Electrophoretic Deposition Rate Research Articles

Electrophoretic Deposition Interferometric Scattering Mass Photometry.

Interferometric scattering microscopy (iSCAT) has rapidly developed as a quantitative tool for the label-free detection of single macromolecules and nanoparticles. In practice, this measurement records the interferometric scattering signal of individual nanoparticles in solution as they land and stick on a coverslip, exhibiting an intensity that varies linearly with particle volume and an adsorption rate that reflects the solution-phase transport kinetics of the system. Together, such measurements provide a multidimensional gauge of the particle size and concentration in solution over time. However, the landing kinetics of particles in solution also manifest a measurement frequency limitation imposed by the slow long-range mobility of particle diffusion to the measurement interface. Here we introduce an effective means to overcome the inherent diffusion-controlled sampling limitation of spontaneous mass photometry. We term this methodology electrophoretic deposition interferometric scattering microscopy (EPD-iSCAT). This approach uses a coverslip supporting a conductive thin film of indium tin oxide (ITO). Charging this ITO film to a potential of around +1 V electrophoretically draws charged nanoparticles from solution and binds them in the focal plane of the microscope. Regulating this potential offers a direct means of controlling particle deposition. Thus, we find for a 0.1 nM solution of 50 nm polystyrene nanoparticles that the application of +1 V to an EPD-iSCAT coverslip assembly drives an electrophoretic deposition rate constant of 1.7 s-1 μm-2 nM-1. Removal of the potential causes deposition to cease. This user control of EPD-iSCAT affords a means to apply single-molecule mass photometry to monitor long-term changes in solution, owing to slow kinetic processes. In contrast with conventional coverslips chemically derivatized with charged thin films, EPD-iSCAT maintains a deposition rate that varies linearly with the bulk concentration.

The reinforcement strategy of electrophoretic deposition coating assisted by PVP for grain boundary diffusion of Nd-Fe-B magnet

In this study, we aimed to enhance the quality of electrophoretic deposition (EPD) coatings for Nd-Fe-B grain boundary diffusion (GBD) by addressing issues related to the adhesion and densification of coating. We introduced a novel approach by incorporating polyvinyl pyrrolidone (PVP) into an alcohol suspension containing TbH3 nano-powders. The addition of PVP resulted in the formation of a dense coating with superior adhesion and a smooth surface. To evaluate the effectiveness of the EPD coating with PVP, we compared the EPD rate of the TbH3 nano-powders alcohol suspension with and without PVP. The EPD rate of the suspension with PVP exhibited a significant 30-fold increase compared to the suspension without PVP, indicating a substantial improvement in the electrophoretic efficiency. Based on our experimental findings, we recommend depositing the EPD coating at a voltage of 120 V and adjusting the deposition time accordingly to achieve a desired coating weight percentage of 1.0 wt% with a thickness of approximately 30 μm. Following the GBD process, the coercivity of the magnet with PVP increased from 1131 kA/m to 1896 kA/m, which improved the high-temperature stability of the magnet. Overall, our research offers a promising approach to overcome the limitations associated with EPD coatings for GBD applications, providing a potential solution for enhancing the performance and industrial viability of these coatings.

Ion Transport in Plasticized Li1.5Al0.5Ge1.5(PO4)3 Based Electrolytes

The development of an efficient devices for energy storage, conversion, and transmission is one of the key priority areas today. At the center of these activities is the development of all-solid-state high-energy and high-power lithium-ion batteries.Our research is focused on the study of ion transport in a plasticized-by-ionic-liquid composite membrane formed by electrophoretic deposition (EPD). The EPD membrane comprises above 85% of high-ion-conductivity ceramic matrix Li1.5Al0.5Ge1.5(PO4)3 (LAGP) and less than 15% polyethyleneimine (PEI). The EPD rate and morphology of the membrane were characterized by SEM, TOFSIMS and DSC methods. 0.3M LiTFSI–PYR14TFSI was infused in the membrane to form a quasi-solid electrolyte. The complex, non-Debye dielectric response of the quasi-solid electrolyte, tested over the temperature and frequency ranges of (-140oC) to (+100oC) and 10-2 – 106 Hz, has been described in terms of several distributed relaxation processes separated by different frequency and temperature ranges. While at low temperatures, the main contribution is from LAGP, in the middle- and high-temperature regions, the superposition of a few non-Arrhenius processes is observed. Relaxation is perturbed by clear phase transition related to melting of the ionic liquid. Different scales of the ionic transport and corresponding relaxation of the apparent dipole moment in the materials are discussed.

