Industrial recognition of the importance of optimising engineering component performance has recently led to a significant increase in the use of surface coating technologies. An important process for the production of such coatings is Physical Vapour Deposition (PVD) which has proved to be a consistent, reliable and improving technique for industry. In the area of advanced wear resistant coatings however, fundamental research to improve deposition efficiency and enhance coating performance has been required. This thesis describes research investigating the following three areas: A series of experiments was carried out to study the design, metallurgy and performance of TiZr, ZrMo and TiMo segmented targets for use in steered cathodic arc evaporation and unbalanced magnetron sputter PVD techniques. A hot isostatic pressing technique was used to manufacture a range of prototype targets by diffusion bonding of appropriate metallic segments to controllable depths. In steered arc evaporation trials, a deleterious evaporation phenomenon occurred at segment interfaces when the cathode spot traversed from high vapour pressure to low vapour pressure materials. Analysis of the spot motion has led to the proposal of a simple model. Reactive unbalanced magnetron sputtering trials successfully produced a range of TiZrN, TiMoN and ZrMoN coatings of compositions in good agreement with Monte-Carlo simulation predictions. However, preferential poisoning of the high reactivity metal segments on TiMo and ZrMo targets was found to occur during high N[2] partial pressure processes. A comparative study of unbalanced magnetron sputtering, steered arc evaporation and the hybrid arc-bond sputter technique has been made during deposition trials on the ternary TiZrN hard coating system. Examination of the influence of two process parameters, substrate bias voltage and nitrogen partial pressure, on the mechanical and physical properties of TiZrN coatings is also reported. Stoichiometric TiZrN films were generally found to exhibit a single phase, face centred cubic structure with lattice parameters which followed Vegard's law. Alteration of the elemental composition of the alloy could be achieved by altering the power to individual magnetron cathodes or varying the current of the arc discharge during co-deposition. Solid solution strengthening mechanisms produced high hardness values (2500-3600H[k]) which maximised as the alloy composition approached Ti[0.6]Zr[0.4]. Further studies have been undertaken where Al was partially substituted for Zr within the lattice to enhance oxidation resistance properties and a range of fully adherent TiAlZrN quaternary films on high speed steel substrates were produced. The development of an original technique for industrial scale fabrication of a range of hard, low period (< 150A) multi-layer PVD thin films is outlined and the effects of substrate rotation velocity, type of rotation (1-fold or 3-fold) and deposition rate have been investigated. The high level of lattice mis-match and substantial differences in dislocation line energy and shear modulus has given rise to TiAlN-ZrN films exhibiting Knoop micro-hardness in excess of 4000H[k]. Bulk and micro-analysis techniques have indicated a reproducible lamella coating structure can be formed, with accurate control of the layer period. Excellent levels of coating adhesion were implemented by a metal ion etch substrate pre-treatment and the deposition of a sputtered base layer and films exhibited relatively low surface roughness and high density. A coating strategy, based upon the reactivity of the individual target materials and the characteristics of arc evaporated and magnetron sputtered vapour fluxes, has been determined which provides high flexibility in the coating elemental composition. The investigations clearly indicate that the multi-layer coating methods utilised allow the deposition of 3rd generation films without a productivity loss in comparison to 1st generation and 2nd generation hard coatings.

