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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Study on the electrodeposition method for Ni-based composite layer coating SiC and Al2O3 particles

Tseng, Shih-hua 03 September 2010 (has links)
Abstract In the study, amounts of ceramic particles in coating layer deposited on the surface of cathode specimen are investigated under two kinds of ceramic particles of Al2O3 and SiC mixed in the Nickel sulfate bath during electroplating or electrophoretic depositing process. According to the IEP of the particles, Al2O3 particles which showed the positive charge in the nickel sulfate bath are deposited onto the work-piece of cathode during electrophoretic deposition (EPD)process. And the other hand, SiC particles which showed Neutral ( or zero ) charge in the same bath are deposited onto the work-piece of cathode during electrolytic deposition (ELD)process. Therefore, it is expect that the composite electro - deposition layers on the work-piece have large amount of particles and high strength are fabricated by using the method of ELD¡VEPD¡VELD in sequence (ELEPIS). In the experiment conditions, the bath mixing the SiC particle with average diameter of 3 £gm and the Al2O3 particle with average diameter of 1 £gm respectively is stirred using the air pump and the magnetic stirrer, concentration of 20 g/L for each particle is seted. EPD is carried out under the apply voltage of 30 V, and ELD is carried out under the current density of 3 ASD. Results show that the amount of Al2O3 particle deposited in the composite coating layer is about 29.25 wt% during EPD, and the amount of SiC particle deposited in the composite coating layer is large and its distribution is uniform during ELD. Moreover, ELEPIS is carried out in the bath mixing 4 g/L of SiC particle and 8 g/L of Al2O3 particle to fabricate the composite coating layer. Result shows that the hardness of composite coating layer is 527 Hv, which is two times of that using traditional ELD method. This indicates that the strength and wear resistance of Ni-SiC- Al2O3 composite coating layer fabricated by ELEPIS method is excellent. Keywords : EPD¡BELD¡BELEPIS
2

Investigations on the Content Increment Method of Dispersive Particles and Wear Characteristics for Composite Electrodepostion Layers

Chen, Ming-Jen 25 July 2005 (has links)
Generally speaking , high volumetric content of particles and well-dispersed condition in the metallic matrix are the purposes in composite electrodeposition for different applications. The composite electrodeposition layer by EPD has high volumetric content of particles but low structure strength. The composite electrodeposition layer by ELD has tight structure but low volumetric content of particles . In this study combines EPD and ELD to produce the composite electrodeposition layer in ELD-EPD-ELD three steps. We hope to combine their advantages .In this study ,we first look for the best operating condition of EPD, then increase the volumetric content of particles with ELD-EPD-ELD(ELEPIS). Finally, it was examined by scratch test to prove the structure strength. By the result of experiment, it can be known that at the voltage 10V,the concentration 100g/L,stirring speed 50rpm is the best operating condition. In the process of ELEPIS, we find that Ni ions permeate into the second layer. In this method, we can produce the electrodeposition layer which of the volumetric content of particles is 4 times the traditional electrodeposition layer. We also propose the possibility of multi-storey ELEPIS composite electrodeposition layer. Finally, by the result of scratch test , it can be known that there are the least cracks in the scratch which of the electrodeposition layer by ELEPIS. Its depth is shallowest and its width is narrowest. It shows that the sample by ELEPIS has excellent performance in structure strength and binding with substrate.
3

The investigation on improving the content of dispersive particles for composite electrodeposition layer

Chang, Chin-hao 29 July 2006 (has links)
Composite electro-deposition always requires high volume fraction of particles and good dispersion and high wear resistance.¡@Composite electro-deposition made by the electrophoretic deposition (EPD) contains high volume fraction of particles but low structural strength, and it made by electrolytic deposition (ELD) are right opposite. Therefore, this study tries to combine the advantages of both EPD and ELD in the sulfamate bath with the average particle size 1
4

REVIT – ETT BRA HJÄLPMEDEL VID KLIMATDEKLARATION? : EN UNDERSÖKNING OM KLIMATDEKLARATION KAN UNDERLÄTTAS AV REVIT / Revit - a good tool for climate declaration? : A study if Revit can simplify climate declaration

