Pre-coated Layer Research Articles

Electrochemical performance of polydopamine-assisted Li[Ni1/3Co1/3Mn1/3]O2/Ketjenblack cathodes

Herein, a Ketjenblack-coated Li[Ni1/3Co1/3Mn1/3]O2 cathode was characterized and compared with a pristine one. The polydopamine pre-coating layer was introduced to facilitate the adhesion between Ketjenblack and pristine powders. Homogenously dispersed Ketjenblack particles on the surface of the pristine powder indicated that the polydopamine layer acted as an effective binding agent. The discharge capacity, cyclic performance, and thermal stability of the Li[Ni1/3Co1/3Mn1/3]O2 cathode were improved by the polydopamine-assisted Ketjenblack coating. This implied that the Ketjenblack layer not only improved the electrical conductivity of the electrode but also protected the electrode from the reactive electrolyte.

Surface modification of Li[Li0.2Ni0.2Mn0.6]O2 nanoparticles with polydopamine-assisted MgF2 coating

Nano-sized Li[Ni0.2Li0.2Mn0.6]O2 powder is vulnerable to reaction with the electrolyte because it has a wide electrolyte/cathode contact area. In order to avoid this, we modified the surface of the nano-sized Li[Ni0.2Li0.2Mn0.6]O2 powder by coating it with MgF2. A polydopamine pre-coating layer served as a binding agent for the homogeneous MgF2 coating on the surface of the Li[Ni0.2Li0.2Mn0.6]O2 nanoparticles. Polydopamine-assisted coating with MgF2 improved the discharge capacity, cyclic performance and thermal stability of the Li[Ni0.2Li0.2Mn0.6]O2 cathode, possibly by suppressing side reactions between the electrolyte and the cathode.

Laser induced forward transfer of Ag nanoparticles ink deposition and characterization

In this work, we report on the printing of silver nanoparticles (Ag NPs) ink by means of laser-induced forward transfer (LIFT) process. The optimum conditions for printing circular shaped features using a Nd:YAG laser at 266nm have been examined. A study of the influence of the laser fluence and the use of a pre-coated intermediate layer (sacrificial layer) on the donor substrate was performed in order to understand how these parameters affect the printed droplets morphology. We also provide a detailed discussion of the influence of the annealing temperature on the printed features morphology and on their resistivity. Based on these results, the conditions have been determined for printing uniform circular shaped droplets with a diameter as small as 25μm and an average thickness of 150nm. Atomic force microscopy on the cured printed droplets revealed a uniform surface morphology with no coffee ring effect. Finally, conductive features with reasonably low resistivity (approximately eleven times that of bulk silver) and at sufficiently low sintering temperatures (100–150°C) were produced on silicon oxide on silicon and flexible polyimide substrates.

Ketjen black/Co3O4 nanocomposite prepared using polydopamine pre-coating layer as a reaction agent: Effective catalyst for air electrodes of Li/air batteries

Abstract A Ketjen black/Co3O4 catalyst nanocomposite was fabricated for use in an enhanced air electrode for Li/air batteries. Polydopamine was used as a coating on Ketjen black to act as a reaction agent, for ensuring homogeneous reaction and adequate distribution of the catalyst nanoparticles on the surface. The results of various characterization analyses indicated successful immobilization of Co3O4 via the polydopamine layer. An electrode prepared using the polydopamine-assisted Ketjen black/Co3O4 nanocomposite exhibited a low overpotential and excellent capacity and cyclic performance, demonstrating the suitability of this novel nanocomposite for use in the air electrode of a Li/air cell.

