Electrophoretic Co-deposition Research Articles

Effect of graphite on microstructure and friction-wear properties of yttria-stabilized zirconia coatings

Yttria-stabilized zirconia and flake graphite composite (C/YSZ) coatings were successfully prepared on a TC4 substrate by electrophoretic co-deposition and sintering at 1100 °C using YSZ nanopowder and flake graphite. The effects of the graphite content on the microstructure and friction-wear properties were investigated. The results indicated that flake graphite agglomerated in the C/YSZ coating. The YSZ coating with 0.6wt.% graphite exhibited the highest toughness with the plastic resistance index (H/E) of 0.0172, which was 6.8 % higher than that of the YSZ coating, and effectively inhibited the formation of coating cracks. However, an increase or a decrease in the graphite content led to a decrease in the toughness of the C/YSZ composite coating. The agglomerated graphite in the C/YSZ composite coating acted as a solid lubricant and affected friction and wear properties. The coefficient of friction (COF) of the 0.6C/YSZ sample was 0.45, which was 40 % lower than that of the YSZ sample. The reason for this was that graphite effectively inhibited the falling-off of debris from the coating surface and reduced abrasive wear. However, an excessive amount of graphite, i.e., in case of the 0.8C/YSZ coating, decreased the roughness of the wear surface, leading to a reduction in the H/E and COF by 24.4 % and 29.7 %, respectively.

Supported g-C3N4/WO3 mixed layers for photocatalytic water remediation

g-C3N4 layers with good mechanical properties, including their cohesion and adhesion to stainless-steel supports, were prepared by the quantitative electrophoretic co-deposition of g-C3N4 and WO3 nanocrystals. It was carried out in a mixture of organic solvents by applying a voltage of 750 V. The typical layer area density was 0.64 mg cm–2. The photocatalytic degradation of 4-chlorophenol under blue-light irradiation showed that the performance of stable composite layers containing 25–50 wt.% of WO3 was only slightly weaker than that of unstable pristine g-C3N4 ones. The high photocatalytic performance was due to g-C3N4, while WO3 contributed to a good mechanical resistance of layers in stirred water. Finally, the composite layers exhibited a very high 4-chlorophenol mineralization of 75% in 24 h, even higher than the corresponding suspensions. Owing to their stability in water and performance, the developed layers are suitable for applications in environmental technologies.Graphic

Application of meglumine for the solubilization of an alginic acid polymer and drug, the synthesis of hydroxyapatite, and the electrophoretic co-deposition

Application of meglumine for the solubilization of an alginic acid polymer and drug, the synthesis of hydroxyapatite, and the electrophoretic co-deposition

(Invited) Structural Lithium-Ion Battery Based on LiFePO4/Reduced Graphene Oxide Composite Cathode and Graphene Anode Prepared via Electrophoretic Deposition on Carbon Cloth

Structural lithium-ion batteries based on binder-free LiFePO4/reduced graphene oxide composite cathode electrode and graphene anode electrode are prepared respectively via electrophoretic co-deposition of LiFePO4, reduced graphene oxide, and carbon black on carbon cloth substrate for the cathode, and graphene oxide and carbon black on carbon cloth substrate for the anode. Following deposition, the electrode materials were dried. The graphene oxide of the anode was reduced to graphene via rapid thermal annealing. Possessing excellent stiffness, strength-to-weight ratio, and good electrical conductivity, the carbon cloth substrate serves multifunctional roles in the battery: as structural reinforcement and mechanical load bearing element and as current collector. Given its good electrical conductivity, high aspect ratio, and high surface area, reduced graphene oxide improves electrical conductivity within the cathode and provides sites for hosting LiFePO4; this enhances reversible Li ion extraction from the host during cycling. Graphene with its good electrical conductivity and high aspect ratio provides sites for insertion of Li ions in the anode; this enhances the aerial lithiation capacity of the battery system. Carbon black enhances conductivity within the two electrodes and reduces interfacial impedance. The electrochemical properties of the electrodes are strongly correlated to their microstructure and phase composition. Electrochemical characterization of the electrodes and their performance in half-cell and full cell configurations are evaluated. Additionally, Li-ion diffusivity within the materials is evaluated with three independent electroanalytical methods, including potentiostatic and galvanostatic and intermittent titration techniques, and electrochemical impedance spectroscopy.

