Conventional Spray Method Research Articles

Rapid preparation of full color spectrum structural color coatings with iridescence effects via spray methods

Differing from conventional spray methods that only produce amorphous photonic crystals, this study innovatively achieves the ordered assembly of poly(styrene-methyl methacrylate-acrylic acid) (P(St-MMA-AA)) microspheres into photonic crystals on the substrate surface by adjusting the spray distance, a simple parameter. The resulting coating exhibits a uniform and iridescent structural color. Simultaneously, employing this technique, P(St-MMA-AA) microspheres with three different diameters (234 nm, 178 nm, and 152 nm) were mixed pairwise and co-organized in an ordered manner on the substrate surface. By adjusting the mass ratio of the two types of microspheres, structural color coatings covering the full visible spectrum were facilely and efficiently prepared. The coatings exhibit iridescence, and the structural colors are true colors with high color quality. Additionally, violet, unattainable in traditional color mixing systems, was achieved. The structural color coatings obtained in this study demonstrate promising applications in areas such as environmentally friendly finishes, optical anti-counterfeiting, and true-color displays.

The performance of a self‐adherent foil system for the corrosion protection of steel substrates for offshore wind tower structures

AbstractThe application of multilayer organic protective coating systems with conventional liquid spray methods is complex, time‐ and energy‐consuming, and it requires extensive technical equipment. An alternative to these methods is the application of thin, self‐adherent foil systems directly to the steel substrate. The corrosion protection performance of newly developed foil systems was tested for various combinations of foil materials and pressure‐sensitive adhesives (with and without corrosion inhibitors) and different surface preparation parameters by means of accelerated cyclic laboratory tests with simulated offshore conditions. The adhesion properties were determined by means of peel tests. The tests were designed, by means of statistical methods (design of experiments, analysis of variance). A foil system with the following factor combination was found to provide an optimum performance: Surface preparation grade: Sa 2½; roughness: Rz = 50–75 µm; abrasive material: high‐carbon steel grit; adhesive layer thickness: 200 g/m2; inhibitor material: calcium aluminum polyphosphate silicate hydrate; foil material: polyvinylchloride (160 µm) + poly(methyl methacrylate) (40 µm).

Microstructure and properties of copper coating by using plasma‐assisted low‐pressure cold spray

AbstractPlasma‐assisted low‐pressure cold spraying and conventional cold spraying methods are used to prepare copper coatings on copper substrates. The thickness, porosity micromorphology, and mechanical and corrosion properties of the copper coating prepared by high‐pressure cold spraying and plasma‐assisted low‐pressure cold spraying are studied. The results indicated that in single‐pass deposition, the copper coating prepared by plasma‐assisted low‐pressure cold spraying has a small porosity and a thick coating under the spraying conditions with the same powder feeding rate, which has a better deposition effect. The coating grains prepared by the plasma‐assisted method undergo a recrystallization process, and the grains are refined. Plasma‐assisted low‐pressure cold spray technology can achieve a good repair effect on parts.

Study on the control effect of Empedobacte brevis on cherry fruit fly

Abstract: Fruit fly is a major boring pest of cherry fruits during the color change and maturity period. It causes serious damage and affects the quality and economic benefits of cherry fruits. In order to clarify the control effect of Empedobacter brevis on cherry fruit fly and provide basis for guiding scientific medication use. The test adopts the conventional spray method, and uses 60g•L-1 spinetoram suspension as a control to compare and analyze the control effects of different dosages of Empedobacter brevis suspension on cherry fruit fly. The results show that on the three cherry varieties of Red lantern, Tieton and Napoleon, the control effects of Empedobacter brevis 600 times and 800 times and spinetoram 1000 times are better, and the control efficiency reaches more than 78-80%. There is no significant difference in control effects among the three, and they are safe for cherry trees. In cherry production, Empedobacter brevis can be promoted and applied as an effective biological agent to control fruit flies.

Design and Optimization of an Umbrella-Type Shield Based on 3D CFD Simulation Technology

Mechanical shields can effectively alleviate the problems of low pesticide utilization and severe environmental pollution. This manuscript uses a computational fluid dynamics (CFD) method to investigate the anti-drift mechanism of mechanical shields, study the airflow forms around them, and establish an accurate simulation model. The aerodynamic characteristics of six shields were studied, and their anti-drift effect was compared. Then, the size and working parameters were optimized using the response surface methodology (RSM). Mechanical shields can significantly improve the fog droplet deposition rate (DR) compared with the conventional spray method (no shield), among which the umbrella-type shield has the best effect; optimizing the size and selecting suitable working parameters can increase the DR to 77.31 %. The field trial showed that the DR of the conventional spray method was reduced by 31.9 % at 5 m/s compared with 3 m/s, while the DR of the shield spray method was reduced by only 3.6 % at 5 m/s compared with 3 m/s, which proved the excellent performance of the mechanical shields. The field trial results were consistent with the CFD simulation, and the relative deviation of the DR between the two was within 4 %, so the accuracy and reliability of the CFD simulation model were proved.

