M. Kalinina, D. A. Dyuskina, S. Mjakin, I. Kruchinina, O. Shilova
Finely dispersed (CeO2)1−x(Sm2O3)x (x = 0.05, 0.10, 0.20) and (CeO2)1−x(Nd2O3)x (x = 0.05, 0.10, 0.15, 0.20, 0.25) powders were synthesized via liquid-phase techniques based on the co-precipitation of hydroxides and were used to obtain ceramic materials comprising fluorite-like solid solutions with CSR in the range 69–88 nm (upon annealing at 1300 °C) and open porosity in the range 0.6–6.2%. The physicochemical properties of the synthesized materials were comparatively characterized. In general, the prepared materials were found to possess a mixed type of electrical conductivity, but in the medium-temperature range, the ionic component was predominant (ion transfer numbers ti = 0.93–0.73 at 300–700 °C). The highest ionic conductivity was observed for CeO2-based samples containing 20 mol.% Sm2O3 (σ700°C = 3.3 × 10−2 S/cm) and 15 mol.% Nd2O3 (σ700°C = 0.48 × 10−2 S/cm) was in the temperature range 500–700 °C. The physicochemical properties (density, open porosity, type and mechanism of electrical conductivity) of the obtained ceramic materials make them promising as solid oxide electrolytes for medium temperature fuel cells.
{"title":"Comparative Study of Physicochemical Properties of Finely Dispersed Powders and Ceramics in the Systems CeO2–Sm2O3 and CeO2–Nd2O3 as Electrolyte Materials for Medium Temperature Fuel Cells","authors":"M. Kalinina, D. A. Dyuskina, S. Mjakin, I. Kruchinina, O. Shilova","doi":"10.3390/ceramics6020073","DOIUrl":"https://doi.org/10.3390/ceramics6020073","url":null,"abstract":"Finely dispersed (CeO2)1−x(Sm2O3)x (x = 0.05, 0.10, 0.20) and (CeO2)1−x(Nd2O3)x (x = 0.05, 0.10, 0.15, 0.20, 0.25) powders were synthesized via liquid-phase techniques based on the co-precipitation of hydroxides and were used to obtain ceramic materials comprising fluorite-like solid solutions with CSR in the range 69–88 nm (upon annealing at 1300 °C) and open porosity in the range 0.6–6.2%. The physicochemical properties of the synthesized materials were comparatively characterized. In general, the prepared materials were found to possess a mixed type of electrical conductivity, but in the medium-temperature range, the ionic component was predominant (ion transfer numbers ti = 0.93–0.73 at 300–700 °C). The highest ionic conductivity was observed for CeO2-based samples containing 20 mol.% Sm2O3 (σ700°C = 3.3 × 10−2 S/cm) and 15 mol.% Nd2O3 (σ700°C = 0.48 × 10−2 S/cm) was in the temperature range 500–700 °C. The physicochemical properties (density, open porosity, type and mechanism of electrical conductivity) of the obtained ceramic materials make them promising as solid oxide electrolytes for medium temperature fuel cells.","PeriodicalId":33263,"journal":{"name":"Ceramics-Switzerland","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2023-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48719347","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}
K. Hoggas, S. Benaissa, A. Cherouana, Sofiane Bouheroum, A. Assali, M. Hamidouche, G. Fantozzi
In this work, a transparent nanostructured ceramic magnesium aluminate spinel (MgAl2O4) was fabricated by Spark Plasma Sintering (SPS) from commercial spinel nano-powders at different temperatures (1300, 1350 and 1400 °C). The sintered samples were thoroughly examined to assess their microstructural, optical, and mechanical properties. Various techniques such as SEM, AFM, spectrophotometer with an integrating sphere, instrumented Vickers indenter, Pin-on-Disk tribometer, scratch tester, and sandblasting device were employed to characterize the sintered samples. The results indicated the significant impact of the sintering temperature on the properties of the spinel samples. Particularly, the samples sintered at T = 1350 °C exhibited the highest Real In-line Transmission (RIT = 72% at 550 nm and 80% at 1000 nm). These samples demonstrated the highest hardness value (HV = 16.7 GPa) compared to those sintered at 1300 °C (HV = 15.6 GPa) and 1400 °C (HV = 15.1 GPa). The measured fracture toughness of the sintered samples increased substantially with increasing sintering temperature. Similarly, the tribological study revealed that the friction coefficient of the sintered spinel samples increased with the sintering temperature, and the spinel sintered at 1350 °C exhibited the lowest wear rate. Additionally, sandblasting and scratch tests confirmed the significant influence of the sintering temperature on the mechanical properties of the fabricated spinels. Overall, the spinel sintered at 1350 °C presented the best compromise in terms of all the evaluated properties.