Lind, Lucas January 2019 (has links)
According to SMHI the largest contributing factor to globalwarming is the increased greenhouse gas emissions in theatmosphere. In year 2018 Boverket submitted a proposal for climatedeclaration on new buildings. In the Boverkets climatedeclaration, a building's climate impact is calculated in the formof carbon dioxide equivalents on the material included in thefoundation, building envelope and the non-load-bearing interiorwalls. The unit in the climate declaration is kg Co2e / kg m2where m2 is BTA for the building.The purpose of the theoretical study was to describe what impactthe climate declaration will have in the building industry. Thepurpose of the empirical study was to investigate whether Revit isa good tool for calculating a building climate impact with a focuson greenhouse gas emissions.The result of the theoretical study indicates that the Boverket'sproposal on climate declaration will not lead to changes in theclimate impact of buildings. The study also shows that there willbe changes in the project planning of buildings and increased timespent by participants as the Boverkets estimation of the timerequired for the climate declaration is approximately 180 hours.The result of the empirical study shows that Revit is a good toolfor climate declaration. The study was based on evaluating Revitby the categories easy-to-use, time-consuming and presentationoptions. This resulted in a SWOT analysis showing Revit'scapacity
5

Predicting feed efficiency in beef cattle; a comparison of direct measures, expected progeny differences, and single nucleotide polymorphism methodologies

Rasmussen, Samantha 01 May 2020 (has links)
Single nucleotide polymorphism (SNP) methodology is being used as a means to determine genetic merit in beef cattle by interrogating animal genomes and associating the findings with performance traits. The ability to predict future trait performance is highly attractive to beef cattle producers as they can make important management and financial decisions earlier and with more certainty. To fully realize the potential of SNP testing technology the methodology must be vetted to assure producer confidence. The purpose of this project is to assess three sources of information for beef cattle trait assessment. These information sources are: SNP testing, Expected Progeny Differences (EPDs) and direct animal measures. To conduct this study, young beef bulls (n=181) consigned to the SIU Beef Evaluation Station were utilized in an 84-day period to obtain direct measures. The SIU Beef Evaluation Station uses the Calan-Broadbent confinement feeding system which allows researchers to monitor individual animal feed intake and weight gain. Feed efficiency traits are important to the cattle industry since feed is generally among the largest input cost to producers. The evaluation of bulls also assesses reproductive and carcass traits which are also important to the producer’s financial success.Individual animal performance information was sent to the bull’s respective breed association for determination of EPD’s. Blood samples were submitted to a commercial company for SNP testing (Igentiy Gold and Igenity Beef Profile, Neogen, Lincoln, NE). Data was analyzed using pairwise comparisons by source of information. Pearson correlations were used to determine the direction and the strength for sources of information to vary together. Data was determined to be correlated when the correlation coefficient was 0.3 < r < - 0.3. No correlation was observed between RFISIU :RFINEO (r = 0.042), RFINEO:F/GSIU (r = - 0.09), RFISIU:ADGNEO (r = 0.091), RFISIU:ADGSIU (r = - 0.039), RFINEO:ADGNEO (r = 0.236), BWNEO:BWSIU (r = 0.115), FRAMESIU:BWSIU (r = 0.111), FRAMESIU:BWEPD (r = 0.159), FRAMESIU:ADGSIU (r = 0.148), FRAMESIU:ADGNEO (r = -0.005), BWSIU:BWEPD (r = 0.256), and BWNEO:BWEPD (r = 0.226). Correlations were observed between RFISIU:F/GSIU (r = 0.455), ADGSIU :ADGNEO (r = 0.353), and FRAMESIU:BWNEO (r = 0.326).This study determined that beef bulls should continue to be performance tested due to discrepancies between sources of information for key animal performance traits. Assessment of SNPs used in the commercial test should continue.
6