Al-Si 도금된 22MnB5강의 핫스탬핑 TWB 적용을 위한 레이저용접성 고찰

Recently the use of ultra high strength steels(UHSS) in structural and safety component is rapidly increasing in the automotive industry. Furthermore, it commonly use in tailor welded blank laser welding process before hot stamping to reduce lightweight vehicle. However TWB process is to be a problem about welded strength after hot stamping because it`s welded before heat treatment. Therefore, in this study, laser welds of TWB after heat treatment were analyzed for changes in the characteristics, especially the impact on the oxidation and decarburization in order to prevent pre-coated Al-Si layer welds on the properties for intensive investigation. As a result, the degradation of the TWB weldments changes in the heat treatment conditions alone, without any pre-treatment of the coating layer has confirmed that there is a limitation on the improvement. Furthermore Al-Si elements are overall distributed on the weldment and it specially concentrated along the fusion line. Hardness value of Al-Si segregation area is less than 350Hv and tensile strength showed just 78~83% compared with substrate. Accordingly, we proved that both side Al-Si coating should be removed in order to ensure the strength of the substrate.

Effects of parameters on formation and microstructure of surface composite layer prepared by lost foam casting technique

Surface composite layer was fabricated on the AZ91D substrate using the lost foam casting (LFC) process. The pre-coating layer reacted with melt substrate and formed the composite layer, and the coating was mainly consist of alloying aluminum powder and low-temperature glass powder (PbO-ZnO-Na2O). The vacuum degree, pouring temperature, mold filling process of melt, and pre-coating thickness played an important role during the formation process of composite layer. The results show that surface morphology of composite layer can be divided into three categories: alloying effect of bad and good ceramic layer, alloying effect of good and bad ceramic layer, composite layer of good quality. The main reason for bad alloying layer is that alloying pre-coating thickness is so thin that it is scoured easily and involved in the melt, in addition, it is difficult for melt to infiltrate into the alloying coating owing to the surface tension of coating when the vacuum degree is excessively low. Bad ceramic layer is because of somewhat lower pouring temperature and the thicker alloying coating, due to the absorption of heat from the melt, making low temperature glass powder pre-coating layer fuse inadequate. Thus, to get good quality composite layer, the process conditions must be appropriate, the result shows that the optimum process parameters are as follows: at a pouring temperature of 800 °C, vacuum degree of −0.06 MPa, alloying pre-coating thickness of 0.4 mm, and low glass powder pre-coating layer thickness of 1 mm.

Spray Pyrolized Pre-coating Layers for Controlled Growth of Zinc Oxide Nanorods by Hydrothermal Process

Seeding is critical for the hydrothermal synthesis of zinc oxide (ZnO) nanorod arrays on solid substrates. Herein, spray pyrolysis is proposed as a simple and efficient technique for the deposition ...

Spray Pyrolized Pre-coating Layers for Controlled Growth of Zinc Oxide Nanorods by Hydrothermal Process

Seeding is critical for the hydrothermal synthesis of zinc oxide (ZnO) nanorod arrays on solid substrates. Herein, spray pyrolysis is proposed as a simple and efficient technique for the deposition of ZnO seeding film on glass. The method involves the in situ formation of ZnO nanocrystals by spraying aqueous solution of zinc acetate on hot substrate (°C) whereby ZnO nanocrystallites with narrow size distribution (4-8 nm) are formed. Majority of the crystals were found to have their polar (0001) facet oriented parallel perpendicular to the substrate surface. Upon hydrothermal growth of ZnO nanorods in an equimolar solution of zinc nitrate and hexamine, it was observed that seeding by spray pyrolysis led to the formation of dense ZnO nanorod arrays that were well aligned and strongly attached to the glass substrates. Keywords: Alignment, Array, Attachment, Controlled, Density, Film, Growth, Hydrothermal, Nanocrystallites, Nanorods, Orientation, Seeding, Spray, Pyrolysis, Polycrystalline, ZnO

Spray Pyrolized Pre-coating Layers for Controlled Growth of Zinc Oxide Nanorods by Hydrothermal Process

Seeding is critical for the hydrothermal synthesis of zinc oxide (ZnO) nanorod arrays on solid substrates. Herein, spray pyrolysis is proposed as a simple and efficient technique for the deposition of ZnO seeding film on glass. The method involves the in situ formation of ZnO nanocrystals by spraying aqueous solution of zinc acetate on hot substrate (°C) whereby ZnO nanocrystallites with narrow size distribution (4-8 nm) are formed. Majority of the crystals were found to have their polar (0001) facet oriented parallel perpendicular to the substrate surface. Upon hydrothermal growth of ZnO nanorods in an equimolar solution of zinc nitrate and hexamine, it was observed that seeding by spray pyrolysis led to the formation of dense ZnO nanorod arrays that were well aligned and strongly attached to the glass substrates.

