Gas metal arc is a high-efficiency and widely used heat source for metal processing applied predominantly in welding and additive manufacturing. In this study, it was applied to welding. It offers high productivity, low production and investment cost, as well as suffers from some drawbacks such as humping or undercut when welding large parts that are curved and impose changing the orientation of the welding torch along the joint path. Deeper process understanding was therefore sought to mitigate these drawbacks. The difficulty is then the non-lineardependence of the process to the welding parameters and material properties. Besides, visual observation of this process is also difficult. For instance, the elevated temperature and the intense radiative emission from the electric arc, smoke, spatter, as well as the non-transparency of the processed alloy can hinder in-process observation or limit it. Process simulation provides a complementary means to reach process knowledge. It was thus the approach used in this study. For this, a thermo-fluid melt pool model that can predict melting and solidification, track free surface deformation, metal transfer, and coalescence with the melt pool was developed. Two main research questions were identified and addressed.The first one led to studying the effect of the substrate orientation during multilayer welding of a V-groove joint with INVAR and gas metal arc. It was foundthat the force balance in the melt pool changes significantly when the workpieceorientation is changed, resulting in distinct melt flow patterns, melt pool and bead geometries, and in some conditions defect initiation such as humping, undercut, and lack of fusion. As a result, multi-layer welding with flat substrate and downhill welding of a 20◦ inclined substrate are recommended with these process conditions. On the contrary, welding of a side inclined substrate and uphill welding of a 20◦ inclined substrate are not recommended. The second question gave rise to the comparative investigation of the three electromagnetic force models commonly used when modelling a melt pool produced by an electric arc. The underlying modelling assumptions were retrieved and investigated. It was found that each of these three models predicts a different melt flow pattern, different heat convection, melt pool shape, free surface oscillation, and interaction with the transferred metal drops, and thus result in different bead geometry. All these models can be adjusted to predict the penetration depth, however, only the most complete of them is recommended for developing a predictive melt pool model. For this, it is proposed as a future work to improve this model through predicting an electromagnetic force that takes also into account the local deformation of the free surface. / Gasmetallbåge är en effektiv och allmänt använd värmekälla vid svetsning och additiv tillverkning. I denna studie tillämpas den på svetsning. Den erbjuder hög produktivitet, låg kostnad vid inköp och användning, såväl som vissa nackdelarsom ojämn "bucklig" svetssträng och smältdiken vid svetsning av stora komponenter som är krökta och medför att svetsbrännarens orientering ändras utmed fogen. Bättre processförståelse eftersträvas därför för att mildra dessa nackdelar. En utmaning är processens icke-linjära beroende av svetsparametrarna och materialegenskaperna. Dessutom är experimentell optisk övervakning svår. Till exempel kan den höga temperaturen och den intensiva elektromagnetiska strålningen från ljusbågen, rök, sprut, såväl som legeringens ogenomskinlighet, förhindra observation under processen eller begränsa den. Processimulering erbjuder en komplementär metod för att nå processkunskap. Det är alltså detta tillvägagångssätt som används i denna studie. För detta har en modell av värme och materialflödena i smältan utvecklats som kan prediktera smältning och stelning, spåra smältytans deformation, metallflöde och koalescens med smältan.Två huvudsakliga forskningsfrågor har identifierats och adresserats. Den första studerade gravitationens påverkan vid flersträngs-, gasmetallbågsvetsning av V-fogar i INVAR. Olika svetslägen har visat sig ha en betydande påverkan på kraftbalanserna i svetssmältan vilket resulterar i distinkta smältflöden, smält- och svetsförbandgeometrier, och under vissa förhållanden svetsdefekter såsom ojämn "bucklig" svetssträng, smältdiken och bindfel. Som ett resultat rekommenderas horisontellt och 20◦ fallande läge vid flersträngssvetsning, medan 20◦ stigande och sidolutande inte rekommenderas. Den andra frågan undersökte inverkan av de tre huvudsakliga modellerna för den elektromagnetiska kraften som idag används vid svetssimuleringar. För modelleringen har antaganden lagts fram och undersökts. Det visade sig att de tre modellerna predikterar olika flödesmönster i smältan, olika värmekonvektion, smältgeometri, ytvågor och interaktion med de överförda metalldropparna, och därmed också predikterar olika svetsstränggeometrier. Alla tre modeller kan justeras för att prediktera svetspenetrationen, men endast den mest kompletta av dessa rekommenderas för sant prediktiv modellering. Det föreslås också att ytterligare förbättra den mest kompletta modellen så att det elektromagnetiska kraftfältet följer deformationen av den fria smältytan. / <p>Submitted papers or manuscripts have been excluded from the fulltext file. </p>