Electrophoretic deposition of inorganic-organic nanocomposites

Zhao, Xinya 07 1900 (has links)
With many processing advantages, electrophoretic deposition (EPD) has been chosen as the fabrication technique for inorganic-organic nanocomposites. However, before the EPD process, avoiding the particles agglomeration is considered a necessary perquisite for the success of fabrication. In this research, two different liquid-liquid extraction methods, one is one-step and the other is two-step, were developed to solve the agglomeration problem of inorganic particles. The adsorption mechanisms of the extractors and extraction mechanisms were investigated during this work. The strong adsorptions provided by –OH groups of the extractors and further Schiff base reaction allowed for the process of extraction. In the fabrication, polyelectrolytes acted as the film forming and charging agents. Relatively stable suspensions with extracted inorganic particles were prepared for the EPD of inorganic-organic nanocomposites. The thickness of deposited films is proportional to the concentration of the suspension and deposition time. With the addition of flame retardant inorganic particles, the prepared nanocomposite films showed an enhanced flame retardant performance. / Thesis / Master of Applied Science (MASc)
7

Fabrication of biomedical composite coatings by electrophoretic deposition and dip coating methods

Wang, Zhengzheng January 2024 (has links)
It is essential to develop a new type of nanocomposite biomedical implant coatings that consist of bioactive ceramics and polymers, as well as customized surface characteristics. These coatings play a vital role in enhancing cell adhesion, proliferation, and interlocking at the interface between bone tissue and the implant. This development is crucial for prolonging the durability of orthopaedic implants. The utilization of combined colloidal and electrochemical processing techniques, specifically EPD and dip coating, enables the fabrication of these novel multi-component materials with relative simplicity. Additionally, they can be utilized to create nanostructures and surface topography that imitate the composition of human skeletal tissue on a nanoscale level. In addition, colloidal-electrochemical processing techniques can be easily scaled up for clinical product development and mass manufacture, unlike many regularly utilized nanotechnology processing techniques. The absence of efficient and biocompatible dispersants and extractors is a significant obstacle to the widespread use of colloidal-electrochemical methods for fabricating novel biomaterials in EPD, as the success of this process relies on the utilization of a stable colloidal precursor. Biomimetics, sometimes known as gaining inspiration from the natural world, is one way to generating effective dispersion and extracting agents. Using this methodology, we identified novel extracting agents. These agents proved to be highly effective in extracting particles and forming composite films that combined organic and inorganic components, containing different sized of silica particles and polyvinylidene fluoride (PVDF). By extending the method, biomimetic inspiration was derived from the human digestive system, to use bile acid salts (BAS) as solubilizing, charging, dispersing and film-forming agents for the preparation of composite coatings, containing water insoluble drugs and proteins. These coatings have the potential to be utilized for targeted administration of antibiotics, thereby preventing surgical infections after implantation. Furthermore, the inclusion of BAS surfactants enables the solubilization and dispersion of hydrophobic drugs and molecules, as well as the creation of composite films with functional properties using EPD. Moreover, a novel technique is devised for the anodic EPD of alginic acid polymer (AlgH) and composite films that contain drug molecules within the AlgH matrix. This approach entailed utilizing L-arginine as an alkalizing agent to enhance the solubility of medicines that have low solubility in water. AlgH and medication molecules are dissolved in water and then deposited via anodic EPD. Dip coating remains a challenging task when it comes to depositing high concentrations of non-toxic solvents containing high molecular weight (MW) polymers, such as poly(ethyl methacrylate) (PEMA) and poly(methyl methacrylate) (PMMA). In this study, we initially suggested the utilization of water-isopropanol as a co-solvent for dissolving high molecular weight PMMA at high concentrations. Additionally, we utilized an advanced dispersion agent to facilitate the solubilization of PEMA. It was discovered that water molecules can surround and solvate the carbonyl groups of the polymers. This technology avoided the use of noxious solvents and a protracted heating process for their elimination. In addition, these coatings have the potential to be integrated with advanced inorganic particles, such as drugs, diamond and HA, for use in biomedical applications. / Thesis / Doctor of Philosophy (PhD) / There is a need to develop new coatings and manufacturing procedures for biomedical implant materials in order to extend the lifespan of orthopaedic implants used in clinical settings and avoid the need for expensive and unpleasant revision surgeries. Bioactive coatings enhance the durability of orthopaedic implants by reducing scar tissue formation and inflammation, while also increasing the chemical and physical bond between the synthetic implant and natural bone. As bone is a natural composite material, our goal in designing replacement materials is to replicate the inherent chemical composition and structure of human bone. Electrophoretic deposition (EPD) is a manufacturing technology that holds significant potential for creating composite coatings that imitate the structure of natural bone. This approach involves the application of an electric field to deposit charged materials onto a conductive substrate. The primary challenge in the manufacturing process of materials utilizing EPD is the tendency of particles in the precursor suspension to coagulate and distribute unevenly. This ultimately results in unwanted characteristics in the final coatings. An effective method to overcome this problem is by use dispersing agents, which are tiny molecules with either positive or negative charges that disperse particles in a suspension through electrostatic repulsion, physical separation, or a mix of both. Traditional dispersing agents have proven effective in various applications; nevertheless, their toxicity renders them unsuitable for the production of biological materials. This study presents the identification of novel dispersion agents, biomedical coatings, and manufacturing techniques for creating coatings that enhance the durability of implants and possess additional functionalities, such as biosensing for disease detection.
8