Reduction of zinc consumption with enhanced corrosion protection in hot-dip galvanized coatings: A process-based cost analysis

To improve sustainability in a hot-dip galvanized coating industry, a series of galvanizing techniques have been developed. Here, a relatively novel galvanizing technique developed to reduce zinc consumption and enhance steel's corrosion protection is investigated in relation to the conventional galvanizing technique. A process-based cost modeling (PBCM) is employed to analyze the process's cost effectiveness and to determine the influence of the cost drivers, including part surface area, coating thickness, and raw materials’ costs. The new process, which involves the use of either electrodeposition or electroless-deposition technique, is found economically attractive if the electrodeposition technique is integrated and the pre-coating layer remains thin. The electroless-deposition integrated process shows promise as zinc and nickel prices increase. Cost reduction of the galvanizing process with pre-coating layers is achieved mainly through reduction of zinc consumption and exclusion of the fluxing step.

Corrosion behavior of heat-treated Fe–Al coated steel in lead–bismuth eutectic under loading

A protective surface alloy coating on steel surfaces can prevent steels from the heavy LBE corrosion in the LBE cooled reactor. Especially, Fe–Al alloy coating on a steel surface is effective for corrosion resistance in LBE due to the self-healing of a thin and stable Al oxide layer on the surface of the coating layer. In order to investigate the utility of the coating layer under the stress due to the hydrodynamic and thermal stress induced in the practical system. The Fe–Al coated 316SS, which was heat-treated after the coating process, was immersed in the stagnant LBE at 650 °C for 250 h with loading to investigate the corrosion behavior of the specimen with the bending stress. The Fe–Al coating layer was not corroded because of the protection by Al oxide scale which was formed on the surface of the coating layer and the interface between the coating and the matrix during the heat treatment process. The coating layer cracked elastically. The LBE penetrated into the cracks and corroded the 316SS matrix and the pre-coating layer. The matrix exhibited the dissolution corrosion caused by the preferential dissolution of Ni and the oxidation forming the Fe oxide and Cr oxide. The coating layer is effective to reduce the surface of the matrix to be corroded by LBE, and can moderate the corrosion of the depth direction.

Corrosion Resistance of Fe-Al-Alloy-Coated Ferritic/Martensitic Steel under Bending Stress in High-Temperature Lead-Bismuth Eutectic

The corrosion test was performed for ferritic/martensitic steel HCM12A with and without Fe-Al alloy coating in LBE at temperatures of 550 and 650°C under loading for an immersion time up to 500 h. After the corrosion test at 550°C for 500 h, both of the uncoated and Fe-Al-coated HCM12A showed a good corrosion resistance without the influence of the tensile stress on the LBE corrosion. On the other hand, after the corrosion test at 650°C, the Fe-Al coating layer on the specimen surface exhibited no LBE dissolution corrosion because of the formation of a stable oxide protection film on the coating layer surface, although the coating layer cracked. The LBE penetrated into the cracks and corroded the base metal and the precoating layer. The uncoated HCM12A exhibited the double oxide layers of FeO and Fe- Cr spinel. The FeO was damaged in the bent zone by the stress, and the Fe-Cr spinel layer was not destroyed by the influence of cracking and the tensile stress. The cracking and stress did not have a large influence on the overall oxidation corrosion rate.