{"title":"Mechanical Behavior of Transparent Spinel Fabricated by Spark Plasma Sintering","authors":"K. Hoggas, S. Benaissa, A. Cherouana, Sofiane Bouheroum, A. Assali, M. Hamidouche, G. Fantozzi","doi":"10.3390/ceramics6020072","DOIUrl":"https://doi.org/10.3390/ceramics6020072","url":null,"abstract":"In this work, a transparent nanostructured ceramic magnesium aluminate spinel (MgAl2O4) was fabricated by Spark Plasma Sintering (SPS) from commercial spinel nano-powders at different temperatures (1300, 1350 and 1400 °C). The sintered samples were thoroughly examined to assess their microstructural, optical, and mechanical properties. Various techniques such as SEM, AFM, spectrophotometer with an integrating sphere, instrumented Vickers indenter, Pin-on-Disk tribometer, scratch tester, and sandblasting device were employed to characterize the sintered samples. The results indicated the significant impact of the sintering temperature on the properties of the spinel samples. Particularly, the samples sintered at T = 1350 °C exhibited the highest Real In-line Transmission (RIT = 72% at 550 nm and 80% at 1000 nm). These samples demonstrated the highest hardness value (HV = 16.7 GPa) compared to those sintered at 1300 °C (HV = 15.6 GPa) and 1400 °C (HV = 15.1 GPa). The measured fracture toughness of the sintered samples increased substantially with increasing sintering temperature. Similarly, the tribological study revealed that the friction coefficient of the sintered spinel samples increased with the sintering temperature, and the spinel sintered at 1350 °C exhibited the lowest wear rate. Additionally, sandblasting and scratch tests confirmed the significant influence of the sintering temperature on the mechanical properties of the fabricated spinels. Overall, the spinel sintered at 1350 °C presented the best compromise in terms of all the evaluated properties.","PeriodicalId":33263,"journal":{"name":"Ceramics-Switzerland","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2023-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47962180","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}
Cristian Abad-Coronel, Ángeles Paladines, A. L. Ulloa, César A. Paltán, J. I. Fajardo
The aim of this study was to evaluate and compare the fracture resistance of definitive zirconia dioxide restorations obtained using a computer-aided design and manufacturing (CAD/CAM) system. Methods: Two groups of ten samples were analyzed for each material (n: 20); the first group was Zolid Gen X Amann Girrbach (ZGX) and the second group was Cercon HT Dentsply Sirona (CDS). The restorations were designed with identical parameters and milled with a CAD/CAM system. Each specimen was load tested at a speed of 0.5 mm/min, with a direction parallel to the major axis of the tooth and with an initial preload of 10 N until fracture using a universal testing machine (Universal/Tensile Testing Machine, Autograph AGS-X Series) equipped with a 20 kN load cell. The results obtained were recorded in Newtons (N), using software connected to the testing machine. Results: Statistically significant differences were found, and the fracture resistance of the monolithic zirconia crowns was lower in the CDS group (1744.84 ± 172.8 N) compared to the ZGX group (2387.41 ± 516 N). Conclusions: The monolithic zirconia CAD-CAM zirconia crowns showed sufficient fracture resistance when used in posterior molar and premolar zones with either material, as they withstood fracture loads greater than the maximum masticatory force.