Advanced TPU/ZnS:Al Flexible Film with Thermo-Force-Optical Response for Smart Clothing

With the continuous development of science and technology, smart sensing wearables have gradually entered people’s lives. However, the prepared wearable material has poor air permeability, poor fit, and does not have multiple modal excitations. In addition, it is not waterproof or even wearable at low temperatures. In this work, a thermoplastic polyurethane (TPU) and ZnS:Al composite film with excellent air permeability has been developed. The TPU/ZnS:Al flexible film can be prepared on a large scale by solution blow spinning (SBS). This fiber membrane can realize the dual response of temperature and stress, and cooperate with the light sensor to realize the transmission of intelligent information. This nanofiber membrane doped with ZnS:Al exhibits a uniform distribution, maintains excellent tensile properties and flexibility, and can adapt to any perfect shape of the fitting surface. Even the average air permeability can be as high as 300 mm s−1, which is 600 times that of conventional spraying methods. The Al introduced in ZnS:Al can stimulate the composite film to emit light, and the luminescence effect can be maintained for about 1 min. These results provide new ideas for the large-scale fabrication of integrated stimulus-responsive photosensitive intelligent wearable devices for various applications.

Evaluation of an electrostatic spray charge system implemented in three conventional orchard sprayers used on a commercial apple trees plantation

Electrostatic sprayers can be an option for increasing the effectiveness of treatments and reducing pesticide consumption, but it still requires more verifications, especially in orchards. The spray deposition performances of three different electrostatic sprayers design were compared for apple tree pesticide application, all of them used with the electrostatic system activated and disactivated, as conventional spray application. Despite designs of particular type sprayers were unique, no significant differences were observed in the normalized deposition and droplets density between the conventional and electrostatic spray methods of the same sprayer, but differences were found between the vertical boom and the pneumatic sprayer in terms of coverage. The normalized deposition values of the three sprayers were very similar, ranging between 1.0 and 1.5 μg cm−2. However, the vertical boom sprayer produced the highest spray coverage, followed by the multi-fan sprayer. In general, the measured values of coverage and deposit obtained were in the three cases similar, independently on the use or not of the electrostatic device, being the sprayer type more affecting parameter rather than the electrostatic charging system. Differences in spray deposition qualities on apple trees were observed among three types of sprayers, but were not for the same sprayer with and without activation of the electrostatic charging system. Appropriate design of orchard sprayers according to the canopy structure seems to be more effective rather than the implementation of electrostatic spray charge system to achieve the European challenge of 50% reduction of pesticides by 2030.

Wetting and deposition behaviors of pesticide droplets with different dilution ratios on wheat leaves infected by pathogens

The pesticide formulations should be diluted to different concentrations according to selected application methods. The structure and properties of crop leaf surfaces can undergo severe changes after infestation with pests or diseases. Previous studies have mostly focused on the interfacial behaviors of pesticide droplets on healthy plant leaves. Here, we prepared 25 % pyraclostrobin microemulsion and diluted it according to different dilution ratios corresponding to low volume and conventional volume spray methods. The dynamic wetting and deposition behaviors of pesticide solution on wheat leaves infected with powdery mildew were investigated. The surface structure and properties of wheat leaves covered by the fungus Blumeria graminis will be changed. Conidia produce more non-polar components. The droplets with low dilution were more likely to deposit and reach the Wenzel state on wheat powdery mildew leaves. However, the droplets with high dilution were difficult to wet and easy to break and rebound from leaf surfaces. This research guides the control of wheat powdery mildew with pesticides under different application methods and the interface interaction between pesticide droplets and hydrophobic leaf surfaces infected by pathogens.

