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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
131

Tribological behaviour of CVD diamondcoated tools during machining of highstrength aluminum alloy : Master thesis project on tribological behavior of super hard materials: chemicalvapor deposition diamond (CVD) coated cutting tools and polycrystalline diamond(PCD) cutting tools used in machining of high strength aluminium alloy

Lundquist, Oskar January 2022 (has links)
Machining of Aluminum can be complicated due to large amounts of adhesion and diffusion of the aluminum onto the cutting tool, causing effects such as built-up layers and built-up edges. This leads to poor surface finishes and can significantly affect the tool life. CVD diamond coated tools have shown to be a potential solution to this problem and is tested and analyzed as such in this thesis. CVD diamond coated inserts are tested and compared to uncoated cemented carbide inserts and Polycrystalline diamond tipped inserts, in milling, turning and in refined tribological methods. The workpiece material in both the machine tests and the tribological tests is a high strength aluminum of the name Alumec 89. The machine tests were performed for 5 and 60 seconds at three cutting speeds, 600, 900 and 1200 m/min, keeping other parameters constant. The cutting inserts, the chips and the generated workpiece surface are examined using LOM, SEM and EDS. In the refined tribological testing, a pin-turning tribometer is used, with pins of uncoated and coated (CVD diamond) cemented carbide pins. These are tested at 5 and 30 seconds at 600 and 1200 m/min, applying a constant force of 10 N. In addition, a friction test was performed to measure the friction of the uncoated and the CVD diamond coated cemented carbide. Like the cutting inserts, the used pins were examined in LOM and SEM. The results show that while a large amount of built-up layer and built-up edges gather when using uncoated cemented carbide tools, only minimal amounts can be detected on CVD diamond and PCD. It has also been shown that the reason for the reduced adhesion in the case of diamond tooling materials is most likely due to the lack of chemical interactions between the diamond and the aluminum. The friction of the CVD diamond material was shown to be lower compared to the cemented carbide. The surface finish generated by the different materials, was the best in the case of PCD while the CVD generated multiple small scratches that severely reduced the surface roughness. This thesis provides some initial basic understanding of the interaction of CVD diamond coated inserts with high strength aluminum alloys.
132

Biologization, Nanotechnology, Simulation: Proceedings of the 1st Joint PhD Conference on Material Science:: from 27.6.-1.7.2022 in Dresden/ Germany and Usti/Česká republika