本研究的目的是评估和比较使用计算机辅助设计和制造（CAD/CAM）系统获得的氧化锆修复体的抗断裂性。方法：每种材料分为两组，每组10个样品（n=20）；第一组为Zolid Gen X Amann Girbach（ZGX），第二组为Cercon HT Dentsply Sirona（CDS）。修复体采用相同的参数设计，并使用CAD/CAM系统进行铣削。使用配备有20kN称重传感器的通用试验机（万能/拉伸试验机，Autograph AGS-X系列），以0.5mm/min的速度、平行于牙齿主轴的方向和10N的初始预载荷对每个试样进行载荷试验，直至断裂。使用连接到测试机的软件，将获得的结果记录在牛顿（N）中。结果：CDS组（1744.84±172.8 N）与ZGX组（2387.41±516 N）相比，整体氧化锆冠的抗断裂性较低，差异具有统计学意义。结论：整体式氧化锆CAD-CAM氧化锆冠在使用任何一种材料的后磨牙和前磨牙区域时都表现出足够的抗断裂性，因为它们能够承受大于最大咀嚼力的断裂载荷。
{"title":"Comparative Fracture Resistance Analysis of Translucent Monolithic Zirconia Dioxide Milled in a CAD/CAM System","authors":"Cristian Abad-Coronel, Ángeles Paladines, A. L. Ulloa, César A. Paltán, J. I. Fajardo","doi":"10.3390/ceramics6020071","DOIUrl":"https://doi.org/10.3390/ceramics6020071","url":null,"abstract":"The aim of this study was to evaluate and compare the fracture resistance of definitive zirconia dioxide restorations obtained using a computer-aided design and manufacturing (CAD/CAM) system. Methods: Two groups of ten samples were analyzed for each material (n: 20); the first group was Zolid Gen X Amann Girrbach (ZGX) and the second group was Cercon HT Dentsply Sirona (CDS). The restorations were designed with identical parameters and milled with a CAD/CAM system. Each specimen was load tested at a speed of 0.5 mm/min, with a direction parallel to the major axis of the tooth and with an initial preload of 10 N until fracture using a universal testing machine (Universal/Tensile Testing Machine, Autograph AGS-X Series) equipped with a 20 kN load cell. The results obtained were recorded in Newtons (N), using software connected to the testing machine. Results: Statistically significant differences were found, and the fracture resistance of the monolithic zirconia crowns was lower in the CDS group (1744.84 ± 172.8 N) compared to the ZGX group (2387.41 ± 516 N). Conclusions: The monolithic zirconia CAD-CAM zirconia crowns showed sufficient fracture resistance when used in posterior molar and premolar zones with either material, as they withstood fracture loads greater than the maximum masticatory force.","PeriodicalId":33263,"journal":{"name":"Ceramics-Switzerland","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2023-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46110564","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}
A. Kurakhmedov, A. Morzabayev, Islam Tleubay, A. Berguzinov, A. Kozlovskiy
The aim of this work is to study the mechanisms of polymorphic transformations in ZrO2 ceramics doped with MgO with different concentrations during thermal isochronous annealing, as well as the effect of the phase composition of ceramics on the change in strength properties and resistance to mechanical stress. Solving the problem of polymorphic transformations in zirconium dioxide by doping them with MgO will increase the resistance of ceramics to external influences, as well as increase the mechanical strength of ceramics. According to the data of X-ray phase analysis, it was found that the addition of the MgO dopant to the composition of ceramics at the chosen thermal annealing temperature leads to the initialization of polymorphic transformation processes, while changing the dopant concentration leads to significant differences in the types of polymorphic transformations. In the case of an undoped ZrO2 ceramic sample, thermal annealing at a temperature of 1500 °C leads to structural ordering due to the partial removal of deformation distortions of the crystal lattice caused by mechanochemical grinding. During the study of the effect of MgO doping and polymorphic transformations in ZrO2 ceramics on the strength properties, it was found that the main hardening effect is due to a change in the dislocation density during the formation of a ZrO2/MgO type structure. At the same time, polymorphic transformations of the m—ZrO2 → t—ZrO2 type have a greater effect on hardening at low dopant concentrations than t—ZrO2 → c—ZrO2 type transformations.
