Pub Date : 2023-11-21DOI: 10.15826/chimtech.2023.10.4.09
E. Lyalin, Larisa Pershina, Evgeniy a Il’ina, Konstantin Druzhinin, Semen Belyakov
Currently, interest to lithium and lithium-ion all-solid-state power sources is rapidly growing all over the world. However, several issues should be addressed before all-solid-state batteries production: high resistance values of the solid electrolyte membrane and poor contact between electrolyte and electrode materials. The transition to thin-film technologies is one of the promising ways to solve these problems. Tape casting can be proposed to obtain thin-film solid electrolytes. In this research, the features of the structure formation, morphology and lithium-ion conductivity of Li7La3Zr2O12 films were investigated. Li7La3Zr2O12 films with the thickness of 35 µm were obtained by tape casting on Ni substrate. The influence of organic components’ content on homogeneous coatings formation was established. Heat treatment conditions for dried films were chosen based on differential scanning calorimetry and optical dilatometry. Phase change from tetragonal to low-temperature cubic modification occurs after annealing the Li7La3Zr2O12 films at 700 °C and higher. The annealed Li7La3Zr2O12 films have developed surface, which can lead to improved contact between the solid electrolyte and an electrode in an electrochemical cell. Li7La3Zr2O12 films annealed at 800 °C have the highest lithium-ion conductivity values (2.5·10–7 and 1.5·10–5 S·cm–1 at 90 and 215 °С, respectively). The technology of Li7La3Zr2O12 films formation with the thickness of ~23 µm by tape casting was developed.
{"title":"Features of forming a low-temperature cubic Li7La3Zr2O12 film by tape casting","authors":"E. Lyalin, Larisa Pershina, Evgeniy a Il’ina, Konstantin Druzhinin, Semen Belyakov","doi":"10.15826/chimtech.2023.10.4.09","DOIUrl":"https://doi.org/10.15826/chimtech.2023.10.4.09","url":null,"abstract":"Currently, interest to lithium and lithium-ion all-solid-state power sources is rapidly growing all over the world. However, several issues should be addressed before all-solid-state batteries production: high resistance values of the solid electrolyte membrane and poor contact between electrolyte and electrode materials. The transition to thin-film technologies is one of the promising ways to solve these problems. Tape casting can be proposed to obtain thin-film solid electrolytes. In this research, the features of the structure formation, morphology and lithium-ion conductivity of Li7La3Zr2O12 films were investigated. Li7La3Zr2O12 films with the thickness of 35 µm were obtained by tape casting on Ni substrate. The influence of organic components’ content on homogeneous coatings formation was established. Heat treatment conditions for dried films were chosen based on differential scanning calorimetry and optical dilatometry. Phase change from tetragonal to low-temperature cubic modification occurs after annealing the Li7La3Zr2O12 films at 700 °C and higher. The annealed Li7La3Zr2O12 films have developed surface, which can lead to improved contact between the solid electrolyte and an electrode in an electrochemical cell. Li7La3Zr2O12 films annealed at 800 °C have the highest lithium-ion conductivity values (2.5·10–7 and 1.5·10–5 S·cm–1 at 90 and 215 °С, respectively). The technology of Li7La3Zr2O12 films formation with the thickness of ~23 µm by tape casting was developed.","PeriodicalId":9964,"journal":{"name":"Chimica Techno Acta","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139254557","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-16DOI: 10.15826/chimtech.2023.10.4.10
Yuri Shklyaev, O. Dizer, Tatyana Lugovitskaya, D. Golovkin, Denis Rogozhnikov
The paper presents a study of the process of nitric acid dissolution of the natural minerals chalcopyrite and bornite. The influence of various parameters, including temperature, nitric acid concentration and particle sizes, on this process was examined. Based on the data obtained, the values of apparent activation energy (57.41 and 42.98 kJ/mol for chalcopyrite and bornite, respectively), empirical orders with respect to nitric acid (1.62 and 1.57 for chalcopyrite and bornite, respectively) and with respect to particle size (–1.16 and –2.53 for chalcopyrite and bornite, respectively) were calculated using the shrinking core model. Generalized kinetic equations for the dissolution process of both minerals were derived. Based on the calculations performed, it was suggested that the dissolution processes of chalcopyrite and bornite under these conditions are limited by internal diffusion.
