Device associated infections are a growing problem in the field of orthopaedics and dentistry. Bacteria adhering to implant surfaces and subsequent biofilm formation are challenging to treat with systemic administered antibiotics. Functionalization of implant surfaces with therapeutic coatings that are capable of inhibiting bacterial adhesion are therefore considered as a straight forward strategy to treat and prevent implant related infections. In this thesis, the use of crystalline, arc deposited TiO2 and biomimetic hydroxyapatite (HA) coatings were evaluated with respect to their potential as antibacterial surface modifications for bone-anchored implants. UV light induced photocatalysis of anatase dominated TiO2 coated surfaces was shown to provide a bactericidal effect against S. epidermidis under clinically relevant illumination times and doses. Major parts of the drug release work carried out was based on biomimetic HA (HA-B) coated fixation pins. The analysis of the coating characteristics revealed that the nanoporous structure of HA-B coatings in addition to the chemical composition and surface charge are essential parameters that influence the drug carrier performance. Loading by adsorption was demonstrated to be a feasible approach to quickly incorporate antibiotics. The controlled release of antibiotics was shown to facilitate bactericidal effects against S. aureus over application-relevant time periods, even when exposed to biomechanical forces during insertion into bone model materials. Antibiotic incorporation during coating growth was shown to promote somewhat longer drug release time periods than those obtained using adsorption loading. In summary, functionalization of implant surfaces with bioactive and biocompatible coatings is a promising concept to impact the clinical success for bone-anchored applications. The additional feature of optional, on-demand antibacterial properties of these coatings through either on-site drug release or photocatalytic antibacterial treatment is advantageous for the prevention and effective treatment of devices-associated infections. Both strategies provide an immediate response to the implant contamination by bacteria and are believed to contribute towards minimizing the origin of post-surgical infections, while at the same time improving the interfacial stability between implant and bone.

Valve stem seal leakage is a major source of fugitive emissions, and controlling these emissions can result in added expense in leak detection and repair programs. Elastomeric O-rings can be used as valve stem seals, and O-ring manufacturers recommend lubrication of elastomeric seals to prevent damage and to assure proper sealing. In this research, a metallic coating was applied as a lubricant using a vacuum vapor deposition process to the surface of elastomeric valve stem seals. Valve stem leak measurements were taken to determine if the coated O-rings, alone or with the recommended lubrication, reduced valve stem seal leakage. This research determined that the metallic coating did not reduce valve stem leakage.

Novel net shaping technique Laser Engineered Net shaping™ (LENS) laser based manufacturing solution (Sandia Corp., Albuquerque, NM); Laser can be used to deposit orthopedic implant alloys. Ti-35Nb-7Zr-5Ta (TNZT) alloy system was deposited using LENS. The corrosion resistance being an important prerequisite was tested electrochemically and was found that the LENS deposited TNZT was better than conventionally used Ti-6Al-4V in 0.1N HCl and a simulated body solution. A detailed analysis of the corrosion product exhibited the presence of complex oxides which are responsible for the excellent corrosion resistance. In addition, the in vitro tests done on LENS deposited TNZT showed that they have excellent biocompatibility. In order to improve the wear resistance of the TNZT system boride reinforcements were carried out in the matrix using LENS processing. The tribological response of the metal matrix composites was studied under different conditions and compared with Ti-6Al-4V. Usage of Si3N4 balls as a counterpart in the wear studies showed that there is boride pullout resulting in third body abrasive wear with higher coefficient of friction (COF). Using 440C stainless steel balls drastically improved the COF of as deposited TNZT+2B and seemed to eliminate the effect of “three body abrasive wear,” and also exhibited superior wear resistance than Ti-6Al-4V.

This project has as main goal to study the influence of the coating thickness, deposited by arc-PVD- technology, on the wear resistance of coated cemented carbide inserts in three different turning operations. An additional effort has also been made to develop a new test method for evaluating flank wear resistance. Three different coating types (Coating A, Coating B and Coating C) have been studied in three distinctive thicknesses (2, 4 and 6 μ m) for each type. For two of the coating types (Coating A and B) special studies has been done with the thickest coating, creating two additional coating versions of the thickest coating, by changing various deposition parameters, with the aim to enhance the cohesive properties of the coating and lower the residual stresses at the cutting edge. The results show increased crater wear resistance with increased coating thickness for all coating types, but the amount of increase changes with coating type (Coating A>B>C). Flaking wear resistance decreased with increased coating thickness for all coating types. Further the high temperature version of Coating A, showed a significant increase in the flaking wear resistance compared to the standard version of Coating A. The flank wear test showed an increased resistance with thicker coatings in all cases except for the 6 μ m version of Coating C. The flank wear resistance of the most flank wear resistant coatings (Coating B, C) was also successfully examined in a new developed test method. The method suppressed excessive crater wear on the rake face and presented a high abrasive wear rate on the flank and some flaking on the rake face. The amount of flaking is judged not to influence the testing of the flank wear resistance. For all the tested coatings in the new test an increase in the coating thickness resulted in better flank wear resistance.

