Papers by Keyword: Electrophoretic Deposition (EPD)

Abstract: In this research, low carbon steel surface was modified using electrophoretic deposition (EPD) technique from a graphene oxide (GO) water suspension. The electrophoretic deposition (EPD) is the technique used for manipulation and deposition of nanomaterials. The GO coating was used as a layer to increase the hardness of low carbon steel. GO was successfully synthesized using the modified Hummers method. EPD technique was performed by applying voltage at 9 volts and the deposition time of 15 mins. The working distance between the cathode and anode was fixed at 15 mm. The GO film had been deposited by EPD technique where it was carburized at 900, 950, 1000 and 1050°C, for 60 mins. The microstructure of the carbide film was investigated using scanning electron microscopy (SEM). As the carburization temperature raised (1050°C), more volume carbon atoms reacted with iron atoms to form iron carbon (Fe₃C) layer on to the substrate surface. The carbide films are columnar crystal growth with a particle size of approximately 50 μm. The growth rate of the carbide films at 1050°C is about 8 µm/min. Energy dispersive X-ray spectrometer (EDS) was studied for chemical elements analysis. Fe, C and O elements were then detected. At carburization temperature of 1050°C, it showed that C element distribution is higher than others’ temperatures. Moreover, the hardness on the carbide films was investigated using a Vickers hardness tester under an applied load of 500 grams for 10 seconds. It was found that the hardness increased with the increasing carburization temperatures. The hardness of low carbon steel is 172.99 ± 2.28 HV. After the carburization processing via GO at temperature of 1050°C, the highest hardness of 821.42 ± 35.33 HV was obtained. It was observed that the mechanical properties of low carbon steel surface were found to be strongly influenced by the process of carburization temperature.

Abstract: Carbon nanotubes are one of the materials that can replace platinum as DSSC’s counter electrode. By utilizing carbon nanotubes (CNT), which is an organic material in place of platinum it is possible to create an inexpensive solar cell. However, there are still many problems with CNT such as low conversion compared with platinum and fast degradation in CNT. At the present time, it is to be large surface area when we fabricate CNT electrode sintered at 500°C with Electrophoretic Deposition (EPD). We measured how conversion efficiency changed by changing sintering temperatures. As a result, when CNT electrode sintered at 500°C, conversion efficiency was the highest and it was 2.46%.

Abstract: Dye Sensitized Solar Cell (DSSC) is more inexpensive and ecofriendly than silicone solar cell from structure. It has been reported that DSSC made by used ruthenium reaches 10.7 % [1]. However there are some contradiction so that a pigment named Ruthenium complex which is toxic is used in it. So we investigated to solve these problems using MK-II dye that is inexpensive and harmless. At the same time, we explored what kind of influence in conversion efficiency from difference of coating thickness by Electrophoretic Deposition (EPD) method. This method can lead to use flexible materials [2]. Because letting to deposit Titanium oxide (TiO₂), we can lower sintering temperature or less to plastic melting point. The result was cell’s conversion efficiency better than others in case of 90sec and 100sec of electrophoresis time. From our experiments it is able to be said that coating thickness made by 90sec and 100sec are suitable, and its difference affect conversion efficiency.

Abstract: Electrophoretic deposition (EPD) is a technique that uses electric field to deposit particles onto a conductive substrate. In this study, EPD technique has been utilized for fabrication of acid functionalized multi-walled carbon nanotubes (f-MWCNTs) and polyaniline (PANi) or denoted as (f-MWCNTs-PANi) nanocomposite film. The nanocomposite was prepared using ex-situ synthesis. This study revealed that the f-MWCNTs and protonated PANi in dimethyl formamide (DMF) can be well dispersed with addition of magnesium nitrate hexahydrate, Mg (NO₃)₂.6H₂O. The fabricated films were characterized by Fourier Transform-Infrared Spectroscopy (FT-IR) and X-Ray Photoelectron Spectroscopy (XPS). Their surface morphologies were characterized by Field Emission Scanning Electron Microscope (FESEM) and Transmission Electron Microscope (TEM). FT-IR results indicate the presence of carboxyl groups in f-MWCNTs spectrum. The presence of PANi was detected in the spectrum of f-MWCNTs-PANi nanocomposite. These results were further supported by FESEM and TEM results that show the morphology of f-MWCNTs and PANi coating around their sidewalls. The use of Mg (NO₃)₂.6H₂O as dispersant for f-MWCNTs and protonated PANi allowed efficient EPD of their nanocomposite film fabrication. The fabricated f-MWCNTs-PANi composite thin film has future application in the development of supercapacitor device.