{"title":"Kinetics of nitric acid leaching of bornite and chalcopyrite","authors":"Yuri Shklyaev, O. Dizer, Tatyana Lugovitskaya, D. Golovkin, Denis Rogozhnikov","doi":"10.15826/chimtech.2023.10.4.10","DOIUrl":"https://doi.org/10.15826/chimtech.2023.10.4.10","url":null,"abstract":"The paper presents a study of the process of nitric acid dissolution of the natural minerals chalcopyrite and bornite. The influence of various parameters, including temperature, nitric acid concentration and particle sizes, on this process was examined. Based on the data obtained, the values of apparent activation energy (57.41 and 42.98 kJ/mol for chalcopyrite and bornite, respectively), empirical orders with respect to nitric acid (1.62 and 1.57 for chalcopyrite and bornite, respectively) and with respect to particle size (–1.16 and –2.53 for chalcopyrite and bornite, respectively) were calculated using the shrinking core model. Generalized kinetic equations for the dissolution process of both minerals were derived. Based on the calculations performed, it was suggested that the dissolution processes of chalcopyrite and bornite under these conditions are limited by internal diffusion.","PeriodicalId":9964,"journal":{"name":"Chimica Techno Acta","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139267912","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-03DOI: 10.15826/chimtech.2023.10.4.08
Lev Danilin, Tatyana Lugovitskaya, Elvira Kolmachikhina, Denis Rogozhnikov
The behavior of the surfactants Tween 80, SaS and alkyl betaine in aqueous and nitric acid environments as promising additives for nitrate leaching of hard-to-process ore concentrates of non-ferrous metals was studied. The influence of surfactant concentration (0.04–1.28 g/dm3), nitric acid concentration (0.1–10 g/dm3) and temperature (295–343 K) on the surface tension, critical micelle concentration (CMC), pH and optical density of aqueous surfactant solutions and surfactant–HNO3–H2O systems was found. The critical micelle concentration of the surfactants used was estimated. A positive effect of nitric acid on the surface activity of surfactants was discovered, which manifests itself in a decrease in both the CMC and the surface tension at the liquid–gas interface. The values of surface activity and Gibbs energy of surfactant micelle formation in aqueous and nitric acid media were calculated. Associative processes in the solutions and compositions were confirmed by measuring the optical density of the systems under study.
{"title":"Colloid-chemical properties of surfactant–nitric acid–water systems","authors":"Lev Danilin, Tatyana Lugovitskaya, Elvira Kolmachikhina, Denis Rogozhnikov","doi":"10.15826/chimtech.2023.10.4.08","DOIUrl":"https://doi.org/10.15826/chimtech.2023.10.4.08","url":null,"abstract":"The behavior of the surfactants Tween 80, SaS and alkyl betaine in aqueous and nitric acid environments as promising additives for nitrate leaching of hard-to-process ore concentrates of non-ferrous metals was studied. The influence of surfactant concentration (0.04–1.28 g/dm3), nitric acid concentration (0.1–10 g/dm3) and temperature (295–343 K) on the surface tension, critical micelle concentration (CMC), pH and optical density of aqueous surfactant solutions and surfactant–HNO3–H2O systems was found. The critical micelle concentration of the surfactants used was estimated. A positive effect of nitric acid on the surface activity of surfactants was discovered, which manifests itself in a decrease in both the CMC and the surface tension at the liquid–gas interface. The values of surface activity and Gibbs energy of surfactant micelle formation in aqueous and nitric acid media were calculated. Associative processes in the solutions and compositions were confirmed by measuring the optical density of the systems under study.","PeriodicalId":9964,"journal":{"name":"Chimica Techno Acta","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139290077","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The electrical conductivity of low concentrations of lanthanum-doped SrTiO3 nanocube ceramics synthesized using the facile solvothermal method in mixed organic and inorganic solvents with cetyltrimethylammonium bromide (CTAB) as a capping agent and tert-butyl amine (TBA) as a mineralizer was investigated. X-ray diffraction patterns confirmed the formation of a high-purity perovskite phase, corresponding to the standard data and the pattern refinement results. The particles of the sample were nanocubes, whereas the La-doped SrTiO3 sample particles were more uniform in size and shape, as shown in TEM images. The FT-IR spectrum confirmed the vibration of the CH3-N+ groups from CTAB and TBA, indicating an electrostatic interaction between their functional groups and the particle surface. Substitution of La3+ ions at low concentrations increased electrical conductivity compared to the undoped SrTiO3 sample. Lanthanum donates excess electrons, thereby increasing the number of electron carriers, which causes a reduction in the band gap energy according to the UV-DRS spectrum analysis using the Tauc equation.