The objective of a coating operation is to transfer a defect free liquid film onto a continuous substrate in order to meet the requirements of the final products. Mainly two concerns govern the process. The first concern is the economics of the process and the second concern is the quality of the coated film. The economics of the process are dictated by the speed of coating and the film thickness. Clearly, higher speeds mean better productivity hence less cost of operation and thinner films are desirable because less material is being used. Quality is governed by film uniformity and integrity, indicating that the film will perform as designed. Film defects such as streaks or tiny air bubbles are indication that the film properties are not uniform rendering it unacceptable to customers. One of the most versatile coating systems to achieve thin films at high speeds is reverse roll coating which has been used for a long time all over the world. At low speed, typically 1m/s, this coating operation is inherently stable and with small gaps of order 100 microns can ii lead to film thickness of order 30-50 microns. Much research, theoretical and experimental, has been devoted to this coating flow but only at low speeds and for large gaps (>100 microns). There are no comprehensive data how very thin films, 20 microns and less (particularly lower limits in the region of 5 microns) can be achieved at high speeds, of 2 or more metres per second. This study is concerned precisely with this aim, that of investigating the effect of large speeds and small roller gaps (rollers nearly touching or in elastohydrodynamic contact) to achieve the very thin films desired by modern applications (electronics, medical and others). In order to achieve this aim, a rig was designed and built to enable to understand the effect of various coating conditions and liquid properties on the metered film thickness and coating instability. To achieve thin films at high speeds, small roll gap and low viscosity are needed, however flow instabilities will develop under these conditions. To achieve stable coating window at high speeds high surface tension is needed. It was found that the roll gap and the viscosity have complicated effect on the coating window. In the case of low viscosity liquid (7mPa.s), small roll gaps are needed, whereas in the case of high viscosity liquid (more than 30mPa.s), large gaps are needed. It was found that Weber number is better describer for ribbing instability in rigid reverse roll coating unlike in rigid forward roll coating in which capillary number is the one. In addition the potential of reverse deformable roll coating (rolls in elastohydrodynamic contact) was investigated in order to achieve much thinner films at higher speeds. As a result of the investigation of reverse deformable roll coating, it was found that there is a possibility to get much thinner stable films at much higher speeds compared to reverse rigid roll coating. The liquid transfer from an applicator roller to a PET film was investigated in this study. It was found that air stagnation at downstream meniscus and air entrainment at upstream meniscus depend on the liquid properties such as viscosity and surface tension and coating conditions such as web tension and wrap angle of web. As a result, wet film instability also depends on liquid properties and coating conditions. It was found that air stagnation causes streaks on the wet film and air entrainment caused bubbles on the wet film. To get a stable wet film, it was found that suitable viscosity and high surface tension were needed.

