Powders

Research

10 pages, 3307 KiB

Open AccessArticle

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 1396

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)

► Show Figures

Figure 1

19 pages, 15967 KiB

Open AccessArticle

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 - 8 Oct 2023

Viewed by 1094

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 Ca_2.57Cu_0.43(PO₄)₂ and CuO. The FTIR spectrum of Ca_2.57Cu_0.43(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)

► Show Figures

Figure 1

10 pages, 2073 KiB

Open AccessArticle

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 - 1 Aug 2023

Cited by 1 | Viewed by 1271

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)

► Show Figures

Figure 1

22 pages, 10276 KiB

Open AccessArticle

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

Cited by 1 | Viewed by 1362

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)

► Show Figures

Figure 1

15 pages, 5010 KiB

Open AccessArticle

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

Cited by 1 | Viewed by 1337

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)

► Show Figures

Figure 1

10 pages, 4132 KiB

Open AccessArticle

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 1536

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)

► Show Figures

Figure 1

16 pages, 5594 KiB

Open AccessArticle

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

Cited by 1 | Viewed by 1544

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)

► Show Figures

Figure 1

20 pages, 6396 KiB

Open AccessArticle

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 - 9 Jun 2023

Cited by 3 | Viewed by 1944

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 ^obsE_a 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)

► Show Figures

Figure 1

19 pages, 4472 KiB

Open AccessArticle

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 - 8 Jun 2023

Viewed by 1217

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)

► Show Figures

Figure 1

13 pages, 6555 KiB

Open AccessArticle

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 - 5 Jun 2023

Cited by 1 | Viewed by 1349

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)

► Show Figures

Figure 1

11 pages, 4063 KiB

Open AccessArticle

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 - 1 Jun 2023

Cited by 1 | Viewed by 1397

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)

► Show Figures

Figure 1

18 pages, 9254 KiB

Open AccessArticle

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 1902

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)

► Show Figures

Figure 1

15 pages, 5852 KiB

Open AccessArticle

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 1555

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 Ca_10−xFe_x(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 Ca_10−xFe_x(PO₄)_6−x(SiO₄)_x(OH)_2−xO_x/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)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Particle Technologies

Share This Special Issue

Special Issue Editor

Special Issue Information

Keywords

Benefits of Publishing in a Special Issue

Published Papers (13 papers)

Research

Further Information

Guidelines

MDPI Initiatives

Follow MDPI