Fabrication of ZrO_2/Mo-Si/Ni Functionally Graded Material by Dip-Coating

A slurry dip-coating technique was developed for fabrication of Zr02/Mo-Si/Ni functionally graded material (FGM)on the stainless steel substrate. The rheological behavior of ZrO2-Ni-ethanol slurry was characterized by viscositytest. The amount of polyvinyl butyral (PVB) additives, which served as the dispersant and binder in ZrO2-Ni-ethanolslurry, was optimized. The results showed that the characters of mixed slurries with added 9 vol. pct (relativelyto total powders) MoSi2 powders prepared by mechanical alloying changed little. The stainless steel substrate wascoated several times by dipping in the slurries, and followed by drying in air every dipping. After debinding in Arin graphite die, the coated FGM plate was finally hot pressed at 1300℃ for 1 h under the pressure of 5 MPa in Arin the same die. Microstructural observations of the sintered FGM specimens revealed that the graded layers wereformed on the stainless steel substrate, in which no cracks were observed.

Influence of Sn Low Doping on the Morphological, Structural and Optical Properties of ZnO Films Deposited by Sol Gel Dip-Coating

In this work, Undoped Zinc Oxide (ZnO) and Sndoped Zinc Oxide (ZnO:Sn) films have been deposited by sol-gel dip coating method, where the Sn/Zn atomic ratio was 3% and 5% in the solution. The effects of Sn incorporation on morphological, structural and optical properties of ZnO films were investigated. The Scanning Electron Microscopy (SEM) showed that the morphological surface of the films was affected by Sn low doping. The X-Ray Diffraction (XRD) patterns showed that all films have polycrystalline structures, and the doping incorporation has not lead to substantial changes in the structural characteristics of ZnO films. The crystallite size was calculated using the well-known Scherrer’s formula and found to be in the range of 23 - 40 nm. The measurements from UV-Visible Spectrophotometer (U-Vis) indicated that the highest average optical transmittance in the visible region was related to Undoped ZnO film, then the optical band gap and Urbach energy values of thin films were calculated. The X-Ray Photoelectron Spectroscopy (XPS) has demonstrated that Sn is incorporated in ZnO lattice.

Comparative Study of Structural, Optical and Electrical Properties of SnO₂Thin Film Growth via CBD, Drop-Cast and Dip-Coating Methods

Tin oxide (SnO2) thin films were deposited on glass substrate by Chemical Bath Deposition (CBD), Drop-Cast and Dip-Coating method. The thin films were post-annealed at 500°C for 2 hours. The structural, optical, and electrical properties of the SnO2 thin films were investigated by using XRD, FTIR, SEM, EDX, UV-Vis spectroscopy, and Electrometer experiment. The XRD patterns of SnO2 thin films deposited on glass substrate by CBD method, Drop-Cast method and Dip-Coating method showed cubic, tetragonal and amorphous structures respectively. The FTIR spectrum exhibited the strong presence of SnO2 with the characteristic vibrational mode of Sn-O-Sn. The SEM analysis was observed that the surface morphology of the thin films toughly depends on the deposition methods of the SnO2 thin films. EDX measurement confirmed that the thin films are the composition of Tin (Sn) and Oxygen (O2). The optical band gap of SnO2 thin films deposited by CBD method, Drop-Cast method and Dip-Coating method is found to be 3.12 eV, 3.14 eV and 3.16 eV respectively. Thin films deposited by Dip-Coating method showed the highest band gap. The electrical results confirmed that the SnO2 thin films are good conductors and pursued Ohm’s Law. These properties of the SnO2 thin films brand are appropriate for application in solar cell assembly, gas sensor devices and transparent electrodes of panel displays.

Dip-coating of SiO2 onto ZnO-SiC Composite Membrane

SiC composite membrane was fabricated by mixing with SiC and ZnO powder. This mixture was pressed and sintered at 1,300 ℃ under air condition. This sintered ZnO-SiC membrane was dip-coated by silica sol and followed by heat-treatment. This membrane was characterized by XRD （X-ray diffraction）, FE-SEM （field emission scanning electron microscopy） and BET （Brunauer-Emmett-Teller） instruments. Hydrogen permeation test was conducted at 0.1 MPa pressure and also variation of temperatures. The obtained value of heat-treated membrane after dip-coating at 298 K was obtained as 1.61 × 10-6 mol/（m2·s·Pa）.