PureFize Technologies AB develops and manufactures a broadband ultraviolet (UVC) light technology device that is mercury-free and based on nanotechnology, using the principle of field emission. The light source is made of Ti and glass, which are hermetically bonded, using a low-temperature glass frit, at elevated temperatures. The bonding procedure will induce stresses in the device originating from the mismatch of the coefficient of thermal expansion (CTE) between the materials. Brittle materials, as glass, withstands tensile stresses poorly. Therefore, the stress magnitude and distribution needs to be understood.  This work develops a quality inspection method for the glass bond and internal stresses, as well as stress simulations of the device, to be used in production at the company. The glass bond width and the internal stresses in the device were classified and analyzed by light optical microscopy and by polarised light optical microscopy. The optical analysis was followed by pressure tests of the devices using a chamber that allowed for pressurized air up to 7 bar. In parallell with the experimental work, stress and deformation simulations of the device using the finite element method (FEM) was made. Data collected from the inspections and pressure tests were compiled and analyzed, showing clear connections between the glass bond quality and the device's ability to withstand external pressure. A narrow glass bond could withstand external pressure poorly, whereas a wide glass bond could withstand external pressure well. Correlations could be made both between the glass bond appearance and the stress patterns, as well as between the FEM simulations and the stress patterns in the device. It is clear that the stresses induced in the device after bonding originates from the CTE mismatch of the bonded components when cooling it from the bonding temperature to room temperature. The pressure testing method proved to be an efficient way of verifying the maximum pressure capacity of the devices.  The knowledge from this thesis can be used when further investigating induced stresses from glas frit bonding.

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.

This study had the purpose to further the use of industrial lasers in the manufacturing of hairpin electric motors by optimizing the process of contacting the hairpins. A problem with laser beam welding of copper is the porosity created in the process which can lead to increased resistance of the welded region along with degraded mechanical properties. By experiment this study aimed to find the optimal parameters to reduce the porosity while maintaining all other requirements for the weld. The track of achieving a satisfactory simulation was done to minimize the need of physical experiments which can be argued as a sustainable development aspect. A set of parameters was found that achieved a low volume of pores, a sufficient weld depth and a desirable bead geometry. Some pores still remained, mostly at the endpoint of the laser path which could be caused by the laser shut-off leading to a keyhole collapse enclosing some pores in that region. The simulation showed promising results in welding depth and melt region. Further work on ramping the laser power at the endpoint could be beneficial for eliminating the remaining porosity as well as refining the simulation in terms of porosity.

The project aims to develop a methodology to study the variation in properties of wood polymer composites (WPC’s) with/without surface treatment at different humidity conditions. The project aims to investigate the behavior of biocomposites at 50%, 80%and 100% relative humidity (RH). Also to clarify if the hydrophilization effect helps to preserve the structural integrity of the materials for longer periods at these conditions. The comparison between biocomposites comprising polypropylene (PP) with both untreated wood fibers (WF) or FibraQ (hydrophobic surface-treated wood fibers from Biofiber Tech) was made. The focus was on the mechanical properties, water absorption, macro- and microstructures. The results show that PP comprising FibraQ exhibits lower moisture uptake than the PP comprising untreated WF at high relative humidity conditions. The mechanical properties did not seem significantly affected by the surface treatment at high relative humidity conditions. It is also concluded that since the study only ran for four weeks, there was not enough time to fully understand the influence of moisture uptake over the materials’ properties.

The purpose of this study was to simulate the liquid flow rate distribution in the etching modules and find the optimal setup in order to achieve a distribution as homogenous as possible. The commercial software Matlab 2015a has been employed for all the numerical simulations. The optimization has been carried out varying several parameters, i.e. spray cross sections of the nozzles, the oscillation parameters, the rotating angle of the nozzles within etching module 1 and the nozzle arrangement inside the modules. Furthermore, the optimization has been carried out separately along the two directions of the modules. The results achieved computationally have been validated via experimental procedures. During this study a specific experimental setup has been developed in order to be able to compare experimental and computational results. The validation process has shown that the computational method matches the experimental results to a good extent. The experimental liquid distribution in etching module 2 widely matches the simulations to a quantitative extent, while the one in etching module 1 provides the same qualitative but different quantitative results.

