- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Preparation of Highly Porous Carbonous Electrodes by Selective Laser Sintering
摘要： Selective laser sintering (SLS) 3D printing was utilized to fabricate highly porous carbonous electrodes. The electrodes were prepared by using a mixture of fine graphite powder and either polyamide-12, polystyrene, or polyurethane polymer powder as SLS printing material. During the printing process the graphite powder was dispersed uniformly on the supporting polymer matrix. Graphite’s concentration in the mixture was varied between 5 and 40 wt % to find the correlation between the carbon content and conductivity. The graphite concentration, polymer matrix, and printing conditions all had an impact on the final conductivity. Due to the SLS printing technique, all the 3D printed electrodes were highly porous. By using polyurethane as the supporting matrix it was possible to produce flexible electrodes in which the conductivity is sensitive to pressure and mechanical stress. Physical properties such as graphite distribution, attachment, and the overall porosity of the printed electrodes were studied using scanning electron microscopy (SEM), helium ion microscopy (HIM), and X-ray tomography. The results show that the combination of chemical design of the printing material and the utilization of SLS 3D printing enables fabrication of highly customizable electrodes with desired chemical, physical, mechanical, and flow-through properties.
关键词： conductivity,graphite,3D printing,selective laser sintering,porous electrodes
更新于2025-09-19 17:13:59
-
Characterization of multi-element impurity deposited on EAST divertor tile using laser-induced breakdown spectroscopy
摘要： Laser-induced breakdown spectroscopy (LIBS) has been applied for the depth-resolved identification of impurity deposited on EAST divertor tile. LIBS spectra show the presence of impurity elements (W, Mo, Li, Na, Ca, Cr) and tile material (C, Si, Ti) in the layer deposited on the graphite tile surface. The analysis of impurity deposition was performed in different positions on tile surface. The results indicate that the interaction of high heat plasma with plasma facing components (PFCs) leads to erosion of Mo from first wall and W from upper divertor. Depth profiling measurements show decay of impurity signals with successive laser shots and non-uniform impurity deposition in the different positions on tile surface. The impurity deposition was also measured at the different depths in the tile. The measurements show a non-uniform deposition at various depths in the deposition layer. Surface morphology and composition of tile were verified by SEM and EDX techniques. The study indicates that LIBS has potential to monitor the erosion and deposition of PFCs in fusion devices. The results obtained from LIBS technique are important for long pulse of H-mode plasma operation in EAST.
关键词： Depth profile,EDX,Graphite tile,Impurity deposition,LIBS,EAST,Plasma facing components
更新于2025-09-16 10:30:52
-
Electrical and optical properties of the specimens with graphene quantum dots prepared by different number of wet transfer
摘要： Graphene quantum dots (GQDs) are grown on the copper foil substrate by the chemical vapor deposition (CVD) synthesis. 1–3 wet transfer numbers are then used in the preparations of the GQDs/glass substrate in order to improve the density and uniformity of GQDs via the stacking of multiple layers. The CH4 input time, ?ow rate, and the number of wet transfer are determined to obtain the optimum conditions in electrical (resistivity) and optical (transmittance) properties. The multilayered graphene is characteristically close to the graphite-like material. The G-band peak intensity in Raman analyses is varied proportional to the density of GQDs. Increasing the wet transfer number can lead to increases in the mean diameter of GQDs and the amount of oxygen vacancies, thus resulting in the rise of carrier concentration and the lowering of carrier mobility. The resistivity varying with the wet transfer number is inversely proportional to the density of GQDs. A bandgap reduction can bring in the lowerings of photoluminescence peak intensities. The specimen with 2 wet transfers has the lowest resistivity and the second highest transmittance of these specimens. GQDs can bring in a signi?cant reduction of resistivity compared to the same substrate without GQD.
关键词： Graphene quantum dots,Wet transfer method,Chemical vapor deposition,Graphite-like material
更新于2025-09-16 10:30:52
-
Formation of a Nanoscale Graphite Hydrosol under the Influence of Terahertz Laser Radiation
摘要： The present report describes a new phenomenon, namely the formation of a nanoscale hydrosol during short-term exposure of the surface of water by focused terahertz radiation of the Novosibirsk free-electron laser. The composition of the particles is completely determined by the material of the container used. Hydrosols are technologically convenient forms for scientific and industrial applications, which are characterized by uniform deposition and high catalytic activity used in medicine, optics, and as a suspension for sample preparation for chemical and elemental analysis. This article presents the results of our study of graphite particles formed in water, a suspension, which is in demand for industrial purposes. Commercially available high purity graphite (99.5%) of GE grade is used. The initial material and the resulting particles are studied using an atomic force and electron microscope with an elemental analyzer.
关键词： terahertz radiation,Novosibirsk FEL,nanoparticles,graphite,hydrosol
更新于2025-09-16 10:30:52
-
Influence of Work Media on Surface Property of Compacted Graphite Cast Iron Processed by Laser Local Processing
摘要： In order to enhance surface property of brake materials, compacted graphite cast iron (CGI) with non-smooth surface was processed by laser local processing. This study focuses on the influence of the work media on wear resistance and thermal fatigue resistance of specimens. The results showed that when the work media were air and water respectively, laser local processing could enhance surface property of CGI. Changing work media could not change phase compositions of the laser processing area, but refined their microstructures, which enhanced their micro-hardness. By this way, the specimens’ wear resistance and resistance to thermal crack initiation were further improved, while their resistance to thermal crack propagation was influenced by cracks on bionic units.