{"title":"Facile synthesis of lanthanum-doped SrTiO<sub>3</sub> nanocubes mediated by cetyltrimethylammonium bromide and tert-butylamine under solvothermal condition and their tunable electrical properties","authors":"Yulia Eka Putri, Humaira Faradilla, Dedi Satria, Diana Vanda Wellia","doi":"10.15826/chimtech.2023.10.4.07","DOIUrl":"https://doi.org/10.15826/chimtech.2023.10.4.07","url":null,"abstract":"The electrical conductivity of low concentrations of lanthanum-doped SrTiO3 nanocube ceramics synthesized using the facile solvothermal method in mixed organic and inorganic solvents with cetyltrimethylammonium bromide (CTAB) as a capping agent and tert-butyl amine (TBA) as a mineralizer was investigated. X-ray diffraction patterns confirmed the formation of a high-purity perovskite phase, corresponding to the standard data and the pattern refinement results. The particles of the sample were nanocubes, whereas the La-doped SrTiO3 sample particles were more uniform in size and shape, as shown in TEM images. The FT-IR spectrum confirmed the vibration of the CH3-N+ groups from CTAB and TBA, indicating an electrostatic interaction between their functional groups and the particle surface. Substitution of La3+ ions at low concentrations increased electrical conductivity compared to the undoped SrTiO3 sample. Lanthanum donates excess electrons, thereby increasing the number of electron carriers, which causes a reduction in the band gap energy according to the UV-DRS spectrum analysis using the Tauc equation.","PeriodicalId":9964,"journal":{"name":"Chimica Techno Acta","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135013353","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-26DOI: 10.15826/chimtech.2023.10.4.06
Khuong T. Truong, Thach H. Pham, Khai V. Tran
The original article, “Khuong T. Truong, Thach H. Pham, Khai V. Tran. The impact of dimethylformamide on the synthesis of graphene quantum dots derived from graphene oxide. Chimica Techno Acta. 2023;10(4):202310405”, is available at: https://doi.org/10.15826/chimtech.2023.10.4.05
原文:“Khuong T. Truong, Thach H. Pham, Khai V. Tran。二甲基甲酰胺对氧化石墨烯衍生的石墨烯量子点合成的影响。中国科技学报，2023;10(4):202310405”，下载网址:https://doi.org/10.15826/chimtech.2023.10.4.05
{"title":"Corrigendum to The impact of dimethylformamide on the synthesis of graphene quantum dots derived from graphene oxide","authors":"Khuong T. Truong, Thach H. Pham, Khai V. Tran","doi":"10.15826/chimtech.2023.10.4.06","DOIUrl":"https://doi.org/10.15826/chimtech.2023.10.4.06","url":null,"abstract":"The original article, “Khuong T. Truong, Thach H. Pham, Khai V. Tran. The impact of dimethylformamide on the synthesis of graphene quantum dots derived from graphene oxide. Chimica Techno Acta. 2023;10(4):202310405”, is available at: https://doi.org/10.15826/chimtech.2023.10.4.05","PeriodicalId":9964,"journal":{"name":"Chimica Techno Acta","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134907800","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-26DOI: 10.15826/chimtech.2023.10.3.17
Nina Cherkasova, Kristina Antropova, Ruslan Kuzmin, Kemal Emurlaev, Ivanna Kuchumova, Nomina Burkhinova, Yulia Zobova
Alumina-zirconia composites containing calcium hexaaluminate in the amount from 0 to 15 wt.% were investigated. The materials were obtained by water dispersion, granulation, axial pressing, and free sintering. Density and open porosity were determined by the hydrostatic weighing method. Phase analysis was performed using synchrotron radiation. Structural investigations were conducted using scanning and transmission electron microscopy. Vickers hardness was determined at a load of 10 kg. Fracture toughness was determined by the indentation method. With increasing CaAl12O19 content in the composites, the relative density decreased from 98.5% to 91.8%, and the open porosity increased from 0.2 to 1.4%. The lattice parameters of t-ZrO2 crystal lattice did not change up to 12 wt.% CaAl12O19, and the degree of tetragonality was 1.435. The degree of tetragonality decreased for the material with 15 wt.% CaAl12O19 and reached 1.420. The lattice parameters of CaAl12O19 decreased with increasing content. Platelet size increased with increasing calcium hexaaluminate content. For the materials containing up to 9 wt.% CaAl12O19, the average length of the platelets was 2 μm, the width was 0.4 μm, and the aspect ratio was 5. For the material with maximum calcium hexaaluminate content, the average length of the platelets was 4.2 μm, the width was 0.6 μm, and the aspect ratio was 7. With increasing CaAl12O19 content, the hardness decreased from 1700±25 to 1390±30 Hv, and the critical stress intensity factor increased by 34% to 6.7±0.3 MPa·m1/2.