The accumulation of undesired matter at heat transfer surfaces (fouling) is a severe problem to industry. The growth of calcium sulphate dihydrate on heated metal surfaces has been examined and a mechanism for the effect of surface roughness on the amount of deposition has been proposed. A novel piece of equipment was designed and constructed in which the growth of crystals on heat transfer surfaces with different surface roughnesses could be observed under controlled solution conditions. The test section was a transparent rectangular channel into Rhich three 25 mm diameter test pieces could be inserted such that the polished faces were planar with the rear face of the channel. The back faces of these test pieces were heated by contact with hot Mater. Using Reynolds numbers of 300 to 13,500 and calcium sulphate 2+ solutions with bulk concentrations from 20 to 50 mH Ca , no gross effect due to surface roughness was seen. However a limited effect, which distinguished grit-blasted surfaces from polished surfaces, was 2+ found in experiments with a bulk concentration from 28 to 33 mH Ca . In all of the experiments it was observed that the presence of bubbles enhanced crystal growth. It was also found that the amount of deposition formed on any surface decreased with decreasing dissolved oxygen content of the bulk solution. It is suggested that a bulk concentration of approximately 33 mH 2+ Ca is a critical level of supersaturation, which corresponds with the so-called metastable limit of supersaturation. The surface roughness effect may be associated with two factors. Firstly, as the critical supersaturation is approached crystal growth is enhanced at certain sites. in particular the edges of bubbles. Secondly, very rough surfaces. such as grit-blasted surfaces. more readily support and initiate bubble formation and consequently the grit-blasted surface shows greater growth. Additional work with a different test rig. using a stagnant solution, indicated that suppression of bubble formation during an experiment, either by initially degassing the surface or by pressurising the system, decreased the amount of crystal growth. This work suggests that a surface roughness effect exists which is related to the presence of bubbles at the surface. Consequently the amount of deposition can be decreased either by controlling the formation of the bubbles (e.g. by completely degassing both the solution and the surface. and pressurising the system). or by polishing the surface. However. the surface roughness effect was most apparent between the very coarse, grit-blasted surfaces (R ~ 2.90 um) and the a medium finish 180 or 240 Grit surfaces (R ~ 0.23 um). a Little or no further improvement was obtained in polishing to a mirror finish. i. e. 0.25 or 0.1 um (R ~ 0.03 um). a further polishing beyond removing gross roughness would not appear to Therefore. for industrial purposes, yield sufficient benefit to justify the large cost involved. It is recommended that further work be undertaken to determine whether the deposition which occurs in the absence of bubbles is influenced by the surface roughness, and whether other chemical system and surfaces behave similar to the calcium sulphate - stainless steel system studied in this work. Moreover, additional work should be undertaken to examine the effect of surface physical properties on crystal and bubble nucleation and growth.

Cross-linked polymers are of great importance to industrial practice and theoretical studies. The unique network structures of these materials have endowed them with many superior properties. In this thesis, we study cross-linked polymers from both of experimental and theoretical sides, with an emphasis on the formation process and properties of the prepared networks. Two specific problems are investigated: development of polymer coatings over solid particles with in situ curing, and molecular dynamics (MD) study of network formation kinetics and structure-property relationship. In the study of polymer coating, a hot-melt coating process for solid particles is developed. Phenolic resin is used to coat the substrates and subsequently cured in situ. Among various processing parameters, temperature is found to play an especially important role in the coating performance. Higher temperature leads to stronger coating layers with better barrier properties, whereas lower temperature is preferable for better surface morphology. These two trends can be partially reconciled with ramping temperature profiles; however, the improvement is eventually limited by the rate of heat transfer. In MD study, the effects of precursor topology on the formation, structure and mechanical properties of polymer networks are studied. Cross-linked polymer networks are synthesized from three sets of precursors with varying chain length. Little difference is observed between these networks in typical properties including radial distribution function, overall statistics of network connectivity, and glass transition behaviors. The elastic modulus of the network is found to correlate strongly with the number of elastic strands in the network, except at the highly-cross-linked limit where substantial discrepancy is observed between networks from different precursors. Although these final networks contain a similar level of structural defects, the choice of precursor has a significant effect on the spatial distribution of the defects, which explains the precursor dependence of their mechanical property observed in the tensile test. / Thesis / Master of Applied Science (MASc)

