Powder Metallurgy and Metal Ceramics最新文献

{"title":"High-Temperature Oxidation of High-Entropy Alcrfeconimnx Alloys","authors":"O. A. Rokytska,&nbsp;M. V. Karpets,&nbsp;M. I. Yakubiv,&nbsp;M. O. Krapivka,&nbsp;A. V. Samelyuk,&nbsp;M. P. Naumenko","doi":"10.1007/s11106-023-00399-w","DOIUrl":"10.1007/s11106-023-00399-w","url":null,"abstract":"<p>The evolution of phase composition and thermal oxidation behavior of high-entropy AlCrFeCoNiMn_<i>x</i> alloys (<i>x</i> = 0.5 and 1) during long-term oxidation at 900°C were studied. A single- phase ordered (B2) bcc alloy formed in the starting as-cast state regardless of manganese content. The scale phase composition varied with exposure time and manganese content. After 10 h of oxidation, high-entropy spinel-type MeMn₂O₄, as well as Mn₃O₄ and Al₂O₃, formed on the AlCrFeCoNiMn alloy, while only Mn₃O₄ and Al₂O₃ oxides emerged on the AlCrFeCoNiMn_0.5 alloy. Increase in the oxidation time for the equiatomic alloy up to 25 h led to spinel NiMn₂O₄ and bixbyite FeMnO₃ in the oxide scale; Mn₃O₄ and Al₂O₃ were also present. The phase composition of the oxidized layer on the AlCrFeCoNiMn_0.5 alloy did not change. After 50 h, the structure of the oxide scale was similar for both alloys and consisted of NiMn₂O₄, FeMnO₃, Mn₃O₄, and Al₂O₃ in different ratios. The oxidation kinetics of the alloys naturally depended on the manganese content: the higher the manganese content, the higher the oxidation rate. A continuous layer of the fcc solid solution rich in chromium, iron, and cobalt was observed under the scale in both alloys. An internal oxidation area was also found in the subscale layer of the AlCrFeCoNiMn alloy. Long-term (more than 50 h) oxidation at 900°C substantially changed the phase composition of the alloy matrices: the bcc (B2) solid solution underwent spinodal decomposition to form bcc and fcc phases and tetragonal σ phase. Analyses of the alloy matrices showed a sharp increase in their microhardness after annealing. This can be attributed to the formation of a significant amount of the σ phase.</p>","PeriodicalId":742,"journal":{"name":"Powder Metallurgy and Metal Ceramics","volume":"62 5-6","pages":"360 - 371"},"PeriodicalIF":0.9,"publicationDate":"2023-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138951157","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Catalytic Effect of RTO3 Perovskites on Hydrogen Storage and Hydrolysis Properties of Magnesium Hydride","authors":"O. P. Kononiuk,&nbsp;I. Yu. Zavaliy,&nbsp;V. V. Berezovets,&nbsp;A. R. Kytsya,&nbsp;I. V. Lutsyuk,&nbsp;L. O. Vasylechko,&nbsp;M. V. Chekailo,&nbsp;Yu. M. Solonin","doi":"10.1007/s11106-023-00400-6","DOIUrl":"10.1007/s11106-023-00400-6","url":null,"abstract":"<p>The method of reactive ball milling was used to synthesize MgH₂-based composites adding nanoparticles of complex oxides RTO₃ (R-rare earth and T-transition metals) as catalysts and graphite. All composites contain 5 wt.% of complex oxides Dy_0.5Nd_0.5FeO₃ and TbFe_0.5Cr_0.5O₃ synthesized by the sol-gel method, and some of them additionally contain 3 wt.% of graphite. The oxides have an orthorhombic perovskite structure (GdFeO₃ type) and are characterized by an average particle size of 80–300 nm. The effect of perovskites on the hydrogenation of magnesium during the milling process and the improvement of hydrogen sorption-desorption kinetics is demonstrated. The Mg–Dy_0.5Nd_0.5FeO₃ and Mg–TbFe_0.5Cr_0.5O₃ composites absorbed 6.7 and 6.2 wt.% of hydrogen, respectively. X-ray powder diffraction after ball milling did not reveal any new compounds, except magnesium hydride. Thermal desorption from these composites occurs in two stages at temperatures above 300°C. The activation energy (<i>E</i>_a) of hydrogen desorption was determined by the Kissinger method. For the composite with TbFe_0.5Cr_0.5O₃, <i>E</i>_a is 123 kJ/mol, and for the composite with Dy_0.5Nd_0.5FeO₃ <i>E</i>_a = 147 kJ/mol. These composites were also tested as materials for hydrogen generation by hydrolysis in pure water and MgCl₂ water solutions. In pure water, the hydrogen yield during hydrolysis ranged from 320 to 350 ml per gram. The conversion degree was significantly improved by the addition of MgCl₂. It reached 90% (~1400 ml/g) after 30 min of hydrolysis for the MgH₂–nano-TbFe_0.5Cr_0.5O₃. These characteristics show that the synthesized MgH₂–nano-RTO₃ composites can be used in hydrogen generation systems.