Particle Technologies

A special issue of Powders (ISSN 2674-0516).

Deadline for manuscript submissions: closed (31 March 2023) | Viewed by 13419

Special Issue Editor

Institute of Solid State Chemistry and Mechanochemistry, Siberian Branch, Russian Academy of Sciences, 630090 Novosibirsk, Russia
Interests: materials chemistry; mechanochemistry; self-propagating high temperature synthesis (SHS); powder technologies

Special Issue Information

Dear Colleagues,

I am happy to serve as a Guest Editor of a new Special Issue for Powders entitled “Particle Technologies”, with a focus on the mechanochemical techniques of powder fabrication. Mechanochemical methods make it possible to obtain powders in an activated, highly dispersed state and can be used for the synthesis of new materials and the development of new production technologies. The products of mechanosynthesis and mechanical treatment include nanosized powders, composite powders and supramolecular systems. Interest in mechanochemical methods is growing every year. At the same time, the fundamentals and applications of the mechanochemical processes are still a matter of scientific debate. In the field of mechanochemistry, the following problems need to be solved: (i) determining the causes of changes in the reactivity of solids during mechanical activation; recently, organic molecular crystals have attracted special attention in this regard; (ii) finding new ways of applying mechanochemcal methods to the synthesis of highly dispersed systems of various chemical compositions and structures with controlled properties; (iii) understanding the physical/chemical nature of the powder composites and supramolecular systems formed during mechanical activation of multicomponent mixtures; and (iv) developing highly dispersed systems, which can become the basis of new catalysts, sorbents or medical drugs with improved properties.

This Special Issue will focus on the structure and properties of the powders obtained by the mechanochemical methods. Materials fabricated by consolidation of the powders synthesized by the mechanochemical methods are also of interest for this Special Issue.

Prof. Dr. Nikolay Z. Lyakhov
Guest Editor

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Powders is an international peer-reviewed open access quarterly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • mechanochemistry
  • powders preparation
  • mechanical activation
  • mechanical properties
  • severe plastic deformation
  • microstructure of mechanocomposites
  • mechanochemical synthesis of powders
  • nanosized powders
  • powder modified polymer composites

Published Papers (13 papers)