The contamination of 316L stainless steel surfaces within an electrospray ionisation source of a mass spectrometer is investigated. An accelerated method of contamination is used. Following initial test method development and investigation of the contamination resulting on the ion transfer components (sample cone, outer cone and extraction cone), flat samples are employed within the ionisation source. This enables characterisation of the contamination composition, morphology and build-up with time. Blood plasma is introduced into the mass spectrometer as it is a widely analysed substance that is known to result in contamination. The contamination from a mixture of human blood plasma, diluted in methanol, and a water/acetonitrile mobile phase is found to contain inorganic NaCl crystals embedded in a matrix of organic residues. The morphology shows self-organising features as the contamination builds. A model is proposed to explain the morphology, involving rapid evaporation of the droplets that impinge on the stainless steel surface. Two types of surface modification are considered for the stainless steel: electrochemically grown films and coatings deposited by vapour deposition. A method for electrochemical film growth is developed, enabling nanoporous films to be formed on the stainless steel in 5 M sulphuric acid at 60°C by square wave pulse polarisation between active or transpassive and passive potentials. The films are characterised using glow discharge optical emission spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, Rutherford backscattering spectroscopy and nuclear reaction analysis. The films are shown to be chromium- and molybdenum-rich relative to the substrate, and to consist mainly of sulphates, oxides and hydroxides. The morphology and composition of the films are discussed in relation to the polarisation conditions and mechanism of film formation. A range of vapour deposited coatings are considered: TiN, TiC, TiB2, Graphit-iC, and diamond-like carbon coatings with Si and N2 dopants and with varying sp2:sp3 ratios. In addition, a hydrophobic coating is deposited on the stainless steel by immersion, in order to provide a significant variation in surface energy. Surface analysis of the coatings is carried out, considering their sp2:sp3 ratios, their electrical conductivities, their water contact angle, and the various components of the surface energy. The contamination build-up on the surface of uncoated 316L stainless steel is compared with that on stainless steel with the various surface modifications. A method for quantification of the build-up of contamination on flat samples is developed using white light interferometry. The surface modifications which result in the slowest contamination build-up with time are then applied to the ion transfer components of the mass spectrometer. The robustness of the mass spectrometric response for the selected coated surfaces is compared with that of the uncoated stainless steel. The electrochemically grown films and two of the doped diamond-like carbon coatings are found to be successful in reducing the build-up of contamination.

Made available in DSpace on 2014-10-09T12:33:47Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:04:00Z (GMT). No. of bitstreams: 0 / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:33:47Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:04:00Z (GMT). No. of bitstreams: 0 / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP

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Sedan 1951 har Tetra Pak tillverkat livsmedelsförpackningar, formsprutningsverktyg och fyll-ningsmaskinerna för livsmedelsförpackningar. En del livsmedelsförpackningar som t.ex. gräddeoch yoghurt kan ha en formsprutad topp av plast. Det är nödvändigt att den formsprutade plas-ten stelnar så snabbt som möjligt. För att minska tiden för stelning så används formverktygmed hög värmeledningsförmåga, detta för att få stabila detaljer och ändå göra det möjligt atthålla en hög produktion. En acceptabel livslängd på verktygen uppnås genom att de ytbeläggs.Ytbeläggningen består dels av en hårdanodiserad yta, ett lager av teflon. Dessvärre har teflonen sämre värmeledningsförmåga än metaller som formverktygen är tillverkad i. I detta arbetehar en metod för att avgöra hur mycket ytbeläggningen påverkar värmeledningen utvecklats.Resultaten av arbetet kommer användas för att kunna göra nya materialval. Under projektetutvecklas en testrigg där testerna visar att verktyg utan ytbeläggning har en värmelednings-förmåga som är 24% bättre än för belagda verktyg. Därmed finns det mycket att vinna på attanvända en annan ytbeläggning. / Tetra Pak has since 1951 manufactured food packaging, injection molding tools and fillingmachines for food packaging. Some of the food packaging as for cream and yogurt may havea injection molded plastic top. It is necessary that the injection molded plastic solidifies asquickly as possible. In order to reduce the time for solidification, molding tools with highthermal conductivity are used, in order to obtain stable details and still make it possible tokeep a high production. To achieve an acceptable tool life, they are coated. The surface coatingconsists partly of a hard anodized surface and a layer of teflon. Unfortunately, teflon has worsethermal conductivity than metals that the molding tools are made of. In this project, a methodto determine how much the surface coating affect the thermal conductivity is being developed.The results of the project will be used to make new material choices. During the project, atest rig is developed where the tests show that tools without surface coating have a thermalconductivity that is 24% better than for coated tools. That means there are a lot to gain byselect a new surface coating.