{"title":"Features of calcium hexaaluminate formation in alumina-zirconia ceramics","authors":"Nina Cherkasova, Kristina Antropova, Ruslan Kuzmin, Kemal Emurlaev, Ivanna Kuchumova, Nomina Burkhinova, Yulia Zobova","doi":"10.15826/chimtech.2023.10.3.17","DOIUrl":"https://doi.org/10.15826/chimtech.2023.10.3.17","url":null,"abstract":"Alumina-zirconia composites containing calcium hexaaluminate in the amount from 0 to 15 wt.% were investigated. The materials were obtained by water dispersion, granulation, axial pressing, and free sintering. Density and open porosity were determined by the hydrostatic weighing method. Phase analysis was performed using synchrotron radiation. Structural investigations were conducted using scanning and transmission electron microscopy. Vickers hardness was determined at a load of 10 kg. Fracture toughness was determined by the indentation method. With increasing CaAl12O19 content in the composites, the relative density decreased from 98.5% to 91.8%, and the open porosity increased from 0.2 to 1.4%. The lattice parameters of t-ZrO2 crystal lattice did not change up to 12 wt.% CaAl12O19, and the degree of tetragonality was 1.435. The degree of tetragonality decreased for the material with 15 wt.% CaAl12O19 and reached 1.420. The lattice parameters of CaAl12O19 decreased with increasing content. Platelet size increased with increasing calcium hexaaluminate content. For the materials containing up to 9 wt.% CaAl12O19, the average length of the platelets was 2 μm, the width was 0.4 μm, and the aspect ratio was 5. For the material with maximum calcium hexaaluminate content, the average length of the platelets was 4.2 μm, the width was 0.6 μm, and the aspect ratio was 7. With increasing CaAl12O19 content, the hardness decreased from 1700±25 to 1390±30 Hv, and the critical stress intensity factor increased by 34% to 6.7±0.3 MPa·m1/2.","PeriodicalId":9964,"journal":{"name":"Chimica Techno Acta","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134907264","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-23DOI: 10.15826/chimtech.2023.10.3.16
Ruslan Kuzmin, Roman Khabirov, Anna Mass, Elena Lozhkina
The magnetic properties of Mn-Zn ferrites depend strongly on the microstructure, chemical and phase composition. In this paper the effect of synthesis and sintering conditions on the structure, phase composition and properties of Mn-Zn ferrites is investigated. The specimens for the study were obtained by pressureless sintering. The magnetic properties were measured on a B-H analyzer. The structure was investigated by XRD and SEM. Materials with an average grain size of 2.2 μm were obtained by sintering at a temperature of 1265 °C. It was found that an increase in the synthesis temperature from 700 to 1000 °C promotes the growth of the initial magnetic permeability of these materials from 1100 to 1370. The rapid cooling of the powders synthesized at 1000 °C allows maintaining a high content of the spinel phase. In the structure of materials obtained by sintering powders with initially high spinel content at 1300 °C, grains of abnormally large size are formed. This leads to an increase in the initial permeability, magnetic induction at Hm = 1200 A/m, f = 10 kHz and magnetic losses at high frequencies (up to 500 kHz). A material with fine-grained structure was obtained by using air at the heating stage of pressureless sintering. This contributed to the reduction of magnetic losses without a significant decrease in Bm.