{"title":"Study of the Mechanisms of Polymorphic Transformations in Zirconium Dioxide upon Doping with Magnesium Oxide, as Well as Establishing the Relationship between Structural Changes and Strength Properties","authors":"A. Kurakhmedov, A. Morzabayev, Islam Tleubay, A. Berguzinov, A. Kozlovskiy","doi":"10.3390/ceramics6020070","DOIUrl":"https://doi.org/10.3390/ceramics6020070","url":null,"abstract":"The aim of this work is to study the mechanisms of polymorphic transformations in ZrO2 ceramics doped with MgO with different concentrations during thermal isochronous annealing, as well as the effect of the phase composition of ceramics on the change in strength properties and resistance to mechanical stress. Solving the problem of polymorphic transformations in zirconium dioxide by doping them with MgO will increase the resistance of ceramics to external influences, as well as increase the mechanical strength of ceramics. According to the data of X-ray phase analysis, it was found that the addition of the MgO dopant to the composition of ceramics at the chosen thermal annealing temperature leads to the initialization of polymorphic transformation processes, while changing the dopant concentration leads to significant differences in the types of polymorphic transformations. In the case of an undoped ZrO2 ceramic sample, thermal annealing at a temperature of 1500 °C leads to structural ordering due to the partial removal of deformation distortions of the crystal lattice caused by mechanochemical grinding. During the study of the effect of MgO doping and polymorphic transformations in ZrO2 ceramics on the strength properties, it was found that the main hardening effect is due to a change in the dislocation density during the formation of a ZrO2/MgO type structure. At the same time, polymorphic transformations of the m—ZrO2 → t—ZrO2 type have a greater effect on hardening at low dopant concentrations than t—ZrO2 → c—ZrO2 type transformations.","PeriodicalId":33263,"journal":{"name":"Ceramics-Switzerland","volume":"1 1","pages":""},"PeriodicalIF":2.8,"publicationDate":"2023-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69565610","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}
Valeri V. Poluektov, V. Petrov, M. I. Ojovan, S. Yudintsev
Uranium-containing glass samples with an age of 140–145 million years were collected within the volcanic rocks of the largest volcanic-related uranium ore deposit in the world. Main features of their composition are high concentrations of silica and uranium, the largest for the rocks of this type. In contrast to this, the ages of fresh (unaltered) low-silica natural glasses of a basic composition (basalts) usually do not exceed a few million years. The volcanic low-silica glass is unstable at longer times and in older ancient rocks is transformed into a crystalline mass. The geochemistry of uranium including the behavior in solids and solutions is similar to that of long-lived transuranic actinides such as radioactive Np and Pu from high-level radioactive waste. This allows uranium to be used as a simulant of these long-lived hazardous radionuclides both at the synthesis and for the study of various nuclear wasteforms: glasses, glass crystalline materials and crystalline ceramics. The data obtained on long-term behavior of natural glasses are of importance for prognosis and validation of stability of nuclear wasteforms disposed of in geological disposal facilities (GDF).
{"title":"Uranium Retention in Silica-Rich Natural Glasses: Nuclear Waste Disposal Aspect","authors":"Valeri V. Poluektov, V. Petrov, M. I. Ojovan, S. Yudintsev","doi":"10.3390/ceramics6020069","DOIUrl":"https://doi.org/10.3390/ceramics6020069","url":null,"abstract":"Uranium-containing glass samples with an age of 140–145 million years were collected within the volcanic rocks of the largest volcanic-related uranium ore deposit in the world. Main features of their composition are high concentrations of silica and uranium, the largest for the rocks of this type. In contrast to this, the ages of fresh (unaltered) low-silica natural glasses of a basic composition (basalts) usually do not exceed a few million years. The volcanic low-silica glass is unstable at longer times and in older ancient rocks is transformed into a crystalline mass. The geochemistry of uranium including the behavior in solids and solutions is similar to that of long-lived transuranic actinides such as radioactive Np and Pu from high-level radioactive waste. This allows uranium to be used as a simulant of these long-lived hazardous radionuclides both at the synthesis and for the study of various nuclear wasteforms: glasses, glass crystalline materials and crystalline ceramics. The data obtained on long-term behavior of natural glasses are of importance for prognosis and validation of stability of nuclear wasteforms disposed of in geological disposal facilities (GDF).","PeriodicalId":33263,"journal":{"name":"Ceramics-Switzerland","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2023-05-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42585015","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}
O. Suvorova, N. Manakova, Andrey I Novikov, D. Makarov
The possibility of obtaining building foamed glass-ceramic using the diamond concentration tailings of the Lomonosov deposit in Arkhangelsk Region, Russia, is demonstrated here. The effect of the tailings’ particle size distribution, feed temperature, the addition of a foaming agent, and the content of oxidizer on the feed charge foaming is established. The process conditions for obtaining foamed glass-ceramic materials are described. The specifications of the materials with the optimal composition (tailings 50 wt.%, glass waste 50 wt.%, SiC 0.5 wt.%, Fe2O3 1 wt.%) foamed at 1020–1050 °C were as follows: apparent density 0.23–0.51 g/cm3, compression strength 0.58–2.40 MPa, water absorption (by volume) 8.7–19.0%. Based on the combination of the measured properties when used in dry conditions, the obtained materials can be considered heat-insulating foam materials. The thermal conductivity was 0.060–0.066 W/m·K.
