Hybrid Powder Research Articles

Effect of Al2O3 on the Microhardness of AMg2/Graphite Nanocomposite Powder Gas Dynamic Coatings on Aluminum Alloys

Mechanically synthesized hybrid powders of the AMg2/graphite + Al2O3 system and coatings deposited by cold gas dynamic spraying from these powders are studied. The effect of Al2O3 concentration in the powder on surface morphology, structure and microhardness of the coatings formed is determined.

Structural and high GHz frequency EMI (electromagnetic interference) properties of carbonyl iron and boron nitride hybrid composites

Hybrid (mix of magnetic Carbonyl Iron and dielectric ceramic Boron Nitride) powders, composites and methods for making these powders that are potentially useful for high frequency EMI (electromagnetic interference) applications are described here. Comparative study of polymer composites, made using these hybrid powders by a speed mixing process and a high energy ball milling method (HEBM), has been conducted and their properties (microstructural and electromagnetic) have been characterized at high GHz frequency bands. Magnetic permeability values of the two different samples are widely different and magnetic loss tangent values for hybrid flakes made using a HEBM process is considerably higher than speed mixed samples, especially at lower GHz frequencies. However dielectric loss tangent values are similar for both samples. EMI (Electromagnetic Interference) absorbing performance of the composites made using the two different hybrid fillers is also compared at 18–40 GHz frequency band using a radar absorption model. It was observed that the speed mixed hybrid filler composite samples show much better EMI absorber performance with a minimum reflection loss value of −12.5 dB at a frequency of 34.5 GHz which is useful for many new emerging industrial applications.

Removal of heavy crude oil from water surfaces using a magnetic inorganic-organic hybrid powder and membrane system

Oil spills are among the most significant threats to aquatic ecosystems. The present work describes the synthesis of different organic-inorganic hybrid matrices with magnetic properties, obtained in the forms of powders and membranes. The powders were synthesized using the following biomass wastes to form the organic phase: coconut mesocarp, sugarcane bagasse, sawdust, and water hyacinth. The resulting powders were denoted HMG-CO, HMG-CN, HMG-SE, and HMG-AP, respectively. Membranes (denoted MHMG-PES) were prepared using polyethersulfone polymer. In both cases, the inorganic phase was cobalt ferrite. The materials were evaluated in terms of their efficiencies in removing crude oil from water surfaces. The presence of organic matter, polyethersulfone, and cobalt ferrite in the structures of the materials was confirmed by XRD and FTIR analyses. The efficiencies of the materials were determined using the Standard Test Method for Sorbent Performance of Adsorbents (ASTM F726-99). Among the hybrids in powder form, the HMG-CN material presented the highest oil removal efficiency (85%, adsorptive capacity of 17 g g−1), which could be attributed to the fibrous nature of the sugarcane bagasse. The MHMG-PES membrane was able to remove 35 times its own mass of oil (adsorptive capacity of 35 g g−1). In addition to this high removal efficiency, an important advantage of MHMG-PES, compared to the HMG-CN hybrid powder, was that the oil could be mechanically removed from the membrane surface, eliminating the need for subsequent time-consuming extraction steps requiring large volumes of organic solvents and additional energy expenditure. When the two materials were used simultaneously, it was possible to remove 45 times their own mass of oil (adsorptive capacity of 45 g g−1), with the adsorptive capacity of HMG-CN increasing by 23%. This high adsorptive capacity was due to the retaining barrier formed by the HMG-CN hybrid powder, which prevented the oil patch from spreading and enabled its homogeneous removal, which was not possible using MHMG-PES alone. It could be concluded that use of the magnetic hybrids synthesized using biomass wastes, together with the hybrid magnetic membrane, provided an effective and inexpensive technological alternative for the removal of oil from water surfaces.

