Spray coating of polysulfone/poly(ethylene glycol) block polymer on macroporous substrates followed by selective swelling for composite ultrafiltration membranes

Polysulfone(PSF) is extensively used for the production of ultrafiltration(UF) membranes thanks to its high strength,chemical stability,and good processibility.However,PSF is intrinsically hydrophobic,and hydrophilic modification is always required to PSF-based membranes if they are intended to be used in aqueous systems.Facile strategies to prepare hydrophilic PSF membranes are thus highly demanded.Herein we spray coat a PSF-based amphiphilic block polymer onto macroporous substrates followed by selective swelling to prepare flat-sheet PSF UF membranes.The polymer is a triblock polymer containing PSF as the majority middle block tethered with shorter block of polyethylene glycol(PEG) on both ends,that is,PEG-b-PSF-b-PEG.We use the technique of spray coa ting to homogeneously dispense diluted triblock polymer solutions on the top of macroporous supports,instantly resulting in uniform,defect-free polymer coating layers with the thickness down to ~1.2 μm.The bi-layered composite structures are then immerged in ethanol/acetone mixture to generate mesoscale pores in the coating layers following the mechanism of selective swelling-induced pore generation,thus producing composite membranes with the mesoporous triblock polymer coating as the selective layers.This facile strategy is free from additional hydrophilic modification and much smaller dosages of polymers are used compared to conventional casting methods.The pore sizes,porositie s,hydrophilicity,and consequently the separation properties of the membranes can be flexibly tuned by changing the swelling duration and the composition of the swelling bath.This strategy combining spray coating and selective swelling is upscalable for the production of highperformance PSF UF membranes.

Study on the Training Strategy of High Skilled Talents of Spray Coatings for Automobile in Secondary Vocational School——from the Perspective of Made in China 2025 Strategy

Made in China 2025 Strategy requires a large number of high skilled talents,which the high-skilled talents are the core backbone of skilled workers and a significant force to promote technological innovation and realize the transformation of scientific and technological achievements.In this study,combined with automotive spraying industry characteristics,four cultivation strategies are established by the construction of the system of high-skilled talent formation,training mode of on-campus+on-job highskilled talents,the common trail of national certification and enterprise certification and the star system spiraling excitation in order to create a new growth path for the cultivation of high-skilled talents in automobile spraying.

Parameter Optimization of Amalgamated Al2O3-40% TiO2 Atmospheric Plasma Spray Coating on SS304 Substrate Using TLBO Algorithm

SS304 is a commercial grade stainless steel which is used for various engineering applications like shafts, guides, jigs, fixtures, etc. Ceramic coating of the wear areas of such parts is a regular practice which significantly enhances the Mean Time Between Failure (MTBF). The final coating quality depends mainly on the coating thickness, surface roughness and hardness which ultimately decides the life. This paper presents an experimental study to effectively optimize the Atmospheric Plasma Spray (APS) process input parameters of Al2O3-40% TiO2 ceramic coatings to get the best quality of coating on commercial SS304 substrate. The experiments are conducted with a three-level L18 Orthogonal Array (OA) Design of Experiments (DoE). Critical input parameters considered are: spray nozzle distance, substrate rotating speed, current of the arc, carrier gas flow and coating powder flow rate. The surface roughness, coating thickness and hardness are considered as the output parameters. Mathematical models are generated using regression analysis for individual output parameters. The Analytic Hierarchy Process (AHP) method is applied to generate weights for the individual objective functions and a combined objective function is generated. An advanced optimization method, Teaching-Learning-Based Optimization algorithm (TLBO), is applied to the combined objective function to optimize the values of input parameters to get the best output parameters and confirmation tests are conducted based on that. The significant effects of spray parameters on surface roughness, coating thickness and coating hardness are studied in detail.

Experimental modeling of polymer latex spray coating for producing controlled-release urea

Spray coating of polymer latex onto fertilizer particles in a fiuidized bed for producing controlled-release urea is an environment friendly technology as it does not need any toxic organic solvent. Since the spray coating process in a fluidized bed occurs in the presence of particle collisions, the coating of the particles is random, intermittent and multiple, thus making it difficult to investigate the film formation process. In this paper, an experimental model apparatus was designed and used to investigate the effects of the key factors in the spray coating process. This apparatus reasonably simplified the complex process to avoid particle collisions and randomness in the coating. The intermittent coating in the fluidized bed was modeled by periodic coating and dewatering in the experimental apparatus. A large area film was obtained, and the film permeability was measured. The effects of atomizing gas flow rate, spray rate of latex, solid content of latex and gas temperature on film structure and film permeability were investigated. It was found that water transfer played a dominant role in the spray coating process.