Whey is a byproduct of cheese making; whey proteins are globular proteins which can be modified and polymerized to add functional benefits, these benefits can be both nutritional and structural in foods. Modified proteins can be used in non-foods, being of particular interest in polymer films and coatings. Food packaging materials, including plastics, can linings, interior coatings of paper containers, and beverage cap sealing materials, are generally made of synthetic petroleum based compounds. These synthetic materials may pose a potential human health risk due to presence of certain chemicals such as Bisphenol A (BPA). They also add to environmental pollution, being difficult to degrade. Protein-based materials do not have the same issues as synthetics and so can be used as alternatives in many packaging types. As proteins are generally hydrophilic they must be modified structurally and their performance enhanced by the addition of waterproofing agents. Polymerization of whey proteins results in a network, adding both strength and flexibility. The most interesting of the food-safe waterproofing agents are the (large aspect ratio) nanoclays. Nanoclays are relatively inexpensive, widely available and have low environmental impact. The clay surface can be modified to make it organophilic and so compatible with organic polymers. The objective of this study is the use of polymerized whey protein (PWP), with reinforcing nanoclays, to produce flexible surface coatings which limit the transfer of contents while maintaining food safety. Four smectite and kaolin type clays, one treated and three natural were assessed for strengthening qualities and the potential waterproofing and plasticizing benefits of other additives were also analyzed. The nutritional benefits of whey proteins can also be used to enhance the protein content of various foodstuffs. Drinkable yogurt is a popular beverage in the US and other countries and is considered a functional food, especially when produced with probiotic bacteria. Carbonation was applied to a drinkable yogurt to enhance its benefits. This process helps reduce the oxygen levels in the foodstuff thus potentially being advantageous to the microaerophilic probiotic bacteria while simultaneously producing a product, somewhat similar to kefir, which has the potential to fill a niche in the functional foods market. Yogurt was combined with a syrup to reduce its viscosity, making it drinkable, and also to allow infusion of CO2. This dilution reduced the protein content of the drink and so whey protein concentrate was added to increase levels in the final product. High-methoxyl pectins were used to provide stability by reducing the tendency of the proteins to sediment out. The objectives of this study were to develop a manufacturing technology for drinkable carbonated symbiotic yogurts, and to evaluate their physicochemical properties. Two flavors of yogurt drink, pomegranate and vanilla, were formulated containing inulin as prebiotic, along with probiotic bacteria, producing symbiotic dairy beverages.

Polymer Electrolyte Membrane Fuel Cell (PEMFC) systems are promising technology for contributing to meet the deficiency of world`s clean and sustainable energy requirements in the near future. Metallic bipolar plate (BPP) as one of the most significant components of PEMFC device accounts for the largest part of the fuel cell`s stack. Corrosion for metallic bipolar plates is a critical issue, which influences the performance and durability of PEMFC. Corrosion causes adverse impacts on the PEMFC`s performance jeopardizing commercialization. This research is aimed at determining the corrosion resistance of metallic BPPs, particularly stainless steels, used in PEMFC from different aspects. Material selection, coating selection, manufacturing process development and cost considerations need to be addressed in terms of the corrosion behavior to justify the use of stainless steels as a BPP material in PEMFC and to make them commercially feasible in industrial applications. In this study, Ti, Ni, SS304, SS316L, and SS 430 blanks, and BPPs comprised of SS304 and SS316L were examined in terms of the corrosion behavior. SS316L plates were coated to investigate the effect of coatings on the corrosion resistance performance. Stamping and hydroforming as manufacturing processes, and three different coatings (TiN, CrN, ZrN) applied via the Physical Vapor Deposition (PVD) method in three different thicknesses were selected to observe the effects of manufacturing processes, coating types and coating thicknesses on the corrosion resistance of BPP, respectively. Uncoated-coated blank and formed BPP were subjected to two different corrosion tests: potentiostatic and potentiodynamic. Some of the substantial results: 1- Manufacturing processes have an adverse impact on the corrosion resistance. 2- Hydroformed plates have slightly higher corrosion resistance than stamped samples. 3- BPPs with higher channel size showed better corrosion resistance. 4- Since none of the uncoated samples meet the 2015 target of the U.S. Department of Energy, surface coating is required. 5- ZrN and CrN coated BPPs exhibited higher corrosion resistance meeting DOE target while TiN coated samples had the lowest corrosion resistance. Higher coating thicknesses improved the corrosion resistance of the BPPs. 6- Process sequence between coating and manufacturing is not significant for hydroforming case (ZrN and CrN) and stamping case (CrN) in terms of the corrosion resistance. In other words, coating the BPP`s substrate material before manufacturing process does not always decrease the corrosion resistance of the BPPs.

