The use of offshore wind turbines as a source of renewable energy is promising. However, many challenges have to be solved before they will be cost effective. The operation time, without any maintenance required, is desired to be as long as possible, because downtime and maintenance costs are high. Thus it is important that the rotating parts in the turbine have a long operational time. The harsh marine environment, combined with the desire for elongated operating times and little or no maintenance, give rise to many tribological challenges. It is important that the chosen materials and lubricants can withstand the marine environment, and the high loads. The effect of marine environment on lubricating properties of lubricants is not well understood. The objective of this thesis has been to investigate this effect. Two lubricants that are commonly used as gear lubricants in onshore wind turbines were tested in this work; polyalphaolefin and polyalkylene glycol. They were both contaminated with different amounts of artificial seawater in order to investigate the effect on the lubricating properties. The lubricants were tested in a rotating ball-on-disc tribometer, with self-mated stainless steel, and self-mated silicon carbide. Stainless steel was selected as it is commonly used in gear bearings, whereas silicon carbide was chosen due to its promising excellent properties. The results obtained from this work show that PAO has a very low saturation limit for water, and an emulsion will be formed even at low contamination levels. This made the lubricant unstable, and the measured COF were unstable. It was found that the amount of two-body abrasive wear increased as a function of seawater content. The PAG lubricant managed to dissolve much larger quantities of seawater that PAO. But even though the system was one-phased, the results for COF were unstable. Wear induced pitting was found for both clean and contaminated lubricant. It is believed that it is caused by the additive package of the lubricant. For dry tribological testing COF was found to be mush less for self-mated silicon carbide than for self-mated stainless steel. This is as expected, since silicon carbide has shown outstanding tribological properties in previous work.For self-mated silicon carbide testing only abrasive wear could be found for both dry contact, and lubricated. The results from PAO contaminated with seawater, showed a clear increase in COF as a function of seawater content. Further, the COF all stabilized after the running-in period. PAG showed no such trend with increasing amounts of seawater, but the standard deviation of the measurements increased.

Through this study it has been observed that in contrast to propargyl esters which give cyclopropyl products, the high reactivity of propargyl acetals allows a new tandem cyclization to take place, resulting in bicyclic products. It has also been found that steric effects may cause propargyl acetals to react by unexpected pathways. NMR studies confirmed a particularly high reactivity of propargyl acetal compared to propargyl ester. These results show how molecular diversity can easily be achieved by varying the substrates in gold(I) catalysis.