Electrophoretically deposited LAGP-based electrolytes - Structure and ion transport in plasticized systems

The development of an efficient devices for energy storage, conversion, and transmission is one of the key priority areas today. At the center of these activities is the development of all-solid-state high-energy and high-power lithium-ion batteries.Our research is focused on the study of ion transport in a plasticized-by-ionic-liquid composite membrane formed by electrophoretic deposition (EPD). The EPD membrane comprises above 85% of high-ion-conductivity ceramic matrix Li1.5Al0.5Ge1.5(PO4)3 (LAGP) and less than 15% polyethyleneimine (PEI). The EPD rate and morphology of the membrane was characterized by ESEM, TOFSIMS and DSC methods. 0.3 M LiTFSI–PYR14TFSI (IL) was infused in the membrane to form a quasi-solid electrolyte. The complex, non-Debye dielectric response of the quasi-solid electrolyte, tested over the temperature and frequency ranges of (−140 °C) to (+100 °C) and 10−2 – 106 Hz, has been described in terms of several distributed relaxation processes separated by different frequency and temperature ranges. While at low temperatures, the main contribution is from LAGP, in the middle- and high-temperature regions, the superposition of a few non-Arrhenius processes is observed. Relaxation is perturbed by clear phase transition related to melting of the ionic liquid. Different scales of the ionic transport and corresponding relaxation of the apparent dipole moment in the materials are discussed.

Fabrication of TiB2 coatings by electrophoretic deposition of synthesized TiB2 nanoparticles in molten salts

This paper presents a novel process for preparation of TiB2 coatings, which is a combination of synthesis of TiB2 nanoparticles by borothermal reduction of TiO2 in molten NaCl–KCl–AlF3 system and subsequent electrophoretic deposition of the as-synthesized TiB2 nanoparticles in the same molten salts system. The electrophoretic deposition under various cell voltages was carried out, which resulted in preparation of dense and relatively flat TiB2 coatings. The effect of applied cell voltages on the electrophoretic deposition rate and mechanical properties of produced TiB2 coatings has been presented. The thickness of the coatings increased with the rise of cell voltages due to elevated migration and deposition rate of TiB2 nanoparticles. The hardness of the fabricated TiB2 coatings was assessed by nanoindentation, indicating that the values of hardness and elastic modulus increased with elevated electrophoretic voltages, which probably has an influence on the structure of the TiB2 coatings. Under the cell voltage of 1.2 V, the values of hardness and elastic modulus could reach 32.4 ± 1.2 GPa and 420.2 ± 23.9 GPa, respectively. This proposed process should also be applied for preparation of additional types of transition metal diboride coatings.

Electrophoretic deposition of alginate coatings from different alcohol-water mixtures

ABSTRACT Alginate coatings were fabricated by electrophoretic deposition (EPD) using alcohol (methanol, ethanol and isopropanol)-water mixtures at different ratios. Water electrolysis and so current density increased with water content and EPD time leading to the more bubbles in coatings. EPD rate increased with water amount due to the increase in concentration of H+ and Alg− ions and reduction in solution viscosity. According to the results of kinetics, optical microscopy and corrosion analyses the coating deposited at 10 V for 1 min from the ethanolic solution with 60 vol.-% of water was selected as the optimum coating for in-vitro cell culture and antibacterial analyses. There was almost 30% rise in cell expansion for the sample with optimum coating after 7 days compared to the blank. Also, the coated sample showed antibacterial activity against Bacillus bacteria.