Nanopartiklar (NP) erbjuder unika möjligheter för medicinska tillämpningar, inklusive kontrollerad frisättning av cancerläkemedel, användning som bildkontrast vid avbildningsprocedurer eller hypertermisk behandling av cancerceller. Flash nanoprecipitation (FNP) producerar NPs för att kombinera dessa tillämpningar i en snabb, billig och skalbar beläggningsprocess. Användning av FNP med en Multi-Inlet Vortex Mixer (MIVM) är en lovande metod för att enkelt belägga hydrofoba oljesyra järnoxid NP (IONP) med olika biokompatibla block-copolymerer. Amfifila block-copolymerer baserade på hydrofil polyetylenglykol (PEG) och hydrofob poly(laktid) (PLA), poly(laktid-co-glykolid) (PLGA) eller poly(kaprolakton) (PCL) syntetiserades framgångsrikt. Den organiska katalysatorn 1,8-diazabicyclo[5.4.0]undec-7-en (DBU) användes för att öka biokompatibiliteten hos de resulterande polymererna PEG-PLA, PEG-PL7,5KG2,5KA och PEG2K-PCL2K. Syntes av hydroxylterminerad poly(akrylsyra) (PAA-OH) följt av polymerisation med PLGA prövades. De amfifila blockpolymererna användes i kombination med stabilisatorn polysorbat 80 (Tween80®) i FNP för att bilda nakna polymera NP med en MIVM som reaktor. DLS och STEM bekräftade partikelstorlekar mellan 50 - 100 nm. Tillsatsen av 13 ± 2 nm hydrofoba oljesyra-IONPs gav en ökning av partikelstorleken samt en ökning av partikelstabiliteten över tid. STEM-bilder visade att enstaka IONPs fästs på utsidan av de polymera NPs. Hydrofoba interaktioner mellan polymeren och oleinsyra-IONPs är möjliga. För att uppnå inkapsling av oljesyra-IONPs bör justeringar av processparametrarna för FNP övervägas i framtida forskning. Ytterligare experiment krävs för att utforska möjliga läkemedelstillsatser, frisättningsmekanismer och hypertermi hos de polymerbelagda IONP-partiklarna. / Nanoparticles (NPs) offer unique possibilities for medical applications, including the controlled release of cancer drugs, the use as imaging contrast during imaging procedures or the hyperthermic treatment of cancer cells. Flash nanoprecipitation (FNP) produces NPs to combine these applications in a fast, cheap, and scalable coating process. The use of FNP with a Multi-Inlet Vortex Mixer (MIVM) is a promising method to easily coat hydrophobic oleic acid iron oxide NPs (IONPs) with various biocompatible block-copolymers. Amphiphilic block-copolymers based on hydrophilic polyethylene glycol (PEG) and hydrophobic poly(lactic acid) (PLA), poly(lactic-co-glycolic acid) (PLGA) or poly(caprolactone) (PCL) were successfully synthesized. The organic catalyst 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) was used to increase biocompatibility of the resulting polymers PEG-PLA, PEG-PL7.5KG2.5KA and PEG2K-PCL2K. The synthesis of hydroxyl terminated poly(acrylic acid) (PAA-OH) followed by the polymerization with PLGA was attempted. The amphiphilic block-copolymers were used in combination with the stabilizer polysorbate 80 (Tween80®) in FNP to form bare polymeric NPs using a MIVM as the reactor. DLS and STEM confirmed particle sizes between 50 - 100 nm. The addition of 13 ± 2 nm hydrophobic oleic acid IONPs yielded an increase in particle size as well as increase in particle stability over time. STEM images showed attachment of single IONPs to the outside of the polymeric NPs. Hydrophobic interactions between the polymer and oleic acid IONPs are possible. To achieve encapsulation of the oleic acid IONPs, adjustments to the process parameters of FNP should be considered in future research. Additional experiments are required to explore possible drug addition, release mechanisms and hyperthermia behavior of the polymer coated IONPs particles.