</p>","PeriodicalId":742,"journal":{"name":"Powder Metallurgy and Metal Ceramics","volume":"62 5-6","pages":"372 - 381"},"PeriodicalIF":0.9,"publicationDate":"2023-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138949378","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Properties of Nanostructured Carbon Fiber Material and Process Features of Its Use in Producing Tableted Enterosorbent for Medical Applications","authors":"V. P. Serhieiev,&nbsp;I. V. Kononko,&nbsp;N. V. Boshytska,&nbsp;V. D. Klipov","doi":"10.1007/s11106-023-00393-2","DOIUrl":"10.1007/s11106-023-00393-2","url":null,"abstract":"<p>An experimental technique was developed for the production of tableted nanostructured fibrous enterosorbent for medical applications using a nanostructured activated carbon fiber material of solid-phase pyrolytic origin, created by our research team. The properties of the main active ingredient in the pills, as an effective adsorbing component, were studied. The porous structure parameters were examined with the desiccator method based on the absorption of benzene vapors, while the specific surface area was analyzed with the Brunauer–Emmett–Teller (BET) method. Spectrophotometric methods were employed to determine the concentration of the sorbate in solutions. The microstructure of the samples was studied using a scanning electron microscope (Superprobe-733 X-ray microanalyzer, JEOL, Japan). Energy-dispersive X-ray analysis provided data on the chemical composition and biocompatibility of the samples, serving as an integral indicator. Conditions for the key stages in the enterosorbent production process were experimentally tested. The influence of different types of binders on the process properties of the tablet charge and on the characteristics of test enterosorbent pills was analyzed. The novelty of the developed process was the use of material with special characteristics, promoted by bound carbon nanoforms present in its structure, for enterosorbent production. Improvements in the process operations were proposed, such as decreasing the compaction speed and simultaneously increasing the time the tablet charge was kept under pressure, leading to the redistribution of strains. It was proposed that the compaction process be conducted using punches with a flat surface of purity class 10 to prevent sticking. Therefore, our research team developed tableted enterosorbent with typical features of its main component—nanostructured activated fibrous carbon material—as an effective adsorbent for a relatively wide range of different compounds.</p>","PeriodicalId":742,"journal":{"name":"Powder Metallurgy and Metal Ceramics","volume":"62 5-6","pages":"293 - 301"},"PeriodicalIF":0.9,"publicationDate":"2023-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138819861","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Synthesis of Fine MoSi2–Si3N4 Composite Powders","authors":"I. V. Kud,&nbsp;R. V. Lytvyn,&nbsp;L. A. Krushynska,&nbsp;O. M. Myslyvchenko,&nbsp;R. M. Mediukh,&nbsp;O. B. Zgalat-Lozynskyy","doi":"10.1007/s11106-023-00391-4","DOIUrl":"10.1007/s11106-023-00391-4","url":null,"abstract":"<p>The features peculiar to the solid-state synthesis of MoSi₂ through vacuum heat treatment of a powder mixture of molybdenum and silicon nitride, as a precursor, in the temperature range 1000–1400°C were examined. X-ray diffraction established that the solid-state interaction began at 1100°C and progressed through the reaction diffusion of highly active silicon, resulting from the decomposition of Si₃N₄, into molybdenum to form lower Mo₃Si and Mo₅Si₃ silicide phases. In the temperature range 1100–1300°C, the redistribution of phases occurred: the contents of the starting molybdenum and β-Si₃N₄ components in the reaction mixtures gradually decreased, while the contents of lower molybdenum silicides increased. Molybdenum disilicide formed in situ at 1400°C via successive development of lower silicide phases. The final product contained Mo₅Si₃. This was attributed to a deficiency of silicon as it evaporated at a temperature above 1200°C. This led to the conclusion that the addition of 20 wt.