Effect of pH on the electrophoretic deposition of chitosan in different alcoholic solutions

Electrophoretic deposition (EPD) of chitosan coatings was carried out using alcohol (methanol, ethanol and isopropanol)-water mixtures with different contents of acetic acid. EPD rate increased with AA content to the maximum and then decreased with its further addition. EPD rate was higher in smaller molecular size alcohols due to their lower viscosities leading to the higher mobility for protonated chitosan ions. Current density increased during EPD from solutions with higher AA contents due to the enhanced water electrolysis. There were bubbles in the coatings deposited from methanolic, ethanolic and isopropanolic solutions with AA ≥ 0.1, AA ≥ 0.5 and AA ≥ 10 Vol%, respectively, due to the intensive water electrolysis. The coatings deposited from methanolic, ethanolic and isopropanolic solutions with 0.05, (0.05 and 0.1) and 5Vol% of AA, respectively, had the highest corrosion resistance in simulated body fluid (SBF) due to their bubble-free structures.

Electrophoretic deposition of titania nanostructured coatings for photodegradation of methylene blue

The suspensions of titania nanoparticles were prepared in different alcohols (methanol, ethanol, isopropanol and butanol) using polyethyleneimine (PEI) as dispersant. The results of sedimentation, conductivity, zeta potential, FTIR and thermal analysis showed that PEI macromolecules are protonated in the suspensions and then adsorbed on the particles enhancing their positive surface charge and so colloidal stability. Optimum concentration of PEI (PEI*) was lower in large molecular size alcohols due to its higher adsorption efficiency. PEI* was 0.75, 0.5, 0.5 and 0.25 g/l in methanolic, ethanolic, isopropanolic and butanolic suspensions, respectively. Electrophoretic deposition (EPD) was performed at 60 V in different alcoholic suspensions. EPD rate was the fastest in the suspensions with PEI* due to the highest mobility of particles. In contrast to the coatings deposited for 1 min from isopropanolic and butanolic suspensions, those deposited at same conditions from methanolic and ethanolic ones severely cracked during drying owing to their higher thickness and lower PEI contents (acting as the binder). The coatings deposited from methanolic and ethanolic suspensions with PEI* had finer and rougher microstructures. The sintered coating deposited at 60 V for 10 s from ethanolic suspension with PEI* had crack-free microstructure with the thickness of ≈ 130 μm. This coating degraded ≈ 24% of methylene blue from its aqueous solution (30 ml with the concentration of 5 mg/l) within 2 h under UV illumination. Photodegradation of MB on the surface of titania coating obeyed the first order kinetics law.

Electrophoretic deposition of fiber hydroxyapatite/titania nanocomposite coatings

Hydroxyapatite/titania nanocomposite coatings were electrophoretically deposited from ethanolic suspensions of titania and fiber shaped hydroxyapatite (FHA) nanoparticles. Triethanolamine (TEA) was used to enhance the colloidal stability of particles in suspensions. Electrophoretic deposition (EPD) was performed using the suspensions with different concentrations (wt%) of titania/FHA particles. EPD rate decreased more rapidly with time for suspensions with higher wt% of FHA due to the higher voltage drop over the deposits shaped from them. Stacking of long FHA particles on the substrate during EPD resulted in the formation of coarse pores in the deposits. It was found that titania nanoparticles can more efficiently infiltrate through and fill the pores in TEA containing suspensions due to the stronger electrostatic repulsion force between pore walls (FHA) and titania nanoparticles in them. The coatings deposited from the suspensions with 50wt% of FHA or more did not crack during drying due to the significant reinforcement action provided by high wt% of FHA in them. Nanocomposite coatings deposited from TEA containing (2mL/L) suspensions with 50 and 75wt% of FHA had the best corrosion resistance in simulated body fluid (SBF) solution due to their crack-free microstructure and efficiently filled pores.