Process-structure-property relationship for plasma-sprayed iron-based amorphous/crystalline composite coatings

This study explores the fabrication of Fe-based amorphous/crystalline coating by air plasma spraying and its dependency on the coating parameters(plasma power,primary gas flow rate,powder feed rate,and stand-off distance).X-ray diffraction of the coatings deposited at optimized spray parameters showed the presence of amorphous/crystalline phase.Coatings deposited at a lower plasma power and highest gas flow rate exhibited better density,hardness,and wear resistance.All coatings demonstrated equally good resistance against the corrosive environment(3.5wt%NaCl solution).Mechanical,wear,and tribological studies indicated that a single process parameter optimization cannot provide good coating performance;instead,all process parameters have a unique role in defining better properties for the coating by con-trolling the in-flight particle temperature and velocity profile,followed by the cooling pattern of molten droplet before impingement on the substrate.

Understanding Spray Coating Process: Visual Observation of Impingement of Multiple Droplets on a Substrate

Spray coating is a facile deposition process with numerous existing and emerging applications. However,spray coating is a stochastic process comprising impingement of many droplets which upon impact on a heated substrate may dry or solidify individually or coalesce first to form a thin liquid film and then dry to yield a thin solid film. There is very limited knowledge on how this process occurs; therefore in this work, high speed imaging is used to visualize the spray coating process. Two model solutions including food-dye with properties like those of water, and poly(3, 4-ethylenedioxythiophene) : poly(styrenesulfonate)(PEDOT : PSS), a polymeric solution, are sprayed onto permeable glossy paper and regular impermeable glass substrates. Substrates are kept at room temperature and 80?C elevated temperature. In some cases, a vertical ultrasonic vibration is imposed on the substrate to study its effect on the coating process. It is observed that the spray coating process is highly random and stochastic. A higher substrate temperature results in a better coating process in that a more uniform and defect-free coating forms. Imposed vibration in the case of glossy paper substrates results in better droplet spreading and more uniform coating. The results also show that under the conditions of these experiments,impinged droplets dry individually or as islands of multiple coalesced droplets to form a coating. In other words,at used spray flow rate and spray droplet size, a continuous thin liquid film does not form prior to drying even at room temperature. Further systematic studies and high magnification lenses are required to visualize and understand the details of the process.

INVESTIGATION ON MICROSTRUCTURE AND TRIBOLOGICAL PROPERITIES OF CORED WIRE ARC SPRAYED Al/Al _2 O_3 COATINGS

Cored wires for electric arc spraying of Al/Al 2 O 3 MMC coatings were developed, with Al 2 O 3 powder as the core material and commercial aluminium strip as the retaining sheath. The bond strength, Al 2 O 3 content, microstructure, micro-hardness and wear resistance of coatings produced by arc spraying of the cored wires were experimentally investigated and were compared with those of pure aluminum coating.

Effect of Salt Spray Corrosion on Tribological Properties of HVOF Sprayed NiCr-Cr3C2 Coating with Intermediate Layer

The objective of the present work was to determine the influence of the neutral salt spray corrosion on the wear resistance of HVOF sprayed NiCr-Cr3C2 coating with intermediate layer. Ni-Zn-Al2O3 coatings as interlayers were prepared by low pressure cold spray（LPCS） between NiCr-Cr3C2 cermet coatings to form a sandwich structure to enhance the corrosion resistance properties. The tribological properties were examined using the UMT-3 fricition and wear tester by line-contact reciprocating sliding under dry and salt spray one week corrosion. The morphology, element distribution, and phase compositions of the coating and worn sufaces were analyzed by using scanning electron microscopy, energy dispersive spectrometry, and X-ray diffraction respectively. The corrosion behavior of the coating was studied by the open-circuit potential, the electrochemical impedance spectroscopy, potentiodynamic polarization, and salt spray corrosion methods. It is found that the sandwich structured coating has better corrosion resistance than the single layer coating. The results show that under dry wear conditions, the wear mechanism is abrasive and adhesive wear, whereas under salt spray corrosion conditions it becomes corrosion wear. The friction coefficient of the sandwich structured coating after salt spray corrosion is slightly lower than the dry friction coefficient, but the weight of the wear loss is lower than that under dry condition.