3D porous Ti3C2Tx prepared on carbon cloth by electrophoretic co-deposition for enhanced supercapacitor performance

3D porous Ti3C2Tx prepared on carbon cloth by electrophoretic co-deposition for enhanced supercapacitor performance

Corrosion Protection Behavior of Aluminate Ion-Loaded Layered Double Hydroxide Coating on AZ31 Magnesium Alloy

Effect of aluminate ion loading on the corrosion behavior of layered double hydroxide (LDH) coating of Mg-3Al-1Zn (AZ31) alloy was investigated. The corrosion inhibition performance of NaAlO2 for AZ31 was examined by immersion and polarization tests. Then, aluminate ion-loaded LDH (LDHAlO2) was synthesized from hydrotalcite (LDHCO3) and co-deposited with magnesium and aluminum double hydroxide on AZ31 by electrophoretic co-deposition. Polarization, electrochemical impedance (EI) and wet-dry cyclic corrosion tests were conducted on the LDHAlO2- and LDHCO3-coated specimens. Adding 10–50 mmol l−1 NaAlO2 to 0.1 mol l−1 NaCl solution induced a clear passive region on the polarization curves of AZ31 and shifted the breakdown potential over −1.0 V (Ag/AgCl), indicating the corrosion inhibition property of NaAlO2. In the polarization and EI tests, the aluminate ion loading did not noticeably enhance the corrosion protection ability of the LDH coating as shown by higher quasi-passive current density and lower R p than without loading. However, in the wet-dry corrosion tests, the LDHAlO2-coated AZ31 demonstrated less weight gain and fewer clusters of shallow micro-pits, while the LDHCO3-coated AZ31 showed numerous deeper pits on the entire surface. It was revealed that loading aluminate ions to the LDH coatings is promising for enhancing their corrosion protection ability in atmospheric environments.

Synthesis and Characterization of Composite Coating of Iron Oxide and Bioactive Glass, Coated by Electrophoretic co-Deposition Method for Biomedical Applications

Synthesis and Characterization of Composite Coating of Iron Oxide and Bioactive Glass, Coated by Electrophoretic co-Deposition Method for Biomedical Applications

Resveratrol promotes osteogenesis and angiogenesis through mediating immunology of senescent macrophages

Orthopedic implants have been used clinically to restore the functions of the compromised bone tissues, but there is still a relatively high risk of failure for elderly people. A critical reason is pro-inflammatory immune microenvironment created by senescent macrophages with homeostasis imbalance impairs osteogenesis and angiogenesis, two major processes involved in implant osseointegration. The present work proposes to use resveratrol as an autophagy inducing agent to upregulate the autophagy level of senescent macrophages to restore homeostasis, consequently generating a favorable immune microenvironment. The results show 0.1–1 μM of resveratrol can induce autophagy of senescent macrophages, promote cell viability and proliferation, reduce intracellular reactive oxygen species level, and polarize the cells to pro-healing M2 phenotype. The immune microenvironment created by senescent macrophages upon resveratrol stimulation can promote osteogenesis and angiogenesis, as manifested by upregulated proliferation, alkaline phosphatase activity, type I collagen secretion, and extracellular matrix mineralization of senescent osteoblasts as well as nitric oxide production, migration, and in vitro angiogenesis of senescent endothelial cells. In addition, resveratrol-loaded silk fibroin coatings can be fabricated on titanium surface through electrophoretic co-deposition and the coatings show beneficial effects on the functions of senescent macrophages. Our results suggest resveratrol can be used as surface additive of titanium implants to promote osseointegration of elderly people though regulating immunology of senescent macrophages.