Preparation of highly conductive graphene-coated glass fibers by sol-gel and dip-coating method

In order to fabricate highly-conductive glass fibers using graphene as multi-functional coatings, we reported the preparation of graphene-coated glass fibers with high electrical conductivity through solgel and dip-coating technique in a simple way. Graphene oxide (GO) was partially reduced to graphene hydrosol, and then glass fibers were dipped and coated with the reduced GO (rGO). After repeated solgel and dip-coating treatment, the glass fibers were fully covered with rGO coatings, and consequently exhibited increased hydrophobicity and high electrical conductivity. The graphene-coated fibers exhibited good electrical conductivity of 24.9 S/cm, being higher than that of other nanocarbon-coated fibers and commercial carbon fibers, which is mainly attributed to the high intrinsic electrical conductivity of rGO and full coverage of fiber surfaces. The wettability and electrical conductivity of the coated fibers strongly depended on the dip-coating times and coating thickness, which is closely associated with coverage degree and compact structure of the graphene coatings. By virtue of high conductivity and easy operation, the graphene-coated glass fibers have great potential to be used as flexible conductive wires, highly-sensitive sensors, and multi-functional fibers in many fields.

Superhydrophobic and luminescent cotton fabrics prepared by dip-coating of APTMS modified SrAl2O4:Eu2+,Dy3+particles in the presence of SU8 and fluorinated alkyl silane

An organic-inorganic composite dip-coating method was adopted in order to obtain ideal water repellent cotton fabrics. To be specific, a dual-functional coating with both superhydrophobic and luminescent properties was prepared on cotton fabric by using a dip-coating solution comprising （3-aminopropyl） trimethoxysilane （APTMS） modified SrA1204：Eu2＋,Dy3＋particles, SU8, and fluorinated alkyl silane （FAS）. The micro/nano-scale roughness generated by SrA1204：Eu2＋,Dy3＋ particles, together with low-sur- face-energy FAS, rendered the cotton fabric superhydrophobic with a water contact angle of about 160° and a sliding angle as small as 2°. The coated fabric could withstand at least 100 cycles of standard laundry. The emission spectra of the coated fabric showed two emission peaks at 440 and 520 nm, which belonged to the blue and yellow-green color areas, respectively. The afterglow duration of the coated fabric was mainly influenced by the different depths of the trap levels in the SrA1204：Eu2＋,Dy3＋.

Characterization of yttria-stabilized zirconia films deposited by dip-coating on La_(0.7)Sr_(0.3)MnO_(3) substrate:Influence of synthesis parameters

Yttria-stabilized zirconia(YSZ,ZrO_(2)-8%Y2O_(3))films were deposited onto lanthanum strontium manganite(LSM,La_(0.7)Sr_(0.3)MnO_(3))substrates using dip-coating process aiming for the application in solid oxide fuel cells(SOFCs).YSZ precursor was prepared by sol-gel method;three values of the organic/inorganic concentration ratio(1,3 and 5)were utilized and the sol viscosity was adjusted(60 mPa·s and 100 mPa·s)before deposition on the substrate.The influence of these synthesis parameters on the structure and morphology of the deposited films was examined by X-ray diffraction(XRD)and scanning electron microscopy(SEM).The films showed characteristic peaks of LSM,YSZ(with cubic structure)and secondary phases of SrZrO_(3) and La_(2)O_(3).Depending on the synthesis conditions,crack-free,homogeneous and well adhered films were obtained,with thickness of 11-24μm.

