Search

With Sm 0.5 Sr 0.5 CoO 3 microparticles as the raw material, high solar absorptive and high infrared emissive coatings were successfully prepared on 6061 aluminum alloys using a new method including firstly microparticle pre-deposition by gravity and then plasma electrolytic oxidation (PEO) technique. All four coatings were characterized by XRD, SEM and EDS respectively. The solar absorbance (α s ) and infrared emittance (ε T ) were also investigated. The results showed that all four coatings were black and rough; the Na and P elements from the electrolyte were incorporated into the coatings; amorphous compounds containing Na and P also existed in the coatings. All four coatings had a complex multiphase composition mainly consisting of Sm 2 O 3 , SrAl 4 O 7 , AlPO 4 and CoAl 2 O 4 phases, which might derive from drastic reactions under high temperature and high pressure during the PEO process. The surface morphology and the relative content of main crystal phases changed with increasing current density or time. The cross-section of the coatings exhibited a layer structure. As current density or time increased, the α s decreased but ε T increased. All four coatings showed a high solar absorbance value ≥ 0.85 and high infrared emittance value ≥ 0.90, which indicated that the coatings might have promising applications in solar and infrared heating for aluminum alloys. [ABSTRACT FROM AUTHOR]

The present study discusses the development of a simulation model of transient impact between a particle and a substrate. The equations for structural behavior are coupled with those of heat transfer, wherein material properties are taken as temperature dependent. The set of equations is solved with Ansys program using a direct coupling method. At first, structural model is solved without heat transfer. Then, coupled thermo-mechanical model is solved with and without thermoelastic effects. Computational results indicate that thermal consideration has significant effects on contact problem. In addition, it is shown that, themoelasticity consideration is crucial for simulating these problems to determine the structural and thermal parameters. [ABSTRACT FROM AUTHOR]

Optical functional surfaces are key components of nearly every optical device and they have become a special focus in both academia and industry. The no contact, one step, direct, and maskless laser surface texturing technique is one of the most encouraging approaches for realizing the surface functions. We use a high power and high repetition rate ultrafast laser system to produce micro–nano structures on metal surfaces. We demonstrate that metal surface micro–nano structures and correspondingly their optical responses can be facilely tailored by simple controlling the ultrafast laser processing parameters. Nano particles of tens to hundreds nm, sub-micro particles of 0.5–1 μm, fine-micro particles of 1–10 μm, micro particles of 10–50 μm, and coarse-micro particles larger than 50 μm have been fabricated on Cu surfaces. And surface reflection of copper surfaces has been tuned from 10% to 90% in spectra level and from UV to MIR in spectrum range, with unique optical properties like visible selective reflection, linear changing reflection, band reflection, and broadband absorption being achieved. The formation processes of those particle structures as well as the underlying mechanisms for their optical responses are discussed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Addition of 10−2 M cationic surfactants with longer carbon chain to basic solution reduced particle adhesion on InGaAs. • Addition of 10−2 M CTAB into basic solution enhanced formation of bilayer micellar structure on SiO 2 surface. • Adhesion of silica particles on InGaAs surface was reduced with the formation of bilayered CTAB micellar structures. • Interaction force between silica particles and InGaAs was studied to find the relationship of particle adhesion with energy barrier. • Addition of 10−2 M CTAB reduces attraction and enhances repulsion between InGaAs and silica particle surfaces. The surface properties of InGaAs, such as zeta potential, surface energy components, acid–base energy constant, and Hamaker constant and its interaction force with silica particles, have not yet been elucidated. In this study, the adhesion of silica particles on an InGaAs surface in a 1/1/100 ammonium hydroxide (NH 4 OH)–hydrogen peroxide (H 2 O 2)–H 2 O mixture (APM) solution was investigated. In particular, the effect of the addition of cationic surfactants and the concentration of hexadecyltrimethylammonium bromide (CTAB) on the particle adhesion/desorption was examined. To understand the adhesion behavior of silica particles on the InGaAs surface, the Lifshitz–van der Waals energy, acid–base interaction energy, and electrostatic energy between the silica particles and the InGaAs surface were estimated. It was found that the behavior of the energy barrier was strongly related to the number of silica particles that were adhered to the InGaAs. The energy barrier was reduced in the APM solution with 10−4 M CTAB, facilitating the adhesion of silica particles. However, when the CTAB concentration increased to 10−2 M, the energy barrier was elevated, and the adhesion of silica particles was reduced. The adhesion and desorption behaviors of silica particles on the InGaAs surface can be explained by the change in the energy barrier between the particles and InGaAs. [ABSTRACT FROM AUTHOR]