ELECTROPHORETIC DEPOSITION OF ZnO NANORODS AND NANOPARTICLES

A simple route involving the reaction between zinc powder and water under controlled pH and temperature was used to prepare ZnO nanorods (see Panchakarla et al.). Zinc oxide nanoparticles were prepared also using sol–gel method starting from zinc acetate precursor (as per Zang et al.). Thin films were prepare from both nanorods and nanoparticles by electrophoretic deposition (EPD) in aqueous media (see Dogan et al., Wang et al., Lommens et al., Tang et al. and Besra et al.). To have a uniform microstructure in the deposited films, the aqueous suspension was stabilized using an anionic surfactant. The effect of voltage and pH on the rate of electrophoretic deposition from nano zinc oxide colloid was studied in detail. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Atomic force microscopy (AFM) and UV-Vis Spectroscopy were used to characterize Zno thin films after sintering.

A study of the electrophoretic deposition of Bioglass ® suspensions using the Taguchi experimental design approach

This paper presents a study of the Taguchi design method to optimise the rate of electrophoretic deposition (EPD) of Bioglass ® particles from aqueous suspensions. The effect of Bioglass ® concentration, pH and electric field was investigated. An orthogonal array of L 16 type with mixed levels of the control factors was utilized. Multivariate analysis of variance (MANOVA) and regression analysis based on the partial least-square method were used to identify the significant factors affecting the deposition rate and its stability during constant-voltage EPD. It was found that the pH of the suspension significantly influences the deposition rate whereas the applied electric field has the smallest effect on the deposition rate. In addition, the interaction between the Bioglass ® concentration and pH, which are key processing parameters influencing the deposition rate, was found to be significant. Although a high deposition rate was obtained at low electric field (5 V/cm) and pH 7, the instability of the suspension in particular at high Bioglass ® concentrations resulted in an increase in the variability of the deposition rate. The optimal EPD condition predicted was verified by experiments and good qualitative agreement was obtained. The experimental results and statistical analyses are discussed based on the current knowledge of the EPD of ceramic materials.

Effect of Processing Conditions on Curvature of Anode/Electrolyte SOFC Half-Cells Fabricated by Electrophoretic Deposition

Thin-electrolyte anode-supported solid oxide fuel cells (YSZ/NiO–YSZ) were fabricated for intermediate-temperature operation using electrophoretic deposition (EPD). During cosintering, the half-cells were observed to warp—an undesirable characteristic—due to mismatch in the sintering rates. The influence of the temperature for anode presintering—a key processing step—on the curvature of the half-cells induced by sintering was investigated over 700–1400°C. It was found that the maximum curvature occurred for an anode presintered at 900°C, while the minimum was observed at 1200°C. Anode presintering temperature was also found to affect the rate of electrophoretic deposition. At low presintering temperatures, the rate of EPD increased due to the enhancement in substrate (anode) electronic conductivity as a result of an increased percolating network of NiO. Further increases in presintering temperature, however, resulted in a decrease in the EPD rate due to the formation of a surface layer with poor electronic conductivity as a result of NiO diffusion from the NiO-YSZ anode to the sintering crucible.

Electrophoretic deposition of network-like carbon nanofiber as a conducting substrate for nanostructured nickel oxide electrode

A vapor-grown carbon nanofiber (VGCF) film with network-like architecture was fabricated by electrophoretic deposition (EPD) in the isopropanol suspension containing Ni(NO 3) 2 additive. Nickel ions adsorbed on the VGCFs increase the zeta potential of VGCFs, consequently, the EPD rate and nanofiber dispersion are remarkably improved. Nickel deposition is accompanied by reducing the nickel ions on the surface of VGCFs. Nickel appears to be suitable as a conducting metal binder for attaching the VGCFs. EPD of the nickel oxide on VGCF-coated film exhibits excellent capacitive behavior compared with that bare NiO electrode, resulting from the reduced electron conducting and charge-transfer resistances.