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Research

10 pages, 3307 KiB  
Article
Solid Dispersions of Fenbendazole with Polymers and Succinic Acid Obtained via Methods of Mechanochemistry: Their Chemical Stability and Anthelmintic Efficiency
by Salavat S. Khalikov, Ekaterina A. Khakina, Marat S. Khalikov and Anastasiya I. Varlamova
Powders 2023, 2(4), 727-736; https://doi.org/10.3390/powders2040045 - 30 Nov 2023
Cited by 1 | Viewed by 729
Abstract
The substance fenbendazole is included in the composition of many anthelmintic drugs, in which the “chemical stability” parameter is one of the main characteristics when obtaining permission for the use of drugs in veterinary practice. Fenbendazole is characterized by low solubility in water [...] Read more.
The substance fenbendazole is included in the composition of many anthelmintic drugs, in which the “chemical stability” parameter is one of the main characteristics when obtaining permission for the use of drugs in veterinary practice. Fenbendazole is characterized by low solubility in water and therefore the content of the substance is overestimated in its preparations, which increases the cost of the drug as well as the safety risks of pharmacotherapy. The possibilities of mechanochemical modification of fenbendazole were evaluated in order to improve the solubility index. During the mechanical processing treatment of the substance in the presence of polymeric substances, solid dispersions are formed, which have increased solubility and high anthelmintic activity. The inclusion in these dispersions of the third component, which is succinic acid, did not significantly change the solubility of fenbendazole. In all these dispersions, the substance remained unchanged both during the preparation of its solid dispersions and during their storage. When fenbendazole is modified in an organic solvent medium, the substance is partially converted into oxfendazole, which is one of its metabolites. The chemical stability of fenbendazole was confirmed via HPLC/MS and NMR spectroscopy. The anthelmintic activity of these compositions was evaluated and it was found that they have a high nematicidal activity. Full article
(This article belongs to the Special Issue Particle Technologies)
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19 pages, 15967 KiB  
Article
Cu-Substituted Hydroxyapatite Powder: Mechanochemical Synthesis Using Different Copper Sources and Thermal Stability
by Natalya V. Eremina, Natalia V. Bulina, Mikhail A. Mikhailenko, Olga B. Vinokurova, Igor Y. Prosanov and Marina V. Chaikina
Powders 2023, 2(4), 678-696; https://doi.org/10.3390/powders2040042 - 08 Oct 2023
Viewed by 575
Abstract
In this paper, we present results of a study on the possibilities of the mechanochemical synthesis of copper-substituted hydroxyapatite with the replacement of calcium cations by copper cations. During the synthesis, various reagents—sources of copper cations—were used. It was found that the nature [...] Read more.
In this paper, we present results of a study on the possibilities of the mechanochemical synthesis of copper-substituted hydroxyapatite with the replacement of calcium cations by copper cations. During the synthesis, various reagents—sources of copper cations—were used. It was found that the nature of the carrier of the doping cation plays an important role in the formation of the structure of Cu-substituted apatite. It was established that a single-phase material forms most efficiently when copper (II) phosphate is employed; however, even this reagent did not allow the introduction of a large amount of copper into the hydroxyapatite crystal lattice. Out of 10 calcium cations in the unit cell of hydroxyapatite, no more than two could be replaced by copper cations. A further increase in the copper concentration led to the formation of an amorphous product. The degree of copper substitution in hydroxyapatite increases as the oxidation state of copper increases. The thermal stability of the hydroxyapatite with the highest degree of substitution was studied. It was shown that the presence of copper cations significantly decreases the stability of hydroxyapatite. In a temperature range of 550–750 °C, it is gradually decomposed to form a mixture of rhombohedral Ca2.57Cu0.43(PO4)2 and CuO. The FTIR spectrum of Ca2.57Cu0.43(PO4)2, which is a copper-substituted β-Ca3(PO4)2, was first studied. Full article
(This article belongs to the Special Issue Particle Technologies)
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10 pages, 2073 KiB  
Article
Dielectric Performance of UHMWPE-MgFe2O4 Composites Depending on Polymer Crystallinity, and the Concentration and Size of Mechanochemically Synthesized Ferrite Particles