Morphology and phase composition of hybrid powders based on aluminum, synthesized for a gas-dynamic spraying of coatings by milling

Hybrid powders of the AlMg2 + 1 wt % TiC/MWNT + 10−50 wt % Al2O3 system were obtained using the method of mechanical processing in a planetary ball mill. The powders were characterized using the methods of scanning electron microscopy, particle size distribution testing and X-ray analysis. It is shown that an increase in the content of Al2O3 particles from 10 to 50 wt % leads to a decrease in the average particle size of the synthesized powder from 49 to 16 μm, respectively. The proportion of particles smaller than 5 μm, depending on the concentration of Al2O3, varies in the range of 1.2−15.1%. At the same time, the size of the matrix material crystallites decreases from 58 and 52 nm, respectively. The resulting hybrid powder can be used to create functional coatings using cold gas-dynamic spraying.

Synthesis, characterization, and ceramization of a carbon-rich SiCw-ZrC-ZrB2 preceramic polymer precursor

Abstract A precursor (PBSZ) for SiCw-ZrC-ZrB2 hybrid powder was synthesized by chemical reaction of phenol, paraformaldehyde, zirconium oxychloride, boric acid and tetraethylorthosilicate. Results show that zirconium, silicon and boron atoms have been successfully introduced into the branched structure. Decomposition of PBSZ is completed at 800 °C, and it gives amorphous carbon, SiO2, B2O3 and ZrO2 with a yield of 38% at 1200 °C. During the pyrolysis process, ZrB2 and SiC form at about 1500 °C, followed by the appearance of ZrC when the amount of B2O3 is limited. Highly crystallized ZrB2–ZrC–C powder with ZrB2 and ZrC grains evenly distributed in the carbon matrix together with randomly distributed SiC whiskers are obtained after heat-treated at 1800 °C. Further heated at 1900 °C, ZrB2 and ZrC grains grow from 200 to 500 nm, while SiC whiskers show a much smaller diameter size and tend to grow on the ZrB2–ZrC–C block surface. The morphology difference is caused by the larger gas supersaturation and accommodation coefficient of the pore channels on the block surface. In addition, defects of the carbon matrix are cumulated to the highest at 1500 °C and the structure-ordered carbon is obtained after heat treated at 1900 °C.

Effect of type of ceramic particles on efficiency of gas dynamic spraying and hardness of hybrid coatings AlMg6/C60

The hybrid powders AlMg6/C60 + 10-70 wt.% Al2O3 and AlMg6/C60 + 10-70 wt.% AlN were obtained by the method of mechanical synthesis in a planetary ball mill. These powders were used to create coatings using cold gas-dynamic spraying. The influence of the type and concentration of ceramic reinforcement on the growth efficiency and microhardness of the formed hybrid coatings was studied. It has been found out that the use of ceramic particles of AlN (up to 50 wt.%) as a reinforcement contributes to a more efficient growth of the coating compared to Al2O3. At the same time, the microhardness of coatings reinforced with AlN is lower than that containing Al2O3.

Montmorillonite–triclosan hybrid as effective antibacterial additive with enhanced thermal stability for protection of plastic electrical components

The majority of parts used in the electrical apparatus are made of polymer materials; however, pure polymers do not provide the antibacterial functionality. Therefore, in order to add such property to them it is necessary to use antibacterial additives. The study concerned intercalation of triclosan (TCS) as biocide into montmorillonite (MMT) interlayer spaces was performed in order to increase TCS resistance to high-temperature treatment, which is necessary during polymer composite processing. The obtained MMT + TCS hybrids were tested for structural and antibacterial properties. The degree of biocide intercalation was assessed using X-ray diffractometry, by analyzing changes in MMT interlayer distance, and thermal analysis was performed to assess the effect of the intercalation process on the thermal stability of TCS. Antibacterial tests against Gram-negative bacteria (Escherichia coli) and Gram-positive bacteria (Staphylococcus aureus) were also carried out on the obtained MMT + TCS powders in order to confirm the bactericidal properties of TCS released from the clay after the intercalation process. As a final proof of concept, the hybrid powder, namely MMT with incorporated TCS, was incorporated into polycarbonate matrix and antibacterial activity of modified polymer samples was tested. The obtained results have proven that montmorillonite–triclosan hybrid is an effective antibacterial additive with enhanced thermal stability which can be applied for protection of plastic parts used in electrical devices.