Electrophoretic Deposition of Dense Sr‐ and Mg‐Doped LaGaO3 Electrolyte Films on Porous La‐Doped Ceria for Intermediate Temperature Solid Oxide Fuel Cells

AbstractThe application of the electrophoretic deposition (EPD) technique to the preparation of dense La0.8Sr0.2Ga0.8Mg0.2O2.8 (LSGM) electrolyte films for intermediate temperature solid oxide fuel cells (IT‐SOFCs) was investigated. Suspensions of LSGM were prepared in acetone + I2 + H2O dispersion media. The effects of water and iodine content, of the applied voltage, and of powder loading on the EPD rate were systematically studied using metallic substrates (Pt and stainless steel). This allowed to identify the suitable set of EPD process parameters that were used to deposit LSGM films on tape‐cast composite electrodes, composed of lanthanum‐doped ceria (La0.4Ce0.6O2 –x, LDC), polyvinylidene difluoride (PVDF) and carbon powders. After EPD, dense and crack‐free 15 μm thick LSGM films were obtained on porous LDC by co‐firing in air at 1,490 °C. Line profile analyses performed by energy dispersive X‐ray spectroscopy (EDS) did not reveal any interdiffusion of ions across the LSGM/LDC interface. The chemical and structural compatibility of LSGM with LDC was also checked by heat treating a mixture of the two powders (1:1 weight ratio) using the same thermal cycle as that of the LDC/LSGM bi‐layer co‐firing at 1,490 °C. EPD has thus proven to be a viable way for manufacturing anode‐supported LSGM electrolyte films.

Surface reactivity and electrophoretic deposition of ZrO2–MgO mechanical mixture

Electrophoretic deposition (EPD) is a precision technique useful for obtaining high quality ceramic bodies with controlled dimensions and smooth coatings. The electrophoretic deposition rate is highly dependent on the surface chemistry of the powders, especially when dealing with multi-component systems. The objective of this work is to study the surface reactivity of both ZrO2 and MgO in ethanol suspension to provide experimental benchmarks to control EPD of a ZrO2–3 wt% MgO mechanical mixture (Z3M) in ethanol. Infrared spectroscopy (FTIR) showed that ZrO2 surface spontaneously reacts with ethanol, generating negative electrophoretic mobility of the particles (−0.07 × 10−8 V−1 s−1) measured by Electroacoustic Sonic Amplitude (ESA). MgO surface also spontaneously reacted with ethanol, but a positive electrophoretic mobility was observed in this case (0.26 × 10−8 V−1 s−1). Scanning Electron Microscopy of Z3M dried from ethanol suspension showed that MgO particles were located around the ZrO2 particles, forming composite agglomerates, probably due to the electrostatic attraction between MgO and ZrO2 particles. Homogeneous deposits could be obtained from EPD of Z3M ethanol suspensions. Mercury intrusion porosimetry showed that the ZrO2–MgO green deposited bodies using different voltages had similar pores diameters distributions, indicating that the ZrO2–MgO agglomerates are not affected by the increasing deposition rates.

Electrophoretic deposition of YSZ electrolyte coatings for SOFCs

The main purpose of this study was to create crack-free, thin-film electrolyte coatings for solid oxide fuel cells (SOFCs) at low cost. The electrophoretic deposition (EPD) technique was employed to prepare dense yttria-stabilized zirconia (YSZ) thin films on stainless steel and porous strontium-doped lanthanum manganite (LSM) substrates. The LSM substrates were produced by slurry casting and subsequent sintering. The suspensions of YSZ were prepared in pure acetylacetone, ethanol, and in mixtures of the two. The deposition experiments were performed with the YSZ suspensions in different solvents to examine the effects of the solvent on the EPD behavior. The effects of current density and powder concentration on the EPD rate were also studied. The deposited films were dried at room temperature and then sintered at high temperatures. The microstructures of the sintered coatings were observed with scanning electron microscopy. By using a partially sintered LSM substrate and an optimized set of deposition conditions, dense and continuous YSZ thin-film coatings with thicknesses less than 10 μm were achieved.