by Tatiana Kiseleva, Tatiana Grigoreva, Svetlana Kovaliova, Maxim Il’in, Ekaterina Yakuta, Evgeniya Devyatkina, Inna Malyshkina, Ilya Ivanenko, Sergey Vosmerikov and Nikolay Lyakhov
Powders 2023, 2(3), 578-587; https://doi.org/10.3390/powders2030036 - 01 Aug 2023
Viewed by 787
Abstract
Mechanochemically synthesized particles of two types of magnesium ferrites, one of which with structural distortions and an average size of 170 nm, and another that is highly crystalline with an average size of 900 nm, were introduced into a matrix of ultra-high-molecular-weight polyethylene [...] Read more.
Mechanochemically synthesized particles of two types of magnesium ferrites, one of which with structural distortions and an average size of 170 nm, and another that is highly crystalline with an average size of 900 nm, were introduced into a matrix of ultra-high-molecular-weight polyethylene via the milling processing. The final material has been formed by hot pressing mechanocomposites based on ultra-high-molecular-weight polyethylene and magnesium ferrite particles of various fineness and concentration. Structural characteristics were studied using scanning electron microscopy, differential scanning calorimetry and X-ray diffraction analysis. The dielectric properties of the obtained composites were analyzed by testing the frequency dependence of the permeability, dielectric losses, and conductivity. The effect of filler concentration and particle size, as well as the crystallinity of the polymer, on the dielectric properties of the composite material were studied. Full article
(This article belongs to the Special Issue Particle Technologies)
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22 pages, 10276 KiB  
Article
Mechanochemical Synthesis and DC Electrical Conductivity of PANI-Based MWCNT Containing Nanocomposites with Te0 and Bi2Te3 Thermoelectric Nanophase
by Anna V. Zhmurova, Galina F. Prozorova and Marina V. Zvereva
Powders 2023, 2(3), 540-561; https://doi.org/10.3390/powders2030034 - 14 Jul 2023
Viewed by 847
Abstract
Nowadays, the search for the coupled polymer nanocomposite thermoelectrics that exhibit a high value of thermoelectric figure of merit (ZT) and similar behaviour of physical properties for the use as legs of thermoelectric cells is a current challenge. The direct current (DC) conductivity [...] Read more.
Nowadays, the search for the coupled polymer nanocomposite thermoelectrics that exhibit a high value of thermoelectric figure of merit (ZT) and similar behaviour of physical properties for the use as legs of thermoelectric cells is a current challenge. The direct current (DC) conductivity is one of the three important components of thermoelectric figure of merit. The aim of this study was to obtain PANI-based nanothermoelectrics with Te0 and Bi2Te3 nanoparticles and MWCNT by mechanochemical methodology and to investigate the dependency of their DC electrical conductivity on temperature in the 298–353 K range using the Arrhenius and Mott’s variable range hopping (VRH) models. Inorganic Te0 and Bi2Te3 nanoparticles were pre-synthesized by the available and environmentally friendly method using a commercial tellurium powder. The samples obtained were characterized by X-ray diffractometry (XRD), IR and UV-Vis spectroscopy. The XRD study of ES-PANI/Te0 (4.4 wt% Te0) and ES-PANI/Bi2Te3 (2.9 wt% Bi2Te3) nanocomposites found that the nanoparticle average size was 32 nm and 17 nm, respectively. The DC conductivity study of the samples with different nanophase content (2.1, 4.4, 10.2 wt% Te0, 1.5, 2.9, 7.3 wt% Bi2Te3, 1.5 wt% MWCNT) by the two points measurement method reveals the following: (a) the presence of inorganic nanophase reduces the conductivity compared to the matrix, (b) the addition of MWCNT in ES-PANI increases its electrical conductivity, (c) the conductivity of ES-PANI/Te0 as well as ES-PANI/Bi2Te3 nanocomposite rises with the increasing inorganic nanophase content, (d) the observed increase in the electrical conductivity of MWCNT-based nanocomposites with increasing inorganic nanophase content is interrupted by a characteristic area of decrease in its value at average values of inorganic nanoparticles content (at Te0 content of 4.4 wt%, at Bi2Te3 content of 2.9 wt%), (e) a similar DC conductivity behaviour in ES-PANI/Te0—ES-PANI/Bi2Te3 and ES-PANI/Te0-MWCNT—ES-PANI/Bi2Te3-MWCNT nanocomposite pairs is observed. Full article
(This article belongs to the Special Issue Particle Technologies)
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15 pages, 5010 KiB  
Article
Effects of Process Parameters on Cold Spray Additive Manufacturing of Quasicrystalline Al93Fe3Cr2Ti2 Alloy
by Aylanna Priscila Marques de Araujo, Felipe B. Do M. Carmelo, Erlifas M. Rocha, Claudio S. Kiminami and Piter Gargarella
