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Effects of graphene coating on the plastic deformation of single crystal copper nano-cuboid under different nanoindentation modes
摘要： Molecular dynamic simulations of nanoindentation were performed to investigate the effects of graphene coatings on the plastic deformation of copper (Cu) under different indentation conditions. The results show that the graphene coating can dramatically strengthen the load bearing capability of Cu substrate for the displacement-controlled indentation, which is proportional to the number of graphene layers increasing from single to triple. And the load force also increases with the rising indentation speed, causing larger and rapider plastic deformation. For the load-controlled indentation, the graphene coating can protect the Cu substrate from being damaged by the external force. The protection capability of graphene increases as the layers growing to triple at the same loading. What's more, the larger load force can facilitate the increase in penetration depth at the equilibrium state. Our observation provide a better understanding of mechanism of plastic deformation under the effect of graphene covering.
关键词： Plastic deformation,Nanoindentation,Molecular dynamic simulations,Graphene coating
更新于2025-09-23 15:23:52
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Surface functionalization of titanium with zinc/strontium-doped titanium dioxide microporous coating via microarc oxidation
摘要： Deficient osseointegration and implant-related infections are pivotal issues for the long-term clinical success of titanium (Ti) implants. Zinc (Zn) and strontium (Sr) serve dual functions by promoting osteogenesis and inhibiting bone destruction, and Zn has good antibacterial activity. As such, this study examined the preparation of a Zn/Sr-doped titanium dioxide microporous coating (MT-Zn/Sr) on a Ti surface using microarc oxidation (MAO), with Zn and Sr evenly distributed throughout the coating. In vitro, the coating could promote the adhesion, proliferation, differentiation and mineralization of osteoblasts, showing good biological activity. Antibacterial testing demonstrated the good antibacterial activity of the coating, as it inhibited the proliferation of Staphylococcus. In vivo, MT-Zn/Sr promoted early osseointegration between the Ti substrate and the bone tissue. This work is expected to provide a new method for improving the biological activity of Ti implants and thus has important theoretical significance and great clinical prospects.
关键词： Osseointegration,Strontium,Zinc,Titanium coating,Antibacterial property
更新于2025-09-23 15:23:52
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Fabrication of Remarkably Bright QD Densely-Embedded Silica Nanoparticle
摘要： We developed a synthesis method for silica-coated quantum dot (QD)-densely-embedded silica nanoparticle (Si@D-QD@Si NP) with remarkably brighter fluorescence by increasing the number of QDs on silica NPs. Si@D-QD@Si NPs exhibited a narrow size distribution and a high signal reproducibility. Red, green, and blue Si@D-QD@Si NPs were successfully fabricated and characterized. The Si@D-QD@Si NP carried 2.4 times more QDs than previously reported silica-coated QD-embedded silica NP (Si@QD@Si NP). The quantum yield of Si@D-QD@Si NPs was slightly higher than Si@QD@Si NPs. The red Si@D-QD@Si NPs showed approximately 26.6%, the green Si@D-QD@Si NP 36.2%, and the blue Si@D-QD@Si NP 39.3% higher fluorescence intensity compared to the corresponding Si@QD@Si NPs. This result implied that the particles can be used at bio-field with a higher sensitive detection.
关键词： Quantum dot,Quantum yield,Fluorescence,Silica coating,Silica nanoparticle
更新于2025-09-23 15:23:52
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Ultrasensitive LPFG corrosion sensor with Fe-C coating electroplated on a Gr/AgNW film
摘要： This paper presents the first report on an ultrasensitive Fe-C coated long period fiber gratings (LPFG) corrosion sensor with graphene (Gr) and silver nanowire (AgNW) composite as a conductive film for Fe-C electroplating. The Gr/AgNW composite was grown on copper foil, wet transferred and adhered to the curve surface of the fiber optic sensor under atmospheric pressure and heating conditions. For comparison, another Fe-C coated LPFG sensor was prepared with silver nano ink as a conductive film. Both sensors were tested for 72 h in 3.5 wt.% NaCl solution with simultaneous measurements of transmission spectrum and electrochemical impedance spectroscopy. Due to its high optical transparency, the Gr/AgNW composite increased the wavelength sensitivity and service life of a Fe-C coated LPFG sensor by over 90% and 110%, respectively. The effective depth of influence to the evanescent field surrounding the LPFG sensor was 23.6 μm with the silver film and greater than 30 μm with the Gr/AgNW film.