Excellent thermal shock resistance of NiCrAlY coatings on copper substrate via laser cladding

• NiCrAlY layers were prepared on copper substrate via laser cladding technology. • Metallurgical bonding and excellent thermal shock resistance are obtained. • Lifetime of this NiCrAlY layers is much longer than NiCrAlY by other methods. Coatings are widely used to protect substrates in extreme thermal environments (e.g., arc heaters), and thermal shock resistance is a crucial parameter for the coatings, which requires tight interlayer bonding between coatings and substrates. In this work, NiCrAlY coatings were highly required for the pure copper substrate to restrict the electric arc in arc heaters. To overcome the bonding difficulty of coating on the copper surface, the NiCrAlY coatings were prepared by two laser cladding methods: conventional laser cladding (CLC) and high-speed laser cladding (HSLC). The microstructure, composition, and thermal shock resistance of NiCrAlY cladding layers prepared by both methods were investigated. Benefitting from the high cooling rate and high energy density, the HSLC-layer has better composition uniformity and tighter interlayer bonding than the CLC-layer, achieving a 30%–45% improvement in thermal cycling lifetime. Besides, the NiCrAlY layers prepared on copper substrate by both laser cladding methods exhibit 3–10 times better thermal shock resistance than those NiCrAlY layers prepared by conventional spraying methods. It further confirms the great effects of metallurgical bonding and composition uniformity on the thermal shock resistance of coatings. The NiCrAlY layers fail in the form of internal cracking and interface peeling, and the corresponding failure mechanism is discussed.

Spaetzle responds to the process of Neoseiulus barkeri resistance to Beauveria bassiana infection

The application of Beauveria bassiana is proved to be a feasible biological control measure against pest insects and mites (e.g. Liu et al. 2018; Al Khoury et al. 2020). But the complex and variable ecological environment can affect the efficiency of B. bassiana. Due to the powerful search and spread ability of predatory mites, they were proposed to carry and spread pathogenic microbial spores to places that are difficult to be covered by conventional spray methods (Chen et al. 2020; Hao et al. 2021). This biocontrol strategy of combining fungi with predator mites is predicted to play a synergistic role in pest control. Therefore, the tolerance of predator mites to B. bassiana and the underlying mechanism have been the subject of extensive research and remained to be explored further. The infection of insects by B. bassiana can induce insect innate immune response. Spaetzle protein (Spz), as an important ligand of insect Toll pathway, has been demonstrated to play an important role in insect innate immune defense system. 

Porous Covalent Organic Polymer Coordinated Single Co Site Nanofibers for Efficient Oxygen-Reduction Cathodes in Polymer Electrolyte Fuel Cells.

Nitrogen-coordinated single-cobalt-atom electrocatalysts, particularly ones derived from high-temperature pyrolysis of cobalt-based zeolitic imidazolate frameworks (ZIFs), have emerged as a new frontier in the design of oxygen reduction cathodes in polymer electrolyte fuel cells (PEFCs) due to their enhanced durability and smaller Fenton effects related to the degradation of membranes and ionomers compared with emphasized iron-based electrocatalysts. However, pyrolysis techniques lead to obscure active-site configurations, undesirably defined porosity and morphology, and fewer exposed active sites. Herein, a highly stable cross-linked nanofiber electrode is directly prepared by electrospinning using a liquid processability cobalt-based covalent organic polymer (Co-COP) obtained via pyrolysis-free strategy. The resultant fibers can be facilely organized into a free-standing large-area film with a uniform hierarchical porous texture and a full dispersion of atomic Co active sites on the catalyst surface. Focused ion beam-field emission scanning electron microscopy and computational fluid dynamics experiments confirm that the relative diffusion coefficient is enhanced by 3.5 times, which can provide an efficient route both for reactants to enter the active sites, and drain away the produced water efficiently. Resultingly, the peak power density of the integrated Co-COP nanofiber electrode is remarkably enhanced by 1.72 times along with significantly higher durability compared with conventional spraying methods. Notably, this nanofabrication technique also maintains excellent scalability and uniformity.

Vibration and noise analysis of acetoxime modified TiO2 coating over steel alloy

The analysis of vibration over coated sample is required to investigate the vibration and noise damping behaviors of coatings. In this research work, conventional gun spray method is used to coat oxime modified titanium (IV) isopropoxide on steel to find out damping behaviour of coating. The most conventional method modal analysis is used to measure vibration and noise damping of bare and titania coated samples. During vibration test it was observed that a thin coating has improved the vibration and noise damping when compare with bare sample. The surface morphology of coated samples analysis by Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Analysis (EDX) and Atomic Force Microscopy (AFM) revealed that the coating thickness and composition of coating. The results shows that the modified TiO2 coating deposited over steel alloy by gun spry method is uniform, homogenous, crack free, and having high vibration damping behavior.