{"title":"Influence of the powders phase composition and sintering atmosphere on the structure and magnetic properties of Mn-Zn ferrites","authors":"Ruslan Kuzmin, Roman Khabirov, Anna Mass, Elena Lozhkina","doi":"10.15826/chimtech.2023.10.3.16","DOIUrl":"https://doi.org/10.15826/chimtech.2023.10.3.16","url":null,"abstract":"The magnetic properties of Mn-Zn ferrites depend strongly on the microstructure, chemical and phase composition. In this paper the effect of synthesis and sintering conditions on the structure, phase composition and properties of Mn-Zn ferrites is investigated. The specimens for the study were obtained by pressureless sintering. The magnetic properties were measured on a B-H analyzer. The structure was investigated by XRD and SEM. Materials with an average grain size of 2.2 μm were obtained by sintering at a temperature of 1265 °C. It was found that an increase in the synthesis temperature from 700 to 1000 °C promotes the growth of the initial magnetic permeability of these materials from 1100 to 1370. The rapid cooling of the powders synthesized at 1000 °C allows maintaining a high content of the spinel phase. In the structure of materials obtained by sintering powders with initially high spinel content at 1300 °C, grains of abnormally large size are formed. This leads to an increase in the initial permeability, magnetic induction at Hm = 1200 A/m, f = 10 kHz and magnetic losses at high frequencies (up to 500 kHz). A material with fine-grained structure was obtained by using air at the heating stage of pressureless sintering. This contributed to the reduction of magnetic losses without a significant decrease in Bm.","PeriodicalId":9964,"journal":{"name":"Chimica Techno Acta","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135460690","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-20DOI: 10.15826/chimtech.2023.10.3.15
Natalia V. Stepanova, Elena A. Lozhkina
The purpose of the work is to develop a cast antifriction material based on an iron-carbon alloy with a high copper content for use in large, heavy duty sliding friction units. Using the casting method in self-hardening liquid glass mixtures, two specimens of hypereutectoid graphitized steel with different copper contents (0.09 and 8.76 wt.%) were produced. To obtain graphite in the steel structure, modification with the silicocalcium (SiCa) was used. The microstructural examination was carried out using optical metallography, SEM and TEM methods. The impact of copper on the structure as well as the mechanical and antifriction properties of graphitized hypereutectoid steel was studied. It was found that adding 8.76 wt.% of copper to the steel composition leads to an increase in the Brinell hardness level of the material from 250 to 300 HB, ultimate tensile strength from 250 to 380 MPa and compressive strength from 1050 to 1200 MPa, which is associated with an increase in the microhardness of pearlite from 350 to 420 HV. To assess the impact of copper on the sliding friction coefficient of graphitized hypereutectoid steel, a curve of sliding friction coefficient vs applied load was plotted; the experiment was carried out according to the liner-on-disk scheme. The wear resistance of materials under sliding friction conditions was also assessed using this method. Copper alloying has a positive effect on the wear resistance of graphitized hypereutectoid steel by increasing the mechanical properties of the material and also by reducing the level of the sliding friction coefficient under boundary lubrication conditions.
{"title":"Structural transformations and their impact on the mechanical and antifriction properties in the process of alloying graphitized hypereutectoid steel with copper","authors":"Natalia V. Stepanova, Elena A. Lozhkina","doi":"10.15826/chimtech.2023.10.3.15","DOIUrl":"https://doi.org/10.15826/chimtech.2023.10.3.15","url":null,"abstract":"The purpose of the work is to develop a cast antifriction material based on an iron-carbon alloy with a high copper content for use in large, heavy duty sliding friction units. Using the casting method in self-hardening liquid glass mixtures, two specimens of hypereutectoid graphitized steel with different copper contents (0.09 and 8.76 wt.%) were produced. To obtain graphite in the steel structure, modification with the silicocalcium (SiCa) was used. The microstructural examination was carried out using optical metallography, SEM and TEM methods. The impact of copper on the structure as well as the mechanical and antifriction properties of graphitized hypereutectoid steel was studied. It was found that adding 8.76 wt.% of copper to the steel composition leads to an increase in the Brinell hardness level of the material from 250 to 300 HB, ultimate tensile strength from 250 to 380 MPa and compressive strength from 1050 to 1200 MPa, which is associated with an increase in the microhardness of pearlite from 350 to 420 HV. To assess the impact of copper on the sliding friction coefficient of graphitized hypereutectoid steel, a curve of sliding friction coefficient vs applied load was plotted; the experiment was carried out according to the liner-on-disk scheme. The wear resistance of materials under sliding friction conditions was also assessed using this method. Copper alloying has a positive effect on the wear resistance of graphitized hypereutectoid steel by increasing the mechanical properties of the material and also by reducing the level of the sliding friction coefficient under boundary lubrication conditions.","PeriodicalId":9964,"journal":{"name":"Chimica Techno Acta","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135665849","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-12DOI: 10.15826/chimtech.2023.10.3.14
Tatiana Ogneva, Alexander Anisimov, Ruslan Kuzmin, Andrey Tyurin, Yulia Emurlaeva, Natalya Aleksandrova
The fabrication of Ni-Al based metal-intermetallic layered (MIL) composites is one of the actively developing directions in the production of materials for aircraft and space industries. Alternating hard intermetallic layers with ductile metal layers provides a unique combination of mechanical properties. In this study, metal-intermetallic layered composites consisting of Ni and nickel aluminides were fabricated using spark plasma sintering (SPS) of Ni and Al foils 100 and 25 μm in thickness, respectively. Samples sintered at 1100 °C for 0.5, 3, and 8 min were obtained. The purpose of this study was to fabricate Ni-Al MIL composites with increased strength properties using SPS technique and to investigate the effect of sintering duration on structure and properties. The structure of the samples sintered for 0.5 min consisted of Ni layers and intermetallic layers containing the sublayers with stoichiometric and Ni-rich B2 NiAl, L10 twinned martensite NiAl. The tensile strength of such composites was 485 MPa. The intermetallic layers in the sample sintered for 3 min have more Ni-rich NiAl, martensite NiAl, and Ni3Al phases, which promoted to an increase in tensile strength to 575 MPa. The sample sintered for 8 min consisted of Ni and a solid solution of Al in Ni and showed the highest tensile strength, 610 MPa, due to solid solution hardening in the interlayers. The samples did not break when applying bending load, which is the evidence of the good reliability and durability of the composites.