Construção e caracterização eletroquímica de eletrodos baseados em grafeno / Construction and electrochemical characterization of grapheme-based electrodes

Carvalho, Lucas Lodovico de 06 August 2014 (has links)
A demanda crescente por meios de armazenar eficientemente energia elétrica tem incentivado a busca de materiais que melhorem o desempenho específico de dispositivos armazenadores de carga elétrica. Dentre os materiais a base de carbono, destaca-se o grafeno e seus derivados como tendo grande potencial para aumentar o desempenho de tais. Nesse trabalho, estudam-se duas abordagens para a imobilização de grafeno sobre condutores metálicos e o efeito que essas tem na eletroquímica dos sistemas. De maneira geral, evitou-se a utilização de polímeros como aglutinantes na construção de eletrodos, visto que esses podem interferir negativamente na eletroquímica do sistema (além de não serem condutores elétricos, não têm nenhum benefício em relação a aumento de capacitância do eletrodo). As metodologias estudadas podem ser separadas em duas categorias, sendo essas a de eletrodos obtidos por deposição eletroforética de derivados de grafeno e imobilização de grafeno sobre condutores metálicos pelo uso de camadas orgânicas, que servem de ponto de ancoragem para os derivados de grafeno. Os eletrodos foram então caracterizados eletroquimicamente, visando principalmente seu uso em capacitores eletroquímicos. Dentre as técnicas utilizadas para tal, destacam-se o uso de voltametria cíclica e espectroscopia de impedância eletroquímica, além de técnicas não eletroquímicas como espectroscopia Raman, microscopia eletrônica de varredura, microscopia de força atômica e microbalança de cristal de quartzo. De modo geral, pode-se observar que a deposição eletroforética é uma maneira simples de obter eletrodos modificados, e apresenta alta reprodutibilidade. O fato de não possuírem outros compostos químicos que não o grafeno, além de serem altamente rugosos, mostrou que esses eletrodos tem desempenho capacitivo muito bom, sendo o método de obtenção do grafeno e a maneira escolhida para deposição diretamente responsáveis pela morfologia obtida. A construção de eletrodos pela ancoragem de grafeno foi feita com base na (eletro)química de sais de diazônio, que se mostrou bastante promissora quanto a capacidade de se obter uma ligação química estável entre as folhas de grafeno e o metal. A alta reatividade dos sais de diazônio, no entanto, se mostrou danosa a eletroquímica do grafeno, sendo que tais eletrodos não apresentaram nenhuma característica que justificasse seu uso em capacitores eletroquímicos. Assim, os avanços e desafios restantes em relação a essas abordagens na construção capacitores eletroquímicos com alto desempenho específico encontram-se aqui detalhados. / The increasing demand for efficient electrical energy storage devices has pushed research towards materials with potential to increase the specific performance of such devices. Among the carbon-based materials, one that has been heavily studied as a potential candidate to accomplish such feat is graphene and its chemical derivatives. In this work, two methodologies to accomplish graphene immobilization over metallic current collectors are approached, as well as the effects that such approaches have on the electrochemistry of the resulting electrodes. As a general guideline, the usage of polymeric binders as ways of keeping good mechanical stability are avoided, due to their tendency to negatively impact the system\'s electrochemistry (not only they\'re normally electrical in sulators, they also don\'t usually possess any intrinsic electroactivity that could enhance the electrode\'s capacitance). The methodologies in study can be separated into two categories, namely, electrophoretic deposition and usage of organic molecules as anchoring points to attach graphene sheets to the surface. Such electrodes were characterized by a number of electrochemical technics, most prominently cyclic voltammetry and electrochemical impedance spectroscopy in the group of electrochemical technics, and Raman spectroscopy, atomic force microscopy, scanning electron microscopy and quartz crystal microbalance in the group of non-electrochemical technics. Electrophoretic deposition of graphene is proved to be a very straightforward and reproducible way to obtain modified electrodes. Since no chemical compound other than the graphene derivatives are necessary, and that the final electrodes have very rough surfaces, such electrodes have very high capacitance, and those characteristics are direct consequence of the chosen method. Anchoring graphene derivatives on the surface of metallic conductors by the (electro)-chemistry of diazonium salts is shown to be a promising method to achieve strongly bound graphene sheets to a surface. The high reactivity of diazonium salts, though, hampers the electrochemical activity of graphene, and no electrodes suitable to be used in electrochemical capacitors were obtained. In summary, the advances and remaining challenges towards the use of such methodologies in the construction of electrochemical capacitors are presented here.
9

