specific expertise" to "Establishing paths for collaboration" and ultimately "Co-constructing a comprehensive whole." These categories highlight the challenges of coordinating care across both professional and organizational boundaries. In the multifaceted healthcare landscape, effective care coordination occurs when healthcare professionals actively bridge the divides, leveraging their collective expertise. Importantly, organizational boundaries may serve a purpose and should not be dissolved to facilitate effective care coordination. CONCLUSIONS: The key to effective care coordination lies in robust inter-organizational collaboration. Even when patients receive integrated care, healthcare professionals may have fragmented roles. This research emphasizes the importance of clearly defined lines of accountability, reinforcing mutual responsibility and facilitating bridging of professional and organizational boundaries. Healthcare professionals and policymakers can use these insights to effectively utilize inter-organizational collaboration in supporting care coordination for patients with complex care needs.CC BY 4.0</p
Drop Detachment Under Intense Laser Irradiation
No full textDuring laser processing, complex effects can occur regarding the laser-material interactions. A high laser energy input leads to surface melting and even boiling. The resulting recoil pressure can create the so-called keyhole, a vapor channel existing during welding and called cut front during laser cutting. On the keyhole front wall, the induced recoil pressure pushes the melt downwards and can ejects melt drops. Usually, those melt ejections are seen as undesired spattering or necessary waste to enable the cutting. However, outflow characteristics can tell more about the complex process behavior. Therefore, this work aimed to relate melt ejection formation effects to keyhole behavior in order to get a better understanding of the complex laser-matter-interactions and fluid flows. Axial beam shaping was used to create different energy inputs into the keyhole front walls. Beam shaping was done with an optic that can superposition up to four laser beams in axial direction, leading to varying intensity distributions on the inclined keyhole front walls. Based on high-speed image analysis, it was seen that different outflow characteristics occur depending on the beam shapes. A high intensity on the front keyhole wall could be related to high temperatures on the keyhole wall. The outflow mechanism was shown to be able to move from corrugating to atomizing drop generation at increasing temperature due to temperature-dependent material properties. The main influencing factors are assumed to be the vapor speed and the keyhole/drop diameters that define the outflow mechanism.CC-BY 4.0The author acknowledge the funding of PoSAddive – Powder Sheet AdditiveManufacturing (EIT raw materials, No. 22021) and SMART - Surface tension of MetalsAbove vapoRization Temperature (Vetenskapsrådet, No. 2020-04250). </p
Do teachers’ beliefs about the nature and learning of mathematics affect students’ motivation and enjoyment of mathematics? : Examining differences between boys and girls across six countries
No full textMathematics teachers’ beliefs are central to mathematics teaching and student learning. Because different aspects of motivation and affect—particularly enjoyment—primarily develop within the classroom context, examining how different teachers’ beliefs may affect student outcomes in mathematics is imperative. The current study examines teachers’ beliefs about the nature and learning of mathematics in connection to students’ motivation (i.e. intrinsic value, utility value and perceived competence) and enjoyment of mathematics across different settings by considering students’ mathematics achievement, gender and classroom composition (i.e. socioeconomic and behavioural). Data were collected from 3rd- and 4th-grade mathematics teachers (N = 686) and their students (N = 11,782) in six countries (i.e. Norway, Finland, Sweden, Portugal, Estonia and Serbia). A two-level structural equation modelling technique (TSEM) (i.e. student level and classroom level) with random slopes was employed to address our research questions. The results indicate that students’ intrinsic value and perceived competence positively relate to their enjoyment of mathematics in all six countries. Teachers’ beliefs about the nature and learning of mathematics moderate the within-classroom relationship between boys and girls and the motivation and enjoyment of learning mathematics in Portugal and Norway. Unlike boys, girls consistently perceive themselves as less competent in mastering mathematics, even in primary school. Classroom socioeconomic composition had a more pronounced influence on teachers’ beliefs in Sweden, Norway and Serbia. In relation to teachers’ beliefs, classroom behavioural composition was relevant in Estonia and Sweden. In Finland and Norway, classroom composition was essential to boys’ and girls’ differential motivation and enjoyment of mathematics learning. CC-BY 4.0Funding from Research Council of Norway within FINNUT Programme for Research and Innovation in the Educational Sector (grant number 301033)</p
Learning to teach at a norm-critical clinical learning centre : A Phenomenographic study.
No full textBACKGROUND: Campus-based clinical learning centres are used for practice and learning in nursing students' education and can be arenas in which to enhance students' awareness and competence in social justice issues. Norm-critical approaches can be used as pedagogical tools in these centres to prepare students for hands-on caring situations in which social norms can bias the outcome. OBJECTIVES: To describe nursing teachers' conceptions of learning norm-critical approaches and implementing them in a clinical training centre. SETTING AND PARTICIPANTS: The study is based on interviews with 10 teachers at a Swedish university college. METHODS: The data was analysed using a phenomenographic approach. RESULTS: Five categories of description emerged in the analysis that described conceptions related to norm-critical approaches. These categories were: personally developing and meaningful; easily integrated with established nursing concepts; highlighting surrounding power; something to lean on when letting students take the first steps in norm-critical initiatives; and helping implementation in teaching and education. CONCLUSIONS: Teachers who are facing the task of providing norm-critical, practical education to nursing students in campus-based clinical learning environments are ambivalent towards the core principles of norm criticism, which they conceive as natural and provoking, at the same time. We therefore need to un-dramatise norm criticism and better prepare teachers in how to use it. Teachers would benefit from follow-up activities and formal collaborations regarding norm-critical teaching, so that they are given context to discuss, reflect, and learn from each other.CC-BY 4.0</p
A feeling of not being alone : Patients' with COPD experiences of a group-based self-management education with a digital website. A qualitative study.
