Pub Date : 2025-02-19DOI: 10.1016/j.vacuum.2025.114143
Ji-dong Zhang, Lan Zhang, Hui-zhong Ma, Na Li
Using g-C3N4 as a precursor, the in situ synthesis of (AlN + CrC)-reinforced Al0.5CoCrFeNi high-entropy alloy (HEA) was successfully achieved through the spark plasma sintering process. The nitrogen and carbon sources from g-C3N4 react with Al and Cr to form AlN and CrC, respectively, resulting in a (AlN + CrC)/Al0.5CoCrFeNi composite with a network structure. The introduction of reinforcement particles significantly refines the grains of the composite. The meticulously designed (AlN + CrC)/Al0.5CoCrFeNi composite exhibits a hardness of 589 HV and a tensile strength of 1108 MPa. Compared with high entropy alloy, the increases are 33 % and 28 %, respectively. The fracture mechanism of high-entropy alloys primarily involves ductile fracture, while the composite exhibits both ductile and brittle fracture mechanisms. The in-depth analysis of the reinforcement mechanism of network-structured composite materials reveals that Strengthening mechanism main include load transfer, thermal mismatch, solid solution strengthening, the orowan mechanism and synergistic enhancement of different types of particles at multiple scales.
{"title":"The microstructural evolution and enhanced mechanical properties of in-situ (AlN+CrC) reinforced Al0.5CoCrFeNi high-entropy alloy composites","authors":"Ji-dong Zhang, Lan Zhang, Hui-zhong Ma, Na Li","doi":"10.1016/j.vacuum.2025.114143","DOIUrl":"10.1016/j.vacuum.2025.114143","url":null,"abstract":"<div><div>Using g-C<sub>3</sub>N<sub>4</sub> as a precursor, the in situ synthesis of (AlN + CrC)-reinforced Al<sub>0.5</sub>CoCrFeNi high-entropy alloy (HEA) was successfully achieved through the spark plasma sintering process. The nitrogen and carbon sources from g-C<sub>3</sub>N<sub>4</sub> react with Al and Cr to form AlN and CrC, respectively, resulting in a (AlN + CrC)/Al<sub>0.5</sub>CoCrFeNi composite with a network structure. The introduction of reinforcement particles significantly refines the grains of the composite. The meticulously designed (AlN + CrC)/Al<sub>0.5</sub>CoCrFeNi composite exhibits a hardness of 589 HV and a tensile strength of 1108 MPa. Compared with high entropy alloy, the increases are 33 % and 28 %, respectively. The fracture mechanism of high-entropy alloys primarily involves ductile fracture, while the composite exhibits both ductile and brittle fracture mechanisms. The in-depth analysis of the reinforcement mechanism of network-structured composite materials reveals that Strengthening mechanism main include load transfer, thermal mismatch, solid solution strengthening, the orowan mechanism and synergistic enhancement of different types of particles at multiple scales.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"235 ","pages":"Article 114143"},"PeriodicalIF":3.8,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143471669","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-19DOI: 10.1016/j.vacuum.2025.114156
Zhijun Tian , Yanfeng Liu
Evaporation at high altitudes under low atmospheric pressure has garnered significant attention due to its distinct behavior compared to standard pressures. To address the effects of atmospheric pressure, molecular dynamics simulations are conducted on liquid droplets under three different conditions: 0.1 bar, 0.5 bar, and 1 bar. The temporal evolution of macroscopic parameters and the spatiotemporal dynamics of the liquid droplet are analyzed. The results show that reduced interactions, due to the low number density of nitrogen particles, lead to lower heat absorption by the liquid and a thinner liquid-gas interface, resulting in a lower evaporation rate at low atmospheric pressure. An increased initial evaporation rate at 0.1 bar is observed, resembling evaporation into a vacuum. The discrepancy between the D2 law and the MD results increases as the vacuum degree rises, suggesting that the D2 law is not suitable for predicting droplet evaporation behavior under low atmospheric pressure conditions. This work provides a fundamental reference for the design of evaporative cooling systems in high-altitude, low-atmospheric-pressure environments.