Aerosol deposition technology and its applications in batteries

Aerosol deposition(AD)method is a kind of additive manufacturing technology for fabricating dense films such as metals and ceramics at room temperature.It resolves the challenge of integrating ceramic films onto temperaturesensitive substrates,including metals,glasses,and polymers.It should be emphasized that the AD is a spray coating technology that uses powder without thermal assistance to generate films with high density.Compared to the traditional sputter-based approach,the AD shows several advantages in efficiency,convenience,better interfacial bonding and so on.Therefore,it opens some possibilities to the field of batteries,especially all-solidstate batteries(ASSBs)and draws much attention not only for research but also for large scale applications.The purpose of this work is to provide a critical review on the science and technology of AD as well as its applications in the field of batteries.The process,mechanism and effective parameters of AD,and recent developments in AD applications in the field of batteries will be systematically reviewed so that a trend for AD will be finally provided.

Scalable spray coated high performance sulfurized electron transporter for efficient and stable perovskite solar modules

The stability issue has been acknowledged as the bottleneck in the practical application of perovskite photovoltaics,while the stabilized interface between the perovskites and charge transport layers dominates their stability performance under different stresses.Here,we developed a high-performance sulfurized zinc-titanium mixed oxide(ZTO-S)electron transport layer(ETL)to fabricate large-area efficient and long-term 85℃/85%RH stable perovskite solar modules.The scalably prepared ZTO-S using the facile spray coating method demonstrates excellent electron mobility close to that of Zn O,in addition to promoting the uniform crystallization of perovskite film across the entire module via the interaction between surface S and Pb^(2+).Furthermore,this novel coordination stabilized the interface and reduced the interfacial non-radiative recombination defects within the devices,yielding an efficient and stable performance for the modules.High efficiency of 21.73%and 17.50%was achieved for blade-coated 36 cm^(2)and 100 cm^(2)perovskite solar modules,respectively.In addition,the encapsulated module(36 cm^(2))shows an attractive humidity and heat stability(85℃/85%RH)performance with a maintained 93.5%of the initial PCE over 1000 h.

Microstructural and mechanical properties of thermal barrier coating at 1400℃ treatment

Abstract The mechanical properties of plasma-sprayed thermal barrier coating （TBC） play a vital role in governing their lifetime and performance. This work investigated the microstructural and mechanical properties of TBC with high tem- perature treatment at 1 400℃ by scanning electron microscopy and indentation. We calculated elastic modulus and hardness through the application of Weibull statistics analysis. The results indicate that the microstructure of ceramic coat- ing will change continuously at high temperature, and accordingly the porosity decreases due to the grain growths and crack closes. In addition, the elastic mod- ulus and hardness nonlinearly go up with the heat treatment time and go down with increasing porosity. This demonstrates that the microstructural evolution and porosity of TBC are caused by high temperature treatment, and as a result its mechanical properties are influenced.

“Coffee ring” controlment in spray prepared >19% efficiency Cs_(0.19)FA_(0.81)PbI_(2.5)Br_(0.5) perovskite solar cells

Achieving high-quality perovskite films with uniform morphology and homogeneous crystallinity is challenging owing to the coffee ring effect(CRE) in the spray-coating technologies. In this study, an evaporation/spray-coating two-step deposition method is used to fabricate Cs_(0.19)FA_(0.81)PbI_(2.5)Br_(0.5)light harvesters for perovskite solar cells(PSCs). Considering the solid–liquid reaction, we establish a reaction-dependent regulating strategy that inhibits CRE successfully and prepare a high-quality perovskite layer, wherein the solvent for the FAI/Br solution during the spraying process is changed from isopropanol to n-butyl alcohol(NBA). The retarded-drying-enhanced spreading of the NBA solution inhibits contact line pinning to suppress the capillary flows and increases the reaction between metal halides(CsI/PbI_(2)) and organic salts(FAI/Br), which result in a reduction in the accumulation of solutes in the periphery effectively inhibiting CRE. Consequently, we obtain a high performance Cs_(0.19)FA_(0.81)PbI_(2.5)Br_(0.5) PSC with a power conversion efficiency(PCE) of 19.17%. An enlarged perovskite film(10 × 10 cm^(2)) containing 40 sub-cells is prepared. The average PCE of these devices is 18.33 ± 0.56%, proving the reliability of the "coffee ring" regulating strategy. This study provides an effective approach for CRE controlment in spraying technology to achieve high repeatability devices with good performance.