Bergmann, Ute, König, Theresa 02 December 2022 (has links)
Materials scientists from Ústí nad Labem and Dresden met in June of 2022 for the first joint PhD Conference on Material Science, with the special focus on biologization, nanotechnology and simulation. The conference aimed to encourage interdisciplinary exchange between Čzech and German research institutes and promote transnational cooperation on an international level along the Saxon- Čzech border. Due to the restrictions caused by the corona pandemic, several attempts were necessary before the conference, which was first planned in 2020, could finally take place for the first time in 2022. The conference could take place in presence, which was seen as a big plus by all participants, especially as it was the first meeting in this German - Čzech context for most of the participants. The attending scientists (about 60) met at the Institute of Material Science of TU Dresden in Germany for the first half of the week before the conference moved to the faculties of Science and Environment of the Jan Evangelista Purkyně University UJEP in Ústí nad Labem in Čzechia. The organized activities ranged from scientific presentations of current PhD projects and research topics, lab tours in the participating institutions, come-together events such as a guided tour at the dye collection of the TU Dresden and a hiking trip to Bohemian Switzerland. The conference was funded by INTERREG VA Saxony - Čzech Republic - a cooperation programme of the Elbe/Labe region. All participants - PhD students, scientists and staff members of the participating institutions - enjoyed this opportunity to build individual and new contacts, exchange information on current research topics and methods, find starting points for future collaborations between the different research areas and institutions and also discuss the similarities and differences between the German and Čzech research landscape. The purpose of this brochure is to present the institutions with their special topics and laboratories and to present current research topics - on the base of the presented PhD projects.:1 Introduction 2 1.1 Committees 5 2 Presentation of the participating institutes and chairs 5 2.1 Jan Evangelista Purkyně University in Ústí nad Labem 6 2.1.1 Faculty of Science 6 2.1.2 Faculty of Environment 12 2.2 Technische Universität Dresden 17 2.2.1 Institute of Material Science 17 2.3 Fraunhofer Institute for Ceramic Technologies and Systems IKTS 19 2.3.1 Department Bio- and Nanotechnology at IKTS 19 2.4 Institute for Complex Materials, Leibniz-IFW Dresden 21 2.5 TRANS³Net 22 3 Presentation of the PhD topics 23 3.1 Topic: BIOLOGIZATION 23 3.1.1 Ludovico Andrea Alberta: Exploring the effect of Cu additions on the mechanical behaviour of β-TiNb biomaterials 23 3.1.2 Franziska Alt: Formation of a microenvironment for directed differentiation of stem cells in a perfusion bioreactor 25 3.1.3 Dmitry Belyaev: Circular microfluidic systems for electro-chemical continuous monitoring of bio-chemicals in emulsion droplets 27 3.1.4 Constantin Ißleib: Dynamic osteoimmunological crosstalk in a bone replacement context 28 3.1.5 Adela Jagerová: Surface Modification by High-Energy Heavy-Ion Irradiation in Various Crystalline ZnO Facets 29 3.1.6 Nils Kaube: Bioinspired development of artificial enamel via in-situ nano-mineralization 30 3.1.7 Michaela Kocholata: Isolation and characterization of plant derived nanovesicles 30 3.1.8 Zuzana Nejedlá: Dendrimers as Drug Delivery System 31 3.1.9 Jacub Perner: Effect of cold plasma treatment of Poppy and Proso Millet seeds in plasma downer 32 3.1.10 Marina Roshchina: Development of new bacteria-killing coatings on beta-Ti-Nb alloy based on functional oxide nanotubular (ONT) layers 33 3.1.11 Muhammad Saqib: Algorithms and fluid-dynamic experimental platform for in vitro degradation studies of implant materials 34 3.1.12 Jacub Tolasz: Interaction of pollutants on nanoceria 35 3.1.13 Zuzana Žmudová: 3D spheroid culture for in vitro testing of nanoparticles 35 3.2 Topic: METROLOGY 37 3.2.1 Katrien Boonen: The potential of dendrochemistry and dendroecology in pollution research 37 3.2.2 Ivan Lopez Carasco: Development of immobilization protocols for Tro6 and Tro4 aptamers to be used in electrochemical biosensor 38 3.2.3 Jacub Hoskovec: Functionalized electrospun materials for selectvie capture of selected gases 39 3.2.4 Dominic Pilnaj: Applications of gas sensors for air-quality monitoring and identification of volatile organic compounds by GC-HRMS 39 3.2.5 Michaela Průšová: Prostat, Glioblastoma and Mammary carcinoma cells derived exosomes: Their isolation, characterization and loading with doxorubicin 40 3.2.6 Kateřina Přibylová: Preparation of nanostructured surfaces for CO2 Detection, Capture and Utilization 41 3.2.7 Michal Syrový: Chemical modification of PAN – based nanofibrous membranes prepared by electrospinning and their properties for CO2 capture potential 42 3.3 Topic: GEOLOGICAL/MATERIALS 43 3.3.1 Sabine Apelt: Using biomimicry to design anti-ice surfaces for air-water heat pumps 43 3.3.2 Jan Dočkal: Molecular dynamics of interfacial solution structure of alkali-halide electrolytes at graphens electrodes 47 3.3.3 Tereza Dušková: Metal complexes with polyfluorinated NHCs 48 3.3.4 Kristína Fiantoková: Obtaining of the active mass from the spent Li-Ion batteries 48 3.3.5 Stephanie Ihmann: Engineering of bio-based Building and Construction Materials 49 3.3.6 Sara Jalali: Degradable bone substitute materials with load-bearing properties - Fiber-strengthened silica 50 3.3.7 Pavel Kaule: Preparation of heteroborane derivatives for thin film deposition by the covalent bond formation 53 3.3.8 M. Kozakovic: The effect of primary and secondary flows on the homogenization process in a vertical bladed mixer 53 3.3.9 Pavlína Matysová: Molecular Simulation of Salt Hydrates 54 3.3.10 Viktorie Neubertová: Surface functionalization of Ti3C2T MXene for MRI contrast agent 55 3.3.11 Robert Ato Newton: Fuel characteristics of Miscanthus x giganteus biomass produced at the marginal and slightly contaminated by trace elements soils 55 3.3.12 Martin Otto: Bioresorbable Fe-based alloys processed via laser powder bed fusion 56 3.3.13 Petr Panuška: A millifluidic chip for cultivation of fish embryos and toxicity testing fabricated by 3D printing technology 59 3.3.14 David Poustka: Unlocking mass production of photocrosslinked chitosan nanofibers 60 3.3.15 Eliška Rezlerová: Adsorption and Diffusion of Short Hydrocarbons and Carbon Dioxide in Shale Organic Matter: Insights from Molecular Simulations 60 3.3.16 Stefan Weitz: Investigating the material hardness of mollusks shells in dry and wet states by microindentation 61
133