Continuous and highly ordered organic semiconductor thin films via dip-coating:the critical role of meniscus angle

Dip-coating is a low-cost,high-throughput technique for the deposition of organic semiconductors over large area on various substrates.Tremendous studies have been done and many parameters such as withdrawal speed,solvent type and solution concentration have been investigated.However,most of the depositions were ribbons or dendritic crystals with low coverage of the substrate due to the ignorance of the critical role of dynamic solution-substrate interactions during dip-coating.In this study,meniscus angle(MA)was proposed to quantify the real-time in-situ solutionsubstrate interactions during dip-coating.By proper surface treatment of the substrate,the value of MA can be tuned and centimeter-sized,continuous and highly ordered organic semiconductor thin films were achieved.The charge transport properties of the continuous thin films were investigated by the construction of organic field-effect transistors.Maximum(average)hole mobility up to 11.9(5.1)cm2V-1s-1was obtained.The average mobility was 82%higher than that of ribbon crystals,indicating the high crystallinity of the thin films.Our work reveals the critical role of dynamic solutionsubstrate interactions during dip-coating.The ability to produce large-area,continuous and highly ordered organic semiconductor thin films by dip-coating could revival the old technique for the application in various optoelectronics.

Dip-coating of Superhydrophobic Surface on Irregular Substrates for Dropwise Condensation

Herein,self-assembled superhydrophobic composite coatings were successfully prepared using a one-step dip-coating method on different irregular parts.The fluorinated nano-SiO_(2) particles spread into a uniform layer owing to the viscosity of the composite resin.After the optimization of the process,the fabricated nanoporous-structured coating has low adhesion properties with chemical and high thermal stabilities.After baking at 250℃ for 2 h or soaking in a solution of pH=1 or pH=13 for 10 days,the coating could maintain its good superhydrophobicity.The self-ejecting effects of the condensed dewdrops and droplet bounce phenomenon indicate that the coatings can be well-distributed on components of different structures,and they have significant application prospects in irregular parts and industrial production in the near future.

Hyperbranched polymer hollow-fiber-composite membranes for pervaporation separation of aromatic/aliphatic hydrocarbon mixtures

The separation of aromatic/aliphatic hydrocarbon mixtures is crucial in the petrochemical industry.Pervaporation is regarded as a promising approach for the separation of aromatic compounds from alkanes. Developing membrane materials with efficient separation performance is still the main task since the membrane should provide chemical stability, high permeation flux, and selectivity. In this study, the hyperbranched polymer(HBP) was deposited on the outer surface of a polyvinylidene fluoride(PVDF)hollow-fiber ultrafiltration membrane by a facile dip-coating method. The dip-coating rate, HBP concentration, and thermal cross-linking temperature were regulated to optimize the membrane structure.The obtained HBP/PVDF hollow-fiber-composite membrane had a good separation performance for aromatic/aliphatic hydrocarbon mixtures. For the 50%/50%(mass) toluene/n-heptane mixture, the permeation flux of optimized composite membranes could reach 1766 g·m^(-2)·h^(-1), with a separation factor of 4.1 at 60℃. Therefore, the HBP/PVDF hollow-fiber-composite membrane has great application prospects in the pervaporation separation of aromatic/aliphatic hydrocarbon mixtures.

Effects of dip-coated BN interphase on mechanical properties of SiC_f/SiC composites prepared by CVI process

BN interphase was successfully synthesized on SiC fiber fabrics by dip-coating process using boric acid and urea as precursors under N2 atmosphere. The morphology of BN interphase was observed by SEM, and the structure was characterized by XRD and FT-IR spectra. The SiCf/SiC composites with dip-coated BN interphase were fabricated by chemical vapor infiltration （CVI） process, and the effects ofBN interphase on the mechanical properties of composites were investigated. The results show that the SiC fibers are fully covered by BN interphase with smooth surface and turbostratic structure （t-BN）, and the thickness is about 0.4 μm. The flexural strengths of SiCf/SiC composites with and without BN interphase are about 180 and 95 MPa, respectively. Compared with the as-received SiCf/SiC composites, the composites with BN interphase exhibit an obvious toughened fracture behavior. From the microstructural analysis, it can be confirmed that the BN interphase plays a key part in protecting the fibers from chemical attack during matrix infiltration and weakening interfacial bonding, which can improve the mechanical properties of SiCf/SiC composites remarkably.

