ABB Metallurgi tillverkar elektromagnetiska omrörare som används vid framställning av metaller och metallegeringar. De elektromagnetiska omrörarna skiljer sig åt i utförande, storlek och form, vilket innebär stora utmaningar för företaget då nästan varje produkt är helt unik i sina specifikationer. Marknaden är världsomspännande och företaget har kunder världen över. Den allt mer globaliserade marknaden ställer höga krav på företag vad gäller såväl kostnad som kvalitet. Omrörarna säljs, projekteras, konstrueras och tillverkas innan de levereras till kunder världen över.  Eftersom produkterna har sådana stora variationer, både vad gäller form och tekniska specifikationer, tillverkas enbart på kundorder. På en marknad där höga krav på leveransprecision ställs, krävs planering av företagets interna aktiviteter. I utgångsläget används en lista över alla leveransprojekt som delas med alla avdelningar. Däremot upplevs stora glapp mellan avdelningarna intern som skulle kunna undvikas med bättre intern kommunikation och planering. Produktionen ämnar utgå från produktionsstrategin ConWIP (eng. Constant Work-In-Process), vilken är nära besläktad med Kanban inom Lean-filosofin. ConWIP går ut på att eftersträva en jämn produktion där konstant mängd produkter i arbete eftersträvas. Samtidigt saknas en fungerande detaljplanering för produktionen som stödjer denna strategi. Målet med detta arbete är att ta fram ett förslag på uppdaterad planeringsmetod med tillhörande praktisk tillämpning i form av ett planeringsverktyg. För att lyckas med det har en litteraturstudie med fokus på planering med hänsyn till ConWIP-strategin utförts. För att anpassa dessa resultat till fallstudieobjektet har intervjuer på företagets alla avdelningar genomförts. Dessutom har ett benchmarkingbesök genomförts, för att skaffa inspiration kring hur planering fungerar inom företaget ABB. Parallellt har även deltagande i planeringsaktiviteter ägt rum, så väl som deltagande i verksamhetsutvecklingsaktiviteter. Datainsamlingen har visat på komplexiteten i att ta hänsyn till alla möjliga parametrar och begränsningar i en manuellt framtagen produktionsplanering. Därför är det viktigt att planeringens syfte och utformning utformas i linje med vald produktionsstrategi och med hänsyn till de viktigaste parametrarna. De viktigaste parametrarna för ABB Metallurgi anses vara leveransprecision, jämn arbetsbelastning och minskat bundet kapital. Vidare är de mest relevanta begränsningarna, i relation till dessa resultat, möjliga start och slutdatum, kapacitet i tillverkningen och produktionsordningen. Vidare belyser rapporten vikten av förbättrad intern kommunikation. Uppdateringen av planeringsmetod inkluderar därmed typtidplaner för att underlätta kommunikation kring kritiska situationer och framtagning av en verklighetsnära planering. Samplanering av nytillverkning och eftermarkandstillverkning introduceras på produktionsplaneringsnivå. Hjälp för att underlätta strategiska inköp inkluderas, samtidigt som jämn arbetsbelastning och därmed ett jämnt kapacitetsutnyttjande eftersträvas i produktionsplaneringen. / ABB Metallurgy manufactures electromagnetic stirrers used in the production of metals. The electromagnetic stirrers differ in size and shape, which poses major challenges for the company, since almost every product is unique in its specifications. The market is worldwide and the company has therefore customers all over the world. The increasingly globalized market places high demands on companies in terms of cost and quality. The stirrers are sold, projected, constructed and manufactured before being delivered to customers worldwide. Because the products have major variations, both in terms of shape and technical specifications, they are produced exclusively on customer orders. In a market where high demands on delivery reliability are imposed, planning of the company's internal activities is required. Initially, a list of all delivery projects shared with all departments is used. On the other hand, major gap between departments is felt internally that could be avoided with better internal communication and planning. The production is based on the ConWIP production strategy, which is closely related to the Kanban strategy in the Lean philosophy. ConWIP aims to strive for a constant work in process. At the same time, there is no functional detail planning for production that supports this strategy.  The aim of this work is to develop a proposal for updated planning method and associated practical application in the form of a planning tool. To succeed, a literature study focusing on planning regarding the ConWIP strategy has been conducted. To adapt these results to the case study, interviews on all departments of the company have been conducted. In addition, a benchmarking visit has been conducted to gain inspiration about how planning works within the company ABB. Participation in planning activities has also taken place, as well as participation in activity development activities.  The data collection has shown the complexity of considering all possible parameters and limitations in a manually-made production planning. Therefore, it is important that the design of the planning goes in line with the chosen production strategy and regarding the most important parameters. The most important parameters for ABB Metallurgy are delivery precision, even workload and reduced net working capital. Furthermore, the most relevant constraints, in relation to these results, are possible start and end dates, production labor capacity and production scheme for upcoming projects.  Furthermore, the report highlights the importance of improved internal communication. The updating of the planning method thus includes type-time plans to facilitate communication about critical situations and the development of a reality-based planning. Sampling of new manufacturing and after-market production is introduced at the production level of planning. Help to simplify strategic purchases is included, while constant workload and thus even capacity utilization are sought in the production planning tool.