% excess silicon nitride was necessary to produce a homogeneous MoSi₂ phase and up to 40 wt.% excess silicon nitride to produce a two-phase MoSi₂–Si₃N₄ composite powder. The elevated temperature in the synthesis of MoSi₂ compared to conventional synthesis from simple elements was explained by the slow formation of active silicon in the Si₃N₄ dissociation process. Based on the features observed in the solid-state vacuum interaction within the powder mixture of molybdenum and silicon nitride, as a precursor, a method was proposed for producing MoSi₂–Si₃N₄ composite powders, involving the introduction of 30 and 40 wt.% excess Si₃N₄ powder. The synthesis resulted in agglomerated composite powders with a homogeneous distribution of the MoSi₂ and β -Si₃N₄ phases. The MoSi₂ phase exhibited a capsular structure with a smooth surface. The synthesized composite powders are intended for the fabrication of components and parts with high oxidation resistance and corrosion resistance at elevated temperatures.</p>","PeriodicalId":742,"journal":{"name":"Powder Metallurgy and Metal Ceramics","volume":"62 5-6","pages":"265 - 275"},"PeriodicalIF":0.9,"publicationDate":"2023-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138820227","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Effect of Boron Content on the Structure and Mechanical Properties of Electron-Beam High-Entropy AlNiCoFeCrTiB Coatings","authors":"S. O. Nakonechnyi,&nbsp;A. I. Yurkova,&nbsp;P. I. Loboda,&nbsp;Lan Jinlong","doi":"10.1007/s11106-023-00396-z","DOIUrl":"10.1007/s11106-023-00396-z","url":null,"abstract":"<p>High-entropy coatings produced by electron-beam deposition of multicomponent Al‒Ni‒Co‒Fe‒Cr‒Ti‒B_x (x = 0, 0.25, 0.5, and 1 mol) powder mixtures onto steel substrates in vacuum were examined. The effect of boron content on the phase composition, structure, and strength properties of the AlNiCoFeCrTiB_x coatings was studied employing X-ray diffraction, microstructural analysis, and micromechanical tests. The AlNiCoFeCrTi and AlNiCoFeCrTiB_0.25 coatings showed a typical dendritic and interdendritic structure and consisted of two substitutional solid solutions with a body-centered cubic (bcc) structure, differing in lattice parameters. An increase in the boron content to 0.5 mol changed the phase composition and led to the formation of in-situ titanium diboride TiB₂ as fine inclusions and chromium boride Cr₂B as elongated inclusions in the coatings besides the two bcc solid solutions (bcc1 and bcc2). When 1 mol of boron was added, the coatings remained four-phase, while the amount and sizes of TiB₂ and Cr₂B inclusions increased. Moreover, with 1 mol of boron, the ratio between the bcc1 and bcc2 phases increased toward bcc2 because of the removal of chromium and titanium atoms. Mechanical tests showed that the microhardness and yield stress of the AlNiCoFeCrTiB_x coatings produced by electron-beam deposition increased by 1.6 times when boron content raised to 1 mol: from 8.8 and 2.4 GPa for the AlNiCoFeCrTi coatings to 14.2 and 4 GPa for the AlNiCoFeCrTiB coatings. The significant enhancement in the strength indicators (hardness and yield stress) of the high-entropy coatings with greater boron content could be attributed to the solid-solution strengthening effect of interstitial boron atoms and to the strengthening effect of boride phase inclusions.</p>","PeriodicalId":742,"journal":{"name":"Powder Metallurgy and Metal Ceramics","volume":"62 5-6","pages":"326 - 338"},"PeriodicalIF":0.9,"publicationDate":"2023-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138819865","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Influence of Ti + TiC Additive on Thermal Stability and Decomposition Kinetics of Nanosized MgH2 Phase in Mg-Based Mechanical Alloys","authors":"O. G. Ershova,&nbsp;V. D. Dobrovolsky,&nbsp;Yu. M. Solonin","doi":"10.1007/s11106-023-00398-x","DOIUrl":"10.1007/s11106-023-00398-x","url":null,"abstract":"<p>Mechanical alloys Mg + 10 wt.% Ti and Mg + 5 wt.