Abstract: Various kinds of surfactants were added to a cleaning solution and deionized (DI) water, and their effect on the suppression of organic function group formation and particle adhesion to a SiO2 surface was analyzed using multi-internal reflection Fourier transform infrared spectroscopy. The results implied that attached organic functional groups are affected by the chemical structure of a surfactant in DI water. Furthermore, the addition of anionic glycolic acid ethoxylate 4-tert-butylphenyl ether (GAE4E) is the most effective in terms of preventing organic group attachment and particle adhesion to the SiO2 surface, whether it was added to the cleaning solution or post-cleaning rinse water, with or without polystyrene latex particles. Moreover, it was possible to completely prevent particle adhesion to the SiO2 surface with the proper addition of GAE4E in DIO3 solution. [Copyright &y& Elsevier]

Abstract: Particles generated by 2.94μm pulsed IR laser ablation of liquid 3-nitrobenzyl alcohol were irradiated with a 351nm UV laser 3.5mm above and parallel to the sample target. The size and concentration of the ablated particles were measured with a light scattering particle sizer. The application of the UV laser resulted in a reduction in the average particle size by one-half and an increase in the total particle concentration by a factor of nine. The optimum delay between the IR and UV lasers was between 16 and 26μs and was dependent on the fluence of the IR laser: higher fluence led to a more rapid appearance of particulate. The ejection velocity of the particle plume, as determined by the delay time corresponding to the maximum two-laser particle concentration signal, was 130m/s at 1600J/m2 IR laser fluence and increased to 220m/s at 2700J/m2. The emission of particles extended for several ms. The observations are consistent with a rapid phase change and emission of particulate, followed by an extended emission of particles ablated from the target surface. [Copyright &y& Elsevier]

Abstract: Particles were generated from glycerol that was irradiated at atmospheric pressure using a mid-infrared optical parametric oscillator at wavelengths between 2.6 and 3.8μm. The size distribution and quantity of ejected particles with diameters larger than 300nm were measured using an aerodynamic particle sizer. At a given fluence, the particle concentration roughly tracked the infrared absorption spectrum of liquid glycerol. The threshold fluence for particle formation varied between 1000 and 5000J/m2 throughout the measured wavelength range and the minimum fluence corresponds to the IR absorption maxima of glycerol. The mean particle size roughly tracks the inverse of the IR absorption and smaller particles are observed at the greatest IR absorption. The material ejection mechanism is interpreted as an explosive boiling process in the stress confinement regime. [Copyright &y& Elsevier]

Abstract: A novel TOF-SIMS apparatus was designed and constructed aiming at single small particle analysis. The apparatus consisted of high lateral resolution TOF-SIMS part and SEM function for seeking analytical target. A pulsed Ga-focused ion beam (FIB) was also newly developed for this purpose based on state-of-the art ion optics. Secondary ion yield of Al was 1.8×10−2 which is high enough small area analysis, and mass resolution was also acceptable for element analysis. The most prominent feature, lateral resolution, was demonstrated to be 40nm in actual mapping of an IC cross-section. As an application aerosol particles were analyzed individually. [Copyright &y& Elsevier]

