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"Spraying"
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Crop sprayers
\"Big farms need big machines, and crop sprayers are some of the biggest. Farmers use these timesaving devices to spread substances such as fertilizers, pesticides, and herbicides on their crops. While readers learn about the different kinds of crop sprayers, their many parts, and their importance to the farm industry, they'll be impressed by the colorful photographs of the machines in action, including one in the air. The high-interest topic also touches on key science and technology topics.\"-- Provided by publisher.
Book
Influencing Factors and Process Optimization of Al/SiC Powder-cored Wires by Plasma Transferred Wire Arc Spraying
Wire thermal spraying, one of the significant coating preparation technologies in the field of thermal spraying, has the advantages of low cost, high material utilization rate and fast coating deposition. Powder-cored wires, with easily controllable compositions, are used as spraying materials to prepare functional coatings with special properties. Coatings prepared by traditional wire thermal spraying technologies, mainly including wire flame spraying (WFS), wire arc spraying (WAS) and plasma wire spraying, have some defects, such as weak bonding strength and high porosity. In this paper, the plasma transferred wire arc spraying (PTWAS) technology was innovatively proposed, by which Al/SiC powder-cored wires were successfully sprayed to deposit the aluminum (Al)/Nicalon (SiC) composite coating. Furthermore, the influences of spraying current (
I
), argon (Ar) flow rate (
L
Ar
), hydrogen (H
2
) flow rate (
L
H2
) and other factors on Al/Sic powder-cored wires prepared by PTWAS and the optimization of the coating preparation process were mainly studied
via
the single factor method and the response surface methodology. After experimental exploration and analysis, the optimized process parameters were finally determined as follows:
L
Ar
was 120 L min
−1
,
I
was 160 A,
L
H2
was 5 L min
−1
, the spraying distance was 100 mm, the wire feeding speed (
V
) was 0.18 m s
−1
, and the distance between the wire and nozzle (
d
) was 10 mm. It was found in the test that the porosity of the optimized Al/SiC composite coating was only 1.6%, the average microhardness was 102 HV
0.1
, and the average bonding strength was 36.5 MPa. The comprehensive properties of this coating were better than those of the Al/SiC composite coatings prepared by WFS and WAS.
Journal Article
Suspension plasma spray coating of advanced ceramics : thermal barrier applications
\"Suspension Plasma Spray Coating of Advanced Ceramics presents the significance of suspension plasma spray coating of ceramics for thermal barrier applications. It covers suspension formation and optimization in different oxide and non-oxide mixtures and ceramic matrix composites (CMC) of sub-micron and nanosized powders. The book will be useful for professional engineers working in surface modification and researchers studying materials science. This book discusses advanced topics on nanomaterials coatings in monolithic or composite forms as thermal barriers through organic and non-organic based suspensions using high energy plasma spray methods\"-- Provided by publisher.
Book
The Potential of High-Velocity Air-Fuel Spraying (HVAF) to Manufacture Bond Coats for Thermal Barrier Coating Systems
Driven by the search for an optimum combination of particle velocity and process temperature to achieve dense hard metal coatings at high deposition efficiencies and powder feed rates, the high-velocity air-fuel spraying process (HVAF) was developed. In terms of achievable particle velocities and temperatures, this process can be classified between high-velocity oxy-fuel spraying (HVOF) and cold gas spraying (CGS). The particular advantages of HVAF regarding moderate process temperatures, high particle velocities as well as high productivity and efficiency suggest that the application of HVAF should be also investigated for the manufacture of MCrAlY (M = Co and/or Ni) bond coats (BCs) in thermal barrier coating (TBC) systems. In this work, corresponding HVAF spray parameters were developed based on detailed process analyses. Different diagnostics were carried out to characterize the working gas jet and the particles in flight. The coatings were investigated with respect to their microstructure, surface roughness and oxygen content. The spray process was assessed for its effectiveness. Process diagnostics as well as calculations of the gas flow in the jet and the particle acceleration and heating were applied to explain the governing mechanisms on the coating characteristics. The results show that HVAF is a promising alternative manufacturing process.
Journal Article
Concepts and applications of foliar spray for microbial inoculants
Damages of the (agro)ecosystem by extensive use of chemical fertilizers and pesticides, the global dying of bee populations possibly linked to pesticide spraying, and stricter regulations for pesticide use together with successful use of microbials in IPM programs are pushing on the development and commercialization of new microbial products and a large and growing biostimulants and biocontrol market. This review focuses on microbial inoculants including bacteria, fungi, and viruses used as biostimulant or biocontrol agent for foliar application and covers all important steps from inoculant development to successful field application. Topics presented comprise typical spraying equipment including the importance of the spraying process and relating effects, furthermore formulation development including classification and adjuvants, and thirdly regulatory aspects as currently applied or under discussion. Microbial inoculants for foliar spray reported in scientific literature are summarized and contrasted with selected commercial products. Special attention is given to factors most important in microbial spray: (a) type of active ingredient (bacteria, fungi, viruses), (b) mode of action (ingestion, contact, competition), (c) interaction with the plant leaf surface, (d) droplet size in terms of microbe concentration and leaf coverage, and (e) environmental conditions during spraying. Finally, we want to emphasize that timely administration is of utmost importance for successful spraying and maximum efficacy. This might be supported by weather stations and disease/pest models as an important step towards precision farming.
