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RESEARCH ON MINIMUM ENERGY EXCITED TO PLASMA COATING FOR REDUCING RADAR CROSS SECTION OF TARGET
摘要： To reduce the radar cross section (RCS) of a target, plasma coating on perfectly electric conducting plate is studied in this paper. Nonuniform helium plasma produced by a minitype solid rocket engine is with collisional and unmagnetized. Energy excited for generating helium plasma is investigated. Based on the collisional, unmagnetized, and cold plasma model, backscattering RCS is computed by using ?nite-di?erence time-domain method. Principle of RCS reduction is explained. To ?nd minimum input energy while RCS reduced, relationship between input power and RCS reduction is discussed, and numerical optimization is also implemented. We can identify optimal parameters and choose the best electron density pro?le under condition of given input power level.
关键词： Radar Cross Section (RCS),Plasma Coating,Input Power,Electron Density,Finite-Difference Time-Domain (FDTD) Method
更新于2025-09-23 15:21:21
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Thin Film Processes - Artifacts on Surface Phenomena and Technological Facets || Modified Spin Coating Method for Coating and Fabricating Ferroelectric Thin Films as Sensors and Solar Cells
摘要： Spin coating process with a modified spin coater is performed well, especially the second generation of modified spin coater, which has a maximum value of 18,000 rpm, is able for manufacturing/coating photonic crystal‐based ferroelectric thin films that require a high angular velocity (rpm). Ferroelectric thin films that use both 3000 and 6000 rpm have given good results in energy gap, electrical conductivity, etc. In addition, the modified spin coater has also produced several applications such as sensors in the device of blood sugar level noninvasively, sensors in the automatic drying system, sensors in the robotic system, and photovoltaic cells in the system of solar cells/panels which are being developed at present. These applications used ferroelectric material such as barium strontium titanate (BST), lithium niobate (LiNbO3), cuprous oxide (CuO), and lithium tantalate (LiTaO3).
关键词： ferroelectric thin films,solar cells,modified spin coating,sensors
更新于2025-09-23 15:21:21
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Effect of Deposition Pressure, Nitrogen Content and Substrate Temperature on Optical and Mechanical Behavior of Nanocomposite Al-Si-N Hard Coatings for Solar Thermal Applications
摘要： Hard and optically transparent nanocomposite Al-Si-N thin films were deposited using DC magnetron sputtering at different process parameters. There was a significant effect of these parameters on the film properties affecting its mechanical and optical behavior. The nitrogen content or pressure, deposition pressure and substrate temperature strongly influence the phase formation which governs the hardness and optical transparency of the coating. Hardness was measured between 18 and 30 GPa. The band gap could be varied in the range of 3.8-4.2 eV by varying nitrogen pressures in the chamber during deposition. The films showed (0-80)% transparency in UV and visible region depending on the sputtering conditions.
关键词： mechanical behavior,optical coating,nanocomposite hard coatings
更新于2025-09-23 15:21:21
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Size and shape control of monoclinic vanadium dioxide thermochromic particles for smart window applications
摘要： Monoclinic vanadium dioxide (VO2 (M)) was synthesized by the thermolysis of vanadyl ethylene glycolate, which was obtained easily by the precipitation of a vanadium precursor in ethylene glycol solution under atmospheric conditions. The particle size and shape were easily controlled by altering the molar concentration of the vanadium precursor. Thereafter, VO2 (M) composite films were prepared by mixing with poly(vinylpyrrolidone). A high concentration of the vanadium precursor produced small spherical nanoparticles ≈30 nm in size, while lower concentrations afforded large rod-like particles. The composite films fabricated with the VO2 (M) nanoparticles exhibited high luminous transmittance (Tlum = 79%) and IR modulation ability (ΔTIR = 5.6%). This work demonstrates that these VO2 (M) composite films show promise for application in smart windows.
关键词： solar modulation ability,Energy efficiency,size and shape tuning,high luminous transmittance,VO2 (M) particle,thermochromic coating
更新于2025-09-23 15:21:21
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Analysis of the Mo/Mo Nanocrystalline Optical Coating Obtained with the Aid of Simultaneous Deposition and Ion Sputtering
摘要： Structure, optical properties, and resistance to sputtering are studied for a reflecting Mo-coating that is fabricated using magnetron deposition with simultaneous low-energy ion sputtering at the deposition rate that is higher than the etching rate. A Mo-polycrystalline mirror is used as a substrate. It is shown that the coating exhibits textured nanocrystalline structure with a relatively low spread of crystallite sizes and high resistance to sputtering. It is also demonstrated that the spectral reflection coefficient of such a Mo-coating differs from the spectral reflection coefficient of polycrystalline and single-crystalline Mo and the difference results from the effect of the structure of coating on its optical properties. A theoretical model of the coating formation is proposed.
关键词： optical properties,Mo-coating,nanocrystalline structure,ion sputtering,magnetron deposition,resistance to sputtering
更新于2025-09-23 15:21:21
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Effects of TiC on the microstructure and properties of TiC/TiAl composite coating prepared by laser cladding
摘要： In order to study the effect of TiC on the microstructure and properties of cladding coatings, TiC/TiAl composite coatings have been prepared by using a laser cladding technique on TiAl alloy, and the microstructure and properties of the resulting composite coatings have been investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), micro-hardness testing, X-ray stress measurements, friction and wear testing, and an electrochemical workstation. The results showed that when the particle size of TiC is up to micron, the growth of TiC is more developed, the dendrite growth direction is disordered, and the cladding quality is poor. When the particle size of TiC is nanoscale, the morphology of the reinforcement phase TiC is mainly granular and thin rods, which is uniform in the coating and the direction of growth is regular. When the concentration of TiC reaches 20%, the microstructure of the cladding layer grows well and is dense. The microhardness and wear resistance of the coatings prepared by adding nano TiC are better than those of the coatings prepared by micron TiC. When the content of nano TiC in the coatings increases from 10% to 20%, the microhardness and wear resistance of the coatings are obviously improved. The residual stress of the coating is positively related to the crack rate. The residual stress in the coating is tensile stress, and the crack type is the crystal crack in the hot crack. When the particle size of TiC is small and the concentration is high, the coating shows better corrosion resistance.