An electrophoretic co-deposition of metal oxides followed by in-situ copper manganese spinel synthesis on AISI-430 for application in SOFC interconnects

Electrophoretic co-deposition of copper and manganese oxides followed by in-situ reactive sintering is investigated as a method of Cu–Mn spinel coating for application in SOFC interconnects. Effect of electrophoretic deposition parameters including time, voltage, solid concentration and dispersant content on the quality and quantity of deposition are examined. A uniform layer of oxides is co-deposited at 100 V, in 10 min, with 10 g/L oxides in ethanol-acetone solution and 1:16 w/w dispersant:oxides. Based on XRD and SEM-EDS results, rate of Fe and Cr diffusion is unacceptable at above 850 °C. 3 h of sintering in air at 800 and 850 °C is best to synthesize spinel without severe Fe–Cr contamination. In a 100-h cyclic oxidation test, coatings prevent chromium poisoning and reduce the oxidation rate by a minimum of two orders of magnitude decrease in the parabolic rate constant of oxidation from 1.34 × 10−12 in uncoated to 8.50 × 10−14 g2 cm−4 s−1 and 32.3% decrease in Cr at.% in the coated samples.

Corrosion Resistance and Electrical Conductivity of Hybrid Coatings Obtained from Polysiloxane and Carbon Nanotubes by Electrophoretic Co-Deposition.

Nanocomposites developed based on siloxanes modified with carbon nanoforms are materials with great application potential in the electronics industry, medicine and environmental protection. This follows from the fact that such nanocomposites can be endowed with biocompatibility characteristics, electric conductivity and a high mechanical durability. Moreover, their surface, depending on the type and the amount of carbon nanoparticles, may exhibit antifouling properties, as well as those that limit bacterial adhesion. The paper reports on the properties of polysiloxane (PS) and carbon nanotubes (CNT) nanocomposite coatings on metal surfaces produced by the electrophoretic deposition (EPD). A comparison with coatings made of pure PS or pure CNT on the same substrates using the same deposition method (EPD) is provided. The coatings were examined for morphology and elemental composition (SEM, EDS), structural characteristics (confocal Raman spectroscopy), electrical conductivity and were tested for corrosion (electrochemical impedance spectroscopy-EIS, potentiodynamic polarization-PDP). The results obtained in this study clearly evidenced that such hybrid coatings conduct electricity and protect the metal from corrosion. However, their corrosion resistance differs slightly from that of a pure polymeric coating.

Electrophoretic co-deposition of Mn1.5Co1.5O4, Fe2O3 and CuO: Unravelling the effect of simultaneous addition of Cu and Fe on the microstructural, thermo-mechanical and corrosion properties of in-situ modified spinel coatings for solid oxide cell interconnects

A systematic microstructural, thermo-mechanical and electrical characterization of simultaneous Fe–Cu doped Mn–Co spinel coatings processed by electrophoretic co-deposition on Crofer 22 APU is here reported and discussed. An innovative approach for the simultaneous electrophoretic deposition of three spinel precursors is designed, conceived and optimised, with the aim of outlining time- and energy-saving spinel modification routes. The effect of different levels of Cu and Fe co-doping is observed on the stability of the modified Mn–Co spinel phase, the coefficient of thermal expansion (CTE), the corrosion resistance and on the densification behaviour of the obtained coatings. Cu determines an increase of CTE, while Fe has the opposite behavior. The synergic effect of the simultaneous Fe and Cu co-doping results in an improved densification and the stabilization of the MnCo2O4 cubic phase. The most interesting results in terms of corrosion resistance are obtained for the Mn1.28Co1.28Fe0.15Cu0.29O4 spinel.

CdSe-TiO2 nanocomposites film deposited by electrophoretic co-deposition towards quantum dots sensitized solar cells

In this paper, cadmium selenide (CdSe) nanoparticles were used in quantum dots sensitized solar cells (QDSSCs) as photosensitizer. Electrophoretic co-deposition was employed to deposit cadmium selenide – titanium dioxide (CdSe-TiO2) nanoparticles for the preparation of the QDSSC photoanode. Co-deposition of CdSe-TiO2 were used to prevent the need of thermal treatment to the photoanode which could cause cracks on surface. The formation of CdSe-TiO2 nanocomposites could increase the electron injection speed due to interdigitated between CdSe and TiO2 nanoparticles. CdSe nanoparticles were prepared using hot injection methods at reaction temperature 300 °C for 1 min reaction time. Titanium dioxide (TiO2) nanoparticles solution was prepared using surface modification by propionic acid and n-hexylamine. Cu2S/Brass counter electrode was used with polysulphide electrolyte. Prior to electrophoretic deposition (EPD), the CdSe nanoparticles solution were purified for two times. The efficiency of the QDSSC assembled with photoanode deposited with 250 V and 90 s was the highest amongst of the other EPD parameter studied, were at 2.920 × 10−3 %.