Yes / Many drug molecules can be directly used as nanomedicine without the requirement of any inorganic or organic carriers such as silica and liposome nanostructures. This new type of carrier-free drug nanoparticles (NPs) has great potential in clinical treatment because of its ultra-high drug loading capacity and biodegradability. For practical applications, it is essential for such nanomedicine to possess robust stability and minimal premature release of therapeutic molecules during circulation in the blood stream. To meet this requirement, herein, we develop GSH-responsive and crosslinkable amphiphilic polyethylene glycol (PEG) molecules to modify carrier-free drug NPs. These PEG molecules can be cross-linked on the surface of the NPs to endow them with greater stability and the cross-link is sensitive to intracellular environment for bio-responsive drug release. With this elegant design, our experimental results show that the liberation of DOX from DOX-cross-linked PEG NPs is dramatically slower than that from DOX-non-cross-linked PEG NPs, and the DOX release profile can be controlled by tuning the concentration of the reducing agent to break the cross-link between PEG molecules. More importantly, in vivo studies reveal that the DOX-cross-linked PEG NPs exhibit favorable blood circulation half-life (>4 h) and intense accumulation in tumor areas, enabling effective anti-cancer therapy. We expect this work will provide a powerful strategy for stabilizing carrier-free nanomedicines and pave the way to their successful clinical applications in the future. / The National Basic Research Program of China (2013CB933500, 2012CB932400), National Natural Science Foundation of China (61422403), Natural Science Foundation of Jiangsu Province (BK20131162), QingLan Project, Collaborative Innovation Center of Suzhou Nano Science and a Project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD).

Novel on-line methods are presented for the extraction, preconcentration and analysis of zwitterionic biomolecules using sol-gel-coated columns coupled to a conventional UV/visible detector. The presented approaches do not require any additional modification of the commercially available standard CE instrument. Extraction, stacking, and focusing techniques were used in the preconcentration procedures. The positively charged sol-gel coatings were created using N-octadecyldimethyl[3-(trimethoxysilyl) proply]ammonium chloride (C18-TMS) in the coating sol solutions. Due to the presence of a positively charged quaternary ammonium moiety in C18-TMS, the resulting sol-gel coating carried a positive charge. The negatively charged sol-gel coatings were due to the presence of sulfonate groups, which was formed from the oxidation of thiol groups in precursor mercaptopropyltrimethoxysilane (MPTMS) by hydrogen peroxide. Besides MPTMS, tetramethoxysilane (TMOS) and n-octadecyltriethoxysilane (C18-TEOS) were also used to prepare the sol solution for the creation of the negatively charged coatings. For extraction, the pH of the samples was properly adjusted to impart a net charge opposite to the sol-gel coatings. When a long plug of the sample was passed through the sol-gel-coated capillary, extraction was achieved via electrostatic interaction between the charged sol-gel coating and the charged sample molecules. The extracted analytes were then desorbed and focused via local pH change and stacking. The local pH change was accomplished by passing buffer solutions with proper pH values, while a dynamic pH junction between the sample solution and the background electrolyte was utilized to facilitate solute focusing. The developed methods showed excellent extraction and preconcentration effects on both positively and negatively charged sol-gel-coated columns. On-line preconcentration and analysis results obtained on the sol-gel coated columns were compared with those obtained on an uncoated fused silica capillary of identical dimensions using conventional sample injections. The described procedure provided a 150 000-fold enrichment effect for alanine on the positively charged sol-gel-coated column. On the negatively charged sol-gel-coated column, the presented sample preconcentration technique provided a sensitivity enhancement factor (SEF) on the order of 3 x 103 for myoglobin, and 7 x 103 for asparagines. The developed methods provided acceptable repeatability in terms of both peak height and migration time.