关键词： TiAl alloy,TiC/TiAl composite coating,Laser cladding,Properties,Microstructure
更新于2025-09-23 15:21:21
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Preparation of ultra-broadband antireflective coatings for amplifier blast shields by a sol–gel method
摘要： A type of λ/4–λ/4 ultra-broadband antire?ective coating has been developed using modi?ed low refractive silica and high refractive silica layers by a sol–gel dip coating method for ampli?er blast shields of the Shen Guang II high power laser facility (SG-II facility). Deposition of the ?rst layer (high refractive index silica) involves baking at 200 ?C in the post-treatment step. The second layer (low refractive index, n = 1.20) uses low refractive index silica sol modi?ed by acid catalysis. Thermal baking at temperatures no less than 500 ?C for 60 min offers chemical stability, ethanol scratch resistance, and resistance to washing with water. The average residual re?ection of dual-side-coated fused silica glass was less than 1% in the spectral range from 450 to 950 nm. Transmission gain has been evaluated by taking into account angular light, and the results show that the transmission gain increases with increasing light incidence. Even at 60?, the transmission spectrum of the broadband antire?ective coating effectively covered the main absorption peak of Nd:glass.
关键词： blast shields,ampli?er,ultra-broadband,sol–gel,antire?ective coating
更新于2025-09-23 15:21:21
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The effects of cathode electrodeposited polymer film on the long vacuum gap breakdown
摘要： Vacuum surface discharge is one of the most important issues for vacuum insulation. In this paper, a method for breakdown ?eld strength enhancement of long vacuum gap is put forward, through depositing polymer dielectric coating on the electrode surface. The physical mechanism that the polymer ?lm changes the electrode surface state is analyzed. After a layer of polymer ?lm is deposited on the electrode surface, the decreased surface ?eld strength and improved micro-surface state both help to suppress the ?eld electron emission from the cathode. The technique of cathode electrodeposition for high polymers such as epoxy resin (ER), epoxy acrylate (EA), polyimide (PI) and poly(ether-ether-ketone) (PEEK) was explored, and the thickness of the electrodeposited coating can reach 20–50 mm. The effects of the electrodeposited polymer coatings of electrodes on the 2.5 cm vacuum gap breakdown were studied under a high-voltage vacuum experiment platform. Experimental results showed that when ER, EA and PEEK coatings with thickness of 25–45 mm were respectively electrodeposited on the 95 cm2 plate cathode, the initial-breakdown ?eld strengths of the 2.5 cm vacuum gap were enhanced by 20.7%–22.4%. The enhancement of the initial-breakdown ?eld strength was restricted by the coating defects, grain boundary defects on the cathode surface, and the micro-triple-point emission after the fusing of some local coating points due to the electron bombardments.
关键词： vacuum gap breakdown,vacuum insulation,cathode electrodeposition,polymer dielectric coating,field electron emission
更新于2025-09-23 15:21:21
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Optimization of synthesis condition of water-resistant and thin titanium oxide layer-coated Ni-rich layered cathode materials and their cathode performance
摘要： In this study, in order to develop water-resistant LiNiaCobAl1?a?bO2 (a > 0.85, NCA) cathode materials which exhibit high-rate performance, the surface coating of NCA with titanium oxide (TiOx) was examined. The synthesis conditions for the TiOx-coated NCA cathode materials were investigated, by taking into account some essential factors in the surface coating of NCA by TiOx, with a view to improving the rate performance. We successfully prepared the TiOx-coated NCA cathode material, the rate performance of which is superior to that of the conventionally prepared NCA cathode materials, typically using a polyvinylidene difluoride (PVdF) binder and N-methyl-2-pyrrolidone (NMP) solvent. Their surface analysis suggested that the specific surface structure of TiOx layer coated on the NCA particle leads to both a water-resistant property and a high permeability of Li+ ions through it in the charging/discharging process.
关键词： Lithium ion secondary battery,Water-based hybrid polymer binder,TiOx coating layer,Water resistance,Ni-rich lithium transition metal oxide
更新于2025-09-23 15:21:21
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A review on the laser welding of coated 22MnB5 press-hardened steel and its impact on the production of tailor-welded blanks
摘要： The current demand for vehicles with high fuel efficiency, improved safety and enhanced crash-worthiness qualities is being met by making use of high strength components with tailored mechanical properties which are made using tailor-welded blanks. During their production, the surface of the blank needs to be protected against oxidation and decarburisation. Protective coatings are used to protect the steel surface, with Aluminium-Silicon or Zinc-based coatings being the most popular. This work provides a review on the state-of-the-art as well as the issues associated with the laser welding of coated 22MnB5 grade steel to be used in the production of tailor-welded blanks. The paper provides a summary of existing solutions available to overcome these issues while discussing their limitations and the potential for future work.
关键词： Fibre laser welding,tailor-welded blanks,22MnB5,Zn-Coating,press-hardened steel,ultra-high strength steel,Al–Si coating,hotstamped parts
更新于2025-09-23 15:21:01