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Thesis: Sc. D., Massachusetts Institute of Technology, Department of Metallurgy, Division of Ceramics, 1945 / Vita. / Bibliography: leaves 91-156. / Sc. D. / Sc. D. Massachusetts Institute of Technology, Department of Metallurgy, Division of Ceramics

The perovskite solar cells have attracted much attention recently due to their low fabrication cost and high power conversion efficiency. However, the instability of such devices remained a serious challenge, which is yet to be resolved despite many attempts. In this thesis, the moisture degradation mechanism has been uncovered. It was found that the perovskite structure can be reconstructed when annealed at around 90℃, which leads to a reversible device of a much higher device lifetime. Following the experimental explorations, modelling work has also been conducted to simulate the water diffusion during the degradation and recovery. It was found that the moisture diffusion was initiated at the surface imperfection, where the activation energy for diffusion can be reduced. Based on these discoveries, a fresh structural negotiation method has been proposed to obtain a stable FAPbI3 phase of a suitable bandgap for photovoltaics, which showed a reduced Gibbs free energy of 0.12eV compared with the δ phase. In addition, the activation energy for such phase transition was calculated to be 0.45eV, meaning that the discovered phase is protected by both thermodynamics and kinetics. All this opens an unprecedented avenue in perovskite research, which will hopefully be of intrinsic interest to the broad materials research community as well. / Thesis / Doctor of Philosophy (PhD)

The theory of the lamellar eutectoid reaction by volume diffusion has been extended to account for solute segregation within the product phases and the effect of dilute third element additions. It has been demonstrated for symmetric binary systems that the segregation can account for 10% or more of the free energy stored in the product phases and can lead correspondingly to a predicted lamellar spacings appreciably greater than those obtained when segregation is neglected. This segregation is relatively high in the systems Cu-In, Cu-Be and Ag-Cd and may account for the fact that a secondary coarse-grained pearlitic reaction follows the initial fine grained one in these systems. The binary theory has been-used to analyse the available data for the eutectoid reaction in the Cu-Al and Fe-C systems and satisfactory agreement is obtained. The theory for ternary systems, while complete in principle, proves to be. intractable in all but the simplest version of the solution thermodynamics. It is concluded that the effect of the third element on the binary eutectoid reaction is mainly through its effect on the phase diagram, the ternary cross effects in the diffusion matrix tending to cancel out. Any additional element which lowers the eutectoid temperature will retard the reaction. / Thesis / Doctor of Philosophy (PhD)

Eutectic Fe-C, Ni-C and Fe-C-Si alloys have been solidified directionally in an electron-beam floating zone apparatus under carefully controlled conditions and the resulting morphologies in these alloy systems have been studied as a function of rate. In addition, the transition from the stable iron-graphite (grey iron) to the metastable iron-iron carbide (white iron) mode has been observed and has been related to the iron-carbon/iron-iron carbide double phase diagram by means of undercooling measurements. Interlamellar spacing measurements carried out on both the graphitic and carbidic modes using material of the same composition and purity under identical experimental conditions showed a λaR-1/2 and a λaR-1/3 relationship in the iron-graphite and iron-iron carbide eutectic systems, respectively. / Thesis / Doctor of Philosophy (PhD)

Using the maximum bubble pressure method of density determination, the density-composition relationship of iron silicates in contact with solid iron at 1410°C has been determined. The "iron oxide" in an iron silicate has been replaced by calcium oxide, manganous oxide, cobaltous oxide, nickel oxide and calcium fluoride and the density-composition relationships occurring have been obtained. The calculated oxygen density-composition relationships have been interpreted in terms of the effects of silica concentration and cationic species on the anionic configuration occurring in the melts and this interpretation has been correlated with recently-developed thermodynamic models of silicate anion configuration in basic binary silicate systems. / Thesis / Doctor of Philosophy (PhD)

Title: Ion Impact Phenomena in Anodic Oxides, Author: Lam Q. Nghi, Location: Thode / <p>In this thesis results are presented relating to sputtering coefficients of Kr on anodic oxides, high-dose depth distributions of Kr in Al2O3, Nb2O5, and WO3, and amorphization in crystalline WO3.</p> <p>The comparison of the experimental sputtering data with Sigmund's theory permits the surface binding energy to be estimated. Possible contribution of volatility to sputtering will be discussed for the case of volatile oxides with stable gaseous multimers, namely MoO3, V2O5, and WO3.</p> <p>The pronounced "range shortening" has been studied in detail for high doses of Kr in Al2O3, Nb2O5, and WO3, and is shown analytically to be reasonable whenever there exists an appropriate spatial variation in the diffusion activation enthalpy. Effects of pre-bombardment and post-bombardment on depth distributions, as well as information on the migration of implanted dopants near room temperature, are argued as providing a self-consistent explanation for the above-mentioned "range shortening".</p> <p>Depths of amorphization due to ion impact have been measured with WO3. They are then used to deduce the critical fraction of atomic displacements leading to amorphization, the mean size of discrete disordered regions, and estimates of the damage mean range for Kr-WO3.</p> / Thesis / Doctor of Philosophy (PhD)

Title: Ion-Bombardment-Induced Structural Transformations in Oxides, Author: Hassein M. Naguib, Location: Thode / <p>In this dissertation, transmission electron microscopy, reflection electron diffraction, gas-release,and electrical-conductivity measurements have been used to study bombardment-induced structural transformations in oxides, and their implications to other non-metallic substances. Results are presented for bombardment-induced crystallization of amorphous thin films of ZrO2; bombardment-induced amorphization of crystalline pellets of TeO2, MoO3, V2O5 and Bi2O3; and high-dose formation of lower oxides with MoO3 and V2O5. Using the results of this experimental study along with information concerning 30 other solids, a thermal-spike model and a bond-type criterion are shown to be successful in predicting the behaviour of these materials under ion impact.</p> / Thesis / Doctor of Philosophy (PhD)