Study on the Electronic Band Structure of the Spinel Superconductor LiTi2O4 / Studie om den Elektroniska Bandstrukturen hos Spinel Supraledaren LiTi2O4

Di Berardino, Gaia January 2022 (has links)
This master’s thesis focuses on investigating the electronic properties of the superconducting spinel compound LiTi2O4 by means of computational and experimental effort. The title compound has been extensively studied in the past years, being the only known superconducting spinel oxide with relatively high Tc = 11.5 K. Even so, the origin of its superconducting mechanism is under debate, and its anomalous superconductivity is still inquired. Thanks to the recently developed ability to produce high-quality epitaxial LiTi2O4 thin films, a renewed research interest in this compound has matured. With this work, we partake in this challenge and present combined experimental and computational results on the electronic band structure of the material. Density functional theory (DFT) has been employed for the first principle electronic structure calculations performed with the Quantum ESPRESSO software. Furthermore, thin-film samples were in-situ realized with the pulsed laser deposition (PLD) method and investigated through the angle-resolved photoemission spectroscopy (ARPES) technique conducted at the ULTRA end-station of the SLS synchrotron facility at PSI in Switzerland. Here, we report the computed electronic band structure of LiTi2O4, with a detailed investigation of its density of states and Fermi surface. Further, we compare these calculations with the obtained experimental ARPES data. Emerging from this study are results supporting the non-conventional superconducting nature of LiTi2O4, which presents coexisting correlation effects, such as electron-phonon coupling and enhanced electron-electron interactions. / Denna masteruppsats fokuserar på att undersöka de elektroniska egenskaperna hos det supraledande spinellmaterialet LiTi2O4 med hjälp av datorsimuleringar samt experimentella mätningar. LiTi2O4 har studerats omfattande under de senaste åren, eftersom den är den enda kända supraledande spinelloxiden med relativt hög Tc = 11.5 K. Trots det är ursprunget till dess supraledande mekanism debatterad, och meaknismen för dess okonventionella supraledning är fortfarande inte helt förstådd. Tack vare den nyligen utvecklade förmågan att producera tunna högkvalitativa epitaxiella LiTi2O4 filmer, har ett förnyat forskningsintresse för denna förening mognat. Med detta arbete deltar vi i denna utmaning och presenterar kombinerade experimentella och beräkningsresultat om materialets elektroniska bandstruktur. Densitetsfunktionsteori (DFT) har använts för principiella elektroniska strukturberäkningar utförda med Quantum ESPRESSO-mjukvaran. Vidare realiserades tunnfilmsprover in-situ med pulsed laser deposition (PLD) medoden och undersöktes experimentellt via vinkelupplöst fotoemissionsspektroskopi (ARPES) som utfördes vid ULTRA-ändstationen på SLS synkrotronanläggningen vid PSI i Schweiz. Här rapporterar vi den beräknade elektroniska bandstrukturen för LiTi2O4, med en detaljerad undersökning av dess tillståndstäthet och Fermi-yta. Vidare jämför vi dessa teoretiska beräkningar med de erhållna experimentella ARPES data. Resultat från denna studie stöder den icke-konventionella supraledande naturen hos LiTi2O4, som också uppvisare samexisterande korrelationseffekter, såsom elektron-fononkoppling samt starka elektron-elektron-interaktioner.
134