Powders 2023, 2(3), 525-539; https://doi.org/10.3390/powders2030033 - 14 Jul 2023
Viewed by 793
Abstract
Quasicrystalline Al93Fe3Cr2Ti2 (at.%) gas-atomized powders, which exhibit a metastable composite microstructure, were used to produce coatings by cold spray additive manufacturing processing (CSAM) using different processing parameters. The metastable composite microstructure provides the Al93Fe [...] Read more.
Quasicrystalline Al93Fe3Cr2Ti2 (at.%) gas-atomized powders, which exhibit a metastable composite microstructure, were used to produce coatings by cold spray additive manufacturing processing (CSAM) using different processing parameters. The metastable composite microstructure provides the Al93Fe3Cr2Ti2 alloy with excellent mechanical properties. At the same time, the metastability of its microstructure, achieved by the high cooling rates of the gas atomization process, limits the processability of the Al93Fe3Cr2Ti2 powder. The purpose of this study was to investigate the effect of process parameters on the CSAM of quasicrystalline Al93Fe3Cr2Ti2 powder. The powder was sieved and classified to a size range of −75 µm. Using N2 carrier gas combined with different temperatures, pressures, nozzle apertures, and deposition substrate conditions, cold-sprayed coatings were produced. The porosity and thickness of the coatings were evaluated by image analyses. By SEM, XRD, DSC, and TEM, the microstructure was identified, and by Vickers microhardness, the mechanical properties of the coatings were investigated. Dense (≤0.50% porosity) and thick (~185.0 µm) coatings were obtained when the highest pressure (4.8 MPa), highest temperature (475 °C), and lowest nozzle aperture (A) were used in combination with an unblasted substrate. The SEM, XRD, and DSC data showed that the composite powder’s microstructure was retained in all coatings with no decomposition of the metastable i-phase into equilibrium crystalline phases. Supporting these microstructural results, all coatings presented a high and similar hardness of about 267 ± 8 HV. This study suggests that the CSAM process could, therefore. produce metastable quasicrystalline Al93Fe3Cr2Ti2 coatings with a composite microstructure and high hardness. Full article
(This article belongs to the Special Issue Particle Technologies)
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10 pages, 4132 KiB  
Article
Cu-10 wt.% Al Alloys Produced by Spark Plasma Sintering of Powder Blends and a Mechanically Alloyed Mixture: A Comparative Investigation
by Aigul A. Ondar, Dina V. Dudina, Tatiana F. Grigoreva, Evgeniya T. Devyatkina, Sergey V. Vosmerikov, Arina V. Ukhina, Maksim A. Esikov, Alexander G. Anisimov and Nikolay Z. Lyakhov
Powders 2023, 2(3), 515-524; https://doi.org/10.3390/powders2030032 - 10 Jul 2023
Cited by 2 | Viewed by 906
Abstract
Cu–Al bronzes are interesting metallic materials, demonstrating higher hardness, higher wear resistance, higher corrosion resistance and a lower friction coefficient as compared with unalloyed copper. The powder metallurgy approach to the fabrication of these alloys presents opportunities to tailor their phase composition and [...] Read more.
Cu–Al bronzes are interesting metallic materials, demonstrating higher hardness, higher wear resistance, higher corrosion resistance and a lower friction coefficient as compared with unalloyed copper. The powder metallurgy approach to the fabrication of these alloys presents opportunities to tailor their phase composition and grain size. In the present work, the structural characteristics, phase composition and properties of Cu-10 wt.% Al alloys obtained by spark plasma sintering (SPS) of powder blends and a powder obtained by mechanical alloying (based on Cu(Al) solid solution) are reported. Alloys with different interaction degrees between the metals were obtained by SPS. The blends demonstrated better sinterability than the mechanically alloyed powder: a nearly fully dense alloy was obtained by SPS of the blend at 480 °C, whereas a temperature of 800 °C was necessary to consolidate the mechanically alloyed powder. The hardness and electrical conductivity of the sintered alloys were comparatively analyzed. It was shown that the Cu-10 wt.% Al alloys obtained without the mechanical alloying stage possess hardness and electrical conductivity comparable to those of the alloys obtained from the mechanically milled powder. Full article
(This article belongs to the Special Issue Particle Technologies)
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16 pages, 5594 KiB  
Article
Wet Ball Milling Applied to Production of Composites and Coatings Based on Ti, W, and Nb Carbides
by Marina Eryomina and Svetlana Lomayeva
Powders 2023, 2(2), 499-514; https://doi.org/10.3390/powders2020031 - 15 Jun 2023