L'exportation des mangues est limitée par le mûrissement rapide et la prolifération microbienne sur les fruits. Cette thèse propose une nouvelle approche sûre et saine utilisant des molécules d'origine naturelle pour améliorer la conservation post-récolte des mangues et ainsi participer à la préservation de la santé des consommateurs et à une amélioration des potentialités du commerce international de certains pays exportateurs. Ces travaux ont montré que l'immobilisation du système lactoperoxydase dans le film de chitosane appliqué sur l'épiderme des mangues pouvait maintenir la qualité microbiologique et physicochimique des fruits traités. Le couplage Chitosane-Système lactoperoxydase a prolongé la durée de conservation des mangues durant plus de deux semaines sans altérer leurs qualités organoleptiques.Ce travail a permis également de mettre en évidence la synergie entre le système lactoperoxydase et la concentration de chitosane. Un enrobage optimum de 1% de chitosane a permis de fixer le système enzymatique et de maintenir les mangues en bon état sanitaire. La présence d'iode dans le système lactoperoxydase n'agit pas de manière significative sur la conservation des mangues. / The mango export is limited by the rapid ripening and microbial growth on the fruit. This thesis proposes a new approach to safe and healthy using natural molecules to improve post-harvest conservation of mango and thus help preserve the health of consumers and improved the potential of international trade in certain exporting countries. This work shown that the immobilization of the lactoperoxidase in the chitosan film and applied as coating of mangoes could maintain the microbiological and physicochemical quality of fruits. Chitosan-coupling lactoperoxidase system extended the shelf life of mangoes for over two weeks without affecting their organoleptic quality.This work also helped to highlight the synergy between the lactoperoxidase and the concentration of chitosan. An optimum coating made from 1% chitosan allowed to fix the enzyme system and to maintain the mangoes in a good sanitary condition. The presence of iodine in the lactoperoxidase does not act significantly on the conservation of mangoes.

Le développement d'une méthode efficace de séparation/purification d'hydrogène représente une nécessité primordiale pour améliorer les rendements de production des systèmes énergétiques futurs. En effet, le procédé de reformage classique de production d'hydrogène conduit à un mélange complexe de gaz à haute température (au-delà de 523 K) qui limite l'utilisation de H2 dans diverses applications. La réalisation de membranes hautement sélectives à l'hydrogène apparaît alors comme un point essentiel pour augmenter la production d'hydrogène. Les membranes à base de silice ont largement été étudiées en vue de répondre à cette problématique. Malgré leurs excellentes performances, elles ne pourraient être compétitives à l'échelle industrielle qu'après amélioration de leur résistance à la vapeur d'eau en température (lixiviation). Des travaux antérieurs menés à l'IEM ont montré les performances de membranes « SiCN » en termes de perméance et de permsélectivité. Sur la base de ces résultats, nous avons développé des membranes non-oxydes autour du quaternaire « SiZrCN ». L'incorporation de Zr avait pour objectif d'améliorer la tenue en température des membranes et de fait leur sélectivité. Ce projet de thèse a été divisé en trois tâches principales : la première a consisté en la synthèse d'un précurseur moléculaire contenant les éléments Si, Zr, C, N ; la seconde a porté sur la préparation par PECVD de membranes denses non oxydes et la dernière partie a permis d'évaluer les performances de ces membranes en séparation de gaz. Un précurseur moléculaire « single source » a été synthétisé avec succès autour du quaternaire « SiZrCN », de tension de vapeur adéquate pour un dépôt par PECVD. Des films minces ont ainsi été déposés sur des supports variés afin d'obtenir des membranes sans défauts de surface conduisant à une perméance à He de 1,7.10-7 mol.m-2.s-1.Pa -1 et à une sélectivité idéale He/N2 (estimée) de 1300 à T = 423 K et Delta p = 1,105 Pa. / The development of an efficient hydrogen separation/purification method represents a tremendous requirement to enhance the production yields of future energy systems. Indeed, the reforming process commonly used for hydrogen production leads to a complex gas mixture at high temperature (beyond 523 K) that limits the H2 use in various applications. The elaboration of highly hydrogen selective membranes appears to be a determining step to expand hydrogen production. Silica-based membranes have been largely studied to respond this problematics. In spite of their excellent performances, they could only be competitive from an industrial point of view after improvement of their low resistance to water vapor at high temperature (lixiviation). Previous works completed at IEM have demonstrated the good performances of “SiZrCN” membranes in terms of permeance and permselectivity. Based on these results, we developed new non-oxide membranes in the quaternary system “SiZCN”. The incorporation of Zr aimed to enhance the temperature resistance of the membranes and then their selectivity. This thesis project was divided into three major tasks : the first one has consisted in the synthesis of a molecular precursor containing the Si, Zr, C, N elements ; the second one was focused on the preparation by PECVD of dense non-oxide membranes and the last one was meant to evaluate the performances of these membranes in gas separation. A single source molecular precursor was successfully obtained in the system “SiZrCN” usable for PECVD. Thin films were thus deposited over various supports to obtain defect free membranes presenting a He permeance of 1,7.10-7 mol.m-2.s-1.Pa-1 and a (estimated) He/N2 ideal selectivity of 1300 at T = 423 K and Delta p = 1.105 Pa.