Construção e caracterização eletroquímica de eletrodos baseados em grafeno / Construction and electrochemical characterization of grapheme-based electrodes

Lucas Lodovico de Carvalho 06 August 2014 (has links)
A demanda crescente por meios de armazenar eficientemente energia elétrica tem incentivado a busca de materiais que melhorem o desempenho específico de dispositivos armazenadores de carga elétrica. Dentre os materiais a base de carbono, destaca-se o grafeno e seus derivados como tendo grande potencial para aumentar o desempenho de tais. Nesse trabalho, estudam-se duas abordagens para a imobilização de grafeno sobre condutores metálicos e o efeito que essas tem na eletroquímica dos sistemas. De maneira geral, evitou-se a utilização de polímeros como aglutinantes na construção de eletrodos, visto que esses podem interferir negativamente na eletroquímica do sistema (além de não serem condutores elétricos, não têm nenhum benefício em relação a aumento de capacitância do eletrodo). As metodologias estudadas podem ser separadas em duas categorias, sendo essas a de eletrodos obtidos por deposição eletroforética de derivados de grafeno e imobilização de grafeno sobre condutores metálicos pelo uso de camadas orgânicas, que servem de ponto de ancoragem para os derivados de grafeno. Os eletrodos foram então caracterizados eletroquimicamente, visando principalmente seu uso em capacitores eletroquímicos. Dentre as técnicas utilizadas para tal, destacam-se o uso de voltametria cíclica e espectroscopia de impedância eletroquímica, além de técnicas não eletroquímicas como espectroscopia Raman, microscopia eletrônica de varredura, microscopia de força atômica e microbalança de cristal de quartzo. De modo geral, pode-se observar que a deposição eletroforética é uma maneira simples de obter eletrodos modificados, e apresenta alta reprodutibilidade. O fato de não possuírem outros compostos químicos que não o grafeno, além de serem altamente rugosos, mostrou que esses eletrodos tem desempenho capacitivo muito bom, sendo o método de obtenção do grafeno e a maneira escolhida para deposição diretamente responsáveis pela morfologia obtida. A construção de eletrodos pela ancoragem de grafeno foi feita com base na (eletro)química de sais de diazônio, que se mostrou bastante promissora quanto a capacidade de se obter uma ligação química estável entre as folhas de grafeno e o metal. A alta reatividade dos sais de diazônio, no entanto, se mostrou danosa a eletroquímica do grafeno, sendo que tais eletrodos não apresentaram nenhuma característica que justificasse seu uso em capacitores eletroquímicos. Assim, os avanços e desafios restantes em relação a essas abordagens na construção capacitores eletroquímicos com alto desempenho específico encontram-se aqui detalhados. / The increasing demand for efficient electrical energy storage devices has pushed research towards materials with potential to increase the specific performance of such devices. Among the carbon-based materials, one that has been heavily studied as a potential candidate to accomplish such feat is graphene and its chemical derivatives. In this work, two methodologies to accomplish graphene immobilization over metallic current collectors are approached, as well as the effects that such approaches have on the electrochemistry of the resulting electrodes. As a general guideline, the usage of polymeric binders as ways of keeping good mechanical stability are avoided, due to their tendency to negatively impact the system\'s electrochemistry (not only they\'re normally electrical in sulators, they also don\'t usually possess any intrinsic electroactivity that could enhance the electrode\'s capacitance). The methodologies in study can be separated into two categories, namely, electrophoretic deposition and usage of organic molecules as anchoring points to attach graphene sheets to the surface. Such electrodes were characterized by a number of electrochemical technics, most prominently cyclic voltammetry and electrochemical impedance spectroscopy in the group of electrochemical technics, and Raman spectroscopy, atomic force microscopy, scanning electron microscopy and quartz crystal microbalance in the group of non-electrochemical technics. Electrophoretic deposition of graphene is proved to be a very straightforward and reproducible way to obtain modified electrodes. Since no chemical compound other than the graphene derivatives are necessary, and that the final electrodes have very rough surfaces, such electrodes have very high capacitance, and those characteristics are direct consequence of the chosen method. Anchoring graphene derivatives on the surface of metallic conductors by the (electro)-chemistry of diazonium salts is shown to be a promising method to achieve strongly bound graphene sheets to a surface. The high reactivity of diazonium salts, though, hampers the electrochemical activity of graphene, and no electrodes suitable to be used in electrochemical capacitors were obtained. In summary, the advances and remaining challenges towards the use of such methodologies in the construction of electrochemical capacitors are presented here.
10

Élaboration et caractérisation de revêtements submicroniques obtenus par électrodéposition de nanoparticules de silice. / Development and characterization of submicron coatings obtained by electrodeposition of silica nanoparticles.