Denne masteroppgaven har tatt for seg undersøkelser av stål designet for lavtemperaurappliksjoner ved bruk av elektronmikroskop i kombinasjon med diffraksjon av tilbakespredte elektroner (Electron Backscatter Diffraction - EBSD). Målet med oppgaven var å bruke EBSD-teknikken i kombinasjon med in situ deformasjon og en spesiallaget kaldfinger for å kunne studere materialene ved lave temperaturer. To ulike stål ble undersøkt; et smidd finkornet strukturelt stål (F70) og et varmvalset supermartensittisk rustfritt stål (Supermartensitic Stainless Steel - SMSS).F70-stålet ble sveisesimulert for å oppnå en mikrostruktur tilsvarende interkritisk grovkornet HAZ (Heat Affected Zone). Dette ble gjort ved en tosykel sveisesimulering. Prøvestaver av materialet ble varmet opp med en ønsket makstempertur på Tp1= 1350°C og Tp2= 780°C. For å undersøke effekten av ulike avkjølingshastigheter ble halvparten av prøvestavene avkjølt med Dt8/5 = 5 sekund, og den andre halvparten med Dt8/5 = 15 sekund. Ved sveising av stål kan det dannes lokale sprø soner som martensitt/austenitt-faser (MA-faser). Bilder tatt i lysmikroskop viser at strukturen til sveisesimulert F70-stål består av martensitt og noe bainitt. MA-faser er lokalisert langs korngrensene.EBSD-teknikken krever at materialet på forhånd gjennomgår en tilfredsstillende prøvepreparering for å gi gode resultater. Det var tidligere etablert en tilfredsstillende prepareringsteknikk for SMSS. I denne oppgaven ble to ulike prepareringsmetoder testet på sveisesimulerte prøver av F70-stål, som er et forholdsvis nytt materiale. Metodene som ble testet var ionesputtering og elektropolering. Preparerte prøver ble undersøkt med EBSD for å analysere kvaliteten på prepareringen. Det viste seg at MA-fasene reagerte annerledes på prepareringen enn resten av strukturen, og det var derfor vanskelig å få disse fram på EBSD-skann. De to prepareringsmetodene ga også forskjellige utfall for andel austenitt (g-fase) i stålet. Da det i hovedsak er MA-fasene som er interessante ved in situ undersøkelser ble det besluttet å ikke gjennomføre disse på F70-stålet, da en tilfredsstillende preparering må etableres først. Ved bruk av EBSD-teknikken kan orienteringsdataene som lagres behandles i programvaren TSL OIM Analysis 5.32, som tilbyr ulike renseoperasjoner. Grain CI Standarization gir alle punktene i et korn, innenfor en gitt vinkeltoleranse, samme CI-verdi som den maksimale CI-verdien funnet blant punktene i dette kornet. Det er også mulig å legge på et CI-filter som fjerner alle punkter med en CI ≤ 0,05, og erstatter disse med svarte eller grå piksler. Effekten av disse to operasjonene ble undersøkt på et EBSD-skann av SMSS tatt ved romtemperatur, uten noe form for deformasjon. Renseoperasjonene førte til at 8,1 % av alle punkter ble fjernet. 3,8 % av disse var av g-fasen, som utgjør kun 17,3 % av skannet før renseoperasjonene ble benyttet. Punkter som fjernes ligger i hovedsak i forbindelse med korngrenser eller øyer av restaustenitt. For SMSS som inneholder rundt 20 vol.% restaustenitt i opprinnelig (dvs. interkristisk glødet) tilstand, ble det gjennomført undersøkelser av deformasjonsindusert fasetransformasjon ved bruk av in situ strekktesting med påfølgende EBSD karakterisering. Undersøkelsene ble utført ved romtemperatur og -80°C. Et spesiallaget strekkbord ble montert på SEM (Scanning Electron Microscope) stagen med prøven fastmontert, og en kaldfinger ble brukt for å kjøle ned prøven. EBSD karakteriseringen ble foretatt uten deformasjon og ved 1, 2, 3 og 4 % forlengelse. En sammenligning av resultatene ved romtemperatur og -80°C ble deretter utført. Det ble konkludert med at øyer av restaustenitt transformeres til martensitt som følge av plastisk deformasjon i større grad ved -80°C, som følge av høyere termodynamiske drivkrefter for reaksjonen. Ved romtemperatur var det mulig å verifisere at martensitten som ble dannet oppfyller Kurdjomov-Sachs kriteriet som beviser at den er korrekt indisert. Dette var vanskelig å verifisere for lavtemperatursforsøkene, da skannene har en mye lavere kvalitet.

AISI 316/316L has traditionally been used in offshore topside environments when operating under low temperatures. It has been observed that the AISI 316/316L piping suffer from severe attacks of pitting and crevice corrosion on external surfaces. It is therefore important to emphasise the comments within the statements that give the limitations on the use of the material. While temperature is the main parameter in the standards, there seem to be others, such as location, presence of tags and coating, which affect the initiation and propagation of pitting and crevice corrosion. This thesis discusses the various operating parameters that affect the susceptibility to pitting and crevice corrosion of AISI 316/316L piping and proposes procedures for identifying piping that are most prone to attack, and calculations of the probability of failure of such piping.In the first part of the thesis, a literature survey of the parameters that affect the pitting and crevice corrosion of AISI 316/316L in an offshore environment is presented. In the second part, a procedure for the identification of piping that is prone to pitting and crevice corrosion is presented. This procedure has been developed taking into consideration the parameters that are assumed to be important and suitable for use in RBI analysis. In the first step, the parameters that affect both pitting and crevice corrosion, that is, the chloride content due to the location of the pipe, coating and temperature, were considered to be the most important ones. In the second step, the possibility of crevice corrosion was assessed. In the third part, a procedure for assessing the possibility of pitting corrosion in the offshore topside environment based on the pitting potential was developed. The temperature of the external pipe surface was used to find the solubility of NaCl in water. The chloride concentration was used to determine the in order to find the possibility of pitting in the topside offshore environment. The last step was to develop a procedure for calculating the probability of failure of a pipe as a function of time. In this step, the functional life of the coating and the rate of pitting corrosion have been considered.