{"title":"Obtaining Foamed Glass-Ceramics from Diamond Concentration Tailings","authors":"O. Suvorova, N. Manakova, Andrey I Novikov, D. Makarov","doi":"10.3390/ceramics6020068","DOIUrl":"https://doi.org/10.3390/ceramics6020068","url":null,"abstract":"The possibility of obtaining building foamed glass-ceramic using the diamond concentration tailings of the Lomonosov deposit in Arkhangelsk Region, Russia, is demonstrated here. The effect of the tailings’ particle size distribution, feed temperature, the addition of a foaming agent, and the content of oxidizer on the feed charge foaming is established. The process conditions for obtaining foamed glass-ceramic materials are described. The specifications of the materials with the optimal composition (tailings 50 wt.%, glass waste 50 wt.%, SiC 0.5 wt.%, Fe2O3 1 wt.%) foamed at 1020–1050 °C were as follows: apparent density 0.23–0.51 g/cm3, compression strength 0.58–2.40 MPa, water absorption (by volume) 8.7–19.0%. Based on the combination of the measured properties when used in dry conditions, the obtained materials can be considered heat-insulating foam materials. The thermal conductivity was 0.060–0.066 W/m·K.","PeriodicalId":33263,"journal":{"name":"Ceramics-Switzerland","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2023-05-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49546902","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}
A. Kholodkova, M. Kornyushin, M. A. Pakhomov, A. Smirnov, Yu. D. Ivakin
A developing energy-saving approach of cold sintering in a pure aqueous medium was applied to the preparation of α-Al2O3 ceramics and performed on spark plasma sintering equipment. The initial γ-Al(OH)3 and γ-AlOOH powders and the cold-sintered ceramics were studied by X-ray diffraction analysis, infrared spectroscopy, thermal analysis, and scanning electron microscopy to reveal the chemical and structural transformations they experienced during the cold sintering. At 450 °C and 70 MPa, initially γ-AlOOH transformed into a fragile α-Al2O3 material. Porous α-Al2O3 ceramics with about 60% porosity were obtained after cold sintering of γ-Al(OH)3 in the same conditions combined with subsequent annealing at 1250 °C for 3 h. The role of water molecules in the studied processes was considered as the enhancement of structural mobility in the cold-sintered material due to its reversible hydroxylation similar to earlier investigated supercritical water actions on the precursors during α-Al2O3 formation. Further improvement of the cold sintering setup and regimens would open prospects in α-Al2O3 ceramics manufacturing by an ecologically benign route.