TiB 2/Ni coatings on surface of copper alloy electrode prepared by electrospark deposition

In order to improve the lifespan of spot-welding electrodes used for welding zinc coated steel sheets, titanium diboride was deposited onto their surface after precoating nickel as an intermediate layer. The microstructures and phase compositions of TiB 2 and Ni coatings were characterized by SEM and XRD. The coating hardness was measured using a microhardness tester. The results indicate that a satisfactory TiB 2 coating is obtained as a result of the intermediate nickel layer acting as a good binder between the TiB 2 coating and the copper alloy substrate. Owing to its capacity of deforming, the precoated nickel layer is dense and crack free, while cracks and pores are observed in the TiB 2 coating. The hardness of the TiB 2/Ni coating decreases with the increase of voltage and capacitance because of the diffusion of copper and nickel and the oxidation of the coating materials. Because of the good thermal and electrical conductivities and high hardness properties of TiB 2, the deformation of the electrode with TiB 2/Ni coating is reduced and its spot-welding life is by far prolonged than that of the uncoated one.

Fabrication and characterization of solar cells containing polydiacetylene

This report deals with a study of the incorporation of an amphiphilic polydiacetylene, poly(PCDA) in a polymer bulk heterojunction solar cell with MEH-PPV. A poly(PCDA) inserted layer was prepared by spin-coating a poly(PCDA) solution on PEDOT:PSS/ITO coated glass slide. The solar cells structure was completed by spin-coating MEH-PPV solution and Al sputtering, respectively, on top to form ITO/PEDOT:PSS/PDA/MEH-PPV/Al structure. Comparing to the device without poly(PCDA) layer, the current density–voltage characteristics of the device with poly(PCDA) showed an increase of the power conversion efficiency from 0.00035 to 0.00057%, fill factor from 0.18 to 0.19, open circuit voltage from 0.93 to 1.02 V and short-circuit current density from 0.0021 to 0.0029 mA/cm 2 under Air Mass 1.5 simulated solar illumination (100 mW cm −2). The surface morphology of the poly(PCDA) layer studied by AFM imaging revealed that the pre-coated layer of PEDOT:PSS layer improved the roughness and surface coverage of poly(PCDA) on the silicon wafer. Cyclic voltametry gave the HOMO and the LUMO of poly(PCDA) of −5.9 and −4.1 eV, respectively. UV–Vis absorption spectroscopy of poly(PCDA) film showed the absorption band in the range of 500–750 nm with the maximum absorption at around 680 nm.

Active layer transfer by stamping technique for polymer solar cells: Synergistic effect of TiO x interlayer

Several groups reported fabrication method of organic solar cells through a stamping technique by using PDMS mold. Although PDMS is a good stamp material, they have several problems in polymer transfer printing, especially when we use organic solvent (easily swollen). In this study, the polymer solar cells with an active layer of BHJ are successfully prepared via a simple imprinting transfer technique with help of UV-curable resin-coated polycarbonate (UV-PC) film. The transferred BHJ active layer from UV-PC film was perfectly retained at 220-nm thick on top of the PEDOT:PSS-coated ITO glass, and the device showed enhanced J sc and device performance up to 3.19% after insertion of the TiO x interlayer between the active layer and Al cathode. This unique imprinting transfer can be considered as an alternative approach to replace the spin-coating when the matters, pre-coated layers are affected by the solvent for next layer.

Submicron powdered activated carbon used as a pre-coat in ceramic micro-filtration

The aim of the research is to show the bene fi ts of the use of submicron powdered activated carbon (SPAC) in combination with ceramic microfi ltration. The SPAC is applied to the surface as a pre-coat layer. The goals are to improve the removal of NOM and organic micro-pollutants. The SPAC pre-coat layer is also used to reduce fouling of the microfi ltration membrane (without the use of a coagulant). Additionally, virus removal might be increased by the SPAC-layer. The results are presented from laboratory scale experiments with fl at sheets membranes and from pilot experiments with a ceramic membrane module. The laboratory scale experiments show good results for NOM-removal and atrazine removal. Although the empty bed contact time is very short (>1 s), actual breakthrough curves are observed for these two components. The small particle size is benefi cial for the adsorption kinetics of the components. In laboratorys’ experiment, the SPAC also contributed to physical removal (straining) of biopolymers du...