No full textAIM: To describe patients' with chronic obstructive pulmonary disease (COPD) experiences of group-based self-management education with a digital website. DESIGN: A qualitative approach with a phenomenologicalmethod. Patients participating in an earlier study, with self-experience of COPD as a special competence, were involved as research partners at the design of this study. METHODS: Eleven individual and two group interviews with five participants in each group were conducted. RESULTS: Group-based self-management education with a digital website supports learning. Sharing experiences with others in similar situations creates security and reduces the feeling of being alone. Based on questions and discussion in the group, and through self-reflection, general information is transformed into useful knowledge and understanding of one's own situation. COPD information on the website provides an opportunity to gain knowledge continuously based on needs that contributes to learning. This research has demonstrated that adapting learning activities to individual learning styles increases sustainability of learning. Sharing experiences reduces feelings of loneliness. It is therefore important to create spaces for sharing experiences and in-depth reflection that support learning over time.CC-BY 4.0We would like to thank the Research and Development Centre at Skaraborg Hospital Skövde, Sweden and the Skaraborg Institute, Sweden for their support (Dnr. 19/1034)</p
Nurses' experiences of meeting children during needle procedures
No full textBackground: Nursing children is sometimes complicated as needle procedure can involve fear and pain. Nurses have expressed lack of knowledge and experience from the education. Aim: The aim was to describe nurses' experiences of meeting children during needle procedures. Method: A literature-based method involving eight analysed qualitative articles according to Friberg's five-step model to contribute to evidence-based nursing. Results: Three themes emerged: the nurse's responsibility, the nurse's pedagogical approach in needle procedures and the importance of the health care environment. Based on themes, eight sub-themes were identified: adapting information and communication, inviting participation, giving children courage, discovery of children’s strategies, to take support through play, to use distraction, the impact of the care environment and the impact of the caregiver. Conclusion: The literature study demonstrates that nurses, with the help of responsiveness and adaption, facilitates the child creating individual strategies which mitigates fear and pain during needle procedures. The nurse must create conditions for a positive meeting where the child is seen as a competent participant. Furthermore, the health- or medical care environment has proven important, and the nurse is responsible for letting the child get used to the environment before performing needle procedures. Experiences from a negative meeting follows the child to adult age and could create a behavior where necessary healthcare is avoided which contributes to unequal healthcare. Less experienced nurses need more knowledge and experience, enabling the nurse to contribute with evidence-based care that reduces children's discomfort.Syftet med studien var att beskriva sjuksköterskors erfarenheter av att möta barn vid nålprocedurer. Studiens resultat beskriver sjuksköterskans ansvar och pedagogik i mötet med barn vid nålprocedurer som har betydelse för att bidra till en god omvårdnad. Att bjuda in till delaktighet, anpassa information samt kommunicera på ett sätt som barnen förstod påverkade barns upplevelse av nålproceduren och gjorde att barnen upplevde kontroll och fick ett ökat välbefinnande. Resultatet ger förslag på sjuksköterskors olika pedagogiska tillvägagångssätt för att upptäcka barns behov av stöd och tillämpning av strategier som hjälpte barn att hantera nålprocedurer. Sjuksköterskor förklarar att leken har betydelse för barn på olika sätt. Leken bidrar till information, delaktighet, kunskap samt distraktion som genom ett positivt möte minskade barns rädsla och smärta. Att vara lyhörd och uppmärksam på barnets signaler bidrar till att sjuksköterskor förstår barnens behov vid nålprocedurer. Bristande kunskap hos sjuksköterskor om barns behov av stöd bidrar till ett vårdlidande i form av rädsla och smärta. Författarnas slutsats är att sjuksköterskor kan med hjälp av evidensbaserade omvårdnadsåtgärder och kunskap om möten med barn arbeta barncentrerat och minska barns obehag vid nålprocedurer.Att vara barn och genomgå en nålprocedur kan väcka rädsla och obehag. Sjuksköterskor har ett ansvar att möta barnet utefter ålder, utveckling och mognad samt bidra till en stöttande vårdmiljö. Barnet ska stå i centrum för omvårdnaden och sjuksköterskor behöver skapa förutsättning för en familjecentrerad vård. Studiens resultat innefattar åtta kvalitativa artiklar som har analyserats enligt Fribergs fem-stegsmodell. Analysen resulterade i tre teman och åtta underteman. Författarna anser att när sjuksköterskan har kunskap om möten med barn vid nålprocedurer kan sjuksköterskan stärka barnets resurser och främja barnets hälsa
Machining of Compacted Graphite Iron : A review
No full textCompacted Graphite Iron (CGI) represents a unique combination of the characteristics of grey and spheroidal cast irons, sparking significant interest over the past two decades, particularly as a favoured material in several automotive industry applications, including engine components and heavy-duty vehicle parts. Despite its growing prominence, the full potential of CGI remains underutilised, primarily due to its lower productivity rate compared to grey cast iron. This paper comprehensively reviews existing research on CGI machining, emphasising the challenges and exploring opportunities for development in this field. A detailed comparison between the machining of compacted graphite iron, grey cast iron and spheroidal graphite cast iron is provided, highlighting the unique characteristics associated with CGI. The influence of microstructure and chemical composition on machining processes is thoroughly examined and deliberated. Moreover, this review delves into the effects of various process variables on CGI machining, including cutting tools, lubrication, and cooling methods. The paper concludes by discussing potential future trends and innovations in CGI machining, offering a prospective outlook on how these developments could bridge the productivity and literature gap and enhance the utilisation of CGI in industrial applications. © 2024 The Author(s)CC BY 4.0</p