Development of Microstructure and Properties of Multicomponent MoS2/HA/PEEK Coatings on a Titanium Alloy Via Electrophoretic Deposition and Heat Treatment

In this study, molybdenum disulfide nanosheets, bioactive hydroxyapatite particles of two types in various amounts, and PEEK 704 microparticles were electrophoretically co-deposited to fabricate multicomponent coatings on Ti-13Nb-13Zr alloy substrates. A mixture of pure ethanol and cationic chitosan polyelectrolyte was used as a dispersion medium. The kinetics and mechanism of deposition were investigated. The kinetics depended significantly on the suspension’s chemical composition and the voltage used during EPD. Cationic chitosan provided the steric stabilization of the suspension and enabled cathodic co-deposition of all coating components. Green macroscopically homogeneous coatings were subsequently heat treated. The treatment densified the coatings and caused the formation of a stable semi-crystalline PEEK matrix consisting of spherulites. The MoS2 nanosheet packages, separate HA particles and their agglomerates were embedded in the coating matrix. After heat treatment, both types of coatings, differing in HA type, were characterized by excellent adhesion to the substrate and moderate scratch resistance. During surface topography investigation, it was found that coatings containing smaller HA nanoparticles had a slightly lower surface roughness. The coatings raised the corrosion resistance of the titanium alloy substrate in Ringer’s solution. The possibility of the electrophoretic co-deposition of various ceramic and PEEK particles to develop multicomponent coatings, as well as their contribution to enhancing titanium alloy surface properties, represents an important input in further developing superior bioactive titanium implants.

Development of Carbon Fiber-Based Ni(OH)2 Electrode for Application in Urea Wastewater Treatment/Hydrogen Production

Introduction Urea-containing wastewater is discharged every day from factories, agricultural fertilizers, and human/animal urine, etc. If we do not properly teat it in time, it will cause environmental pollution, health hazards and other problems. Conversely, treating urea-containing wastewater can produce H2 energy source through an electrolysis process [1], which is considered attractive due to its lower electrolysis voltage than that for water splitting. In the past, nickel hydroxide (Ni(OH)2) has been used as a catalyst material for urea oxidation reaction (UOR), because it has several advantages such as cheap and good catalytic effect on urea. However, UOR performance is still not satisfied due to poor material design for electrodes, and thus needs to be improved. In light of this, our research is committed to developing a composite electrode integrating Ni(OH)2, carbon nanotubes (CNTs), and carbon fibers (CFs). The electrode allows to enhance UOR performance, which can simultaneously benefit urea degradation and H2 production. Experimental CFs were used as the electrode substrate, and Ni(OH)2 were deposited on the CFs surface together with carbon nanotubes (CNTs), through a one-step electrophoretic co-deposition method. Afterward, the composite was further experienced a hydrothermal reaction to complete the fabrication of the Ni(OH)2/CNT/CF electrode. SEM, XRD, Raman spectroscopy, and TGA were used to examine the material properties of the composite electrode. A three-electrode electrolytic system composed of the composite electrode, a Pt counter electrode, and a Ag/AgCl reference electrode was set up to treat the urea-containing wastewater. During the treatment, cyclic voltammetry and linear sweep voltammetry were applied to investigate the Ni(II)/Ni(III) redox reaction and UOR. Details about the electrode kinetics were also discussed. Results and Discussion The experimental results show that the Ni(OH)2/CNT/CF electrode has more favorable UOR performance compared to the Ni(OH)2/CF and CF ones. In addition, the α-Ni(OH)2-phase catalyst is found to present better electrocatalytic activity than the β-Ni(OH)2-phase catalyst. This could be due to larger d spacing of (001) plane in α-Ni(OH)2, allowing more inserted water molecules than those in β-Ni(OH)2. Accordingly, it expedites ion transport between the Ni(OH)2 sheets and repeated Ni(II)/Ni(III) transformation during continuous UOR [2], corresponding to better electrochemical performance. On the other hand, doping CNTs is found to benefit the increased reaction area and electrical conduction of the composite electrode. As a result, the required overpotential for UOR is reduced and the reversibility of Ni(II)/Ni(III) redox reaction is improved, leading to more efficient UOR.