Charlot, Aude 27 June 2014 (has links)
L'élaboration d'un revêtement submicronique est réalisée par électrodéposition de nanoparticules de silice (EPD = ElectrophoreticDeposition). Cette approche permet de contrôler l'épaisseur des dépôts, qui est un paramètre à ajuster pour élaborer un revêtement sélectif absorbeur de type capteur photothermique. La nature du revêtement recherché est un co-dépôt de silice et de carbone. Pour la compréhension et le contrôle des mécanismes de dépôt par EPD, le dépôt de silice seule est étudié. Deux systèmes ont été investigués : de la silice déposée sur du wafer de silicium ou sur du platine, notés respectivement SiO2/Si et SiO2/Pt. Une suspension colloïdale commerciale, le Ludox® HS-40, est utilisée pour permettre la dilution de sols stables de nanoparticules de silice monodisperses (12 nm de diamètre), chargées négativement. Un EPD anodique est réalisé en milieu aqueux grâce à ce sol.Le potentiel, la concentration initiale en nanoparticules et la durée de dépôt ont été explorés. Lorsque le potentiel appliqué est trop élevé, le phénomène d'électrolyse de l'eau est observé. Plus particulièrement, le système à base de platine se trouve limité par ce phénomène à partir d'un potentiel de +2V. La forte conductivité de ce substrat favorise le phénomène de dégagement gazeux. Ce bullage subséquent, dégrade la cohésion du revêtement. Néanmoins, l'application d'un potentiel inférieur au potentiel d'électrolyse de l'eau permet de bonnes conditions de dépôt. Des phénomènes similaires ont également été observés avec le système SiO2/Si. Les propriétés semi-conductrices du wafer de silicium permettent cependant d'appliquer des potentiels plus élevés (jusqu'à +40 V), en limitant le phénomène d'électrolyse. L'optimisation des conditions de dépôt sur ces deux systèmes ont permis d'obtenir des conditions expérimentales de dépôt compatibles avec l'objectif fixé, à savoir : un potentiel de +1 V pour le système SiO2/Pt et de +3 ou +30 V pour le système SiO2/Si, une concentration comprise entre 1 et 10 %mass, et une durée de dépôt de 1h.Dans les conditions optimales définies précédemment, les propriétés physico-chimiques de la suspension initiale ont été modifiées par l'ajout d'un co-solvant (EtOH), d'un sel (Na2SO4) ou d'un polymère (PAA out PVA) afin d'étudier l'influence du milieu dispersant, de la conductivité de la suspension ou du potentiel zêta des nanoparticules sur l'épaisseur des dépôts. Ces ajouts ont permis d'augmenter l'épaisseur des revêtements, notamment pour le système SiO2(EtOH)/Pt et les systèmes à base de PAA. L'ajout d'un composé carboné (PVA, PAA) dans la suspension a également été étudié afin d'obtenir après calcination (500°C) un revêtement présentant des caractéristiques intéressantes pour l'application envisagée. Les revêtements de type SiO2(PAA)/Pt présentent une certaine sélectivité optique. Toutefois les valeurs du ratio alpha/epsilon restent inférieures à 7, ce