Investigation on MoS_2 and Graphite Coatings and Their Effects on the Tribological Properties of the Radial Spherical Plain Bearings

With constant enlargement of the application areas of the spherical plain bearings,higher quality lubrication of the bearings is required.To solve the lubricating problems of spherical plain bearings under high temperature,high vacuum,high speed,heavy loads and strong oxidation conditions,it is urgent for us to develop more excellent self-lubricating technologies.In this paper,the bonded solid lubricant coatings,which use inorganic phosphate as the binder,the mixture of MoS2 and graphite with two different weight proportions as the solid lubricant,are prepared by spraying under three different spray gun pressures.The bonding strength tests on the coatings show that the best spraying pressure is 0.2 MPa and the better mixing proportion of MoS2 to Graphite is 3：1.Then for the radial spherical plain bearings with steel/steel friction pair,after the coatings are made on the inner ring outer surfaces,the friction coefficient,the wear loss and the friction temperature of the bearings under four oscillating frequencies are investigated by a self-made tribo-tester.The test results,SEM of the worn morphologies and EDS of worn areas show that tribological properties of the bearing are obviously improved by the bonded solid lubricant coatings.When sprayed under the spray gun pressure of 0.2 MPa,the bearings have better anti-friction and anti-wear properties than those sprayed under 0.1 MPa and 0.3 MPa.Further as proved from the XPS analysis,between the coating with 3：1 mixing ratio of MoS2 to Graphite and the coating with 1：1 ratio,the former has less oxidation occurred on the surface and therefore has better tribological characteristics than the latter.This paper provides a reference to developing a new product of the radial spherical plain bearings with high bonding strength,oxidation resistance and abrasion resistance.

Corrosion of Carbon Steel under Epoxy-varnish Coating Studied by Scanning Kelvin Probe

The corrosion behavior of partly coated carbon steel was investigated by salt spray test and scanning Kelvin probe （SKP） in order to understand the long-term corrosion behavior of coated carbon steel in marine atmosphere environment. The localized corrosion was accurately characterized by SKP in both coated and uncoated regions. The SKP results showed that Volta potential varied with the test time, and the more the corrosion products, the more positive the potential. The borderline between coated and uncoated regions of partly coated steel shifted towards the coated side with the increasing of test time. The coating disbonding rate could be determined according to the shift of potential borderline measured by SKP. The corrosion mechanism of partly coated steel in NaCl salt spray was discussed according to the potential maps and corrosion morphologies.

Influences of substrate temperature on microstructure and corrosion behavior of APS Ni_(50)Ti_(25)Al_(25) inter-metallic coating

In the present investigation, Ni_（50）Ti_（25）Al_（25）（at.%） mechanically alloyed powder is deposited on carbon steel substrate.Before the coating process, the substrate is heated to temperature ranging from room temperature to 400℃. The microstructure, porosity, microhardness, adhesion strength, and corrosion behavior of the coating are investigated at different substrate temperatures. Results show that coating porosity is lower on high temperature surface. Microhardness and adhesion strength of the deposition layer on the substrate without preheating have lower values than with preheating. The polarization test result shows that corrosion performance of the coating is dependent on micro cracks and porosities and the increasing of substrate temperature can improve the quality of coating and corrosion performance.

Bismuth-Complex-Incorporated Nanocellulose Sheet for Biomedical Application:A Review on New Nanocellulose Composites

Antibiotic resistance is one of the major issues in the medical field and a potential threat to human health.However,newly emerging antimicrobial compounds failed to combat antimicrobial resistance developed by bacterial pathogens.Recently,a bismuth-based complex has been developed to eradicate antimicrobial-resistant microorganism infections.The complex is known as organobismuth(III)phosphinate,which is said to be a potential broad-spectrum antimicrobial agent.This complex has been incorporated into the nanocellulose suspension to fabricate a biomedical composite for various applications.The composite can be fabricated by two methods namely vacuum filtration and spray coating.In this paper,the surface and topography of the composite are investigated and discussed in terms of SEM micrographs and their antimicrobial potential.This review focuses on the organo-bismuth nanocellulose composite and its biomedical application in the future.