关键词： Long period fiber gratings,Silver nanowire,Corrosion sensor,Fe-C coating,Graphene
更新于2025-09-23 15:23:52
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Enhancement of substrate-coating adherence of boron-doped diamond electrodes by nanosecond laser surface texturing pretreatment
摘要： To improve the substrate-coating adherence of Nb-based boron-doped diamond (BDD) electrodes, laser surface texturing (LST) pretreatment was investigated. Substrates were textured by a Nd:YAG laser (1.06 μm radiation, 20 ns) with several laser parameters such as single pulse energy and scanning spacing, then coated with a BDD film by hot filament chemical vapor deposition (HFCVD). Characteristics of the substrates and BDD thin film electrodes were investigated. The results revealed that periodic valley-like structures were fabricated on substrate surfaces. LST pretreatment can significantly enhance the substrate-coating adherence of BDD electrode samples, and the laser cleaning step can effectively remove the surface oxide layer generated by laser pretreatment. Single pulse energy is a crucial influencing factor, the proper pulse energy can provide the best adherence property, providing sufficient surface treatment effect, promoting nucleation, release residual stress and promote the mechanical interlock. Suitable scanning spacing can further improve the coating adherence, and the match of scanning spacing and single pulse spacing can effectively avoid the directional peeling.
关键词： Laser cleaning,BDD electrode,Laser surface texturing,Substrate-coating adherence
更新于2025-09-23 15:23:52
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Assessment of Bamboo Charcoal/Nano-TiO2 (BC/TiO2) Composite Material and Its Application in Photocatalytic Coating
摘要： The bamboo charcoal/nano-TiO2 (BC/TiO2) composite material is designed and prepared for further improving photocatalytic property of TiO2. Assessment of BC/TiO2 composite material and its application in photocatalytic coating are investigated by nitrogen absorption test, scanning electron microscopy-energy disperse spectroscopy (SEM-EDS) characterization and photocatalytic and mechanical properties analysis. The results show that optimal ratio of TiO2 to BC is 0.03. Rhodamine B (RhB) degradation ratio can reach 62.9% under 4 h UV light irradiation, which is 43.7% higher than pure TiO2 sample. The specific surface area (SBET) and the total average pore size (D) of BC/TiO2 can reach 388.33 m2/g and 3.71 nm, respectively. Moreover, the photocatalytic coatings prepared mainly by BC/TiO2 and polyacrylic emulsion (PAE), not only show satisfactory mechanical properties, but also have excellent photocatalytic property. When the addition of BC/TiO2 composite materials is 6%, the photocatalytic property of coating is optimal, RhB degradation ratio can reach 83.7% under 8 h UV light irradiation. Also the adhesion, pencil hardness and impact resistance reach 2 level, 2H and 44 kg cm, respectively.
关键词： Bamboo charcoal,Nano-TiO2,Photocatalytic,Coating
更新于2025-09-23 15:23:52
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Silica-coating of nano-$$\hbox {Y}_{3} \hbox {Al}_{5} \hbox {O}_{12}{:}\hbox {Ce}^{3+}$$Y3Al5O12:Ce3+ synthesized by self-combustion
摘要： Y2.91Ce0.09Al5O12 is obtained by self-combustion, grinding and sol–gel coating. X-ray diffraction, transmission electron microscopy, photoluminescence and absorption measurements were used to identify the structural and optical properties of each step of the process. The process is composed of a combination of chemical and physico-chemical processes including combustion and thermal steps, followed by grinding, powder dispersion by acidic passivation, stabilization of particle dispersions with citrate ligands and embedding of yttrium aluminium garnet (YAG) particles into SiO2 shells using a seeded growth process before drying. The initial state of the obtained powder is composed of 35 nm crystallites, sintered and agglomerated. The grinding step breaks the sintered bridge, while the passivation and citrate adsorption steps separate the particles by electrostatic repulsion before the silica coating. The optical characterizations are performed and compared separately for the powdered samples that represent the initial and ?nal states of our process, and the dispersion sample represents the intermediate state of our process. The optical measurement revealed an important amount of optical defects at the surface of the particles, compared with micrometric commercial particles. The grinding, nitric acid and citrate steps remove some of these defects. The ?nal state of the sample still possesses lower quantum ef?ciency than that of a micrometric sample, but the SiO2 coating allows for a perfect separation of the particle, suitable for implementation in small devices.