Synthesis of low-cost Ti4O7 membrane electrode for electrooxidation of tetracycline under flow-through conditions: Performance, kinetics and mechanism

The high cost of anode material and the limitation of liquid-mass transfer on anode surface in electrochemical advanced oxidation processes always restrict the removal efficiency of organics. To overcome the limitations, this study synthesized a low-cost Ti4O7 membrane electrode by simple sol-gel method, and developed a flow-through electrooxidation system based on Ti4O7 membrane electrode. The membrane electrode presented high crystallinity, high specific surface area (10.18 m2/g), concentrated pore sizes distribution (0.1–1 µm), and high oxygen evolution potential (2.2 V vs. SHE). Furthermore, compared with stirring conditions, the flow-through conditions could enhance the liquid-mass transfer on anode surface, resulting in a high tetracycline degradation efficiency (97.24%) and a low energy consumption (0.18 kWh/gDOC). High degradation rates of tetracycline (more than 95%) were both observed with the initial tetracycline concentration ranged from 10 to 50 mg/L. The increase of pipeline pressure and current density had positive influence on tetracycline degradation. Hydroxyl radicals and sulfate radicals produced on the electrode surface are the main oxidants for tetracycline degradation. The degradation pathway of tetracycline included oxygenation, hydroxylation, demethylation, decarbonylation, ring-open, and C-N bond cleavage. Compared with materials prepared by conventional hot pressing and plasma spraying method, this simply synthesized Ti4O7 membrane electrode exhibited efficient oxidation capability and competitive electric cost for contaminants degradation, demonstrating its practicability, feasibility, and facilitation for the potential application.

A Matrix Sublimation Device with an Integrated Solvent Nebulizer for MALDI-MSI.

The current matrix deposition methods in MALDI-mass spectrometry imaging (MALDI-MSI) face technical problems related to the inhomogeneous distribution of crystals and the low analyte extraction and cocrystallization efficiency. In this work, an integrated matrix sublimation device with synchronous solvent nebulization was developed for MALDI-MSI. Droplets of solvents were directly introduced into the chamber of the sublimator by using a miniaturized ultrasonic nebulizer unit. The synchronous and asynchronous working modes of solvent nebulization and matrix sublimation were systematically investigated. Imaging of both protein and small metabolite distributions in mouse brain tissue sections was successfully performed using the developed matrix deposition device. The sensitivity and quality of the images were clearly improved in synchronous mode compared with those of the conventional spray and sublimation methods. These results demonstrate that the integrated device with both solvent nebulization and matrix sublimation is a useful tool in MALDI-MSI applications.

A Study on YSZ Abradable Seal Coatings Prepared by Atmospheric Plasma Spray and Mixed Solution Precursor Plasma Spray

The yttria-stabilized zirconia (YSZ) ceramic has been proved to be a promising material for abradable seal coatings. In this research, abradable seal coatings named C-YSZ and M-YSZ were prepared by applying the conventional plasma spraying method with improved nanostructured powders and by the mixed solution precursor plasma spraying technique, respectively. A study on the microstructure, mechanical properties, oxidation resistance and hot corrosion resistance was conducted on both C-YSZ and M-YSZ coatings by using scanning electron microscopy, transmission electron microscopy, muffle furnace and x-ray diffractometer. The results show that the C-YSZ coating presents larger-size pores with denser YSZ structures and grains showing size larger than 100 nm distributed around the pores compared with M-YSZ, in which the pores are much smaller and the grain size is 20-30 nm. As a result, the M-YSZ coating displays lower hardness and bond strength compared with C-YSZ. The oxidation tests show that the M-YSZ coating possesses better oxidation resistance due to the nanostructure topcoat compared with C-YSZ. However, the hot corrosion tests indicate that both the C-YSZ coating and the M-YSZ coating fail to present ideal hot corrosion resistance.

The Influence of the Powder Characteristics on 316L Stainless Steel Coatings Sprayed by Cold Gas Spray

Thermally sprayed 316L stainless steel coatings are commonly used on metallic structures due to their corrosion and wear resistance when compared to carbon steel. Cold Gas Spray (CGS) is a convenient thermal spray process to deposit 316L coatings, producing thick and very dense coatings, with almost no deleterious changes on the feedstock properties to the coating condition. The powder characteristics have influence on the microstructure of the coating, such as porosity and oxide contents, which alter its corrosion and wear behavior. CGS is an efficient technique to reduce the problems associated with material melting commonly found in other conventional thermal spray methods. In this work, different 316L powders, produced by different manufacturers, were deposited by CGS, applying the same equipment and parameters, with the objective to evaluate the relation between the powders’ characteristics and coating properties. Their microstructure, adherence, hardness, as well as the performance on corrosion and wear testing were evaluated. The water atomized powders presented in general better results than gas atomized powders.

