This study presents a dual Eulerian–Lagrangian particle approach for time-accurate computational fluid dynamics (CFD) modeling of volcanic ash in gas turbine engines and initial results. The objective is to enable high-fidelity simulations of calcia–magnesia–alumina-silica (CMAS) particles in gas turbine engines to better predict deposition and particle paths to rapidly test mitigation solutions. The approach uses a primarily first principles framework to account for the various physical phenomena in the system. Particles are modeled using Lagrangian methods which track individual particles and Equilibrium Eulerian methods which track particles in terms of concentration densities. Lagrangian methods become prohibitively expensive for fine particles. Eulerian methods are physically appropriate for fine particles but become inaccurate for large particle sizes. A dual approach using both Eulerian and Lagrangian methods allows for optimal computational cost with maximum accuracy. Simulation results using the proposed approach are compared against experimental data for a representative gas turbine engine blade.

Nanoparticles are often used for both metals and non-metals, in cosmetics, home appliances, electrical products, as well as paints and inks. Nanoparticles are commonly produced by the vapor phase method or the liquid phase method. However, it is still difficult to produce nanoparticles with complicated shapes, such as raspberry-shaped particles. In this study, we demonstrated that nano-raspberry particles can be made by coating the surface of the small- and the large-sized silica nanoparticle with a reactive, chemically adsorbed, monomolecular film and then by bonding the smaller nanoparticles to the surface of the larger nanoparticle. Furthermore, by preparing a fractal surface structure on a flat substrate surface, a super-water and oil repellent surface, which can potentially improve the application performance, was successfully produced.

Ceramic–metal composites are an important group of materials that have gained interest recently because of their peculiar properties. There have been numerous studies on the reinforcement of alumina through the incorporation of various ductile metals in it. However, these studies have been limited to determining the effect of the addition of metals on the mechanical properties of ceramics, without determining the effect of these metal additions on other physical properties of the resulting composite. In this way, in agreement with the obtained results, we have that because of the conductive nature of metals, there is a considerable decrease in the electrical resistivity of alumina, mainly when copper is added to it. However, in terms of optical performance, alumina matrix composites showed significant changes in absorbance in the visible spectra. The addition of iron, titanium, and yttrium enhanced the absorbance of alumina, whereas manganese addition significantly decreased the optical absorption.

This work studied the relationship between embedded particle volume fraction and magnetic particle orientation distribution in aligned 325 mesh barium hexaferrite (BHF) and polydimethylsiloxane (Sylgard 184; Dow Corning) magnetoactive elastomer (MAE) composites. BHF particles were aligned within the elastomer in the out-of-plane direction, as the material cured. Particle orientation distribution was defined herein by observations of the population of directions at which particle magnetizations resided; magnetization coincides with the physical crystallographic c-axis of BHF. The work used results of vibrating sample magnetometry experiments on MAEs with increasing volume concentrations of embedded ferromagnetic particles (10–30 v/v%) to determine changing widths of analytical particle distribution functions used to describe the range of particle orientations. With over 80% confidence, results showed that MAE composites having the intermediate 15 v/v% had the highest degree of magnetic (and thereby physical) alignment as well as magnetic remanence.

The constant search for the improvement of the performance of materials of industrial application, evaluated under aspects of weight reduction, greater resistance, greater resistance to wear and better thermal stability, among others, associated with the search for the development of ecologically viable products, that convert the context of environmental degradation in preservation and sustainability, reflects the need to conduct research that results in new materials. The objective of this work is to obtain composites of the AA6061 aluminum alloy reinforced with different contents of coke coal blast-furnace slag by powder metallurgy. The processing of these materials was done by sieving, mixing and compacting powders of reinforced aluminum alloy with 5, 10 and 15% of blast-furnace slag. The cold uniaxial compaction was realized at a pressure of 500MPa. The obtained materials were sintered at 580°C for 3h under inert atmosphere. Unreinforced aluminum alloy samples were also produced. The characterization of the materials was realized by density and hardness measurements and three-point bending tests. The analysis of its microstructure was realized by scanning electron microscopy. As results, the composites presented a homogeneous distribution of the reinforcing particles and also a progressive improvement of the hardness and the bending strength with the increase of the slag content, producing an increase of 79% in hardness and 128% in flexural strength, when compared to the material without reinforcement obtained by the same process. Such results give the coke coal blast-furnace slag a new possibility of exploitation in the metal-mechanical sector, besides contributing with the environmental issue.