Extraction and Analysis of Marine Lipids with Emphasis on Phospholipids- Evaluation and Improvement of Methods

Reaksjoner med vinylderivater i nærvær av gull(I)katalysator. Sykloaddisjoner og dimeriseringsreaksjoner er studert.

Prosessert mat utgjør en av de største kildene til natrium i vestlig kosthold. Et forhøyet inntak av natrium er forbundet med høyt blodtrykk, noe som øker risikoen for hjerte- og karsykdommer. Denne kunnskapen har økt interessen for kjøtt- og fiskeprodukter med lavere NaCl-innhold - såkalte lavsaltprodukter. Lavere natriuminnhold oppnås ved å redusere mengden NaCl og/eller tilsette salterstattere.Formålet med denne studien var å undersøke hvordan ulike konsentrasjoner av NaCl, KCl og MgCl2 påvirker proteinløselighet i fisk. Forskjeller mellom ferskt og fryst råstoff for filet og farse av sei, hyse, torsk og kvitlaks ble undersøkt for å finne ut om KCl og MgCl2 kan brukes som salterstattere i farseprodukter av disse fiskeslagene. Målinger av proteinløselighet ble satt i sammenheng med målinger av pH og vannbindingsevne (VBE) i de ulike råstoffene. Påvirkning av Na-alginat, Na-alginat+NaCl og NaCl på proteinløselighet i farser av fersk og av fryst hyse ble undersøkt, og koblet opp mot de funksjonelle egenskapene til et varmebehandlet modellprodukt. Varmepåvirkning på VBE i farser med og uten tilsatt NaCl ble undersøkt.Proteinløselighet var høyest i fersk filet og sank som en følge av frysing og kverning. For fersk filet ble det ikke funnet forskjeller mellom sei, hyse og torsk i mengde ekstrahert saltløselig protein (SLP). For fryst filet ble det generelt sett ekstrahert en større mengde SLP fra hyse enn fra sei og torsk. For fersk farse ble det ekstrahert mest SLP fra torsk, men for farse av fryst råstoff ble det ekstrahert mest SLP fra kvitlaks. Når mengde ekstrahert SLP og SDS-PAGE-profil ble tatt i betraktning, ble 0,6 M NaCl vurdert som den beste proteinekstraktanten. Tett etter 0,6 M NaCl fulgte 0,3 M MgCl2 og 0,3 M NaCl. 0,3 M KCl, 0,6 M MgCl2 og 0,6 M KCl ble vurdert som de dårligste proteinekstraktantene. Dette skyldtes i hovedsak at myosinets tunge kjede generelt ikke så ut til å bli ekstrahert med de to sistnevnte, noe som kan ha betydning for geldannings- og vannbindingsevnen til produktet. Ekstraksjon av myosinets tunge kjede med 0,3 M KCl så ut til å være råstoffavhengig. På grunnlag av dette ble 0,3 M MgCl2 vurdert som den beste salterstatteren. Tilsetningsstoffer til farser av hyse, slik som Na-alginat, Na-alginat+NaCl og NaCl hadde alle en positiv effekt på proteinløselighet, og så ut til å kunne kompensere for bruk av en dårlig proteinekstraktant eller en proteinekstraktant med lav konsentrasjon. Varmebehandling av farser/puddinger med og uten tilsetninger viste at VBE nådde et minimum ved rundt 50 grader celcius, og at den økte ved høyere temperaturer, trolig som en følge av gelning av myosin. VBE var lavest i råstoff uten tilsetning, og økte ved tilsetning av NaCl, Na-alginat + NaCl og Na-alginat. Av tilsetningsstoffene hadde Na-alginat (med eller uten NaCl) best effekt, både på VBE, drypptap og tekstur. pH varierte i sei, hyse, torsk og kvitlaks, og økte etter frysing. For ferskt råstoff viste VBE en svak positiv korrelasjon med pH (10% signifikansnivå), men for fryst råstoff var det ingen klar sammenheng. For torsk og hyse økte VBE litt som en følge av frysing (5% signifikansnivå), mens den sank for sei.