Abstract: Local charge neutralization using secondary electrons generated by an electron beam (EB) for SEM was devised and examined. Neutralization with a high-energy EB compared with conventional very low-energy EB requires no pulsing scheme for TOF-MS extraction voltage. Direct irradiation of high-energy EB to the insulating particle was not effective for neutralization. It was shown that the use of secondary electrons induced by EB-irradiation not on the particle directly but on a metal substrate vicinity of the particle. Charge neutralization was found to be effective even when the EB spot was distant (60μm). [Copyright &y& Elsevier]

Abstract: Laser ablation of copper metal in water was performed in order to obtain copper oxide particles. Scanning electron microscopy, energy dispersive X-ray fluorescence spectrometry, transmission electron microscopy, and electron diffraction were conducted in order to determine the size, shape and structure of the particles. The source of the O atoms in the copper oxide particles is the surrounding water molecules. The copper oxide particles obtained by laser ablation were both crystalline and amorphous. The crystalline particles were determined to be paramelaconite Cu4O3. [Copyright &y& Elsevier]

Abstract: We demonstrate the approach of diamond growth on levitating seed particles in a rf plasma. We introduce a hot filament chemical vapor deposition (CVD) technique into the rf plasma chamber in order to obtain improved crystal growth. Firstly, we confirmed diamond nucleation on seed particles placed on a Si substrate using the hot filament CVD. The deposition conditions, namely the total pressure and the rf power, were chosen so that they correspond to particles levitation conditions. We observe that a hydrogen pre-treatment on the seed particles improves the nucleation. Secondly, we confirm the levitation of particles at high temperatures. Fine particles levitated in a plasma are particularly sensitive to thermophoretic effects due to inhomogeneities in the gas heating. Therefore, proper heating procedures are required for successful particles levitation. [Copyright &y& Elsevier]

Shape properties of talc and quartz particles ground by a laboratory size ball, rod, and autogenous mills were studied using scanning electron microscope (SEM). More than 100 particles were measured to do the shape analysis of each mill product. The wettability behavior of (γc) a highly hydrophobic of talc mineral was determined by contact angle measurements and micro-flotation tests using a contact angle goniometer and EMDEE MicroFLOT test tube, respectively. On the other hand, wettability (γc) of quartz, which is a highly hydrophilic mineral, was determined by the micro-flotation method only. The results showed that the particles ground by rod mill gave higher flatness and elongation ratio, which meant higher hydrophobicity with lower γc values in the separations by flotation method. [Copyright &y& Elsevier]

• ZnO powders were fabricated by sol-gel process with different heating rate. • Effect of the heating rate on structure, optical and photocatalytic properties was investigated. • Non-isothermal and thermodynamic parameters of ZnO powders were studied. • Bulk and surface oxygen vacancies increased as heating rate went up. • ZnO sample prepared at 1 °C/min heating rate exhibited the excellent photocatalytic efficiency. In this work, ZnO particles were fabricated by sol-gel method at different heating rate at 500 °C for 2 h. The ZnO powders were analysed by X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), UV–vis spectroscopy and photoluminescence, respectively. The effect of heating rate on photocatalytic activities of ZnO particles was evaluated by degradation of methylene blue (MB). The non-isothermal kinetics and thermodynamic properties were also estimated. The XRD results showed that ZnO had hexagonal wurtzite structure. The different heating rate didn't influence the surface morphology of ZnO powders. It was observed that the heating rate had a profound effect on reduction of band gap and photocatalytic performances. The band gap of the ZnO particles varied from 3.10 to 3.17. The ZnO sample prepared at 1 °C/min exhibited the highest photocatalytic activity. Its relative photocatalytic degradation rate and kinetic constant were 92.7% and 1.069 × 10-2 min−1, respectively. The results might be ascribed to low bulk vacancies, high surface oxygen vacancies and narrow band gap energy. Also, ZnO photocatalysts showed good stability after four sequence tests. This study provides a new strategy to improve the photocatalytic performances of ZnO photocatalyst for the degradation of organic contaminant. [ABSTRACT FROM AUTHOR]