qui est plus faible que les valeurs obtenues pour le même type de système, avec des procédés sol-gel classiques. / The development of a submicron coating was carried out by electrophoretic deposition (EPD)of silica nanoparticles. This approach allows controlling the thickness of the deposits which is a parameter to adjust to develop a selective absorber coating dedicated to a photothermal sensor. The composition of the desired coating is a co-deposition of silica and carbon. For the understanding and the control of EPD deposition mechanisms, silica deposit is first studied. Two systems were investigated: silica deposited on a silicon wafer or platinum substrate, respectively noted SiO2/Si and SiO2/Pt. A commercial colloidal suspension, Ludox® HS-40, is used to realize stable diluted sols of monodispersed silica nanoparticles (12 nm diameter), negatively charged. Anodic EPD is performed in aqueous medium from this sol.The applied potential, the initial concentration of nanoparticles and the deposition time are investigated. When the applied potential is too high, the water electrolysis phenomenon occurs. More particularly, the platinum-based system is limited by this phenomenon, from a potential of +2 V. The high conductivity of this substrate promotes gassing phenomenon. This subsequent bubbling degrades the cohesion of the coating. However, an applied potential lower than the electrolysis potential gives some good deposition conditions. Similar phenomena were also observed with SiO2/Si system. However, the semiconductor properties of the silicon wafer enable to apply higher potential (up to +40 V) by reducing the phenomenon of electrolysis. Optimizations of the deposition conditions on these two systems have yielded experimental deposition conditions consistent with the objective, namely: a potential of +1 V to SiO2/Pt system and of +3 and +30 V for SiO2/Si system, a concentration between 1 and 10 %mass, and a deposition time of 1 hour.Under optimum conditions defined above, the physicochemical properties of the initial suspension are modified by adding a co-solvent (EtOH), a salt (Na2SO4) or a polymer (PAA or PVA) in order to study the influence of the dispersing medium, the conductivity of the suspension or the zeta potential of the nanoparticles on the thickness of the deposits. These additions have increased the thicknesses of coatings, especially for SiO2(EtOH)/Pt system and systems based on PAA. The addition of some carbon compounds (PVA or PAA) in the suspension was also studied to obtain after calcinations (500 °C) a coating with interesting characteristics for the intended application. Coating obtained with SiO2(PAA)/Pt system exhibit a significant optical selectivity. However, the value of the alpha/epsilon ratio remains below 7, which is lower than the values obtained for the same type of system with conventional sol-gel processes.

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