The main purpose with this investigation was to clarify when or if specific grades will soften or harden during the straightening process in a seven roll cross roll straightening machine. The aim was solely made to include tubes which had been cold worked to achieve high yield strength levels. The straightening process will induce lengthwise tensile and compressive stress and strain. According to theory straightening could therefore also induce considerable Bauschinger effect.  Physical tests, with material from pilgered tubes, in a laboratory environment were performed to give a well-defined set up of the strain levels and sign of the same. Real in process trials were also performed. Parallel to the physical laboratory tests and the real process tests a FEM-simulation and a FEM-model to calculate strain levels was developed.  Two material types were investigated, but the results are only unambiguous for material A. Further investigations need to be done on material B to give a clear picture.

Biogas is a promising alternative fuel with low CO2 emissions and high market potential due to the abundance of organic biomass. Despite being a renewable form of energy, biogas consists of 40-45% CO2, which lowers its calorific value [1]. Various porous materials have been tailored to adsorb CO2 gas from the biogas stream to obtain 95-97% biomethane. Zeolites are one of the promising porous materials that can contribute remarkably in the upgrading process by selectively adsorbing the CO2 gas from biogas [2]. The aim of this thesis is to develop hierarchical structures by novel approaches to enhance their CO2 adsorptive properties. The first part of the study addresses the tailoring of zeolites NaX and CaA binderless beads using the ion-exchange process to acquire high CO2 adsorption capacities of 5.1 mmol/g and 4.3 mmol/g at 298 K with the high mechanical strength of 2 MPa and 1.3 MPa respectively. The ion-exchange process was optimized for NaX and CaA zeolite to obtain high CO2-over-CH4 selectivity of 525 and 1775 respectively. The breakthrough experiments show that the partially ion-exchanged zeolite NaX has high mass transfer kinetics with a CO2 uptake rate of 2.8 mg of CO2/g/s as compared to the zeolite CaA binderless beads. The second part dealt with the structuring of zeolites using freeze granulation and electrospinning techniques. The freeze granulation process was optimized to form granules of 2-3 mm in diameter from NaX and CaA zeolite powder. The CO2-over-CH4 selectivities were investigated using Henry’s law and it shows that the NaX granules offer high selectivity of 214 than the CaA granule, 172 at 273 K and 100 kPa. No physical damage was observed when the granules were subjected to five cyclic breakthrough adsorption-desorption experiments at 4 bar. In addition, NaX granules offer a high uptake rate of 3.6 mg of CO2/g/s with a mass transfer coefficient of 1.3 m/s as compared to the CaA granules. To move further in structuring techniques, electrospinning was used to fabricate hierarchical porous structures. ZSM-5 nanofibers composites were developed from the ZSM-5 nanopowder and polyvinylpyrrolidone (PVP) polymer. Two-step post thermal treatments were carried out: Pre-oxidation and carbonization on ZSM-5 nanofibers composites to form mechanically strong composite structures. The post-carbonized structures showed a 30.4% increase in specific BET surface area than the ZSM-5 nanopowder with the CO2 uptake of 2.15 mmol/g. To investigate the CO2 separation properties, secondary pellet structures were developed with a tensile strength up to 6.46 MPa. The CO2 uptake rate for pellets was 2.3 mg of CO2/g/s without any performance decay after the first cycle with the simulated mass transfer coefficient of 1.24 m/s. [1] J Wang. Decentralized biogas technology of anaerobic digestion and farm ecosystem: Opportunities and challenges, Front.Energy Res. 2 (2014). [2] RV Siriwardane, M- Shen, EP Fisher, J Losch. Adsorption of CO 2 on zeolites at moderate temperatures, Energy Fuels. 19 (2005) 1153-1159.

Aim: The aim of this study is to evaluate if additive manufacturing (AM) is an appropriate manufacturing method for insoles in comparison to vacuum forming (VF) and subtractive manufacturing (SM) in regards of material properties such as abrasion resistance. Background: Traditionally insoles are manufactured with either VF or SM. AM has been around for some decades but implementation into orthotic and prosthetic (O&P) business has not been accomplished yet. Therefore, the quality of the products produced with AM must be tested in comparison with traditional methods. Method: A comparison of samples for the mentioned manufacturing methods was done with the help of an abrasion testing machine with the standard ASTM G133. Two samples were produced from each manufacturing method and respectively tested for one and two hours. All the samples were weighed before and after the tests with the help of a four decimal scale. The difference in weight before and after the test and coefficient of friction was evaluated. The weight difference was analyzed to see how much material had been removed from the sample. The percentage of wear loss was calculated for each specific sample, both for one hour and two hours of testing. No statistical analysis could be made due to the limited amount of samples and testing time. Result: No statistically significant could be found for either wear loss or the coefficient of friction as mentioned above. Conclusion: A conclusion whether which material having the best abrasion resistance for respectively manufacturing method could not be drawn due to limited results. This study can be seen as a pilot study where the methodology can be used in further studies. Further research on AM needs to be conducted.