Alginate is a naturally ocurring polyanion of (1→4)linked β-d-mannuronic acid (M)and its C-5 epimer α-l guluronic acid (G). The polyanion, and particularly longstretches of guluronic acids, chelates and form hydrogels in the presence of divalentcations such as Ca2+ . Chelation occur at physiological conditions and the formed hy-drogels are biocompatible and stable. These properties nominates alginate hydrogelsas promising biomaterials in tissue engineering applications. Encapsulation of cells inalginate beads is easily prepared by mixing cells with high molecular weight alginate,and dripping the solution into a CaCl2 solution. When alginate comes into contactwith Ca2+ ions, alginate beads are immediately formed and the cells are captured ina three dimensional alginate matrix. Once inside the alginate capsule, the cells canbe transplanted into a host deficient in the particular cells. The alginate protectsthe cells against the immune system of the host, opening for allograf transplantationwithout immunosuppressiva. The pores in the alginate network are big enough toenable diffusion of waste and nutrition through the membrane, which is importantfor cell survival.Alginate is in itself not cell adhesive. However, alginate can be tailored into a celladhesive biomaterial by attachement of cell adhesive peptides, such as the RGDmotif found in extracellular matrix molecules such as fibronectin. Coupling of celladhesive peptides increase cell survival in three dimensional alginate matrices. Inthis study, RGD-alginate is tailored with a chemoenzymatic approach that ensuresRGD-coupling to non-gelling residues. This procedure starts with non-gelling man-nuronan that is chemically modified by attachement of the cell adhesive peptideGRGDYP by carbodiimide chemistry. Gelling residues are introduced to peptidecoupled mannuronan by a two step epimerisation catalyzed by the epimerases AlgE4and AlgE6.In this study, the carbodiimide chemsitry used for coupling GRGDYP to mannuro-nan is optimalised to create alginate with more than 0.2% bound peptide. Themodel molecules fluoresceinamine, 4-aminophenol and L-tyrosine-methyl ester areused for optimalisation, and the latter model molecule was found to give the bestrepresentation of peptide coupling to mannuronan. The carbodiimide mediated cou-pling to mannuronan is investigated by varying the pH, temperature and reactantconcentrations. The degrees of coupling for each intervention is assessed by 1 H NMRand UV/vis spectroscopy. The presence of covalently bound by-products, namedN-acylurea adducts, to mannuronan is assessed by 1 H NMR spectroscopy and acontrolled reduction of these unwanted compounds is attempted. The results from the optimalisation indicates that coupling of Me-O-Tyr and GRGDYP to mannuro-nan is concentration-dependent, as an increase in coupling was observed when theGRGDYP and Me-O-Tyr concentrations was increased. The highest peptide incor-poration described in this study was 3.4% GRGDYP coupled to mannuronan, whichis higher compared to similar studies.The optimalised carbodiimide chemistry is applied to a large scale batch of RGD-coupled alginate that is to be used for cell encapsulation of olfactory ensheating cellsfrom neonatal rat brain.High molecular weight alginate was coupled with 0.45% GRGDYP and filtratedwith active coal before cell encapsulation. The coal filtration removed a substantialamount of the unwanted N-acylurea adducts but also removed peptides, resultingin a GRGDYP coupling of 0.1% calculated from UV/vis spectroscopy, and 0.4%calculated from 1 H NMR spectroscopy. This indicates that peptides are associatedwith N-acylurea adducts and that active coal filtration is necessary to remove them.Encapsulation of olfactory ensheating cells to RGD-coupled alginate gave no mor-phology changes or enhanced cell viability compared to non-peptide coupled alginate.It is believed that the low enzymatic action of the AlgE6 epimerase, a low concen-tration of peptides or a combination of both, have influenced the cell viability andlack of morphology changes. Enhanced peptide incorporation can be achieved byincreasing the reactant concentrations of the peptides, but this would lead to a moreexpensive procedure. Increased efficacy, meaning a higher peptide coupling withlower adduct formation, at lower peptide concentrations was not achieved. However,the use of sodium borohydride in combination with periodate oxidised alginates forpeptide coupling should be assessed as a novel approach for increased peptide yieldsat lower peptide concentrations.