Viewed by 931
Abstract
The paper demonstrates the potential of wet ball milling of metals for the synthesis of various carbides and carbohydrides. The work reports on multicomponent carbides formed in Ti-(Cu/Fe/Si)-C, W-Fe-C, and Nb-(Cu/Fe/Si/Al)-C systems, as well as metastable or high-temperature intermetallics formed in Ti-Si, Nb-Si, [...] Read more.
The paper demonstrates the potential of wet ball milling of metals for the synthesis of various carbides and carbohydrides. The work reports on multicomponent carbides formed in Ti-(Cu/Fe/Si)-C, W-Fe-C, and Nb-(Cu/Fe/Si/Al)-C systems, as well as metastable or high-temperature intermetallics formed in Ti-Si, Nb-Si, Nb-Al, and Nb-Cu-Fe systems, which are stabilized with interstitial carbon. The formation of phase composition of powders fabricated under mechanochemical synthesis and subsequent thermal treatment has been studied. The as-fabricated powders have been used to produce bulk compacts and to apply wear-resistant coatings on steel (iron). Full article
(This article belongs to the Special Issue Particle Technologies)
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20 pages, 6396 KiB  
Article
Exploring the Effects of Cramped-Impact-Type Mechanical Action on Active Pharmaceutical Ingredient (Levofloxacin)—Prospects for Pharmaceutical Applications
by Elena Uspenskaya, Anastasia Simutina, Ekaterina Kuzmina, Vasilisa Sukhanova, Timur Garaev, Tatiana Pleteneva, Alena Koldina, Ekaterina Kolyabina, Gleb Petrov and Anton Syroeshkin
Powders 2023, 2(2), 464-483; https://doi.org/10.3390/powders2020028 - 09 Jun 2023
Cited by 1 | Viewed by 1205
Abstract
Mechanochemistry is one of the ten great discoveries of green chemistry methods for synthesizing new substances. A drug substance from the fluoroquinolone group was exposed to high-intensity mechanical impacts using a laboratory knife mill for 21 min and constantly monitored by analyzing samples [...] Read more.
Mechanochemistry is one of the ten great discoveries of green chemistry methods for synthesizing new substances. A drug substance from the fluoroquinolone group was exposed to high-intensity mechanical impacts using a laboratory knife mill for 21 min and constantly monitored by analyzing samples extracted every 3 min with DLS, SLS, LALLS, 2D-LS, optical and digital microscopy, FTIR, and Spirotox methods. A dispersity phenomenon was detected in an area where catastrophic dislocations formed and multiplied via laser methods. The positive correlation between the temperature of deformation and stress was demonstrated, similar to a typical stress–strain curve of a Bochvar–Oding curve and Young’s modulus: the angular coefficient of the straight section to OX was tgα = 10 min−1. Z-Average, ζ-potential, and polydispersity index dependences were represented as discontinuous periodic oscillations analogous to the defect and impurity transitions near the dislocation core. Deformation r from the high-intensity mechanical impact resulted in covalent bonds showing hyper- and hypochromic effects under FTIR spectra, a bathochromic shift of the maximum, and an oscillation emission at 3240 cm−1. A 2D-LS fingerprint diagram obtained via the topological convolution of the light scattering matrix made it possible to distinguish the off-loading samples from the native substance. The investigation of the dissolution kinetics in water via laser diffraction led to conclusions about the limiting diffusion stage and the acceleration of the mechanoactivation of the solid body’s dissolution under both linear and plastic deformation. The acceleration of obsEa of the cell death process in the temperature range from 296 to 302 K indicated a significant (2.5-fold) decrease in the toxicity of the aqueous 9 mM (1:3) sample solution at 21 min compared to that of the native levofloxacin. Adherence to the mechanochemistry laws provides an opportunity for drug repositioning to change their brand status by identifying new physicochemical and biological properties. Full article
(This article belongs to the Special Issue Particle Technologies)
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19 pages, 4472 KiB  
Article
Interaction of Polyphenylsilsesquioxane with Various β-Diketonate Complexes of Titanium by Mechanochemical Activation
by Vitalii Libanov, Alevtina Kapustina, Nikolay Shapkin, Anna Tarabanova and Anna Rumina
Powders 2023, 2(2), 445-463; https://doi.org/10.3390/powders2020027 - 08 Jun 2023
Viewed by 728
Abstract
In the present work, we studied the interaction of polyphenylsilsesquioxane with various β-diketonate complexes of titanium by mechanochemical activation. Polyphenylsilsesquioxane, bis-(2,4-pentanedionate) titanium dichloride, bis-(1-phenyl-1,3-butanedionate) titanium dichloride, and bis-(1,3-diphenyl-1,3-propanedionate) titanium dichloride were used as starting reagents. Various chemical and physicochemical methods of analysis were [...] Read more.