Regarding the great importance of fast cooling in steel industry for the production processes, a deep understanding of heat transfer and fluid dynamics must be held. A steel plate is heated up until a maximum temperature of 700 ⁰ C to be the n cooled down seconds later by a configuration of multi ple impinging water jets. Different flow rates are used simultaneously by different adjacent jets to perform quenching over the sample, so different hardness is obtained in the material over a small area . Temperature drop in time i s measured and monitored by embedded thermocouples and LabVIEW program. To achieve greater understanding of the quenching performance with different flow rates , several parameters are selected to be varied in order to achieve the best working conditions. Jet diameter takes values between 4 and 10 mm, initial temperature of quenching varies from 400 to 700 ⁰ C , subcooling temperature is tested for 65 and 75 K, and jet velocity varies between 1.9 and 3.9 m/s. The result of total number of 9 expe riments shown that v ariation of jet diam eter does not influence substantially on the cooling rate if flow rate is kept constant. High initial quenching temperature (600 - 700 ⁰ C ) led to slightly higher cooling rate in the stagnation region of water jets. The peak value of heat transfer rate in the upwash flow zone was more highlighted for initial quenching temperature 600 ⁰ C and below it. High er values of subcooling and jet velocity produce better cooling rates. The result shown higher jet velocity at one column of water jets changes position of upw ash flow slightly toward the adjacent column of jets with lower jet velocity. In general, the result shown that all the studied parameters did not have negative effect on obtaining various cooling rates over the steel plate.

Additive manufacturing (AM) for metals is a manufacturing process that has increased a lot in popularity last few years as it has experienced significant improvements since its beginning, both when it comes to accuracy and deposition rates. There are many different AM processes where the energy sources and deposition methods varies. But the common denominator is their layer wise manufacturing process, melting layer on layer. AM has a great design freedom compared to conventional manufacturing, making it possible to design new structures with decreased weight and increased performance.  A drawback is slow manufacturing speeds, making it more expensive. But when it comes to low lot sizes and complex structures AM is very competitive. So, for the aerospace and space industry AM is a good option as manufacturing cost is less of an issue and where saving weight is of great concern, both environmentally and economically.  There are however many topics left to research before additive manufactured titanium can be widely adopted for critical components, such as microstructure and texture development and its correlation to mechanical properties. The aim of this work has been to investigate the microstructure and texture of various AM processes. Microstructural features such as prior β grains, grain boundary α (GB-α), α laths, α colonies have been characterized along with hardness measurements for 5 different AM processes. Some of these AM processes have also been investigated in the SKAT instrument in Dubna, Russia, to obtain their texture. These textures have then been compared with one another and correlated to previous microstructural investigations and mechanical properties. This is important knowledge as the microstructure and the texture sets the basis for the mechanical properties. In case there is a high texture, the material can have anisotropic mechanical behavior, which could be either wanted or unwanted for different applications.   Some the findings are that α phase was found to increase in the prior β grain boundary for the AM processes with low cooling rates, while it was discontinuous and even non-present for the AM processes with high cooling rates. The prior β size are larger for the directed energy deposition (DED) processes than for the powder bed fusion (PBF) processes. Parallel bands were present for the DED process while being non-present for the PBF processes. Concerning the texture, it was found that LMwD had a higher texture than EBM and SLM. Texture inhomogeneity was also found for the LMwD process., where two parts of the same sample was investigated and the material closer to the surface had higher texture.

A literature review of medical implant applications of mesoporous silica films was written, highlighting the advantages and limitations of different film synthesis methods. Both films synthesized through the EISA sol-gel method and particulate films, including those synthesized through the direct growth method, were reviewed and discussed. All films were found to have their strengths and weaknesses, however, the films synthesized through the direct growth method was found to be the most promising type for coating implants. In addition to the literature review, copper-doped mesoporous silica films were synthesized on titanium grade 2 substrates. SEM shows that particles grown on all the films and EDX elemental analysis confirms the presence of copper in the material. Nitrogen physisorption measurements show that particles with incorporated copper have a higher specific surface area, and pore volume compared to un-doped particles. No copper content could be confirmed through FTIR. The particles grown on titanium substrates were more rod-like compared to the ones grown on the silicon substrates as control.

Boric acid based fuel and oil additives were investigated in this study, with the aims to gain a deeper understanding of how the boric acid fuel additive behaves, to investigate the effect of low rates of fuel additive addition and tribofilm longevity, and to investigate how boric acid behaves as a hydraulic oil additive. Fuel additive experiments were performed in a reciprocating sliding rig with a cylinder on flat contact geometry with fuel additive sprayed on the contact repeatedly, whereas the hydraulic oil experiments were performed in a reciprocating sliding rig with a ball on flat contact with the oil and additive present from the start. Analysis was performed using vertical scanning interferometry (VSI), scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS). The tribofilms created by the fuel additive provided excellent friction reduction capabilities, even with low or no rate of replenishment. As more additive was sprayed, wear resistance seemed to increase as the surface became increasingly covered. Film coverage need to be less than 20% of the surface in order to gain full friction reducing effects. The hydraulic oil additive had little effect on friction or wear resistance under the used parameters and no tribofilm was found.