Electrochemical fabrication of carbon fiber-based nickel hydroxide/carbon nanotube composite electrodes for improved electro-oxidation of the urea present in alkaline solutions

A Ni(OH)2/carbon nanotube (CNT)/carbon fiber (CF) composite electrode was developed, and its electrode kinetics was investigated to improve its urea oxidation reaction (UOR) performance. The fabrication of the electrode was done using electrophoretic co-deposition combined with hydrothermal reaction. Scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy were used to examine the electrode properties, while cyclic voltammetry (CV), linear sweep voltammetry (LSV), and electrochemical impedance spectroscopy (EIS) were used to study the electrode kinetics. The prepared catalyst that had a flake-like structure was an α phase Ni(OH)2 catalyst, which mixed well with the CNTs to form a composite layer on the CF substrate. The α-Ni(OH)2/CNT/CF electrode displayed satisfactory UOR performance because it had a higher oxidation current and a lower overpotential than those of either the α-Ni(OH)2/CF electrode or CF electrode. These improved properties of the α-Ni(OH)2/CNT/CF electrode can be because of the active and reversible Ni2+/Ni3+ redox reaction, which has high rate constant and anodic transfer coefficient, of the α-Ni(OH)2/CNT composite. Moreover, compared with α-Ni(OH)2/CF or CF electrodes, the α-Ni(OH)2/CNT/CF electrode has a low charge transfer resistance because of the increase in the reaction surface area and electrical conductivity caused by the CNTs. Overall, the composite electrode combines the advantages of the α-Ni(OH)2 catalyst, CNT conductive network, and CF current collector for improved UOR performance, which will be beneficial for urea pollution mitigation and H2 production.

Electrophoretic Co-deposition of Polyetheretherketone and Graphite Particles: Microstructure, Electrochemical Corrosion Resistance, and Coating Adhesion to a Titanium Alloy.

The present study explores the possibilities of fabricating a graphite/polyetheretherketone (PEEK) composite coating on a Ti-6Al-4V titanium alloy through duplex treatment consisting of electrophoretic deposition (EPD) and heat treatment. It has been found that the electrophoretic co-deposition of graphite and PEEK microparticles can be performed from environmentally-friendly pure ethanolic suspensions. Zeta potential measurements and a study of the interaction between both particle types with the use of transmission electron microscopy allowed potential mechanisms of particle co-deposition to be indicated. Microstructure characterization was performed on macro-, micro- and nanoscale using visible light microscopy, X-ray diffractometry and electron microscopy. This allowed the coating homogeneity and distribution of graphite particles in the polymer matrix to be described. Graphite particles in the form of graphene nanosheet packages were relatively evenly distributed in the coating matrix and oriented parallel to the coating surface. The heat-treated coatings showed high scratch resistance and no adhesive type destruction was observed, but they were highly susceptible to deformation. The corrosion measurements were performed with use of electrochemical techniques like open circuit potential and linear sweep voltamperometry. The coated alloy indicated better electrochemical corrosion resistance compared with the uncoated alloy. This work showed the high versatility of the electrophoretic co-deposition of graphite and PEEK particles, which combined with post-EPD heat treatment allows composite coatings to be fabricated with controlled distribution of graphite particles.