% Ti + 5 wt.% TiC (MAs) were synthesized by reactive mechanical alloying (RMA). Thermal stability and hydrogen desorption kinetics of the nanosized MgH₂ phase in the obtained MAs were examined by means of thermal desorption spectroscopy at a hydrogen pressure of 0.1 MPa. The stabilizing effect of Ti on the nanocrystalline structure and growth of the crystallites (grains) of the MgH₂ phase during the cycling was also evaluated. It has been established that the complex doping by Ti and TiC leads to a significant improvement in the desorption of hydrogen in the nanosized MgH₂ phase of MAs. The role of Ti and TiC as alloying elements in improving the hydrogen desorption kinetics of MAs was studied. The catalytic effect of adding 5 wt.% Ti + 5 wt.% TiC to magnesium in improving the kinetics of hydrogen desorption is significantly lower than the catalytic effect of adding 10 wt.% Ti. Due to such alloying, the decrease in the thermodynamic stability of MgH₂ is not established. The average rate of the reaction does not depend on the hydrogen concentration and is equal to the rate constant k = = k₀ exp(–Ea/RT) (the Arrhenius equation). The tested materials showed high potential as hydrogen storage alloys, especially for stationary applications.</p>","PeriodicalId":742,"journal":{"name":"Powder Metallurgy and Metal Ceramics","volume":"62 5-6","pages":"350 - 359"},"PeriodicalIF":0.9,"publicationDate":"2023-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138819868","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of Electrochemical Synthesis Conditions on the Composition, Structure, and Morphology of Tungsten Carbide Powders","authors":"I. A. Novoselova,&nbsp;S. V. Kuleshov,&nbsp;A. O. Omelchuk,&nbsp;V. N. Bykov,&nbsp;O. M. Fesenko","doi":"10.1007/s11106-023-00378-1","DOIUrl":"10.1007/s11106-023-00378-1","url":null,"abstract":"<p>High-temperature electrochemical synthesis (HTES) in molten salts is highly promising among the up-to-date methods for the production of carbide powders. Ultrafine composite powders of tungsten carbides (WC|C, WC|C|Pt, W₂C|WC, and W₂C|W) were synthesized using the HTES method in electrolytic baths with different chemical compositions under various synthesis conditions (cathode current density, CO₂ pressure in the electrolyzer, temperature, and cathode material). Composite powders (up to 3 wt.% free carbon) with a WC particle size of 20–30 nm were prepared using Na, K|Cl (1 : 1)–Na₂W₂O₇ (6.4 wt.%)–CO₂ (1.25 MPa) and Na, K|Cl (1 : 1)–Na₂WO₄ (12.0 wt.%)–NaPO₃ (0.7 wt. %)–CO₂ (1.25 MPa) electrolytic baths at a temperature of 750°C. When the CO₂ pressure was reduced to 0.75 MPa, composite W₂C|WC powders formed at the cathode. The ratio of carbide phases in the composites depended on the initial concentration of tungsten salts in the electrolyte and on the CO₂ gas pressure in the electrolyzer. The addition of Li₂CO₃ (4.5 wt.%) to the electrolytic salt mixture decreased the tungsten carbide particles to 10 nm, changed their morphology, and increased the free carbon content in the composite up to 5 wt.%. The specific surface area of the powder increased by a factor of 4 to 7 (from 20–35 to 140 m²/g). The resulting products were modified with fine platinum particles through the use of platinum cathodes. The HTES method demonstrated its potential for producing tungsten carbide powders with the properties allowing their use as electrocatalysts in the hydrogen evolution reaction. For the WC|C composite powders synthesized in the Na, K|Cl–Na₂W₂O₇–Li₂CO₃–CO₂ system, the hydrogen evolution potential was –0.02 V relative to the normal hydrogen electrode, the overpotential η at a current density of 10 mA/cm² was –110 mV, the exchange current was 7.0 ⋅ 10^–4 A/cm², and the Tafel slope was –85 mV/dec.</p>","PeriodicalId":742,"journal":{"name":"Powder Metallurgy and Metal Ceramics","volume":"62 3-4","pages":"142 - 152"},"PeriodicalIF":0.9,"publicationDate":"2023-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138555003","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tribological Properties of B4C–SiC–hBN Composite Ceramics Sliding Against AISI 347 Steel Immersed in Emulsion","authors":"Dong Liang,&nbsp;Sang Xiong","doi":"10.1007/s11106-023-00381-6","DOIUrl":"10.1007/s11106-023-00381-6","url":null,"abstract":"<p>The powders of hBN, SiC, and B₄C were employed as the raw ingredients to prepare the B₄C–SiC–hBN composite ceramics by a vacuum high-pressure sintering method with hBN and SiC contents in the range of 0, 10, and 20 wt.