CO2 Capture on Polymer-Silica Composites from Molecular Modeling to Pilot Scale

Willett, Erik Amos 23 May 2018 (has links)
No description available.
135

Extremvärdesanalys (SEV) av högkvalitativt verktygsstål : Uppskattning av maximal inneslutningsstorlek i pulverstål / Extreme values analysis (SEV) of high performance tool steel : Prediction of maximum inclusion size in powder steel

Pernefur, Emil January 2017 (has links)
This work were requested by Uddeholms AB. Uddeholm is the worldś leading manufacturer of high performance tool steel for industrial tools. The company exists worldwide and is present in over 100 countries. One of the company’s main production processes is manufacturing powder steels with extremely high quality. In this work, one of these steels has been analyzed to evaluate the presence and distribution of non-metallic inclusions. Higher demands on quality and more global competition worldwide means that you always have to strive towards perfection in the manufacturing processes. Non-metallic inclusions have severe effects on the mechanical properties of steels. That's why it's of utmost importance to investigate their presence in the tool steel and especially their size. The reason for this is because it's the largest inclusions that's the most dangerous for the material. To obtain a statistically number of certainty of the largest of inclusions, very vast areas of steel have to be examined. Therefore a theoretical method of extrapolation is often used instead to approximate the distribution of the largest inclusions. The precision of this method is still very uncertain. Different methods of this kind of analysis do exist. The method applied in this work of degree is extreme values analysis by statistics of extreme values (SEV). To ensure the pre-conditions of the extreme values analysis, a large quantity of powder steel was analyzed. This was done by light-optic microscopy (LOM) and exclusively performed by Uddeholms AB at their R&D-facility (Research and development-facility) in Hagfors. At Karlstad Universityś test-facility specimens were subjected to ultrasonic fatigue testing at 20 kHz. The specimens derived from the same material as the ones examined in LOM. The result from the ultrasonic fatigue testing were that the largest inclusions in the material were found. This was done by applying very high cycle fatigue (VHCF). To calculate the maximum theoretical inclusion size, SEV was used. The extreme values analysis was performed on gathered data from both LOM and VHCF. All fracture surfaces from the ultrasonic fatigue testing were then examined in scanning electron microscope (SEM) at Karlstad University. In SEM, the largest inclusion in every fractured surface was identified and measured. The maximum real inclusion size from the fractured surfaces was then compared to the maximum theoretically calculated inclusion size from the extreme values analysis. As it turned out the real inclusion size proved to be slightly larger than the theoretical. The difference between them was found to be 3,25 µm. Conclusions drawn were that Uddeholms powder steel exhibits very high purity and that extreme values analysis as an analytical method is recommended. However, the analysis should be repeated to underline the chosen solution methodology.
136

Design of a test rig for in situ hydrogen charging of rolling element bearings under load / Design av en testrigg för in situ väteladdning av lager under last