Nanocomposite coatings obtained by electrophoretic co-deposition of poly(etheretherketone)/graphene oxide suspensions

Nanocomposite coatings were successfully prepared by electrophoretic deposition of poly(etheretherketone) (PEEK)/graphene oxide (GO) suspensions. The GO flakes developed a large-scale co-continuous morphology with the basal plane mainly aligned with the coating surface. However, the PEEK particles were also found to be wrapped by GO nanosheets when deposited on the stainless steel substrate. Both phenomena, the co-continuous morphology and the wrapping effect, were dependent on the initial GO content in the suspension and influenced the final morphological characteristics of the thermally treated coatings. The PEEK matrix developed a dendritic morphology during its cooling from the molten state because of transcrystallinity that was induced by the incorporation of GO. The preparation of suspensions involved tip ultrasonication (TS) to deagglomerate, disperse, and mill the PEEK particles. A detailed study of the microstructure revealed that TS tended not only to reduce PEEK particle size, but also to promote an elongated shape, favourable for the nanocomposite coatings.

Iron doped manganese cobaltite spinel coatings produced by electrophoretic co-deposition on interconnects for solid oxide cells: Microstructural and electrical characterization

We report a systematic microstructural and electrical characterization of iron doped Mn–Co spinel coatings processed by electrophoretic co-deposition of Mn1.5Co1.5O4 and Fe2O3 powders on Crofer 22 APU and AISI 441 steel substrates. Iron addition to Mn–Co spinel coating leads to a reduction of the area specific resistance on both substrates, after 3200 h at 750 °C. The Fe doped Mn–Co coating both leads to a thinner oxide scale and reduces the sub scale oxidation for the Crofer 22 APU substrate. Fe doped Mn–Co on AISI 441 shows both a thicker oxide scale and low area specific resistance values, likely due to a doping effect of the oxide scale by minor alloying elements. The different mechanisms by which iron doping of Mn–Co spinels can influence elemental interdiffusion at the steel-oxide scale-coating interfaces and relative contributions to the overall area specific resistance are evaluated by means of advanced electron microscopy. The promising results are further confirmed in a cell test, where the Fe doped MnCo coated interconnect does not induce any degradation of the oxygen electrode, proving its efficiency.

PHOTOCATALYTIC ACTIVITY AND WETTABILITY OF RGO/TiO2 NANOCOMPOSITES PREPARED BY ELECTROPHORETIC CO-DEPOSITION

Reduced graphene oxide (RGO)/TiO2 nanocomposite coating was synthesized using electrophoretic co-deposition (EPD) of graphene oxide and TiO2 colloidal suspension. Direct assembly by EPD facilitated the transformation from GO to RGO and resulted in RGO/TiO2 films on Cu substrate. The prepared samples were characterized by X-ray diffraction, field emission scanning electron microscopy, Fourier transform infrared spectroscopy and Raman spectroscopy. The obtained results proved the presence of titania nanoparticles and RGO planes in the nanocomposite coatings and the reduction of GO during EPD process. Methylene blue photodegradation experiments showed that the degradation efficiency and the reduction rate of the contact angle increased in nanocomposite coatings by 12% and 15%, respectively. There is a direct correlation between the amount of RGO in the coating and the improvement of the photocatalytic activity and wettability.

In-situ Cu-doped MnCo-spinel coatings for solid oxide cell interconnects processed by electrophoretic deposition

Abstract The Cu doping of the Mn–Co spinel is obtained “in-situ” by electrophoretic co-deposition of CuO and Mn 1.5 Co 1.5 O 4 powders and subsequent two-step reactive sintering. Cu-doped Mn 1.5 Co 1.5 O 4 coatings on Crofer22APU processed by electrophoretic co-deposition method are tested in terms of long term oxidation resistance and area specific resistance tests up to 3600 h. The introduction of Cu in the spinel lead to higher level of densification of coatings for all the considered aging periods at 800 °C and stabilizes the cubic phase of the Mn 1.5 Co 1.5 O 4 spinel. Corrosion rate of the Cu-doped Mn 1.5 Co 1.5 O 4 coated Crofer22APU is ∼10x lower than for the uncoated Crofer22APU. The stabilization of the cubic phase due to Cu doping, which reduces the extent of the tetragonal-cubic phase transition and limits possible thermal stresses due to mismatch of coefficients of thermal expansion or volume changes, is reviewed and discussed by means of electrical conductivity measurements together with diffraction patterns and elemental analyses. These novel electrophoretic co-deposited Cu-doped MnCo spinel coatings represent an innovative approach to obtain coatings with higher density and have future applications in the view of reaching lower rates of Cr evaporation form the steel.