Preparation and Properties of Dip-coated CeO_2-TiO_2 Thin Golden Glass Film

The golden and ultraviolet-absorbed CeO2-TiO2 film was prepared on soda-lime glass substrate with the thickness of 2 mm via the sol-gel method. The transmission spectra in range of 200 nm-800 nm were measured, and the crystallization, the abrasion and acid resistance were also investigated. The appropriate sol contents and heat-treatment schedule were determined. The results indicate that the appropriate molar ratio of Ce/Ti was 3：5 to 5：6. The ultraviolet-absorbance ability increased with the increase of the Ce/Ti molar ratio, but when the Ce/Ti molar ratio was higher than 1.5, the homogeneity of the film was deteriorated. With the increase of heat-treatment temperature, the main wavelengths of the color of the coated glasses were equal, but the color＇ s saturation decreased; the transmission peaks were the same, while the intensity of the peaks decreased. The roughness, abrasion and acid resistance of the film were also enhanced at the same time. The appropriate heat- treatment temperature may be 340℃.

Thermophysical and Mechanical Properties of ZrO_2 (CaO) Powder and Colloidal Zirconia Sol Dip-Coat Layer Used for Titanium Investment Casting

Both green and residual bending strength of the dip-coat layer composed of ZrO2 (CaO) powder and colloi-dal zirconiz sol binder are sutdied and the effects of process factrs on the strength of dip-coat layer are interpreted,using the results of TG-DTA ,TMA and SEM analyses of the fracture morphology of the coating layer and following the strength theory for porous body.

Effect of silica nanoparticles/poly(vinylidene fluoride-hexafluoropropylene) coated layers on the performance of polypropylene separator for lithium-ion batteries

In an effort to reduce thermal shrinkage and improve electrochemical performance of porous polypropylene （PP） separators for lithium-ion batteries, a new composite separator is developed by introducing ceramic coated layers on both sides of PP separator through a dip-coating process. The coated layers are comprised of heat-resistant and hydrophilic silica nanoparticles and polyvinylidene fluoride-hexafluoropropylene （PVDF-HFP） binders. Highly porous honeycomb structure is formed and the thickness of the layer is only about 700 nm. In comparison to the pristine PP separator, the composite separator shows significant reduction in thermal shrinkage and improvement in liquid electrolyte uptake and ionic conduction, which play an important role in improving cell performance such as discharge capacity, C-rate capability, cycle performance and coulombic efficiency.

Preparation and Characterization of Alumina Membranes on Capillary Supports： Effect of Film-coating on Crack-free Membrane Preparation

Ceramic capillary membrane has received much attention due to its relatively high pack density and favorable mechanical strength.However,it is difficult to prepare capillary membrane on its thin support by a dip-coating method.In this study,alumina microfiltration membranes were prepared on the inner surface of alumina capillary support(outer diameter 4 mm,inner diameter 2.5 mm)by a dip-coating method.Scanning electron microscopy(SEM)observation,gas bubble pressure(GBP)method and membrane permeation test were carried out to evaluate membrane performance.Two major effects in preparation of crack-free membrane,capillary filtration and film-coating,upon the thin support were studied.The as-prepared crack-free membrane presents a narrow pore size distribution,a mean pore size of about 0.6μm and a high pure water flux of 86000 L·m -2 ·h -1 ·MPa.It is proved that the membrane thickness should be sufficiently large to overcome the defects of support surface,but it is only one of the prerequisites for the formation of crack-free membrane.Furthermore,it is demonstrated that the capillary filtration effect is greatly restricted for thin capillary support with the dip-coating method and the film-coating effect plays a crucial role in the formation of crack-free membrane.

Electrochemical Properties of Poly(ethylene oxide)(PEO) Doped TiO_2-PEO Films Prepared by Sol-gel Dip Coating Technique

PEO modified Ti02 -PEO organic-inorganic hybrid thin films were prepared via, sol-gel dipping process on glass substrate pre-coated with ITO. The preparation parameters were studied. Electrochemical and optical properties of the films were characterized by cyclic voltammetric response and visible transmittance. X-ray diffraction (XRD) was used to determined the crystalline structure of the gel. The results show the sols added with PEO have acceptable stable periods for practical use. The PEO modified optical transitivity of the hybrid films has heavy effects on the crystallization of TiO2 during structural evolution because of the interaction between PEO and Ti02 . PEO-TiO2 films have better electrochemical activity than the TiO2 equivalent behaved as higher Li + insertion/extraction current density and cyclic reversibility.

