75 research outputs found
Tribological behavior of RF sputtering WS2 thin films with vacuum annealing
No full textAbstractThin films of tungsten disulfide (WS2) were deposited on 3Cr13 martensitic stain less steel substrate by RF sputtering. The as-deposited films were annealed at 200,400 and 600°C for 2h in vacuum. The vacuum degree was 510-4Pa. Composition, surface morphology, structure properties and tribological behavior were studied by EDS, SEM, X-ray diffraction techniques and tribometer, respectively. At 200°C, the films showed low crystallization structure and the tribological behavior was not improved obviously. But at 400°C, the films tribological behavior were improved obviously and non-crystalline to hexagonal structural transition appeared. When annealing temperature rose to 600°C, the films were desquamated from substrate. The results suggested that suitable vacuum annealing was able to promote crystallization and improve tribological performance of RF sputtering WS2 films
Experimental Research on the Preparation of K(2)CO(3)/Expanded Vermiculite Composite Energy Storage Material
No full textThermochemical adsorption energy storage is a potential energy utilization technology. Among these technologies, the composite energy storage material prepared by K(2)CO(3) and expanded vermiculite (EVM) shows excellent performance. In this paper, the influence of the preparation process using the impregnation method and vacuum impregnation method on K(2)CO(3)/EVM composite material is studied. The preparation plan is further optimized with the solution concentration and the expanded vermiculite particle size as variables. In the experiment, mercury intrusion porosimetry (MIP) is used to measure the porosity and other parameters. Additionally, with the help of scanning electron microscopy (SEM), the morphological characteristics of the materials are obtained from a microscopic point of view. The effects of different preparation parameters are evaluated by comparing the experimental results. The results show that the K(2)CO(3) specific gravity of the composite material increases with the increase of the vacuum degree, up to 70.440 wt.% (the vacuum degree is 6.7 kPa). Expanded vermiculite with a large particle size (3~6 mm) can carry more K(2)CO(3), and content per cubic centimeter of K(2)CO(3) can be as high as 0.466 g
Novel Strategies Targeting Obesity and Metabolic Diseases
No full textThis eBook is a collection of articles from a Frontiers Research Topic. Frontiers Research Topics are very popular trademarks of the Frontiers Journals Series: they are collections of at least ten articles, all centered on a particular subject. With their unique mix of varied contributions from Original Research to Review Articles, Frontiers Research Topics unify the most influential researchers, the latest key findings and historical advances in a hot research area! Find out more on how to host your own Frontiers Research Topic or contribute to one as an author by contacting the Frontiers Editorial Office: frontiersin.org/about/contac
Influence of a Scanning Radial Magnetic Field on Macroparticle Reduction of Arc Ion-Plated Films
No full textCathode spot motion influences the physical characteristics of arc plasma and the related macroparticles (MPs) in resultant films; these MPs limit the application of arc ion plating (AIP). In this paper, a scanning radial magnetic field (SRMF) was applied to the cathode surface to control the cathode spot motion and reduce the MP contamination in the deposited films. It was shown that film surface morphologies prepared using SRMF were better than those using a static radial magnetic field (RMF). The improvement was greater with increased scanning range and frequency. Using SRMF, cathode spot motion was confined to a spiral trajectory on the cathode surface and the spots moved over a large area and at a fast-moving velocity. Both the large moving area and the fast velocity decreased the temperature on the cathode surface and thus reduced the emission of the MPs
Numerical Study on Collision-Less Plasma Sheaths of RF-Glow Discharge
No full textAbstractA self-consistent mathematic model for radio frequency (RF) glow discharge was proposed to investigate the spatiotemporal evolvement of collision-less plasma sheaths at different plasma characteristics, in which the influences of ion motion by instantaneous sheath electric field were considered and the present model would be suitable for describing the spatiotemporal characteristics plasma sheaths with wide RF-frequency ranges. The instantaneous relationship between the voltage on the RFbias electrode and the sheath thickness was determined by an equivalent circuit model coupled with a fluid model. The periodic distributions of voltage on RF-bias electrode, sheath thickness, sheath electric field, density of ion and electron in sheath were obtained by numerical methods based on the present model. It was found that the distribution of electrode voltage presents nonsinusoidal waveform which is different from the sinusoidal waveform assumptions of other researches. The numerical computation results show that β, the ratio of RF frequency and ion plasma frequency, is an important parameter that affects RF plasma sheath's features: the motion and density distribution of ion are mostly controlled by instantaneous sheath electric field if β<1; however, when β>1, the ion motion could be determined by the average field intensity of plasma sheath, and the ion density could almost not be changed
- …