Gas turbine engine efficiency needs to be raised in order to decrease fuel consumption, greenhouse gas emissions, and expenses. Efficiency may be improved in two ways: by reducing engine weight and raising intake temperatures. At intake temperature, conventional nickel-based alloys are already on the verge of failure, meaning there is a need and demand of materials which can withstand higher temperatures. Silicon Carbide Ceramic Matrix Composites (SiC CMCs) are being investigated as a potential replacement for superalloys due to their superior physical properties, such as their low weight and high melting point (approximately one-third of superalloys' weight). However, using SiC CMCs has a serious disadvantage. The mass recession of the SiC is caused by the volatilization of silicon hydroxide, which is caused by oxidation and reactivity with water vapor under the working conditions of gas turbine engines. Therefore, a shielding layer is used to prevent oxidation of the SiC CMCs. This protective coating (EBC) goes by the name of Environmental Barrier Coating. Thermal spray techniques such as atmospheric plasma spray and suspension plasma spray, which employ powder as the feedstock, are used to deposit EBC on SiC CMCs. For EBC to perform well, the coating must be crystalline, reasonably thick to sustain harsh environment, and devoid of cracks. EBC was deposited in order to look at how the spray parameters affected the microstructure. SEM pictures were used to quantify the coating's porosity and the severity of the cracks. To investigate the production of thermally grown oxide (TGO) in the coating and substrate and check how EBCs perform under thermal cyclic fatigue loading, a thermal cyclic fatigue test was conducted. The XRD analysis is performed to ascertain the proportion of crystalline and amorphous phases in the coating, which unfortunately is still in the process to be completed. In the as-sprayed coating samples we can see that when there are more amount and larger pores, we see less number of cracks and vice versa. The effect of spray parameters can be seen on the coatings. Comparing to SPS trial 1, the SPS trial 2 coatings are denser with less number of cracks and has good adhesion. Still the SPS trial 2 coating did not achieve better microstructure in terms of density, and cracks compared to the APS coatings but further looking into the parameters, more desirable coatings can be achieved. After TCF testing, a layer of TGO was seen at the bond coat/topcoat interface, and there was no failure of the coating seen.

Stålfronter är Cibes mest eftertraktade alternativ av karm och dörrkombination till den offentliga marknaden såsom skolor och gallerior på grund av den robusta konstruktionen. Det förekommer dock problem med tillverkningseffektivitet, hantering och korrosion. Problematiken som uppstår har tydligt samband med karmens nuva-rande sammansvetsade konstruktion, samt att de inte är konstruerade att installeras i korrosiva miljöer. Genom förundersökningar hur dagens tillverkning ser ut och vad som önskas i konstruktionen ställdes ett kvalitetshus upp. Från kvalitetshuset utgavs, genom viktning, de viktigaste önskemålen som arbetet bör uppfylla. Det viktigaste var att konstrukt-ionen ska vara modulär, därefter önskades minskad variation och korrosionshärdiga alternativa material. Med hjälp av idégenerering togs olika koncept fram vilka alla förutom de mest lovande eliminerades. Det slutliga konceptet innebär en modulär karm där variationen av moduler uppgår till 39 för att bibehålla samma mängd karmvariationer som da-gens konstruktion, det vill säga 146 karmvariationer. Det togs även fram tre material för eventuell tillämpning i olika miljöer. Två av materialen har lägre pris än dagens (DC01 och DX51+Z275), dessutom har två av dem högre korrosionshärdig-het (DX51+Z275 och SS-EN 1.4404). Konceptets hållfasthet verifierades med håll-fasthetsberäkningar kompletterat med FE-analys. Det framtagna konceptet leder till effektivare tillverkningsprocess genom att färre produkter behöver lagras och hanteras. Materialpriserna och hållfastheten i koncep-tet är dock uppskattad till viss grad och behöver vidare verifieras. / Steel fronts is Cibes most sought after frame and door combination to the public market such as schools, malls etc. because of the robust construction. However, there are problems with manufacturing efficiency, handling, and corrosion. The problems that arise are significantly connected to the construction being delivered from a subcontractor as a complete welded sheet metal construction. In addition, they are not designed to be installed in corrosive environments. Through preliminary investigations how today's manufacturing takes place and what is desired in the construction a QFD was made. By weighting, the QFD presented the most important qualities which the work should fulfill. The most important quality was that the construction must be modular, followed by reduced variation and corrosion resistant alternatives. With the help of idea generation methods, different concepts were developed, which all but the most promising were to be eliminated. The final concept includes a modular frame where variations of modules is 39 to maintain the same amount as today´s construction with 146 frame variations. Three materials were also con-cluded for possible application in different environments. Two of the materials have a lower price than the material used today (DC01 and DX51+Z275), in addition, two of them have a higher corrosion resistance (DX51 + Z275 and SS-EN 1.4404). The strength of the concept was verified with strength analysis supplemented with FE analysis. The developed concept leads to more efficient manufacturing process in that fewer products need to be stored and handled. However, the material prices and the strength of the concept are appreciated to a certain extent and need to be further verified.