PREPARATION OF POLYVINYLIDENE FLUORIDE/POLYVINYL DIMETHYLSILOXANE COMPOSITE HOLLOW FIBER MEMBRANES AND THEIR SEPARATION PROPERTIES

Microporous polyvinylidene fluoride(PVDF)hollow fibre membranes were spun using the dry-wet phaseinversion method.By means of dip-coating technique,a uniform coating with thickness of around 5-12 μm of polyvinyldimethylsiloxane(PVDMS)was formed on the surface of porous PVDF hollow fibers.The structural parameters of PVDFsubstrate membrane were estimated by gas permeation test.Using N_2/O_2 as the medium,the separation properties ofPVDMS-PVDF composite hollow fiber membranes were also evaluated experimentally.The experimental data of bothpermeability and selectivity are in good agreement with the theoretical results predicted by the presented pore-distributionmodel.In order to obtain the compact composite membrane free of defects by the dip-coating technique,the thickness ofPVDMS skin must be higher than 5 μm.

Highly-transparent Perovskite Thin Films Obtained by a Wet Chemical Processing Method

Barium titanate thin films are widely used for making the multilayer capacitors. High transmittance barium titanate thin films are rarely reported in the literature. This work reports a new sol-gel routine for obtaining high transmittance BaTiO3 (BTO) thin films, then the optical responses of the products are evaluated. Experimental results show that the topography and morphology of BTO coating are improved using our established method and thus the better optical responses have BTO obtained. It is seen that the optical losses of BTO thin coating are lower in contrast to similar works. Results also indicate that increment of the calcination temperature reduces the thin films transparency and thickness. Other results show that an increase in the withdrawal rate of the substrate from the sol results in an increase in the BTO coating thickness and a decrease in transparency of the BTO coating. The prepared highly transparent nanothin films are amorphous due to the maximum temperature experienced and are as thin as 30 nm. We think that obtained BTO thin coatings are desired for optical and electro-optical applications.

Supramolecular PS-P4VP diblock copolymer thin films slowly dip-coated from chloroform solutions

This contribution shows the strong influence of using chloroform instead of THF on the characteristics of thin films of supramolecular block copolymers of poly(styrene-b-4-vinyl pyridine) dip-coated in the so-called "capillarity" regime from solutions containing 1-naphthol or 1-naphthoic acid.The small molecule content in the dip-coated films was investigated by infrared spectroscopy and the film morphology by atomic force microscopy.It was found that the small molecule content in the films is constant with dip-coating rate in the range investigated,but it is higher for 1-naphthoic acid than for 1-naphthol.The main morphology observed was in the form of "islands" and "holes",which is typical of flat-on lamellae.These findings are related to hydrogen-bonding between the small molecule and pyridine being conserved in chloroform and to the good solubility of both blocks in this solvent,with differences between the two small molecules related to their differing H-bond strengths.These findings contrast strongly with what was observed previously using THF as a solvent,for which the SM content increases with dip-coating rate and the morphologies are mainly spherical and cylindrical in the same parameter range.

UV-triggered Polymerization of Polyelectrolyte Composite Coating with Pore Formation and Lubricant Infusion

Porous coatings with the features of muti-interfaces and high specific surface area have emerged as an excellent material platform for the manipulation of porous structures.Layer-by-layer(Lb L)assembly technique has been widely used in preparing porous polyelectrolyte coatings.However,the efficient construction of stable film from the Lb L technique is still a question.Herein,we reported a new solution to construct a stabilized polyelectrolyte coating with porous structures.Inspired by the mechanical reinforcement of double-network hydrogel,we constructed the poly(ethylenimine)(PEI)/poly(acrylic acid)(PAA)coating by in situ photopolymerization of acrylic acid in the PEI network instead of assembling PEI and PAA.Compared with the Lb L films,the in situ polymerized coating kept higher stability after 30 iterations of friction.Porous structures could also be constructed after acid treatment,which was utilized to load lubricant to enhance the lubricating property of the coating.This work provides a new method for the construction of dynamic and stable polyelectrolyte coatings,expediting more development of practical applications.