{"title":"Water-Assisted Cold Sintering of Alumina Ceramics in SPS Conditions","authors":"A. Kholodkova, M. Kornyushin, M. A. Pakhomov, A. Smirnov, Yu. D. Ivakin","doi":"10.3390/ceramics6020066","DOIUrl":"https://doi.org/10.3390/ceramics6020066","url":null,"abstract":"A developing energy-saving approach of cold sintering in a pure aqueous medium was applied to the preparation of α-Al2O3 ceramics and performed on spark plasma sintering equipment. The initial γ-Al(OH)3 and γ-AlOOH powders and the cold-sintered ceramics were studied by X-ray diffraction analysis, infrared spectroscopy, thermal analysis, and scanning electron microscopy to reveal the chemical and structural transformations they experienced during the cold sintering. At 450 °C and 70 MPa, initially γ-AlOOH transformed into a fragile α-Al2O3 material. Porous α-Al2O3 ceramics with about 60% porosity were obtained after cold sintering of γ-Al(OH)3 in the same conditions combined with subsequent annealing at 1250 °C for 3 h. The role of water molecules in the studied processes was considered as the enhancement of structural mobility in the cold-sintered material due to its reversible hydroxylation similar to earlier investigated supercritical water actions on the precursors during α-Al2O3 formation. Further improvement of the cold sintering setup and regimens would open prospects in α-Al2O3 ceramics manufacturing by an ecologically benign route.","PeriodicalId":33263,"journal":{"name":"Ceramics-Switzerland","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2023-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42292579","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}
Irina Khadyrova, V. Suvorova, A. Nepapushev, D. Suvorov, K. Kuskov, D. Moskovskikh
Nanostructured single-phase hafnium-zirconium carbonitride powders were synthesized using a simple and fast mechanochemical synthesis approach. The critical milling duration, after which a (Hf,Zr)(C,N) solid solution formation inside a jar occurred via mechanically induced self-sustained reaction (MSR), was 10 min. After 30 min of treatment, a solid-gas reaction was completed, and as a result, a homogeneous (Hf,Zr)(C,N) powder consisting of 10–500 nm submicron particles was obtained. The phase and structure evolution of the powders after different treatment durations allowed for the establishment of possible reaction mechanisms, which included the formation of Hf/Zr/C-layered composite particles, their interaction via MSR, and further grinding and nitridization. Spark plasma sintering (SPS) was used to produce bulk hafnium-zirconium carbonitride ceramics from nanostructured powder. The sample had higher values of relative density, hardness, and fracture toughness than those for binary compounds of a similar composition.
{"title":"Hafnium-Zirconium Carbonitride (Hf,Zr)(C,N) by One Step Mechanically Induced Self-Sustaining Reaction: Powder Synthesis and Spark Plasma Sintering","authors":"Irina Khadyrova, V. Suvorova, A. Nepapushev, D. Suvorov, K. Kuskov, D. Moskovskikh","doi":"10.3390/ceramics6020067","DOIUrl":"https://doi.org/10.3390/ceramics6020067","url":null,"abstract":"Nanostructured single-phase hafnium-zirconium carbonitride powders were synthesized using a simple and fast mechanochemical synthesis approach. The critical milling duration, after which a (Hf,Zr)(C,N) solid solution formation inside a jar occurred via mechanically induced self-sustained reaction (MSR), was 10 min. After 30 min of treatment, a solid-gas reaction was completed, and as a result, a homogeneous (Hf,Zr)(C,N) powder consisting of 10–500 nm submicron particles was obtained. The phase and structure evolution of the powders after different treatment durations allowed for the establishment of possible reaction mechanisms, which included the formation of Hf/Zr/C-layered composite particles, their interaction via MSR, and further grinding and nitridization. Spark plasma sintering (SPS) was used to produce bulk hafnium-zirconium carbonitride ceramics from nanostructured powder. The sample had higher values of relative density, hardness, and fracture toughness than those for binary compounds of a similar composition.","PeriodicalId":33263,"journal":{"name":"Ceramics-Switzerland","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2023-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45785722","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}
M. Kalinina, D. A. Dyuskina, I. Polyakova, S. Mjakin, I. Kruchinina
Finely dispersed (CeO2)1−x(Nd2O3)x (x = 0.05, 0.10, 0.15, 0.20, 0.25) powders are synthesized via liquid-phase techniques based on the co-precipitation of hydroxides and co-crystallization of nitrates. The prepared powders are used to obtain ceramic materials comprising fluorite-like solid solutions with the coherent scattering region (CSR) of about 88 nm (upon annealing at 1300 °C) and open porosity in the range of 1–15%. The effect of the synthesis procedure and sintering additives (SiO2, ZnO) on physicochemical and electrophysical properties of the resulting ceramics is studied. The prepared materials are found to possess a predominantly ionic type of electric conductivity with ion transfer numbers ti = 0.96–0.71 in the temperature range of 300–700 °C. The conductivity in solid solutions follows a vacancy mechanism with σ700 °C = 0.48 × 10−2 S/cm. Physicochemical properties (density, open porosity, type and mechanism of electrical conductivity) of the obtained ceramic materials make them promising as solid oxide electrolytes for medium temperature fuel cells.