Hybrid Powders: Scratch Resistance and Good Flow

Hybrid Powders: Scratch Resistance and Good Flow

Preparation and Antitumoral Activity of Au-Based Inorganic-Organometallic Nanocomposites.

The synergy between gelator molecules and nanostructured materials is currently a novel matter of study. The possibility to carefully design the skeleton of the molecular entity as well as the nanostructure's morphological and chemical features offers the possibility to prepare a huge variety of nanocomposites with properties potentially different than just the sum of those of the individual building blocks. Here we describe the synthesis and characterization of nanocomposites made by the unconventional combination of phosphine-Au(I)-alkynyl-based organometallic gelating molecules and plasmonic Au nanoparticles. Our results indicate that the interaction between the two moieties leads to a significant degree of aggregation in both hydrophilic and hydrophobic media, either when using DAPTA or PTA-based organometallic molecules, with the formation of a sponge-like hybrid powder upon solvent evaporation. The biological activity of the nanocomposites was assessed, suggesting the existence of a synergetic effect evidenced by the higher cytotoxicity of the hybrid systems with respect to that of any of their isolated counterparts. These results represent a preliminary proof-of-concept for the exploitation of these novel nanocomposites in the biomedical field.

Thermoelectric Transport Properties of Interface-Controlled p-type Bismuth Antimony Telluride Composites by Reduced Graphene Oxide

We report the thermoelectric transport properties of interface-controlled p-type bismuth antimony telluride (BST) composites using reduced graphene oxide (rGO). The composites were prepared by the spark plasma sintering (SPS) of BST–graphene oxide (GO) hybrid powder, which could induce the in situ reduction of GO into rGO. Compared to the pristine BST, the interface-controlled BST composites exhibited degraded electrical conductivities with similar Seebeck coefficients, consequently resulting in decreased power factors. However, thanks to the suppressed lattice thermal conductivity by the rGO network at the grain boundaries, this disadvantage could be compensated in terms of ZT. Our results will be helpful for understanding thermoelectric transport properties of various graphene-hybrid thermoelectric materials.

Enhanced Electromagnetic and Microwave Absorption Properties of Hybrid Ti3SiC2/BaFe12O19 Powders

In this work, Ti3SiC2 powders were composited with BaFe12O19 to improve electromagnetic and microwave absorption properties. The hybrid Ti3SiC2/BaFe12O19 powders were prepared in two different ways: mechanical mixing and auto-combustion. The electromagnetic and microwave absorption properties of the powders were investigated in the frequency range of 8.2–12.4 gigahertz (GHz). For the hybrid Ti3SiC2/BaFe12O19 powders, the complex permittivity was higher while the complex permeability was lower than individual BaFe12O19 powders. In addition, the hybrid powders prepared by auto-combustion had higher complex permittivity and permeability than the mechanical mixing powders. The most favorable absorption performance was obtained for the sample with a thickness of 2.4 mm. The reflection loss value below − 5 decibels (dB) was in the frequency range of 9.3–12.4 GHz, with a minimum reflection loss value of − 14.6 dB at 10.9 GHz.

Hexagonal Boron Nitride/Microfibril Cellulose/Poly(vinyl alcohol) Ternary Composite Film with Thermal Conductivity and Flexibility.

Microfibril cellulose (MFC), which is detrimental to soil cultivation and environmental protection, is derived from waste pineapple leaves. Hexagonal boron nitride (h-BN) was modified with polydopamine (PDA)—PDA@h-BN named pBN, and then combined with MFC to prepare a novel hybrid powder. The effect of PDA on h-BN and the binding effect between pBN and MFC were characterized by X-ray photoelectron spectroscopy (XPS), Thermogravimetric (TG), scanning electron microscopy (SEM), and Fourier Transform-Infrared (FT-IR). Poly (vinyl alcohol) (PVA) was used as an eco-friendly polymeric matrix to prepare a pBN-MFC-PVA composite film. The mechanical strength, hydrophobicity, and thermal conductivity of the film were studied and the results confirmed that h-BN was chemically modified with PDA and was uniformly distributed along the MFC. The thermal conductivity of the pBN-MFC-PVA composite film increased with the addition of a pBN-MFC novel powder. MFC acted as “guides” to mitigate the h-BN agglomerate. In addition to the possible usage in the pBN-MFC-PVA composite film itself, the pBN-MFC hybrid powder may be a potential filler candidate for manufacturing thermal interface materials and wearable devices or protective materials.