Moström, Oskar January 2023 (has links)
This Master's thesis is part of the Hydrogen Embrittlement in Rolling element bearings project (HERo) initiated at Luleå University of Technology (LTU), with the primary objective of determining critical hydrogen concentrations in bearing steel for rolling element bearings. The specific aim of this Master's thesis is to design a test rig that enables the investigation of the effects of hydrogen embrittlement on rolling element bearings under load. The design process focused on ease of manufacture and assembly. The developed test rig includes an electric motor, a pneumatic load application mechanism, and an electrochemical cell. Using the leverage principle, a thrust roller bearing is loaded vertically, while it is driven by an electric motor that is connected to the bearing with a tyre coupling. The electrochemical cell, which consists of a reference electrode, counter electrode, and the test bearing as the working electrode, is used to charge the test bearing with hydrogen. The cell was designed to be easily accessible between tests to facilitate the change of thrust roller bearings. The test bench enables the analysis of rolling element bearings that are exposed to simultaneous hydrogen embrittlement and realistic operating conditions. / Detta examensarbete är en del av Hydrogen Embrittlement in Rolling element bearings-projektet (HERo) som pågår vid Luleå tekniska universitet (LTU), med huvudmålet att bestämma de kritiska vätekoncentrationerna i lagerstål för rullningslager. Det specifika målet med detta examensarbete är att konstruera en testrigg för att direkt undersöka effekten av väteförsprödning av lager i en simulerad verklig tillämpning. Designprocessen fokuserade på enkel tillverkning och montering.  Den utvecklade testriggen inkluderar en elmotor, en pneumatisk lastpåläggnings-mekanism och en elektrokemisk cell. Med hjälp av hävstångsprincipen belastas ett axiellt rullager vertikalt, medan det drivs av en elmotor via en däckkoppling. Den elektrokemiska cellen, som består av en referenselektrod, motelektrod och testlagret som arbetselektrod, används för att införa väte i lagret. Cellen har konstruerats på ett sätt som underlättar byte av testlager mellan testerna.  Testriggen skapar därmed möjligheten att analysera rullningslager som utsätts för väteförsprödning under realistiska driftförhållanden. / Diese Masterarbeit ist Teil des Hydrogen Embrittlement in Rolling element bearings-Projekts (HERo), das an der Technischen Universität Luleå (LTU) initiiert wurde, mit dem primären Ziel, kritische Wasserstoffkonzentrationen für Lageranwendungen zu bestimmen. Das spezifische Ziel dieser Masterarbeit ist es, einen Prüfstand zu konstruieren, um die Auswirkungen von Wasserstoffversprödung auf Rollenlager im Belastungszustand zu untersuchen. Der Schwerpunkt des Designprozesses lag darauf, eine einfache Fertigung und Montage des Prüfstandes zu gewährleisten.  Der entwickelte Prüfstand umfasst einen Motor, einen Mechanismus zur Lastaufbringung und eine elektrochemische Zelle. Mithilfe des Hebelgesetzes wird das Testlager vertikal belastet, während es mithilfe eines Elektromotors und einer Reifenkupplung angetrieben wird. Die elektrochemische Zelle, bestehend aus Referenzelektrode, Gegenelektrode, und dem Testlager als Arbeitselektrode, dient dazu, Wasserstoff in das Testlager einzubringen. In ihrem Design wurde darauf geachtet, dass sie zwischen den Tests leicht zugänglich ist, um den Austausch der Testproben zu erleichtern. Der Prüfstand ermöglicht somit die Analyse von Rollenlagern, die sowohl Wasserstoffversprödung als auch realistischen Betriebsbedingungen ausgesetzt sind.
137

Synthesis and Characterization of Zeolitic Materials Using Phosphorous Organic Structure Directing Agents