{"title":"Effect of Synthetic Approaches and Sintering Additives upon Physicochemical and Electrophysical Properties of Solid Solutions in the System (CeO2)1−x(Nd2O3)x for Fuel Cell Electrolytes","authors":"M. Kalinina, D. A. Dyuskina, I. Polyakova, S. Mjakin, I. Kruchinina","doi":"10.3390/ceramics6020065","DOIUrl":"https://doi.org/10.3390/ceramics6020065","url":null,"abstract":"Finely dispersed (CeO2)1−x(Nd2O3)x (x = 0.05, 0.10, 0.15, 0.20, 0.25) powders are synthesized via liquid-phase techniques based on the co-precipitation of hydroxides and co-crystallization of nitrates. The prepared powders are used to obtain ceramic materials comprising fluorite-like solid solutions with the coherent scattering region (CSR) of about 88 nm (upon annealing at 1300 °C) and open porosity in the range of 1–15%. The effect of the synthesis procedure and sintering additives (SiO2, ZnO) on physicochemical and electrophysical properties of the resulting ceramics is studied. The prepared materials are found to possess a predominantly ionic type of electric conductivity with ion transfer numbers ti = 0.96–0.71 in the temperature range of 300–700 °C. The conductivity in solid solutions follows a vacancy mechanism with σ700 °C = 0.48 × 10−2 S/cm. Physicochemical properties (density, open porosity, type and mechanism of electrical conductivity) of the obtained ceramic materials make them promising as solid oxide electrolytes for medium temperature fuel cells.","PeriodicalId":33263,"journal":{"name":"Ceramics-Switzerland","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2023-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48129116","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}
I. Zhushchikhovskaya, I. Buravlev, A. A. Karpenko, Anastasia A. Lazina, A. N. Fedorets
This paper considers the results of an examination of painted pottery from prehistoric sites of the Prmor’ye region (Southern Russian Far East) in the northwestern part of the Sea of Japan basin. Red-painted and black-painted ceramic wares occur here only in the remains of the Yankovskaya archaeological culture dated to the 1st mil. BCE. Red painting appears as a colored surface coating, and black painting is represented by very simple drawn patterns. Until recently painting decorations have not been intentionally studied. The objects of our investigation are a small series of red-painted and black-painted ceramic fragments originated from archaeological sites. The methods of optical microscopy, SEM-EDS, and Raman spectroscopy were applied to the study of research materials. As a result, the data on characteristics of texture and composition of red and black paints were obtained. Both were determined to be pre-firing paints. Red paint is a clayish substance mixed with natural ochre pigment containing the hematite coloring agent. Black paint is carbon-based. Black carbon and burnt bone are recognized as colorants. The presented materials are new evidence of pottery paint technologies in prehistoric Eurasia.
{"title":"Red and Black Paints on Prehistoric Pottery of the Southern Russian Far East: An Archaeometric Study","authors":"I. Zhushchikhovskaya, I. Buravlev, A. A. Karpenko, Anastasia A. Lazina, A. N. Fedorets","doi":"10.3390/ceramics6020064","DOIUrl":"https://doi.org/10.3390/ceramics6020064","url":null,"abstract":"This paper considers the results of an examination of painted pottery from prehistoric sites of the Prmor’ye region (Southern Russian Far East) in the northwestern part of the Sea of Japan basin. Red-painted and black-painted ceramic wares occur here only in the remains of the Yankovskaya archaeological culture dated to the 1st mil. BCE. Red painting appears as a colored surface coating, and black painting is represented by very simple drawn patterns. Until recently painting decorations have not been intentionally studied. The objects of our investigation are a small series of red-painted and black-painted ceramic fragments originated from archaeological sites. The methods of optical microscopy, SEM-EDS, and Raman spectroscopy were applied to the study of research materials. As a result, the data on characteristics of texture and composition of red and black paints were obtained. Both were determined to be pre-firing paints. Red paint is a clayish substance mixed with natural ochre pigment containing the hematite coloring agent. Black paint is carbon-based. Black carbon and burnt bone are recognized as colorants. The presented materials are new evidence of pottery paint technologies in prehistoric Eurasia.","PeriodicalId":33263,"journal":{"name":"Ceramics-Switzerland","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2023-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44794059","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}
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