Optimizing the Coverage Density of Functional Groups over SiO2 Nanoparticles: Toward High-Resistant and Low-Friction Hybrid Powder Coatings.

Hybrid powder coatings (HPC) with low friction and high hardness enhance the sliding speed and allow interlocking or meshing products to slide effortlessly within each other, saving energy. In automobiles, they decrease fuel consumption and greenhouse gas emission. In the present work, a new insight of the key role played by the coverage density of triethoxyphenylsilane (TPS) grafted to SiO2 nanoparticles over the friction coefficient, hardness, elastic modulus, and roughness of HPC is presented for the first time. In all cases, a very low amount (0.1 wt %) of functionalized or unfunctionalized SiO2 nanoparticles were added to a powder-coating formulation based on polyester resin. HPC formulated with functionalized nanoparticles at a suitable coverage density (HPC–TPS3) exhibited significantly low friction coefficient (μ = 0.12), strong wear resistance (under dry sliding conditions at 1 and 5 N of load), low roughness (Rq = 3.5 nm), and high hardness and elastic modulus on the surface. We demonstrated that it is possible to tune the macroscopic properties by varying only the coverage density of TPS that is chemically attached to SiO2 nanoparticles. Also, a physicochemical explanation was disclosed, wherein a hydrophilic–hydrophobic balance between −OH and phenyl groups was proposed. In all cases, the phenyl group allows the migration of functionalized nanoparticles through the polyester matrix, enhancing the hardness and elastic modulus on the surface. Thus, the functional nanomaterial design with tunable coverage density is a powerful tool to improve the physical and superficial properties of powder coatings using low amounts of nanomaterial.

Synthesis of VB2-V3B4-V2B3/VC hybrid powders via powder metallurgy processes

The present study reports the in-situ synthesis of hybrid powders containing vanadium borides (VB 2 , V 3 B 4 and V 2 B 3 ) and vanadium carbide (VC) using powder metallurgy methods. VB 2 -V 3 B 4 -V 2 B 3 /VC hybrid powders were synthesized from V 2 O 5 , B 2 O 3 and C powder blends via a carbothermal reduction route assisted by mechanical milling. Powder blends were mechanically milled up to 5 h in a high-energy ball mill. The milling process reduced the crystallite size, increased the uniformity of the particle distribution and hence increased the reactivity of the starting powders. As-blended and milled powders were annealed at different temperatures (1400, 1500 and 1600°C) for 12 h to investigate the probability of achieving vanadium boride and carbide phases simultaneously. Annealed powders were characterized using X-ray diffractometer (XRD), scanning electron microscope/energy dispersive spectrometer (SEM/EDS) and particle size analyzer. In case of using annealing temperature of 1400°C, VB 2 -V 3 B 4 -V 2 B 3 /VC hybrid powders were obtained with an amount of unreacted V 2 O 5 . Annealing temperatures of 1500 and 1600 ° C resulted in the formation of VB 2 , V 3 B 4 , V 2 B 3 and VC phases. Milling affected the weight percentages of the phases as well as the type of major boride phase.

Structure and Efficiency of Gas-Dynamic Deposition of Hybrid Coatings Based on a Nanocrystalline Aluminum Matrix

Gas-dynamic deposition of mechanically synthesized hybrid powders based on a nanocrystalline matrix AMg2 strengthened by nanocrystalline graphite and micro-sized Al2O3 particles is performed. The effect of Al2O3 content in a charge, varied in the range of 10–90 wt.%, on the grain size composition of the synthesized hybrid powder is studied. The structure-phase composition of synthesized hybrid powders and formed coatings was studied by X-ray diffraction analysis. Quantitative estimates are obtained of the Al2O3 content in the hybrid coatings formed. The influence of Al2O3 content in the powder on the efficiency of the gas-dynamic spraying of a hybrid coating is determined. The rational content of Al2O3 in powder is determined ensuring efficient hybrid coating deposition.