关键词： Self-combustion,YAG,core–shell,SiO2 coating
更新于2025-09-23 15:23:52
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Neural network-based hybrid signal processing approach for resolving thin marine protective coating by terahertz pulsed imaging
摘要： A novel approach was presented to enhance the capability of resolving thin coating layers using terahertz pulsed imaging (TPI) based on a neural network-based hybrid signal procession method, which is of great significance for in-line painting applications. In the present work, Terahertz detected signals were obtained by numerical simulation using finite difference time domain (FDTD) method. Models of marine protective coatings with different coating structures were calculated and analyzed. Different signal pre-processing techniques, including Fourier deconvolution, Fast Fourier Transform and wavelet analysis, were employed on the terahertz signals respectively to obtain various signal features. The processed signal was subsequently adopted as the input vectors for a neural network (NN). The optimization procedure for determining the architecture of neural network was investigated and the evaluated results obtained by the different networks were compared. Furthermore, the predicted results of thinner coating layer obtained by multiple-regression analysis method and BP network prediction method respectively were compared. The analysis demonstrated that the best prediction performance was achieved by neural network technique combined with wavelet analysis. Therefore, the hybrid signal processing approach could be recommended for terahertz non-destructive testing applications of marine protective coating.
关键词： Terahertz pulsed imaging,Non-destructive testing,Neural network,Thin marine protective coating
更新于2025-09-23 15:23:52
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Microstructure and tribological properties of laser cladded self-lubricating nickel-base composite coatings containing nano-Cu and h-BN solid lubricants
摘要： In the present work, nickel-base composite powder (Ni60), nickel-base composite powder with the addition of h-BN solid lubricants (h-BN/Ni60) and nickel-base composite powder with the addition of nano-Cu encapsulated h-BN solid lubricants (nano-Cu/h-BN/Ni60) were used as raw materials to synthesize three different coatings on Q235 steels by laser cladding. Microstructures of these coatings were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Raman spectroscopy. Tribological properties of these coatings were investigated at the temperatures from 25 °C to 600 °C. High temperature micro-hardness measurement was performed by Vickers micro-hardness tester. The results showed that the h-BN particles survived after laser cladding and displayed a homogeneous distribution in the nickel-base composite matrix. The encapsulation of h-BN by nano-Cu resulted in an increase of h-BN content in the coating. Although the addition of nano-Cu and h-BN led to a decrease on hardness, the nano-Cu/h-BN/Ni60 coating had the lowest friction coefficient and wear rate among the three coatings in a wide range of temperature from 25 °C to 500 °C. The mechanism of wear reduction by addition of nano-Cu encapsulated h-BN solid-lubricants was also discussed in this research.
关键词： Laser cladding,Self-lubricant coating,Steel substrate,Wear,Wide temperature range,Nickel-base composite
更新于2025-09-23 15:23:52
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Preparation of multicomponent thin films by magnetron co-sputtering method: The Cu-Ti case study
摘要： The paper discusses the preparation of multicomponent thin films of Cu-Ti composite with desired elemental composition using the pulsed magnetron co-sputtering technology. The technological goal described in the paper was deposition the Cu-Ti composite with elemental ratio of about 50/50 at.%, which is close to the eutectic point from the Cu-Ti alloy system. A large difference in the sputtering yield (about seven-fold) of Cu and Ti metals was challenging, because of the features of used power supplies. Desired concentrations of the Ti and Cu elements were obtained as a result of application of multimagnetron sputtering system, where magnetrons were equipped with the Ti or Cu targets. Additionally, pulse power supply was used together with the pulse width modulation controller. Moreover, the article presents investigations of structural and mechanical properties of deposited Cu, Ti and Cu-Ti films with elemental composition of ca. 50/50 at.%. It was found that the two component Cu0.5Ti0.5 thin films were composed of Cu4Ti3 nanocrystallites built-in an amorphous matrix. As compared to the pure Cu and Ti thin films, the prepared composite exhibited improved hardness and better elasticity reflected in lower values of the Young’s modulus. The results of nanoindentation investigations showed that the Cu0.5Ti0.5 composite thin film was characterized by the hardness of 7.59 GPa.
关键词： thin film,CuTi alloy,multicomponent coating,magnetron sputtering
更新于2025-09-23 15:23:52