Mechanical and electrical properties of In-Bi solder at Bi 2212 superconductor interface with annealed Ag spray layers and Ag precoating layers

The electrical properties of solder contact layers between Cu-Ni shunt metal and tube type Bi 2212 superconductor that is applied in superconducting fault current limiter were studied. The contact properties of the solders are improved not only by Ag precoating layers, but also by the pre-sprayed Ag layer and subsequent Ag precoating layers. The annealed Ag sprayed layers onto Bi 2212 superconductor prior to Ag electroplating work as protecting layers for the superconductor from plating solutions. The contact angle of the electroplated Ag layer is 42.91° and decreases to 15.25° and 5.88° with Ag sprayed layer and additional Ag electroplated layers. The Ag sprayed layer with suitable annealing prior to Ag electroplating improves contact strength of the Ag electroplated layer by about 12% due to denser microstructure of the Ag electroplated layers.

In Situ Synthesis and Microstructure Manipulation of SAPO-5 Films over Porous α-Al2O3 Substrates

The synthesis and microstructure manipulation of SAPO-5 films on porous alpha-Al2O3 substrates (samples F-1 through F-6) have been studied with the main focus on the effect of Si content, substrate setting, and the structure-directing function of a precoated chitosan thin layer. Without the chitosan layer, the supported SAPO-5 film synthesized under traditional heating is not continuous with either pin holes or crystal boundaries. The preferentially c-oriented SAPO-5 top-layer over a closely packed layer of SAPO-5 crystals was synthesized on the porous alpha-Al2O3 substrate using the chitosan thin layer as the structure-directing matrix. According to the characterization using scanning electron microscopy (SEM) and X-ray diffraction (XRD), the thickness of the c-oriented SAPO-5 top-layer is changed from 1.5 to 10 microm while keeping the thickness of the packed layer of SAPO-5 crystals almost unchanged. Electron probe microanalysis (EPMA) demonstrates that P, Al, Si, and C contents within the two-layer film are uniformly distributed. The percentage of c-oriented crystal grains in the resulting SAPO-5 films evaluated by using the pole-figure analysis is over 70% (71.2% for F-4, 74.2% for F-5, and 75.9% for F-6). On the basis of our experimental observations, it has been indicated that the gradual dissolution of chitosan in the acid precursor solution is accompanied with the formation of the SAPO-5 top-layer and the packed layer of SAPO-5 crystals in the hydrothermal reaction, and both the surface and the entire body of the chitosan layer serve as a three-dimensional structure-directing matrix.

Highly electrocatalytic reduction of nitrite ions on a copper nanoparticles thin film

High dense Cu nanoparticles thin films, with the average size of 25.1 nm, were prepared by electrodeposition Cu nanoparticles on Au electrodes pre-coated 1-decanethiol layers (Cu NPs/thiol/Au). It shows high electrocatalytic capability for the reduction of nitrite ion (NO 2 −) and exhibits a good reproducibility, which can be utilized as efficient electrochemical sensors. The detection limit of NO 2 − approaches ∼10 −7 mM and the response time is fast with the average time of 2 s.

Preparation and Performance of Pre-coated Carbon Layer for Carbon/Carbon Composites

Pre-coated carbon layers on the surface of carbon/carbon composites were prepared firstly by slurry and high-temperature treatment for preparing the anti-oxidation coating with SiC concentration gradient.The micrographs and microstructures of the pre-coated carbon layer were characterized by SEM,Raman and XRD.The effects of different graphite content and carbonization temperature on the microstructure of pre-coated carbon layer were investigated.The bonding strength between the carbon layer and the C/C composites was also measured.The results show that the as-prepared carbon layer is dense and the bend strength reaches 10.5MPa.The structures of the pre-coated carbon layer are influenced by the graphite content and carbonization temperature,and the pre-coated carbon layers with different structures are obtained.