%, respectively. A pin-on-disc testing equipment was used to assess the tribological properties of B₄C–SiC–hBN composite ceramics with various hBN and SiC content when sliding against AISI 347 steel immersed in the emulsion. The experiment’s findings indicate that the sliding COF of the B₄C/AISI 347 steel pair marginally drops as the sliding distance increases. Besides, the sliding COF of the B₄C–10 wt.% SiC–20 wt.% hBN/AISI 347 steel pair rapidly declines. By tribopairs of B₄C–SiC–hBN composite ceramics against AISI 347 steel under the condition of lubrication by water-based emulsion, the steady-state friction may move into a state of mix lubrication as the hBN concentration rises, improving the tribological performance. The steady-state COF considerably decreases to 0.01 from 0.386 as the hBN and SiC concentration is increased to 20 wt.% and 10 wt.% from zero, showing a decreasing trend for both the B₄C–SiC–hBN pin and AISI 347 steel disc samples’ COWs. The steady-state friction of tribopairs of B₄C–SiC–hBN composite ceramics against AISI 347 steel may enter a state of mixed lubrication in the emulsion. The wear resistance of composite ceramics was improved by the addition of hBN and SiC particles because of their lubricating and reinforcing effects. These findings offer valuable insights into the design and development of advanced composite ceramics for various industrial applications that require improved tribological properties.</p>","PeriodicalId":742,"journal":{"name":"Powder Metallurgy and Metal Ceramics","volume":"62 3-4","pages":"195 - 202"},"PeriodicalIF":0.9,"publicationDate":"2023-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138534434","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Wear-Resistant Composites Produced from Tool Steel Waste for Contact Joints of High-Speed Printing Machines","authors":"T. A. Roik,&nbsp;O. A. Gavrysh,&nbsp;Iu. Iu. Vitsiuk,&nbsp;V. V. Kholiavko","doi":"10.1007/s11106-023-00385-2","DOIUrl":"10.1007/s11106-023-00385-2","url":null,"abstract":"<p>The paper examines the effect of doping elements on the structurization and properties of a new antifriction composite produced from grinding waste of the R2AM9K5 high-speed tool steel and CaF₂ solid lubricant. The composite is intended for operation at loads of 2.0–3.0 MPa and high rotation speeds (5,000–7,000 rpm) in contact joints of high-speed printing machines. The production process imparted a heterophase structure to the antifriction composite. The composite consists of a metal pearlite–carbide and carbonitride matrix and CaF₂ solid lubricant particles being evenly distributed in it. Valuable Mo, Cr, W, V, N, and Co doping elements contained in the R2AM9K5 steel waste particles promote the formation of strengthening phases in the composite’s metal matrix. In combination with CaF₂ solid lubricant, these strengthening phases impart high antifriction properties to the material under high-speed friction at speeds up to 7,000 rpm and loads of 2.0–3.0 MPa. Comparative tests of the new R2AM9K5 steel + (4.0−8.0)% CaF₂ composite demonstrated significant advantages in the antifriction properties over cast brass, currently used for units of modern rotary printing machines and can perform effectively only under continuous liquid lubrication. The R2AM9K5 steel waste composite containing CaF₂ solid lubricant permanently forms a protective antifriction film on the contact surfaces in the friction process, which was confirmed by electron microscopy studies. Under these friction conditions, the film is continuous, uniform, and smooth and is constantly restored on its worn areas, leading to self-lubrication. When the rotation speed increases up to 8,000 rpm, the composite antifriction properties decrease as the film on the contact surfaces becomes discontinuous. The research allowed operating limits to be determined for applying the new composite and proved the effectiveness of industrial grinding waste in developing high-quality structural materials through a reasoned choice of secondary raw materials, considering the nature of doping elements present in them.