Unlike the conventional layer by layer growth ,three dimensional growth experiments of SiC single crystal by the Chemical Particle Deposition (CPD)method were carried out both on the polar and nonpolar plane of the SiC seed crystal. The comparison of the morphology of the grown crystals on both samples indicated that the electric field formed by the seed crystal strongly effected the diffusion of the supplied Si and C atoms and their compounds to grow the epitaxial crystal. In spite of the low ionicity of Si-C bonds, this remarkable effect of the electric field on the three dimensional crystal growth mechanism in the CPD method strongly suggested its contribution to the ordering of the stacked layers with its long working range, beyond the deformed boundary layers between the seed surface and the grown crystal.

Spherical particles are routinely monitored and described by hydrodynamic diameters determined, e.g., by light scattering techniques. Non-spherical particles such as prolate ellipsoids require alternative techniques to characterize particle size as well as particle shape. In this study, oligo(ε-caprolactone) (oCL) based micronetwork (MN) particles with a shape-shifting function based on their shape-memory capability were programmed from spherical to prolate ellipsoidal shape aided by incorporation and stretching in a water-soluble phantom matrix. By applying light microscopy with automated contour detection and aspect ratio analysis, differences in characteristic aspect ratio distributions of non-crosslinked microparticles (MPs) and crosslinked MNs were detected when the degrees of phantom elongation (30-290%) are increased. The thermally induced shape recovery of programmed MNs starts in the body rather than from the tips of ellipsoids, which may be explained based on local differences in micronetwork deformation. By this approach, fascinating intermediate particle shapes with round bodies and two opposite sharp tips can be obtained, which could be of interest, e.g., in valves or other technical devices, in which the tips allow to temporarily encage the switchable particle in the desired position.

To obtain a fine-grained Mg matrix, the (submicron + micron) bimodal size SiC particle reinforced AZ91 (SiCp/AZ91) composite was subjected to forging followed by the extrusion process first. Then, the fine-grained bimodal size SiCp/AZ91 composite was compressed at 270–370 °C with 0.1–0.001 s−1. The result indicated that the refinement of the Mg matrix contributed to its deteriorated strength at high temperature. However, the grain size is not the only factor influencing flow stress but the SiCp also plays an important role. The effect of SiCp on the fine grained Mg matrix depends on grain size and dislocation density, both of which strongly depend on temperature and strain rate. As compared with the fine grained Mg matrix reinforced by single size SiCp, the one with bimodal size SiCp unusually exhibit lower flow stress during hot compression. The calculated activation energy of the bimodal size SiCp/AZ91 composite is higher than the micron SiCp/AZ91 composite; however, nearly the same as the submicron SiCp/AZ91 composite, and the deformation of which was thought to be controlled by ∼1 vol% submicron SiCp.

Morphological control of energetic materials (EM) is highly desired because ill-defined morphology arising from variations in processing method and supplier make it impossible to reproducibly engineer their physicochemical properties. As the most powerful, non nuclear energetic material to date, 2,4,6,8,10,12-hexanitro -2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) has been the subject of significant interest for improved applications in military grade explosives. Here we report a new method for recrystallization of CL-20 from irregular bulk EMs using a surfactant assisted self-assembly process to produce uniform spherical micron-sized particles. Detailed electron microscopy studies indicate that surfactant plays a critical role in controlling CL-20 morphology. Combined X-ray diffraction and Raman spectroscopy results reveal that the resultant spherical CL-20 particles exhibit an orthorhombic β-phase crystal structure. This material is expected to display enhanced functional reproducibility due to its monodisperse nature as well as decreased shock sensitivity due to their sub-micron particle size.