Layer formation of 2,5-dihydroxybenzoic acid crystals via mist deposition for mass spectrometry imaging of biological samples

Dihydroxybenzoic acid (DHB) crystal layers were formed via mist deposition. Crystal layers exhibiting whiskers measuring a few hundred micrometers were formed at a nozzle temperature of 200 °C. DHB crystal layers exhibited strong absorbance in the ultra-violet wavelength regions, and Raman spectroscopy confirmed their vibrational property. The lipid component was analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry imaging using a DHB crystal layer as the mass ionization assist agent. Cholesterols, diacylglycerides, and triglycerides were detected as sodium adducts. By preventing heterogeneous co-crystallization with analytes, mass images were clearer than when using the conventional aerosol spray method.

Fabrication of layered porous TiO2/carbon fiber paper decorated by Pt nanoparticles using atomic layer deposition for efficient methanol electro-oxidation

Abstract A novel anode electrode consisting of Pt NPs on layered porous TiO2/CFP (Pt/LP-TiO2/CFP) was fabricated by an innovative approach, which can be directly integrated in membrane electrode assembly (MEA) as the catalyst layer without any binder. Firstly, a two-step anodization method was applied to prepare a layered porous TiO2 on the CFP as a hybrid support, and then Pt NPs are deposited onto it by atomic layer deposition (ALD) technology. It effectively prevents Pt nanoparticles from detachment, migration, and aggregation during the catalyst preparation and electrochemical reaction process. The electrocatalytic performance of Pt/LP-TiO2/CFP electrode for methanol oxidation reaction exhibits excellent mass activity (1182.8 mA mgPt−1), enhanced stability, and CO tolerance, which is much better than those of the Pt/HT-TiO2/CFP and the Pt/C/CFP electrode prepared by conventional hydrothermal and spray method, respectively. The reason can be attributed to the unique structure of layered porous TiO2 supports, strong metal−support interactions (SMSI) between ALD Pt NPs and the LP-TiO2/CFP, and more exposed active sites for methanol oxidation. The presented ALD approach is an effective strategy for the homogeneous distribution of precious Pt nanoparticles on a binder-free and porous electrode for the design of advanced catalysts.

Yttrium Aluminum Garnet Powder Feedstock for Atmospheric Plasma Spray

High demands for higher turbine efficiency bring attention to newer and more advanced insulating materials for the high temperature components in the turbine. Yttrium aluminum garnet (YAG) has shown good insulating properties in the previous published research, such as higher temperature limitation and better resistance to calcium–magnesium–alumina–silicate environmental contaminant penetration than the more conventional yttria-stabilized zirconia systems. Whereas in literature, coatings of YAG are typically prepared by solution deposition processes, in the present work YAG powder has been prepared for more conventional thermal spraying methods. The goal is to show the potential YAG powders have as a thermal barrier coating. Different approaches for obtaining a successful deposition and a good coating have been explored. Small-sized industrial-supplied powder and larger in-house-made powder have been compared, emphasizing the importance of energy used for deposition and crystallinity in the final coating. Highly crystalline material has successfully been produced with F4 atmospheric plasma spray system without post-treatment or substrate heating.

A Device for Collecting Thrips1 from Medium- and Tall-Sized Trees

Monitoring is a key activity in management of pests such as phytophagous thrips (Thysanoptera). Sampling thrips on medium and tall trees has been difficult without appropriate tools. The study compared the number of thrips collected and collection time by a new method of top-canopy spraying with an original device that is more efficient and practical versus two other collection methods, beating and conventional spraying. Design, construction, and validation of the thrips-collecting device for sampling top strata of orchard trees such as avocado (Persea americana Mill.) are presented. Similar numbers of thrips were collected with conventional methods and the new collecting device. Average collection time between spraying and beating methods was reduced 48 and 67%, respectively. Using the device to collect thrips at top strata of trees resulted in less risk to collectors in an effortless way. Use of the thrips-collecting device for the top part of the canopy and the conventional spraying method for the lower part could improve detection of phytophagous thrips, and might enhance efficiency of control methods by implementing them in a timely way.