In the present work, we studied the interaction of polyphenylsilsesquioxane with various β-diketonate complexes of titanium by mechanochemical activation. Polyphenylsilsesquioxane, bis-(2,4-pentanedionate) titanium dichloride, bis-(1-phenyl-1,3-butanedionate) titanium dichloride, and bis-(1,3-diphenyl-1,3-propanedionate) titanium dichloride were used as starting reagents. Various chemical and physicochemical methods of analysis were used to study the synthesis products. The composition of the obtained compounds has been determined. It is shown that under conditions of mechanochemical activation, high-molecular-weight products with a Si/Ti ratio different from the specified ones are formed. In addition, under the action of mechanical stresses, the initial titanium complexes (except for acetylacetonate complex) polymerize with the formation of coordination of high-molecular-weight compounds, which are destroyed by the addition of ethyl alcohol. It has been established that with an increase in the volume of the organic ligand, titanium atoms enter the polymer siloxane chain to a lesser extent. This work is aimed at finding efficient and environmentally friendly methods for the synthesis and modification of organometallic macromolecular compounds. Full article
(This article belongs to the Special Issue Particle Technologies)
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13 pages, 6555 KiB  
Article
Morphological Changes in Betulin Particles as a Result of Polymorphic Transformations, and Formation of Co-Crystals under Heating
by Svetlana A. Myz, Anatoly A. Politov, Svetlana A. Kuznetsova and Tatyana P. Shakhtshneider
Powders 2023, 2(2), 432-444; https://doi.org/10.3390/powders2020026 - 05 Jun 2023
Viewed by 927
Abstract
Changes in the morphology of betulin crystals during heating at selected temperatures corresponding to polymorphic transformations were investigated. It was shown that the prismatic crystals of starting betulin form III were converted into needles at 120 °C after water removal, followed by the [...] Read more.
Changes in the morphology of betulin crystals during heating at selected temperatures corresponding to polymorphic transformations were investigated. It was shown that the prismatic crystals of starting betulin form III were converted into needles at 120 °C after water removal, followed by the III→II polymorphic transformation. During further heating up to 180 °C, the whiskers of betulin form I were grown. Experiments on betulin heating in the presence of dicarboxylic acids, adipic or suberic showed that the morphological changes can serve as a test for the formation of cocrystals. According to morphological changes, the formation of cocrystals of betulin with adipic acid under heating was identified. The interaction of adipic acid vapor with the surface of betulin crystals was suggested. In contrast, morphological changes in the mixture of betulin and suberic acid under heating provided only the evidence of polymorphic transformations of the components. The results on cocrystal formation by heating were compared with the preparation of cocrystals by the liquid-assistance grinding method. Despite the fact that polymorphic forms with a high surface area were formed when betulin was heated, dissolution studies showed that the starting betulin polymorph III exhibited the highest dissolution rate in comparison with betulin polymorphs obtained under heating. Full article
(This article belongs to the Special Issue Particle Technologies)
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11 pages, 4063 KiB  
Article
Mechanochemically Assisted Synthesis of Cu–Ag Microflakes
by Alexander M. Vorobyev, Olga A. Logutenko, Tatyana A. Borisenko and Alexander I. Titkov
Powders 2023, 2(2), 421-431; https://doi.org/10.3390/powders2020025 - 01 Jun 2023
Viewed by 891
Abstract
In this work, a simple, inexpensive, and eco-friendly synthesis method of Cu−Ag microflakes has been developed. Firstly, Cu nanoparticles were synthesized by the reduction of copper nitrate in ethylene glycol at 180 °C in the presence of NaOH. The as-synthesized Cu powder was [...] Read more.