Evaluation of structural damage and pH of nail plates of hands after applying different methods of decorating.

The purpose of this study was to evaluate the effect of nail polish, gel polish hybrid, gel nail, and acrylic nail powder and the removal of these formulas on the nail plates properties, particularly the influence of different coatings on morphology and pH. The morphology and structure of nail plates were analyzed with use of scanning electron microscopy. The pH values of the nail plates of hands were measured using the system Courage & Khazaka. The analysis of morphology and structure of the surface of nail plates showed distinct changes caused by decorative coatings. The most common ones include fragility and splitting of the nails. The pH value measured in the whole group ranged from 5.21 to 7.00. The methods used to prepare nails for decoration and all methods of removing the applied preparations damage the healthy nail plates. The most common changes are brittleness and nail splitting. The nail polish remover causes less damage than acetone, and the use of a nail drill machine and nail file causes the greatest destruction of nail plates. The biggest effect on the pH change has the gel polish hybrid, gel nail, and acrylic nail powder, causing the pH value of nail plates to rise above 6.0, whereas after the application of the nail polish, the pH of the plates was on average 5.8 which is closest to the normal value, assumed as physiological.

Embedding anti-counterfeiting features in metallic components via multiple material additive manufacturing

The aerospace, automotive and medical industries are suffering from significant number of counterfeited metallic products that not only have caused financial losses but also endanger lives. The rapid development of additive manufacturing technologies makes such a situation even worse. In this investigation, we successfully applied a novel hybrid powder delivery selective laser melting (SLM) approach to embed dissimilar tagging material (Cu10Sn copper alloy) safety features (e.g. QR code) into metallic components made of 316 L stainless steel. X-ray imaging was found to be a suitable method for the identification of the embedded safety features up to 15 mm in depth. X-ray fluorescence was used for the chemical composition identification of the imbedded security tagging material. A criterion for the selection of tagging material, its dimensions and imbedding depth is proposed. The multiple material SLM technology was shown to offer the potential to be integrated into metallic component production for embedding anti-counterfeiting features.

Effect of addition of clay minerals on the properties of epoxy/polyester powder coatings

Abstract Powder coatings have been used for coating metal substrates in industrial applications. The incorporation of nanofillers as muscovite mica and montmorillonite (MMT) can improve the properties of the coatings. The objective of this study is to develop, apply and characterize a hybrid powder coating (30% epoxy/70% polyester) adding nanofillers in concentrations of 2, 4 and 6 phr separately in a twin screw extruder. The characterization of the coatings was performed by thermal, mechanical and chemical analysis. The incorporation of clay into the polymer increased the surface roughness resulting in a diffuse reflection of incident light and on a gloss reduction. The muscovite mica presented a lamellar structure, constituted by a set of overlapping parallel plates. The morphology analysis showed that the MMT presented irregular agglomerates resulting in inferior mechanical properties to coatings with muscovite mica. In the salt spray test, all samples showed high corrosion protection, around 850 hours.

Development of Carbon Nanotube-copper Hybrid Powder as Conductive Additive

Development of Carbon Nanotube-copper Hybrid Powder as Conductive Additive

Photoacoustic Spectroscopy Investigation of Zinc Oxide/Diatom Frustules Hybrid Powders

Photoacoustic spectroscopy investigation was carried out on ZnO nanoparticles grown at 80 °C on porous surface of diatomite (DE) by sol–gel technique, using zinc acetate dihydrate as ceramic precursor and triethanolamine to mediate the surface growth of the nanoparticles. Absorption and scattering characteristics of hybrid ZnO/DE powder in the UV–Vis range were inferred by photoacoustic spectroscopy, and results were analyzed based on Helander’s theory. In particular, we discussed in detail the procedure to calculate the absorption and scattering spectra of the hybrid powder showing how from the scattering coefficient in the 300–450 nm range it is possible to obtain information on the size distribution of the ZnO nanospheres. By applying photoacoustic spectroscopy for different modulation frequencies, we showed that is also possible to perform a size distribution depth profile of the ZnO aggregates, opening the way to interesting developments in this research field.