Additive manufacturing (AM) is a growing process interesting many companies in many industries. Thereare multiple processes within the familty of AM, but this study focuses on laser blown powder (LBP). LBP involves a laser beam focused on the substrate with powder being blown into the laser beam. The laser beam melts both the powder and the surface of the substrate and as the laser beam moves and the melt pool solidies it leaves a bead of solid material behind. These beads are placed next to each other creating a layer which are then stacked, building the wanted geometry. As the method develops new materials are tested and this study analyses Haynes 282 powder onto Inconel 718 substrate. Multiple process parameters are involved in the LBP method and this study focuses on the impact of laser effect and scanning speed. Each value on the process parameters was inspired by previous reports with similar equipment and process. The laser effect ranges from 1600 W to 700 W, scanning speed ranges between 900 mm/min to 300 mm/min and the powder feeding rate was also varied from 4 g/min to 3 g/min. Each sample was built as a single bead and a multilayer specimen, which is ve layers and 16 beadswide at the bottom and 12 beads wide at the top. When analyzing the samples images from microscopes were mostly used for obtaining results. An image software called ImageJ allowed measurements in an image to obtain penetration depth or primary dendrite arm spacing. ImageJ also allowed measurements of porosity by turning the image binary and calculate the fraction of white and black. The results consists of numerical values and visual analysis of the bead geometry, minimum and maximum penetration, microstructure, porosity, hardness and cracks. The results show an increased bead width around 2 mm to 4 mm and decreased bead height around 0,2 mm to 0,7 mm of single beads with increased laser effect. Increased maximum penetration depth around, 200 μm to 500 μm, withincreased laser effect. More remelt between each deposited layer causing longer dendrites with increasinglaser effect. Porosity is decreased with an increased laser power, going from 0,04 % to 0,15 %. No distinct difference in hardness is observed between the samples, ranging between 255 HV to 310 HV. It is believed that aging causes the increased hardness right above the fusion zone. Cracks were found between dendrites and is believed to be caused by Laves-phases. Most results are comparable to previous similar studies, both as trends and numerical values. The statistics of the study is limited, meaning that all results should not be taken as granted but as a general guide line for more studies. The purpose and goals of the study has been met and completed.

Additive manufacturing, AM, is a general term for several different methods that aredefined by adding material instead of subtracting it as the traditional manufacturingmethods do. Being able to produce complex and high-strength metal componentsthrough AM has become an important research and development area in recentyears. This thanks to the short lead-time and increased level of complexity. AM ofmetal components is still a relatively new manufacturing method and there are someuncertainties regarding the process. This thesis considers the mechanical propertiesand material characterization of additive manufactured aluminum components fromthe powder AlSi10Mg. These components exhibit layer structure with a very fineunique microstructure. Due to the layer structure, test rods in two differentdirections were manufactured; vertical and horizontal, and analyzed in case of anyanisotropy occurrence. To investigate the mechanical properties and materialcharacterization of the two different AM test rods, fatigue properties, hardness andmicrostructure were analyzed and compared to traditional manufactured test rods ofaluminum alloy Al 6082-T6. This study has not been able to demonstrate that AMaluminum components would behave significantly differently (e.g. with respect to thecorrelation between fatigue resistance and tensile strength) than traditionallymanufactured components when exposed to fatigue stresses.

Abstract Purpose: The purpose of the study is to develop a model that will facilitate the choice of maintenance strategy within the Swedish pulp and paper industry. Without compromising system availability, the model aims to reduce inventory holding costs. Methodology: At first, a literary research was conducted to create a holistic view over the chosen topic, in time it developed into a literature framework. Secondly, a case study was conducted in order to obtain empirical data. The data were obtained through interviews and archival records. The literature framework and the empirical data were then cross-analyzed with each other. Findings: In this thesis, a model has been developed based on previously applied and accepted methods. The methods have been identified and described in order to provide a strategy in which the inventory levels- and value could be lowered. The findings indicate that the organization must seek to assign ABC-classified and VED-analyzed components different maintenance actions in order to reduce the total cost. Theoretical contribution: This thesis contributes to a methodology development regarding spare parts management. It aims to add knowledge to the existing gap regarding spare parts order point and batch size. The thesis provides a procedure in which systems including critical and expensive components are evaluated in order to assign them the appropriate maintenance. Practical relevance: The model has only been exemplified by using a system position from Stora Enso Skutskär, the numerical values are examples. The model must be tested with real values and the risk analysis must be carried out with a group of employees with great insight regarding the selected component and system position. Limitations: This thesis is delimited to spare parts management and inventory management. The study only involves one Swedish organization, whereas the organization and its spare parts management illustrates the complexity concerning spares. The model will not be verified as the focus is to highlight the research gap and to develop the model.