关键词： Work media,Laser,Compacted graphite cast iron,Wear resistance,Thermal fatigue resistance
更新于2025-09-16 10:30:52
-
Thermal and Physical Performance of Heat Sink for Light-Emitting Diode Improved with Expanded Graphite
摘要： In this study, the fabrication of working expanded graphite based heat sink was carried out as follows. Briefly, the round heat sink were composed of graphite as an active material, Cu and Al as heat transfer enhancement material and resin as a binder. The prepared round heat sinks were characterized by X-ray diffraction and scanning electron microscopy. After chemical intercalation treatment and heat treatment at 673-1073 K, it was clearly seen that the spacing of the interlayers of graphite flakes increased. The metal modified graphite heat sinks in our experiment exhibited a good rate of capability in physical performances. Sample GA10-400 showed a best and most high density, highest thermal diffusivity and thermal conductivity
关键词： Physical performance,Density,Thermal diffusivity and conductivity,Graphite,Heat transfer
更新于2025-09-16 10:30:52
-
Simple preparation of graphene quantum dots with controllable surface states from graphite
摘要： Graphite is economic and earth-abundant carbon precursor for preparing graphene quantum dots (GQDs). Here, we report a facile and green approach to produce GQDs from graphite flakes via a pulsed laser ablation (PLA) method assisted by high-power sonication. A homogeneous dispersion of graphite flakes, caused by high-power sonication during PLA, leads to the formation of GQDs following a laser fragmentation in liquid (LFL) rather than laser ablation in liquid (LAL) mechanism. The final product of GQDs exhibits the distinct structural, chemical, and optical properties of pristine graphene itself. However, graphene oxide quantum dots (GOQDs) with abundant surface oxygen-rich functional groups are readily formed from graphite flakes when high-power sonication is not employed during the PLA process. GQDs and GOQDs show a significantly different luminescence nature. Hence, selective production of either functional GQDs or GOQDs can be achieved by simply turning the high-power sonication during the PLA process on and off. We believe that our modified PLA process proposed in this work will further open up facile and simple routes for designing functional carbon materials.
关键词： high-power sonication,graphene quantum dots,luminescence,pulsed laser ablation,graphite flakes
更新于2025-09-16 10:30:52
-
Optical properties of laser-modified diamond: From visible to microwave range
摘要： We have measured the optical properties of a graphitised layer with dc conductivity of 305 W–1 cm–1 produced by excimer laser irradiation (KrF, t = 20 ns, l = 248 nm) of a polycrystalline diamond surface grown by chemical vapour deposition. Studies have been conducted in a wide range of wavelengths: from far-IR to visible spectral regions. The resulting constants of the Drude model are the basic parameters for calculating the electromagnetic response of diamond/graphite photon elements or metamaterials fabricated using the direct laser writing method.
关键词： optical properties,diamond,metamaterials,spectroscopy,nanocrystalline graphite,laser
更新于2025-09-16 10:30:52
-
Comparison thermochemical and thermophysical performances analysis in laser processing by dynamic heat-matter diffusion coupling simulation and corresponding experiment validation
摘要： The laser-matter interaction contains complex thermophysical and thermochemical responses. The variation of energy and composition happen in thermophysical and thermochemical process will totally change the interaction behaviors. In order to obtain an accurate mechanism and promote the understanding of laser-matter interaction, all thermophysical and thermochemical responses, especially the thermochemical part, should be considered and investigated. In this study, a coupled heat-matter diffusion model based on thermodynamic chemical equilibrium finite-element method and thermochemical ablation theory was established. The materials with complex reaction enthalpy change in high temperature environment were chosen to validate the model. The results show that this model is accurate, as the maximum error of back-surface temperature response is just 4.0% between experimental and calculation values. The detailed variations of composition, temperature and optical reflection were obtained and analyzed, which is in good agreement with the experiment. This coupled heat-matter diffusion model including all thermophysical and thermochemical response has the great potential in nearly all laser-matter interaction involved application.
关键词： Coupled heat-matter diffusion method,Laser ablation,Graphite/SiO2 composite,Carbothermic reaction,Finite-element
更新于2025-09-16 10:30:52
-
Demonstration of Solar Cell on a Graphite Sheet with Carbon Diffusion Barrier Evaluation
摘要： An amorphous Si (a-Si) solar cell with a back reflector composed of zinc oxide (ZnO) and silver (Ag) is potentially the most plausible and flexible solar cell if a graphite sheet is used as the substrate. Graphite supplies lightness, conductivity and flexibility to devices. When a graphite sheet is used as the substrate, carbon can diffuse into the Ag layer in the subsequent p-i-n process at 200–400 °C. To prevent this, we added an oxide layer as a carbon diffusion barrier between the carbon substrate and the back reflector. For the carbon diffusion barrier, silicon oxide (SiO2) or tin oxide (SnOx) was used. We evaluated the thermal stability of the back reflector of a carbon substrate using secondary-ion mass spectrometry (SIMS) to analyze the carbon diffusion barrier material. We confirmed the deposition characteristics, reflectance and prevention of carbon diffusion with and without the barrier. Finally, the structures were incorporated into the solar cell and their performances compared. The results showed that the back reflectors that were connected to a carbon diffusion barrier presented better performance, and the reflector with an SnOx layer presented the best performance.
关键词： flexible device,carbon diffusion barrier,a-Si solar cell,carbon substrate,graphite sheet
更新于2025-09-16 10:30:52