Despite applications of foamed bitumen technology in pavement construction in various places around the world, there are still several aspects about this technology that are not clear. In addition, knowledge on foamed bitumen technology is mainly empirical and lacks scientific basis. This study addresses some of the aspects for foamed bitumen technology such as: Investigation of any effects in binder composition during the production process for foamed bitumen; assessment of the effect of bitumen source on foamed bitumen characteristics; development of a rational method to optimise foamed bitumen characteristics and conditions; evaluation of aggregate particle coating within foamed bitumen mixes; further improvements in the mix design procedure specifically the method of compaction and optimum bitumen content determination stages are suggested.  Fourier transform infrared spectroscopy techniques were used to investigate any changes in bitumen composition after the production process of foamed bitumen. Fourier transform infrared tests were done on foamed bitumen and neat bitumen specimens for two bitumens with similar penetration grades. Foamed bitumen characteristics of three bitumens were established by producing foamed bitumen at temperatures of 150ºC up to 180ºC and foamant water contents of 1, 2, 3, 4 and 5%. From the analysis of variation of foamed bitumen characteristics (maximum expansion ratio and half-life) at different temperatures a new method based on the equi-viscous bitumen temperature to optimize foamed bitumen conditions and characteristics was proposed. Rice density and surface energy concepts were used to evaluate aggregate particle coating with foamed bitumen. A granite aggregate divided into three different size fractions and three sets of foamed bitumen produced from three bitumen penetration grades were used. A gyratory laboratory compaction procedure for laterite gravels treated with foamed bitumen was established using the modified locking concept. Three laterite gravels with different chemical composition were mixed with foamed bitumen produced from one penetration bitumen grade. The resulting mixes were compacted up to 200 gyrations and the corresponding compaction curve defined in terms of height versus number of gyrations noted. In addition, the optimum moisture content requirements at the modified locking point were determined. 3D packing theory concepts, primary aggregate structure porosity and an indirect tensile strength criteria were employed to determine optimum bitumen content for foamed bitumen mixes.  Fourier infrared techniques revealed that foaming did not cause any changes in the bitumen chemistry, implying that the foamed bitumen production process may possibly be a physical process. Characterisation of foamed bitumen produced from three bitumen penetration grades showed that foamed bitumen characteristics (maximum expansion ratio and half-life) were mainly influenced by binder viscosity rather than the source. The equi-viscous temperature seemed to provide a suitable criterion at which foamed bitumen with optimum characteristics could be produced. Rice density results showed that aggregate size fraction, binder expansion ratio and viscosity influenced aggregate particle coating. For the coarser aggregate fraction, results revealed that binder coating seemed to be mainly influenced by temperature. Whilst for fine aggregate fraction the coating was mainly influenced by surface area. Surface energy results revealed that foamed bitumen exhibited better coating attributes than neat bitumen. A new laboratory compaction procedure for laterite gravels treated with foamed bitumen based on the modified locking point was developed. The modified locking point represents the state at which maximum aggregate particle interlock occurs when mixes are compacted in the field. It is based on the iii analysis of the rate of change for the gyratory compaction curve. The compaction curve in this case is defined in terms of compaction height versus number of gyrations. Gradation analysis beyond the modified locking point showed that aggregate particle breakdown occurred. Analysis of the optimum moisture at the modified locking point revealed that the moisture conditions were less than the aggregate optimum moisture conditions. It is recommended that this point be used to determine the optimal compaction characteristics of foamed bitumen mixes.  Aggregate structure porosity and an indirect tensile strength criteria can be used to determine the bitumen content that could be used in design of foamed bitumen mixes. This would reduce the amount of resources required since the bitumen content could be estimated prior to carrying out the actual laboratory work given that the aggregate grading is known. The aggregate structure can be divided (based on 3D packing theory) into oversize, primary, and secondary structures. The primary structure is mostly responsible for carrying loads whilst the secondary structure fills the voids within the primary structure and provides support to the primary structure. The aggregate size particles constituting the primary structure are deduced as a function of standard sieve sizes using the packing theory concepts. The minimum sieve size for the primary structure is proposed as 1 mm. The oversize structure consists of aggregate particles whose size is greater than the maximum size for the primary structure. The secondary structure consists of aggregate particles whose size is below the minimum size for the primary structure. The primary aggregate structure porosity can be used to establish the starting bitumen content; the bitumen content at which this porosity is 50% is chosen as the initial bitumen content. Indirect tensile strength values corresponding to 50% primary porosity are determined as well as the bitumen contents and compared against the recommended minimum values. / <p>QC 20161012</p>