Simancas Coloma, Jorge 02 September 2021 (has links)
[ES] Las zeolitas son materiales cristalinos microporosos con canales y tamaños de poro de dimensiones moleculares. La estructura y composición de las zeolitas les confiere interesantes propiedades que permiten su aplicación en una amplia gama de aplicaciones industriales como adsorción, separación o catálisis. La síntesis de zeolitas es la etapa más importante para el control de la estructura y composición de las zeolitas y, por tanto, crítica para la optimización de sus propiedades. Esta tesis se ha centrado en la síntesis de zeolitas utilizando compuestos que contienen fósforo (cationes fosfonio y aminofosfonio) como Agentes Directores de Estructura (P-ADE). El uso de compuestos fosforados influye en la cristalización y propiedades de las zeolitas obtenidas en comparación con las zeolitas obtenidas con cationes de amonio clásicos. Los compuestos fosforados se eligieron debido a su diferente química y estabilidad con respecto a los cationes de amonio clásicos comúnmente usados en la síntesis de zeolitas. Estos aspectos se estudiaron con un estudio comparativo de diferentes cationes de amonio y fosforados. Los compuestos de fósforo utilizados en este trabajo han dado lugar a nuevas estructuras cristalinas (ITQ-58 e ITQ-66) y han abierto nuevas vías de síntesis de zeolitas ya conocidas (RTH, IWV y DON), ampliando su gama de composiciones químicas. La descomposición térmica de los P-ADE confinados dentro de las zeolitas da lugar a la formación de especies de fósforo extra-red que permanecen dentro de los canales y cavidades de las zeolitas. Estas especies modulan las propiedades ácidas y de adsorción de los materiales finales dependiendo de los tratamientos post-síntesis. En este trabajo se ha estudiado una ruta para la incorporación de cantidades controladas de fósforo durante la etapa de síntesis. Esto ha permitido controlar la adsorción y las propiedades ácidas en las zeolitas de poro pequeño, lo que no se puede lograr mediante metodologías de post-síntesis. / [CA] Les zeolites són materials cristal·lins microporosos amb canals i mides de porus de dimensions moleculars. L'estructura i composició de les zeolites els confereix interessants propietats que permeten la seua aplicació en una àmplia gamma d'aplicacions industrials com adsorció, separació o catàlisi. La síntesi de zeolites és l'etapa més important per al control de l'estructura i composició de les zeolites i, per tant, crítica per a l'optimització de les seues propietats. Aquesta tesi s'ha centrat en la síntesi de zeolites utilitzant compostos que contenen fòsfor (cations fosfoni i aminofosfoni) com a agents directors d'estructura (P-ADE). L'ús de compostos fosforats influeix en la cristal·lització i propietats de les zeolites obtingudes en comparació amb les zeolites obtingudes amb cations d'amoni clàssics. Els compostos fosforats es van triar a causa de la seua diferent química i estabilitat pel que fa als cations d'amoni clàssics utilitzats en la síntesi de zeolites. Aquests aspectes s¿estudiaren amb un estudi comparatiu de diferents cations d'amoni i fosforats. Els compostos de fòsfor utilitzats en aquest treball han donat lloc a noves estructures cristal·lines (ITQ-58 i ITQ-66) i han obert noves vies de síntesi de zeolites ja conegudes (RTH, IWV i DO), ampliant la seua gamma de composicions químiques. La descomposició tèrmica dels P-ADE atrapats dins de les zeolites dona lloc a la for-mació d'espècies de fòsfor extra-xarxa que romanen dins dels canals i cavitats de les zeolites. Aquestes espècies modulen les propietats àcides i d'adsorció dels materials finals depenent dels tractaments post-síntesi. En aquest treball s'ha estudiat una ruta per la incorporació de quantitats controlades de fòsfor durant l'etapa de síntesi. Això ha permés controlar l'adsorció i les propietats àcides en les zeolites de porus petit, el que no es pot aconseguir mitjançant metodologies de post-síntesi. / [EN] Zeolites are microporous crystalline materials with channels and pore openings of molecular dimensions. The structure and composition of zeolites confers them interesting properties that allow their application in a wide range of industrial applications as adsorption, separation or catalysis. The synthesis of zeolites is the most important stage to control the structure and composition of zeolites, and thus, critical to optimize their properties. This thesis has been focused on the synthesis of zeolites using phosphorous containing compounds (phosphonium and aminophosphonium cations) as Organic Structure Directing Agents (P-OSDA). The use of these phosphorous compounds influence the crystallization and properties of the obtained zeolites compared to zeolites obtained with classical ammo-nium cations. Phosphorous compounds were chosen because of their different chemistry and stabil-ity properties respect to classical ammonium cations commonly used in the synthesis of zeo-lites. These aspects were studied in a comparative study with different ammonium and phosphorous cations. The phosphorous compounds used in this work have yielded new crystalline structures (ITQ-58 and ITQ-66) and opened new routes for the synthesis of already known zeolites (RTH, IWV and DON), widening their chemical composition range. The thermal decomposition of the P-OSDAs entrapped inside the zeolites yields to the formation of extra-framework phosphorus species that remain inside the channels and voids of the zeolites. These species modulate the adsorption and acid properties of the final materials depending on the post-synthesis treatments. In this work, a route for the incorporation of controlled amounts of phosphorus during the synthesis stage has been studied. This has allowed to control the adsorption and acid properties in small pores zeolites, which cannot be achieved by post-synthesis methodologies. / I wish to firstly acknowledge the Spanish Government for the necessary funding for the FPI pre-doctoral fellowship (BES-2013-062999). Also, this thesis would not have been possible without the infrastructures provided by the UPV and the CSIC staff, fused into the ITQ. Furthermore, I want to acknowledge the Microscopy Service of the UPV for their support in sample microscopy characterization / Simancas Coloma, J. (2021). Synthesis and Characterization of Zeolitic Materials Using Phosphorous Organic Structure Directing Agents [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/171267
138

Tribological Evaluation of Lead-Free Materials for Sustainable Sliding Pads in Gearbox Applications / Tribologisk evaluering av blyfria material för miljövänliga glidplattor i växellådor.