</p>","PeriodicalId":742,"journal":{"name":"Powder Metallurgy and Metal Ceramics","volume":"62 3-4","pages":"215 - 224"},"PeriodicalIF":0.9,"publicationDate":"2023-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138534423","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Method of Determining the Liquid Phase Content in the Pelletized Charge for Producing Compacts with the Maximum Strength II. Development of the Method","authors":"S. V. Vashchenko,&nbsp;A. Yu. Khudyakov,&nbsp;K. V. Baiul,&nbsp;Yu. S. Semenov","doi":"10.1007/s11106-023-00377-2","DOIUrl":"10.1007/s11106-023-00377-2","url":null,"abstract":"&lt;p&gt;Researchers of the Nekrasov Iron &amp; Steel Institute, National Academy of Sciences of Ukraine, conduct studies aimed at developing analytical methods for predicting the strength characteristics of pellets. These studies use analyses of phase interaction mechanisms within free-flowing media to develop theoretical ideas on the formation of strong bonds in the pellets through adhesion. This led to the establishment of local models of adhesion processes for two basic particle interaction schemes: ‘particle + particle’ and ‘particle + liquid phase + particle’. Experimental studies undertaken in laboratory premises of the Nekrasov Iron &amp; Steel Institute for the ‘particle + particle’ interaction scheme provided the foundation for a method to determine the strength characteristics of pellets made from fine-grained materials with zero moisture at compaction pressures ranging from 50 to 220 MPa. The first part of the paper justified methodological prerequisites for experiments to study strong bonds within the compacts for the ‘particle + liquid phase + particle’ interaction scheme. The methodological prerequisites accounted for the mechanical, physical, and physicochemical interactions, both between individual particles of the pelletized material and between the charge components (liquid phase). A generalized analysis of the experimental findings allowed evaluating a range of potential adhesion processes for the ‘particle + liquid phase + particle’ interaction scheme, pinpointing their manifestation, examining their nature, and assessing the effect of a liquid phase introduced into the pelletized charge, considering the compaction pressures applied. This paper focuses on experimental findings for the ‘particle + liquid phase + particle’ interaction scheme, establishing analytical relationships between the strength characteristics of pellets and integral indicators of the adhesive bond mechanism in this interaction scheme (in particular, relationship between the bulk density (ρ&lt;sub&gt;0&lt;/sub&gt;) and moisture content (W&lt;sub&gt;m&lt;/sub&gt;) for materials in the first group of systematization). Additionally, an analytical relationship between the compaction factor for compacts produced at a pressure (P) of 220 MPa (K&lt;sub&gt;comp220&lt;/sub&gt;), considering their loosening, and the bulk density of materials (ρ&lt;sub&gt;0&lt;/sub&gt;) in the first group of systematization was established for the first time. Analysis of the findings led to a hypothesis suggesting that the amount of the liquid phase (in particular, water) introduced into the material should be balanced by its potential displacement during compaction to achieve maximum compact strength. Based on the hypothesis, a novel equation was derived to calculate the amount of liquid binder (water) to promote the most favorable conditions for the adhesion processes, thereby imparting the maximum strength to compacts from materials in the first group of systematization. A comparative analysis between the experimental findings and c","PeriodicalId":742,"journal":{"name":"Powder Metallurgy and Metal Ceramics","volume":"62 3-4","pages":"153 - 163"},"PeriodicalIF":0.9,"publicationDate":"2023-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138534418","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}