{"title":"Effect of sintering duration on structure and properties of Ni-Al metal-intermetallic composites produced by SPS","authors":"Tatiana Ogneva, Alexander Anisimov, Ruslan Kuzmin, Andrey Tyurin, Yulia Emurlaeva, Natalya Aleksandrova","doi":"10.15826/chimtech.2023.10.3.14","DOIUrl":"https://doi.org/10.15826/chimtech.2023.10.3.14","url":null,"abstract":"The fabrication of Ni-Al based metal-intermetallic layered (MIL) composites is one of the actively developing directions in the production of materials for aircraft and space industries. Alternating hard intermetallic layers with ductile metal layers provides a unique combination of mechanical properties. In this study, metal-intermetallic layered composites consisting of Ni and nickel aluminides were fabricated using spark plasma sintering (SPS) of Ni and Al foils 100 and 25 μm in thickness, respectively. Samples sintered at 1100 °C for 0.5, 3, and 8 min were obtained. The purpose of this study was to fabricate Ni-Al MIL composites with increased strength properties using SPS technique and to investigate the effect of sintering duration on structure and properties. The structure of the samples sintered for 0.5 min consisted of Ni layers and intermetallic layers containing the sublayers with stoichiometric and Ni-rich B2 NiAl, L10 twinned martensite NiAl. The tensile strength of such composites was 485 MPa. The intermetallic layers in the sample sintered for 3 min have more Ni-rich NiAl, martensite NiAl, and Ni3Al phases, which promoted to an increase in tensile strength to 575 MPa. The sample sintered for 8 min consisted of Ni and a solid solution of Al in Ni and showed the highest tensile strength, 610 MPa, due to solid solution hardening in the interlayers. The samples did not break when applying bending load, which is the evidence of the good reliability and durability of the composites.","PeriodicalId":9964,"journal":{"name":"Chimica Techno Acta","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136013243","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-10DOI: 10.15826/chimtech.2023.10.4.05
Khuong T. Truong, Thach H. Pham, Khai V. Tran
Graphene quantum dots (GQDs) have garnered immense interest in recent years due to their unique optical, electrical, and chemical properties, making them promising candidates for various applications in optoelectronics, bioimaging, and sensing. However, enhancing the control over the size, surface chemistry, and optical properties of GQDs remains a significant challenge. In this study, a novel recipe was proposed to successfully synthesize various GQDs via a typical solvothermal process, which has proven to be a versatile and scalable approach. In addition to the main ingredient – graphene oxide suspension, dimethylformamide (DMF) and hydrogen peroxide serving as a cutting agent were added to the reaction mixture. This synthesis method was found to be more promising than the reference one in which DMF was replaced by double distilled water. Through systematic experimentation, we demonstrated that the addition of DMF enables the successful GQD production over a wider range of reaction times; hence, the UV absorption band and photoluminescence properties of GQDs can be better adjusted. The dependence of photoluminescence on the excitation wavelength was observed in the as-prepared materials as they were excited with a range of wavelengths from 360 to 480 nm. The obtained insights not only advance our understanding of GQD synthesis but also open up avenues for tailoring their properties for specific applications.
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