Comparison of different approaches for direct coupling of solid-phase microextraction to mass spectrometry for drugs of abuse analysis in plasma

The direct coupling of solid-phase microextraction(SPME)to mass spectrometry(MS)(SPME-MS)has proven to be an effective method for the fast screening and quantitative analysis of compounds in complex matrices such as blood and plasma.In recent years,our lab has developed three novel SPME-MS techniques:SPME-microfluidic open interface-MS(SPME-MOI-MS),coated blade spray-MS(CBS-MS),and SPME-probe electrospray ionization-MS(SPME-PESI-MS).The fast and high-throughput nature of these SPME-MS technologies makes them attractive options for point-of-care analysis and anti-doping testing.However,all these three techniques utilize different SPME geometries and were tested with different MS instruments.Lack of comparative data makes it difficult to determine which of these methodologies is the best option for any given application.This work fills this gap by making a comprehensive comparison of these three technologies with different SPME devices including SPME fibers,CBS blades,and SPME-PESI probes and SPME-liquid chromatography-MS(SPME-LC-MS)for the analysis of drugs of abuse using the same MS instrument.Furthermore,for the first time,we developed different desorption chambers for MOI-MS for coupling with SPME fibers,CBS blades,and SPME-PESI probes,thus illustrating the universality of this approach.In total,eight analytical methods were developed,with the experimental data showing that all the SPME-based methods provided good analytical performance with R^(2)of linearities larger than 0.9925,accuracies between 81%and 118%,and good precision with an RSD%≤13%.

Accumulated damage process of thermal sprayed coating under rolling contact by acoustic emission technique

The accumulated damage process of rolling contact fatigue （RCF） of plasma-sprayed coatings was investigated. The influences of surface roughness, loading condition, and stress cycle frequency on the accumulated damage status of the coatings were discussed. A ball-on- disc machine was employed to conduct RCF experiments. Acoustic emission （AE） technique was introduced to monitor thc RCF process of the coatings. AE signal characteristics were investigated to reveal the accumulated damage process. Result showed that the polished coating would resist the asperity contact and remit accumulated damage. The RCF lifetime would then extend. Heavy load would aggravate the accumulated damage status and induce surface fracture. Wear became the main failure mode that reduced the RCF lifetime. Frequent stress cycle would aggravate the accumulated damage status and induce interface fracture. Fatigue then became the main failure mode that also reduced the RCF lifetime.

Influence of Zn and Mg Alloying on the Corrosion Resistance Properties of Al Coating Applied by Arc Thermal Spray Process in Simulated Weather Solution

In this study,Al–Zn and Al–Mg coatings were deposited on steel substrates by an arc thermal spray process.X-ray diffraction and scanning electron microscopy were used to characterize the deposited coatings and corrosion products.Open circuit potential（OCP）,electrochemical impedance spectroscopy,and potentiodynamic studies were used to assess the corrosion characteristics of these coatings after exposure according to the Society of Automotive Engineers（SAE）J2334 solution of varying durations.This solution simulates an industrial environment and contains chloride and carbonate ions that induce corrosion of the deposited coatings.However,the Al–Mg alloy coating maintained an OCP of approximately-0.911 V versus Ag/Ag Cl in the SAE J2334 solution even after 792 h of exposure.This indicates that it protects the steel sacrificially,whereas the Al–Zn coating provides only barrier-type protection through the deposition of corrosion products.The Al–Mg coating acts as a self-healing coating and provides protection by forming Mg_6Al_2（OH）_（16）CO_3（Al–Mg layered double hydroxides）.Mg_6Al_2（OH）_（16）CO_3has interlocking characteristics with a morphology of plate-like nanostructures and an ion-exchange ability that can improve the corrosion resistance properties of the coating.The presence of Zn in the corrosion products of the Al–Zn coating allows dissolution,but,at the same time,Zn_5（OH）_6（CO_3）_2and Zn_6Al_2（OH）_（16）CO_3are formed and act to reduce the corrosion rate.

Influence of laser re-melting and vacuum heat treatment on plasma-sprayed FeCoCrNiAl alloy coatings

FeCoCrNiAl high entropy alloy coatings were prepared by supersonic air-plasma spraying.The coatings were post-treated by vacuum heat treatment at 600 and 900°C,and laser re-melting with 300 W,respectively,to study the influence of different treatments on the structure and properties of the coatings.The phase constitution,microstructure and microhardness of the coatings after treatments were investigated using X-ray diffraction,scanning electron microscopy and energy dispersive spectrometry.Results showed that the as-sprayed coatings consisted of pure metal and Fe-Cr.The AlNi;phase was obtained after the vacuum heat treatment process.A body-centered cubic structure with less AlNi;could be found in the coating after the laser re-melting process.The average hardness values of the as-sprayed coating and the coatings with two different temperature vacuum heat treatments and with laser re-melting were 177,227,266 and 682 HV,respectively.This suggests that the vacuum heat treatment promoted the alloying process of the coatings,and contributed to the enhancement of the coating wear resistance.The laser re-melted coating showed the best wear resistance.