The aim of the present research was to evaluate pectin-gelatine and pectin-collagen polymeric compounds as encapsulating and releasing matrices for whey active peptides with antioxidant properties. Active peptides were obtained by hydrolysis of whey proteins with thermolysin and proteinase enzymes from B. subtilis. The hydrolysates were fractioned and encapsulated in the pectin composite matrices to obtain particles loaded with active whey peptides. The composite particles were analysed by SEM and IR techniques. In addition, they were also tested under simulated gastric conditions to evaluate the encapsulation efficiency and delivering power of the composite materials. The results showed that both encapsulation particles were excellent supports, because they retained to-the peptides and maintained their antioxidant activity during the simulated gastric process (120 min). However, the pectin gelatine particles were digested faster than those of pectin-collagen. The peptides from-encapsulated in pectin-gelatine were released within this time, showing an increment in the-antioxidant activity. Peptides from gelatine protein were also released by the gastric enzymes, and thus also they contributed to the antioxidant activity; in addition to the whey peptides.

The work shows the preparation and characterization of composite materials using a polymer as a matrix (ABS) and carbon black or a graphenic material (graphene or graphene foam). The materials were individually mixed with the polymer and the process parameters were established in an extruder with capacity for temperature control starting at laboratory conditions and up to 600 °C. The process parameters were adjusted to form filaments that were subsequently used in a 3D printer. The parameters of the printing process were adjusted to achieve the production of flat prototypes. These prototypes were characterized by Digital Optical Microscopy. The degree of homogeneity of the prototypes and the working ranges for the graphene material concentrations were determined. Even though the characterizations were done in flat samples, 3D printing allows obtaining a great diversity of structure that broadens the diversity of applications for such kind of composite materials.

A novel synthesis of Al (1xxx)/carbonised coconut shell (CCS) nanoparticles using a ball milling technique was investigated. Initial Al/0.1%CCS powders of an average size of 51.06μm was milled for a period of 70 h. The milled particles at 16, 46 and 70 h were characterized using X-ray diffractomer (XRD), scanning electron microscope (SEM), transmission electron microscope and UV-Vis spectrophotometer. Result revealed that the calculated particle crystallite size from XRD aided with Scherrer’s equation is consistent with particle image sizes obtained from SEM aided with software. TEM image depicted variation in orientation and appearance of the Al 1xxx/0.1% CCS nanoparticles at different milling time. The wide variation in the particle size is attributable to different ball impacts on the individual powders during the ball milling process. Increased maximum absorbance observed with the milled particles when compared with the initial powders is an indication of quantum/nanosizing effect due to ball milling.

We propose a new technique suitable for on-line monitoring of gas phase synthesis of nanoparticles. It is based on aerodynamic focusing of nanoparticles followed by Laser-Induced Breakdown Spectroscopy (LIBS) under vacuum. The laser crosses a beam of particles at low pressure so that the plasma-produced photons to be analyzed are emitted only from the particles. Unlike previous experiments, the background from interaction with the gaseous component is totally eliminated from the collected spectra. Vacuum allows also for easier spectra collection in the UV range. Moreover, as the nanoparticle beam is highly collimated, the optical interface windows are not obstructed by particle deposition and the system can be kept running for hours.

The disposal of materials at the end of their lifecycle, especially for complex manufactured products, presents challenges in terms of both protecting the environment and human health. In particular, used automobiles are disposed of by removal of various component parts, followed by shredding. In this study, air particulates were collected over several days by DRUM impactor downwind of an automobile shredding plant, size separated, and analyzed by scanning and transmission electron microscopy (SEM and TEM), and energy-dispersive x-ray spectroscopy (EDXS), in order to determine their particle size distribution and corresponding chemical composition. Results for larger particles, ranging in size from 2.5 to 10.0 μm, showed mainly diatoms and salts, from the plant’s ocean side location, and aluminosilicates, consistent with geological sources. As particle size decreased from 10 μm to 0.09 μm, particle loading decreased, and composition shifted to mainly oxygen and sulfur, indicative of sulfates, which along with nickel and vanadium that were detected, could be attributed to emissions from nearby shipping traffic. Iron was found to be present, including in spherical particles that were ∼ 2 μm in diameter, indicating they originated from a high temperature process. Spherical iron particles also were found to correlate with plant operations, making them a useful “tracer” material for plant emissions. Lead, cerium, barium, chromium and zinc were also detected and their possible correlation to plant feedstocks is discussed. The implications of these results for the environment, particularly soil and water deposition, and for human health as a result of inhalation, are discussed.