Journal Article
Evaluation and Analysis of Particle Oxidation of HVOF Thermal Spraying Based on GA-BP Neural Network Algorithm
In the process of High velocity oxygen fuel (HVOF) spraying, micron-sprayed particles are bound to oxidize under high temperature oxygen-containing environment, particle oxidation and burning are the key factors affecting coating quality. However, how to quantitatively evaluate and control particle oxidation is the bottleneck problem faced by the industry. In this paper, a three-dimensional transient calculation model of flame flow during HVOF thermal spraying WC-12Co process was established, and the computational fluid dynamics and discrete phase surface reaction model were combined to calculate and reveal the distribution characteristics of flame flow and the oxidation degree for particles during the spraying process. The calculation showed that the oxide layer thickness of particles varies greatly with different particle sizes. The oxide layer thickness of particles with 5 μm size is about 90 Å, and the oxide layer thickness of particles with 60 μm size is only about 8 Å. By adjusting the process parameters of oxygen/fuel ratio, particle size and nitrogen mass flow rate in the model, the output samples of sprayed particle flight temperature, velocity and oxide layer thickness can be obtained. On this basis, the sample data were statistically analyzed based on Genetic Algorithm-Back Propagation (GA-BP) neural network model, and the optimal process parameters for preparing the optimized coating were determined: particle size 27 μm, oxygen/fuel ratio 3.1, nitrogen mass flow rate 0.000363 kg/s. Experiments were carried out with optimized parameters, the results show that the optimized coating has fewer defects, lower oxide content and higher hardness and wear resistance. This study provides an important theoretical basis for quantitative preparation of high quality HVOF spray coatings.
Journal Article
Study on Properties of Pure Al Coatings and Al/SiC Composite Coatings by Plasma Transferred Wire Spraying
Normally, aluminum-based (Al-based) anti-corrosion coatings are prepared by flame spraying and other coating technologies to improve the corrosion resistance of metal materials in the marine environment. However, the prepared coatings are usually found to be poor in quality owing to the shortcomings of traditional thermal spraying technologies, such as flame spraying, including the low jet temperature and low particle in-flight velocity. In this paper, pure Al coatings and Al/SiC composite coatings were prepared on the surface of low-carbon steel by innovatively adopting plasma transferred wire spraying technology and making full use of the technological advantages of plasma spraying. In addition, the experiments have shown that larger SiC particles play a role in shot peening during the spraying process, allowing Al droplets to spread and overlap more fully, effectively improving the density of the coating and reducing defects such as pores and cracks in the coating. However, there is no significant effect on improving the bonding strength of the coating. Therefore, the porosity of pure Al coating and Al/SiC composite coating is 3.9% and 2.5%, respectively; the microhardness is 36 HV
0.1
and 102 HV
0.1
, respectively, increasing by about three times; the bonding strength with the matrix is 39.0 and 36.5 MPa, respectively; the corrosion resistance of Al/SiC composite coating is significantly better than that of pure Al coating, and the wear rate is reduced by 7 times compared to pure Al coating.
Journal Article
Characterization of ZnO-Doped Hydroxyapatite Coatings on PEEK Made by Hybrid Plasma Spraying Process for Biomedical Applications
Due to its similar Young’s modulus to bone, polyetheretherketone (PEEK) shows potential as an alternative to metallic implants, avoiding the stress-shielding effect. Hydroxyapatite (HAp) coatings promote bone growth on the implant surface, while zinc oxide acts as an antibacterial agent. This study aims to develop functional coatings on PEEK that simultaneously stimulate bone growth and exhibit antibacterial properties. ZnO-doped HAp coatings were applied to PEEK using a powder mixture of ZnO/HAp and hybrid process (atmospheric plasma spraying and solution precursor plasma spraying). With powder mixtures, the ZnO content in the coatings could be determined without phase change, with nearly half of the initial ZnO powder lost. Meanwhile, using hybrid methods, the aerosol precursor zinc nitrate couldn’t fully convert into zinc oxide, resulting in the presence of intermediate zinc hydroxynitrate (up to 39.38%) in the as-sprayed coatings. Subsequently, the zinc hydroxynitrate could be converted to zinc oxide after heat treatment.
Journal Article
Design and Experiment of a Breakpoint Continuous Spraying System for Automatic-Guidance Boom Sprayers
Repeated and missed spraying are common problems during the working of boom sprayers, especially in the breakpoint continuous process. Therefore, the present study investigated a breakpoint continuous spraying system for automatic-guidance boom sprayers based on a hysteresis compensation algorithm for spraying. An operational breakpoint identification algorithm, which combines a real-time kinematic global navigation satellite system (RTK-GNSS) and wheel odometer, was proposed; a pre-adjusted proportional-integral-derivative (PID) control algorithm for the opening degree of the proportional control valve was designed in thus study. Tests were conducted to establish equations correlating the opening degree of the proportional control valve, pump output flow rate, and main pipeline flow rate, with an R2 ≥ 0.9525. The time to adjust to the target flow rate was experimentally tested. The breakpoint identification accuracy of the RTK-GNSS and RTK-GNSS + wheel odometer was experimentally assessed. A field spraying deposition variation experiment was conducted. According to the results, the system effectively eliminated missed spraying, with a maximum repeated spraying distance of ≤3.3 m, and it achieved a flow control error within 3%. This system also reduced the repeated spraying area and enhanced the pesticide spraying quality of breakpoint continuous spraying for automatic-guidance boom sprayers.
Journal Article
Agrifac Condor Endurance smashes two world spraying records in Australia in 1 day
Once again, the Agrifac Condor Endurance proves to be a capacity monster. On March 2, at the farm of Karolyn, Tony and Brendan Mason, 35 km east of Perenjori in Western Australia, the Condor Endurance completed 2,638 ha (6,515.86 acres) of summer spraying in nonstop 24 hours. Within this period there was one hour in which the machine sprayed 150.7 ha, a second world record. Agrifac did little preparation leading up to the event. The demonstrator 48 meter HTA Condor Endurance was close by a week before and after a few phone calls, it was all set for the week. The timing was right and the Masons were keen to support the company in setting a new world record for 24 hr spraying.
Journal Article