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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.
1

New Generation Surface treatment for tools : A preliminary study

Massoud, George January 2013 (has links)
The surface finishing technique called black oxidation is currently being used on the tool holders made of low alloyed tool steel produced by Sandvik Coromant. Black oxidation isn’t considered a sufficient technique because it doesn’t make the tool holders look like the quality products that they actually are. The reasoning behind this is that the tool holders can show signs of corrosion after prolonged storing times or in countries with high humidity and temperature. The corrosion doesn’t decrease the tool holders performance, but the customers might believe otherwise. After the black oxidation is performed the surface is oiled which can cause sticky surfaces that rubs off on the person handling the tool holders which is also something that needs to be avoided. The aim of this master thesis was to study potential substitutes to the current surface finishing technique, which could primarily improve the tool holders corrosion resistance and appearance. Other material properties have been studied as well such as hardness, friction coefficient, fatigue- and wear resistance. The cost of some of the different surface finishing techniques has been studied as well, because in order to be interesting their price must match what improvements the technique provides with. A preliminary study was done where the surface finishing techniques that are available in the market has been examined. This has been a theoretical study which means that no experiments were performed and that most of the information available in this study has been obtained from literature and scientific articles. Companies that work with surface finishing has been contacted which shared information about both the theoretical and practical aspects of finishing techniques. Electro- and electroless plating are the two techniques which seem most suited for the replacement of the current method, black oxidation. Polishing and electropolishining can be suitable aswell, but the corrosion resistance barely increases.
2

Hållbara spårvägar / Sustainable Tramway Tracks

Dahlström, Johanna, Hansen, Licette, Hartel, Ellen, Larsson, Francesca, Pettersson, Hanna January 2019 (has links)
The Swedish city of Uppsala is growing and will be expanded. To manage the increase in traffic, a tramway is being planned. It is vital to make the construction and the tramway tracks sustainable. This is explored to study carbon dioxide emissions related to tramway track materials as well as their wear and service life. This project investigates sustainability, the tramway track constituents, rail steel, the rails' wear, rail surface treatments that could minimize wear and increase service life, materials surrounding the rails, and the production of the most used materials in tramway tracks. A literature study is conducted to compare different options for materials and treatments. The municipality of Uppsala's climate goals, technical standards and regulations, articles and studies about the mentioned topics, amongst other sources, are considered and compared. The results include a rough estimation of the material consumption and carbon dioxide emissions. Asphalt tracks have the lowest emissions of the different surrounding material options. The steel consumption and carbon dioxide emissions for the vignole rails are less than for grooved rails and the concrete consumption for grass tracks is slightly less compared to edilon tracks. It is also possible to switch from regular perlitic rail steel to bainitic rail steel when needed. Laser hardening, UNSM, and thermal plasma hardening decrease the rails' wear (rates) considering increased surface hardness. / Uppsala är en växande stad och därför ska Södra staden byggas ut. Spårvagnstrafik planeras för att hantera den kommande trafikbelastning. Det är viktigt att göra konstruktionen av spårvägen till spårvagnen så hållbar och miljövänlig som möjligt. Detta utreds i denna rapport för att undersöka koldioxidutsläpp från spårvägens material samt dess slitage och livslängd. Rapporten undersöker hållbarhet, hur spårvägarna ser ut och dess olika delar, rälstål, rälernas slitage, ytbehandlingar till rälarna som kan minimera slitage och öka livslängden, samt tillverkningen av de mest förekommande materialen i spårvagnars spårvägar. En litteraturstudie genomförs för att jämföra olika materialvals- och behandlingsalternativ. Uppsala kommuns klimatmål, tekniska standarder och regelverk, artiklar och studier om de nämnda ämnena, bland andra resurser, används och jämförs. Studiens resultat inkluderar en grov uppskattning av materialåtgången och koldioxidutsläpp. Det blir minst koldioxidutsläpp från asfaltsspår när det gäller de omgivande materialen. Stålåtgången och koldioxidutsläppen för vignolräler är mindre än för gaturäler och betongåtgången blir lite mindre för grässpår jämfört med edilonspår. Det är även möjligt att byta från vanligt perlitiskt rälstål till bainitiskt rälstål vid behov. Laserhärdning, UNSM och termisk plasma härdning minskar rälernas slitage med avseende på framförallt ökningar av ythårdhet.

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