Sonication is a commonly used method for particle removal from various surfaces. There has been a growing interest in the use of combination of two or more acoustic frequencies for cleaning as it is expected to achieve better particle removal efficiency and lower feature damage compared to a single frequency acoustic system. In this study, stable and transient cavitation characteristics in de-ionized water subjected to dual-frequency irradiation have been illustrated using experimentally obtained absolute values of cavitation pressures and pressure-frequency spectra. Comparison of the calculated ratio of stable cavitation pressure to transient cavitation pressure suggests that dual-frequency mode has the potential to reduce feature damage while maintaining the particle removal efficiency compared to low frequency ultrasonic field. These observations are further confirmed from the results of damage studies conducted on aluminum coated glass samples.

Surfactants are commonly used as additives in cleaning formulations during acoustic cleaning of semiconductor surfaces. Since surfactants are surface active, they can affect cavitation characteristics and, therefore, influence cleaning efficiency and damage to the surface. In this work, stable and transient cavitation pressures were characterized in Triton® X-100 containing aqueous solutions subjected to single frequency and dual-frequency sound fields using acoustic emission measurements. The hydrophone based technique allowed quantitative measurements of the absolute pressure values from stable and transient cavitation fields. The ratio of stable cavitation pressure to transient cavitation pressure under different conditions indicated that surfactants can play an important role in reducing feature damage while maintaining particle removal efficiency. Damage studies conducted on aluminum coated glass samples further confirmed these results.

Understanding particle adhesion is vital to any industry where particulate systems are involved. There are multiple factors that affect the strength of the adhesion force, including the physical properties of the interacting materials and the system conditions. Surface roughness on the particles and the surfaces to which they adhere, including roughness at the nanoscale, is critically important to the adhesion force. The focus of this work is on the capillary force that dominates the adhesion whenever condensed moisture is present. Theoretical capillary forces were calculated for smooth particles adhered to smooth and rough surfaces. Simulations of the classical centrifuge technique used to describe particle adhesion to surfaces were performed based on these forces. A model was developed to describe the adhesion of the particles to the rough surface in terms of the adhesion to a smooth surface and an ‘effective’ contact angle distribution.

Cleanliness is a prerequisite for obtaining economically feasible yield levels in the semiconductor industry. For the next generation of lithographic equipment, EUV lithography, the size of yield-loss inducing particles for the masks will be smaller than 20 nm. Consequently, equipment for handling EUV masks should not add particles larger than 20 nm. Detection methods for 20 nm particles on large area surfaces are needed to qualify the equipment for cleanliness. Detection of 20 nm particles is extremely challenging, not only because of the particle size, but also because of the large surface area and limited available time.

In 2002 TNO developed the RapidNano, a platform that is capable of detecting nanoparticles on flat substrates. Over the last decade, the smallest detectable particle size was decreased while the inspection rate was increased. This effort has led to a stable and affordable detection platform that is capable of inspecting the full surface of a mask blank.

The core of RapidNano is a dark-field imaging technique. Every substrate type has a typical background characteristic, which strongly affects the size of the smallest detectable particle. The noise level is induced by the speckle generated by the surface roughness of the mask. The signal-to-noise ratio can be improved by illuminating the inspection area from nine different angles. This improvement was first shown on test bench level and then applied in the RapidNano3. The RapidNano3 is capable of detecting 42nm latex sphere equivalents (and larger) on silicon surfaces. RapidNano4, the next generation, will use 193 nm light and the same nine angle illumination mode. Camera sensitivity and available laser power determine the achievable throughput. Therefore, special care was given to the optical design, particularly the optical path. With RapidNano4, TNO will push the detection limit of defects on EUV blanks to below 20nm.