In this work, a simple, inexpensive, and eco-friendly synthesis method of Cu−Ag microflakes has been developed. Firstly, Cu nanoparticles were synthesized by the reduction of copper nitrate in ethylene glycol at 180 °C in the presence of NaOH. The as-synthesized Cu powder was then dispersed in a mixture of ethyl alcohol and a dispersant followed by the mechanochemical treatment of the dispersion in a ball mill resulting in the formation of Cu flakes of approximately 0.2 μm thick and 2.7 μm lateral size. Next, by adding AgNO3 dissolved in H2O into the Cu particle dispersion, the bimetallic Cu−Ag microflakes were prepared. The particles so prepared were investigated by X-ray phase analysis and electron microscopy. It was shown that the Cu−Ag bimetallic particles were also flake-like in shape and similar in size to the original Cu microflakes. The effect of synthesis conditions, including parameters of mechanochemical processing, on thickness, size, and uniformity of the bimetallic microflakes was studied. The results obtained in this study were compared with those obtained by wet chemical synthesis alone. The flake-like Cu–Ag particles are supposed to be used in the manufacture of conductive pastes, adhesives, and composites for printed electronics. Full article
(This article belongs to the Special Issue Particle Technologies)
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18 pages, 9254 KiB  
Article
Mechanical Alloying of Copper- or Iron-Based Metallic Binders for Diamond Tools
by Pyotr Vityaz, Svetlana Kovaliova, Viktor Zhornik, Tatiana Grigoreva and Nikolay Lyakhov
Powders 2023, 2(2), 403-420; https://doi.org/10.3390/powders2020024 - 22 May 2023
Cited by 3 | Viewed by 1086
Abstract
Powder mixtures based on copper or iron are used as metal binder materials in the manufacturing of abrasive and cutting tools. This article discusses some aspects and possibilities of using a high-energy ball milling process to modify the structure and properties of Cu-Sn, [...] Read more.
Powder mixtures based on copper or iron are used as metal binder materials in the manufacturing of abrasive and cutting tools. This article discusses some aspects and possibilities of using a high-energy ball milling process to modify the structure and properties of Cu-Sn, Cu-Sn-Ti and Fe-Ti powders, their sintered materials and composites with diamond. The structures of powders and sintered materials, as well as the binder-to-diamond interfaces in metal matrix composites with diamond fillers, were studied by XRD analysis, scanning electron microscopy and X-ray spectroscopy. Tribological properties and thermal stability of materials in the temperature range of 250–800 °C were investigated. Various mechanisms of dispersion strengthening during the heating of sintered materials are described. It is shown that due to the grain boundary distribution of titanium, it is possible to obtain single-phase powders in the form of a supersaturated solid solution of CuSn20Ti5 and FeTi20, which ensure the formation of thermally hardened alloys with a microhardness of 357–408 HV and 561–622 HV, respectively, in the temperature range of 350–800 °C. The wear resistance of sintered powder alloys increases more than twice. Furthermore, the simultaneous enhancement in both the strength and ductility of metal–diamond titanium-containing composites is achieved through the nanostructural state and the formation of a thin layer (up to 2 μm) of titanium carbide at the interface between the metal matrix and diamond. The developed alloy shows great potential as a binder in diamond tools which are designed for machining abrasive materials. Full article
(This article belongs to the Special Issue Particle Technologies)
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15 pages, 5852 KiB  
Article
Thermal Stability of Iron- and Silicon-Substituted Hydroxyapatite Prepared by Mechanochemical Method
by Svetlana V. Makarova, Natalia V. Bulina, Olga B. Vinokurova and Arcady V. Ishchenko
Powders 2023, 2(2), 372-386; https://doi.org/10.3390/powders2020022 - 11 May 2023
Cited by 1 | Viewed by 1065
Abstract
In this study, hydroxyapatite with the substitution of calcium cations by iron and phosphate by silicate groups was synthesized via a mechanochemical method. The as-prepared compounds have the general formula Ca10−xFex(PO4)6−x(SiO4)x(OH) [...] Read more.
In this study, hydroxyapatite with the substitution of calcium cations by iron and phosphate by silicate groups was synthesized via a mechanochemical method. The as-prepared compounds have the general formula Ca10−xFex(PO4)6−x(SiO4)x(OH)2−xOx/2 with x = 0–1.5. The thermal stability of the as-prepared compounds was studied by ex situ annealing of powders in a furnace. It has been established that, at 800 °C for x ≤ 0.5, a partial decomposition of the substituted apatites occurs with the formation of the β–Ca3(PO4)2 phase. At high “x” values, the formation of this phase starts at the lower temperature of 700 °C, followed by the formation of Fe2O3 at 900 °C. The introduction of iron and silicate ions into the hydroxyapatite lattice was shown to decrease its thermal stability. Full article
(This article belongs to the Special Issue Particle Technologies)
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