Abstract: Zinc oxide (ZnO) films on graphite substrate were fabricated using electrophoretic deposition (EPD) method. The effect of concentration and applied voltage in EPD were determined in which the mass of deposited ZnO depends on the applied voltage and not on the concentration. Sensitization of film with palladium chloride (PdCl₂) was done through dipping method. The optimum number of dipping is 20. The sensitized samples were subjected to annealing at 100 °C for 30 minutes. The morphology of the films was analyzed through scanning electron microscopy (SEM) which showed the porosity and thickness of the samples. The IV characterization of the samples was done via four-point probe method and the resistivity and resistance were calculated. The resistivity and resistance were found to be lowest in graphite substrate while the films with palladium (Pd) showed lower values of resistivity and resistance than the films without palladium. . A three trial gas sensing experiment at room temperature was performed in which the response of the film to butane/propane gas (LPG) was tested and showed that it successfully sensed the gas. The sample with Pd deposited at the highest applied voltage showed the best gas response and response time among the other samples.Zinc Oxide (ZnO) films on graphite substrate were fabricated using Electrophoretic Deposition (EPD) method. The effect of concentration and applied voltage in EPD were determined in which the mass of deposited ZnO depends on the applied voltage and not on the concentration. Sensitization of film with Palladium Chloride (PdCl₂) was done through dipping method. The optimum number of dipping is 20. The sensitized samples were subjected to annealing at 100 °C for 30 minutes. The morphology of the films was analyzed through Scanning Electron Microscopy (SEM) which showed the porosity and thickness of the samples. The IV characterization of the samples was done via four-point probe method and the resistivity and resistance were calculated. The resistivity and resistance was found to be lowest in graphite substrate while the films with palladium (Pd) showed lower values of resistivity and resistance than the films without palladium. . A three trial gas sensing experiment at room temperature was performed in which the sensitivity of the film to butane/propane gas (LPG) was tested and showed that it successfully sensed the gas. The sample with Pd deposited at the highest applied voltage showed the best sensitivity and response time among the other samples.

Abstract: Magnesium and its alloys are potential biodegradable implant materials. However, they are characterized by rapid degradation in the electrolytic environment of the body. This phenomenon might result a sudden implant failure before bone restoration was complete, or inflammation subsided. This research will explore ways to improve the corrosion resistance of AZ31 magnesium alloy by improving the coating layer of hydroxyapatite (HA) through multiple coating layers by an electrophoretic deposition (EPD) process. In this study, the quality of the coating layer was improved by multiple coating processes without using any binders. X-ray diffraction spectrometer (XRD) showed that an amorphous structure of HA was successfully deposited on the AZ31 alloy. Scanning electron microscopy (SEM) has been used to observe that the morphology of the AZ31 alloy coated with multiple layers of HA has a denser coating structure with improved adhesion at the interface as compared to the single coating layer. A denser coating structure with greater bonding between the coating layer and the substrate is expected to protect the substrate from a high corrosion rate, thus resulting in a longer period of biodegradation as in implant in the electrolytic environment.

Abstract: This study examines two things about a dye sensitized solar cell (DSSC) to improve power conversion efficiency. One is how to make ZnO-coated TiO2 electrode. The other is how to make carbon nanotube (CNT) electrode. First, we considered the process of making the ZnO-coated TiO₂ electrode of the DSSC. This ZnO coating of the DSSC is important for the increase of power conversion efficiency. The fabrication method of the ZnO-coated TiO₂ electrode was simple dip coating. This method uses the immerse of the zinc acetate dehydrate [Zn (CH₃COO₂)・2H₂O] solution. This method can make the cheap ZnO-coated TiO₂ electrode. However, this method has a slightly negative effect, which is filling in holes of the porous TiO₂ layer. We tried to improve this negative effect. We changed the concentration of a zinc acetate dehydrate solution from low to high. Also, we changed the immersing time of the zinc acetate dehydrate solution. We did the control of the band gap of ZnO-coated TiO₂ electrode of DSSC for increasing power conversion efficiency. Second, we substituted CNT for counter electrodes to improve the performance of DSSC. As a manufacture method of CNT electrode, we used electrophoretic deposition (EPD). After that, we baked this CNT electrode and measured its specific surface area. We tried to improve specific surface area by changing baking temperature.

Abstract: Porous titanium samples of cp Ti grade IV were obtained by space-holder technique (50%vol of NH₄HCO₃, 800 MPa, 1250 oC during 2h in high vacuum), producing a good balance between stiffness and mechanical strength. The samples were coated with chitosan/45S5 bioactive glass composite by electrophoretic deposition. Homogeneity, infiltration efficiency, and coatings integrity (cracking and adhesion) were evaluated in order to establish correlations with processing parameters. SEM, FTIR, and contact profilometry were performed for detailed characterization of the coatings; and micro-mechanical properties (P-h curves and scratch testing) were set-up as well. Optimum EPD parameters were 25V, 7 min and suspension containing 0.5 g/L chitosan and 1.5 g/L BG a titanium structure with pore sizes greater than 200 μm are required.

Abstract: Chitosan – graphene oxide (GO) composite coatings intended for antibacterial applications were obtained by cathodic electrophoretic deposition (EPD) on stainless steel. The coatings were characterized using SEM, FTIR, contact angle and roughness measurements and by antibacterial studies against E.coli. The coating was observed to consist of a polymer matrix with embedded, agglomerated graphene oxide sheets. A decrease in bacteria cell viability of at least 50 % was measured on the chitosan – GO surface in comparison to uncoated stainless steel.

Abstract: Three different glasses were synthesized by doping 45S5 bioactive glass with B₂O₃. The bioactivity of the glasses was evaluated by immersion in simulated body fluid (SBF) up to 3 days; all glasses showed the precipitation of hydroxyapatite (HAp) after one day of soaking in SBF. Electrophoretic deposition (EPD) was used to prepare PEEK/B₂O₃-doped 45S5 glass composite coatings on stainless steel substrates. The coatings were characterized by means of tape test (ASTM D3359-B), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), contact angle measurements, thermogravimetric analysis and in vitro bioactivity test. All composite coatings exhibited a porous and homogenous structure with a hydrophobic surface, according to the wettability test. The in vitro test in SBF demonstrated that the coatings were highly bioactive.