Electrophoretic deposition of YSZ electrolyte coatings for solid oxide fuel cells

The main purpose of this study was to create crack-free thin film electrolyte coatings for solid oxide fuel cells at low cost. Electrophoretic deposition (EPD) technique was employed to prepare dense yttria-stabilized zirconia (YSZ) thin films on stainless steel and porous strontium-doped lanthanum manganite (LSM) substrates. The LSM substrates were produced by slurry casting and subsequent sintering. The suspensions of YSZ were prepared in pure acetylacetone, ethanol, and in mixtures of the two. The deposition experiments were performed with the YSZ suspensions in different solvents to examine the effects of the solvent on the EPD behavior. The effects of current density and powder concentration on the EPD rate were also studied. The deposited films were dried at room temperature and then sintered at high temperatures. The microstructures of the sintered coatings were observed with scanning electron microscopy. By using a partially sintered LSM substrate and an optimized set of deposition conditions, dense and continuous YSZ thin film coatings with thicknesses less than 10 μm were achieved.

The effect of In 2O 3 conductive coating on the luminescence and zeta potential of ZnS:Cu, Al phosphors

Phosphors used in CRTs have been coated with In 2O 3 conductive layer derived from the hydrolysis of indium chloride. It was found that brightness of the phosphors rises initially with the amount of InCl 3, reaches a maximum at 10 wt.% InCl 3 and then decreases when more InCl 3 was added. With 10 wt.% InCl 3 coating, the brightness of ZnS:Cu, Al phosphor increases by 24% at 800 V and 1 μA while very little changes were observed in the luminescent emission peak and CIE color loci. The luminescence decay times increase with the increase of the conductive coating. However, they are shorter than 0.7 μs for samples with the amount of coating ranging from 0 to 20 wt.% InCl 3 and are suitable for display applications. Conductive coating affects the surface chemistry of the phosphor particles, enhances the zeta potential of ZnS:Cu, Al in IPA solution, and, consequently, increases the electrophoretic deposition rate of the phosphors onto substrate. The zeta potential of 10 wt.% InCl 3 coated ZnS:Cu, Al in isopropyl alcohol solution is 32 mV as compared to 1.2 mV of that of the uncoated ZnS:Cu, Al. Besides, the electrophoretic deposition rate of the 10 wt.% InCl 3 coated ZnS:Cu, Al (0.23 mg/s) is larger than that of the uncoated phosphor (0.17 mg/s).

Electrophoretic deposition of nanosized zeolites in non-aqueous medium and its application in fabricating thin zeolite membranes

Thin zeolite films with thicknesses from several hundred nanometers to a few micrometers have been fabricated through electrophoretic deposition (EPD) in acetylacetone (Acac) and/or isopropyl alcohol (IPA). Various types of nanosized zeolites with different Si/Al ratios ranging from 1.6 (zeolite LTA) to nearly infinity (silicalite-1) were applied to prepare the EPD suspensions and showed different behaviors in EPD. The EPD rate of zeolite particles in non-aqueous medium was much higher than that in aqueous system mainly due to the high voltage applied, and consequently the whole process was usually completed in a few seconds. It was found that the Al/(Si + Al) ratios of zeolites and the chemical/physical properties of the EPD medium were two crucial factors which affected the thickness and density of the zeolite films prepared by EPD. The zeolite films fabricated through EPD could be effectively densified by secondary growth to prepare compact zeolite membranes.

Influence of Washing on Zirconia Powder for Electrophoretic Deposition

The effects of powder washing on the colloidal stability and electrophoretic deposition rate of 3‐mol%‐Y2O3‐doped tetragonal‐ZrO2 powder from ethanol suspensions are shown experimentally. Simultaneous acoustic and electroacoustic measurements make it possible to determine independently particle size and zeta‐potential in concentrated ethanol suspension. It is suggested that ionic (Na+) surface contamination, which is reduced by laundering cycles, is the cause of the low zeta‐potential and deposition rate of the as‐received powder.