This thesis focuses on the topic of PBF-LB applied to titanium alloys. Of allalloys, an α + β is chosen, named Ti-6Al-4V. The selection of this particular alloy is driven by its current widespread use in many industrial applications where high strength coupled with low density are both desirable properties. For the last 50 years, parts made with this alloy have been cast or forged and then machined to achieve the final geometry. There is now an opportunity totransform this process chain by additive manufacturing, hence reducing material waste and achieving near net shape from powder feedstock. The process is summarised as follows: a laser selectively melts areas on a build plate where powder is pre-placed. Then a successive powder layer is spread and the process is repeated until completion. Upon removal of the part from the build plate, loose powder in the chamber is collected and recycled whenever possible. The design freedom provided by powder bed fusion methods enables production of intricate geometries and added functionality, despite the need for post-build consolidation and/or microstructural adjustments. Today’s fine and narrow powder cuts (e.g., 15-50μm) are designed to be coupled with low layer thicknesses (i.e., 30μm) to achieve smooth surfaces and high resolutions of small features e.g., internal cooling channels. However, costs associated with production of fine and narrow powder cuts are substantial as refinement of batches requires multiple sieving steps. In addition, resulting building times are considerably long (i.e., days), therefore a beneficial alternative could be that of exploring higher layer thicknesses together with wider and coarser powder cuts. The main idea of this work is to investigate the effects of employing a powder with a wider size distribution 15-90μm. The aim is to reduce the sievingrequired and consequently decrease the costs of developing and building parts made by PBF-LB. An extensive microstructural investigation is conducted on single tracks and cubes built with 27 different process parameter combinations, which also attempts to establish correlations between characteristics of tracks and responses measured in cubes. As a second step, the amount of residual porosity of asbuilt cubes is chosen as the discriminant for further mechanical testing of sub and super-β transus high-pressure heat treated material. / Den här avhandlingen fokuserar på additiv tillverkning av titanlegeringar med laser pulverbädd metoden. Den legering som främst är i fokus är Ti-6Al-4Vsom är en α+β legering. Anledningen till valet av denna titanlegering är att det är den vanligast förekommande titanlegeringen och att den används i ett antal olika industriella tillämpningar där hög styrka i kombination med låg vikt är önskvärda egenskaper. Under de senaste 50 åren har komponenter utav denna legering tillverkats med gjutning eller smide, följt av bearbetning till slutlig geometri. Med hjälp av additiv tillverkning finns nu en möjlighet att förändra tillverkningskedjan i vilket minskat materialspill och en mer nära-slutgeometri kan erhållas direkt genom användning av metallpulver som utgångsmaterial. Processen kan summeras enligt följande: en laser smälter ett förbestämt område på en byggplatta som täckts mer pulver. Därefter adderas ytterligare ett lager med metallpulver ovanpå, på vilket samma process sker igen, och igen osv, tills hela detaljen är färdigtillverkad. När detaljen ska tas loss ifrån byggplattan samlas det kvarvarande icke-smälta pulvret upp och återanvänds i så stor utsträckning som möjligt. Frihetsgraderna vid design i processen möjliggör tillverkning av komplexa geometrier och adderade funktionaliteter, även fast efterbehandling och/eller justeringar av mikrostrukturen kan behövas. Dagens smala pulverstorleksfördelning (tex 15-50μm) är avsedd att ge tunna lagertjocklekar (tex 30μm) för att åstadkomma en fin yta och hög upplösning av små geometrier, såsom exempelvis interna kylkanaler. Men kostnaderna som det innebär att framställa och sortera ut fina och smala kornstorleksfördelningarär avsevärd eftersom det innebär flera steg med silning. Vidare leder de tunnalagertjocklekarna till långa byggtider (typiskt dagar). Ett alternativ, som därför vore fördelaktigt, är att undersöka möjligheten med att bygga tjockare lager med en bredare och större pulverstorleksfördelning. Huvudfokuset i detta arbete fokuserar på att undersöka effekterna av att använda en bredare pulverpartikelstorleksfördelning 15-90μm, med syfte at minska silningsbehovet och därmed reducera kostnaden för att utveckla och tillverka detaljer med laser pulverbädd additiv tillverkning. En omfattande mikrostrukturundersökning har gjorts på enkelsträngar och kuber byggda med 27 olika processparameter-kombinationer, vilket samtidigt försöker identifiera korrelationer mellan enkelsträngarnas karaktäristik med resultaten uppmätta hos kuberna. I ett nästa steg har material, som tillverkats med processparametrar som renderade i minst/mest porer hos kuberna, mekaniskt provats efter att det högtrycksvärmebehandlats över- respektive under β-transus. / <p>Paper A is not included due to the copyright.</p><p>Paper B and C are to be submitted.</p>