High cost and a short lifetime are the two main reasons why the PEM fuel cell is yet to be commercialized. The bipolar plate in a PEM fuel cell is alone responsible for about 45% of the cost and 85% of the total weight of a single cell. stainless steel has been suggested as material for the bipolar plate because of its good mechanical properties, easy manufacturing and relatively low price. A problem with stainless steel is the Chromium oxide film formed on the surface which causes a high contact resistance. In order to prevent this oxide formation, the stainless steel can be coated. Gold has been suggested as coating, but it is too expensive to be considered a viable alternative. The objective of this thesis was to investigate stainless steel as bipolar plate material for PEM fuel cells. In cooperation with SINTEF polarization tests were done on stainless steel bipolar plates with and without two different coatings; gold and Coating A. The tests were performed in H2SO4 electrolytes with different molarities and additives. Before and after each polarization test Interfacial Contact Resistance (ICR) measurements where done to see how the oxide layer on the stainless steel surface changed during polarization. Gold coated stainless steel was chosen as standard for both the polarization tests and the ICR measurements because of its corrosion resistance.The results obtained from both polarization tests and corresponding ICR measurements showed that the reproducibility was not as good as one had hoped, but this can be explained by low absolute values of the current densities. Gold coated steel proved to be a good standard for the ICR measurements, but due to pitting corrosion the corresponding polarization results were not as promising. The pH in an operating fuel cell was found to be approximately 3.5, and the tests done at different molarities showed that at a lower pH the oxide layer seemed to be thinner and the stainless steel surface thus became more exposed to corrosion. Additions of fluoride and chloride in the amounts expected in an operating fuel cell did not seem to cause any changes for neither the polarization results nor the contact resistance measurements. Stainless steel plates with Coating A showed very small changes in contact resistance after being put trough the polarization tests, but at low potentials the current densities in the polarization test were very high, indicating that components in the coating either catalyzed hydrogen evolution or were reduced themselves. Out of all the ICR measurements, gold coated stainless steel was the only plate satisfying US department Of Energy’s (DOE) resistance requirement for bipolar plates of less than 10 mΩ cm2. The stainless steel plates with Coating A were close to DOE’s requirements for both corrosion current and contact resistance. Non-coated stainless steel was ruled out as bipolar plate material due to high contact resistance measurements.

A study of the influence of artificial ageing temperature on the precipitation behaviour in three distinct direct chill casted and extruded Al-Mg-Si alloys has been carried out. The total amount of alloying elements is approximately the same in these alloys, but the difference is the ratio between these elements. The master thesis is a continuation of the work reported in Characterization of precipitates at maximum hardness in Al-Mg-Si alloys which was written in connection to the course TMT4500 Materials Technology, Specialization Project. The primary objective of this work was to identify the value of maximum hardness, and at what time it is obtained for these alloys after they have been artificially aged, one set at 200 °C and another at 250 °C, i.e. six cases in total. The aim in the master thesis has been to investigate which type and relative amount of needle shaped precipitates that are present, and what size, number density and volume fraction that is responsible for these conditions by using transmission electron microscopy (TEM). In addition, all three alloys have been shown to obtain a local hardness maximum at overaged conditions in the 200 °C case. These conditions have also been analysed by comparing with an overaged condition for KK5 for an ageing time shorter than the one were the local maximum appears. Therefore, ten different conditions have been investigated in total.One sample has been selected from each case based on the hardness curves in the project work, and prepared for analysis in two different TEM instruments. A number of general trends between alloy composition, heat treatment, and the resulting microstructure and hardness that already have been reported, have been verified during the master thesis. The maximum hardness conditions after artificial ageing at 200 °C have been found to be quite different for KK5, KK6 and KK7 in terms of type and relative amount of precipitates, and precipitate size and number density. Artificial ageing at 250 °C has been observed to give very similar values of maximum hardness for the three alloys primarily due to the size and number density of the precipitates. The local maximum hardness peaks observed at overaged conditions after artificial ageing at 200 °C have been seen to be purely due to precipitate size and number density, but the reason for their appearance has not been clarified. The observed differences between the three alloys in each condition and the differences between the conditions themselves for each alloy have been seen to be reflected in both type and relative amount of precipitates, and precipitate size and number density.