Lind, Casper January 2024 (has links)
Today, lead is used in various engineering applications due to its desirable tribological properties. However, the negative health and environmental impacts associated with lead have raised concerns and resulted in regulatory restrictions on its use. It is therefore nessessary to fnd lead-free materials that can provide similar or even better performance than the commonly used lead-containing alloys. Scania, currently uses leaded alloys for a number of gearbox components where sliding wear can be an issue. This study aims to evaluate the tribological properties of fve lead-free alternative materials and assess their suitability as replacement for the currently used material, Leaded Brass. The tests were conducted in a pin-on-disk setup under similar conditions of those found in Scania’s gearbox. The results showed that the friction and wear was similar between Copper Beryllium and Leaded Brass, which indicates that Copper Beryllium is a potential replacement. Additionally, Nedox and Aluminum Bronze (APS) demonstrated signifcantly superior wear resistance, exhibiting 97% less wear compared to Leaded Brass while maintaining similar friction levels. These results underscore the potential for implementing lead-free materials to enhance sustainability and performance in critical applications like gearbox components. / Idag används bly i olika tekniska tillämpningar på grund av dess önskvärda tribologiska egenskaper. Men de negativa hälso- och miljöeffekterna associerade med bly har väckt oro och resulterat i reglerande begränsningar för dess användning. Det är därför nödvändigt att hitta blyfria material som kan erbjuda liknande eller till och med bättre prestanda än de vanligt förekommande blyhaltiga legeringarna. Scania använder för närvarande blyhaltiga legeringar för ett antal växellådskomponenter där glidande slitage kan vara ett problem. Denna studie syftar till att utvärdera de tribologiska egenskaperna hos fem blyfria alternativa material och bedöma deras lämplighet som ersättning för det nuvarande materialet, blyhaltig mässing. Testerna utfördes i en pin-on-disk konfiguration under liknande förhållanden som de som återfinns i Scanias växellåda. Resultaten visade att friktionen och slitage var liknande mellan kopparberyllium och blyhaltig mässing, vilket tyder på att kopparberyllium är en potentiell ersättare. Dessutom visade Nedox och aluminiumbrons (APS) betydligt överlägsen slitagebeständighet, med 97% mindre slitage jämfört med blyhaltig mässing, samtidigt som båda materialen hade liknande friktionsnivåer. Dessa resultat visar potentialen som finns med att implementera blyfria material för att förbättra hållbarheten och prestandan i kritiska tillämpningar som växellådskomponenter. / Heutzutage wird Blei aufgrund seiner wünschenswerten tribologischen Eigenschaften in verschiedenen technischen Anwendungen verwendet. Jedoch haben die negativen gesundheitlichen und Umweltauswirkungen, die mit Blei verbunden sind, Bedenken hervorgerufen und zu regulatorischen Beschränkungen seiner Verwendung geführt. Daher ist es notwendig, bleifreie Materialien zu finden, die ähnliche oder sogar bessere Leistungen als die üblicherweise verwendeten bleihaltigen Legierungen bieten können. Scania verwendet derzeit bleihaltige Legierungen für eine Reihe von Getriebekomponenten, bei denen Gleitverschleiß auftreten kann. Das Ziel dieser Studie ist es, die tribologischen Eigenschaften von fünf bleifreien Alternativmaterialien zu bewerten und ihre Eignung als Ersatz für das derzeit verwendete Material, Bleihaltiges Messing, zu prüfen. Die Tests wurden in einem Pin-on-Disk-Aufbau unter ähnlichen Bedingungen wie in den Getrieben von Scania durchgeführt. Die Ergebnisse zeigten, dass Reibung und Verschleiß zwischen Kupferberyllium und Bleihaltigem Messing ähnlich waren, was darauf hinweist, dass Kupferberyllium ein potenzieller Ersatz sein könnte. Darüber hinaus wiesen Nedox und Aluminiumbronze (APS) eine signifikant überlegene Verschleißfestigkeit auf und zeigten 97 % weniger Verschleiß im Vergleich zu Bleihaltigem Messing bei gleichbleibendem Reibungsniveau. Diese Ergebnisse unterstreichen das Potenzial zur Implementierung von bleifreien Materialien, um die Nachhaltigkeit und Leistungsfähigkeit in kritischen Anwendungen wie Getriebekomponenten zu verbessern.

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