{"title":"A molecular dynamic study on liquid droplet evaporation under low atmospheric pressure conditions","authors":"Zhijun Tian , Yanfeng Liu","doi":"10.1016/j.vacuum.2025.114156","DOIUrl":"10.1016/j.vacuum.2025.114156","url":null,"abstract":"<div><div>Evaporation at high altitudes under low atmospheric pressure has garnered significant attention due to its distinct behavior compared to standard pressures. To address the effects of atmospheric pressure, molecular dynamics simulations are conducted on liquid droplets under three different conditions: 0.1 bar, 0.5 bar, and 1 bar. The temporal evolution of macroscopic parameters and the spatiotemporal dynamics of the liquid droplet are analyzed. The results show that reduced interactions, due to the low number density of nitrogen particles, lead to lower heat absorption by the liquid and a thinner liquid-gas interface, resulting in a lower evaporation rate at low atmospheric pressure. An increased initial evaporation rate at 0.1 bar is observed, resembling evaporation into a vacuum. The discrepancy between the D<sup>2</sup> law and the MD results increases as the vacuum degree rises, suggesting that the D<sup>2</sup> law is not suitable for predicting droplet evaporation behavior under low atmospheric pressure conditions. This work provides a fundamental reference for the design of evaporative cooling systems in high-altitude, low-atmospheric-pressure environments.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"236 ","pages":"Article 114156"},"PeriodicalIF":3.8,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143488196","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-19DOI: 10.1016/j.vacuum.2025.114157
Wenjie Ma , Lei Wei , Leying Zhao , Zhonglin Xiang , Xiaohui Ren
Multifarious manganese oxide materials have been proved to be promising catalysts for efficient peroxymonosulfate (PMS) activation and degradation of recalcitrant pollutants. However, the control of oxidation state of manganese for better catalytic performance is still a formidable challenge. Herein, a novel carbothermal reduction strategy is proposed to fabricate MnOx/nitrogen-doped carbon (Mn-N-C-x) composites with chitosan as carbon and nitrogen source. Specifically, the ratio of Mn(II)/Mn(III) to Mn(IV) and the lattice oxygen amount can be facilely modulated through the reaction between carbon and MnOx, and the optimized Mn-N-C-2/PMS can completely remove 60 mg/L paracetamol in 20 min. Further investigations of reaction parameters such as inorganic anions, natural organic matter (NOM), and actual wastewater indicate the excellent practicality of Mn-N-C-2/PMS systems. Quenching experiments combined with electron paramagnetic resonance (EPR) further disclose the existence of multiple reactive oxygen species like ·OH, SO4·-, 1O2, and O2·-. The plausible degradation mechanism is proposed according to the detected reaction intermediates. This work provide a novel recipe to develop highly efficient MnOx catalysts with controlled oxidation states towards PMS activation and pollutant eliminations for green sustainable technology.
{"title":"Carbothermal reduction mediated oxidation states regulation of MnOx composites as efficient peroxymonosulfate activator for enhanced removal of paracetamol with the generation of multiple reactive oxygen species","authors":"Wenjie Ma , Lei Wei , Leying Zhao , Zhonglin Xiang , Xiaohui Ren","doi":"10.1016/j.vacuum.2025.114157","DOIUrl":"10.1016/j.vacuum.2025.114157","url":null,"abstract":"<div><div>Multifarious manganese oxide materials have been proved to be promising catalysts for efficient peroxymonosulfate (PMS) activation and degradation of recalcitrant pollutants. However, the control of oxidation state of manganese for better catalytic performance is still a formidable challenge. Herein, a novel carbothermal reduction strategy is proposed to fabricate MnO<sub><em>x</em></sub>/nitrogen-doped carbon (Mn-N-C-x) composites with chitosan as carbon and nitrogen source. Specifically, the ratio of Mn(II)/Mn(III) to Mn(IV) and the lattice oxygen amount can be facilely modulated through the reaction between carbon and MnO<sub><em>x</em></sub>, and the optimized Mn-N-C-2/PMS can completely remove 60 mg/L paracetamol in 20 min. Further investigations of reaction parameters such as inorganic anions, natural organic matter (NOM), and actual wastewater indicate the excellent practicality of Mn-N-C-2/PMS systems. Quenching experiments combined with electron paramagnetic resonance (EPR) further disclose the existence of multiple reactive oxygen species like ·OH, SO<sub>4</sub><sup>·-</sup>, <sup>1</sup>O<sub>2</sub>, and O<sub>2</sub><sup>·-</sup>. The plausible degradation mechanism is proposed according to the detected reaction intermediates. This work provide a novel recipe to develop highly efficient MnO<sub><em>x</em></sub> catalysts with controlled oxidation states towards PMS activation and pollutant eliminations for green sustainable technology.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"235 ","pages":"Article 114157"},"PeriodicalIF":3.8,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143463388","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-19DOI: 10.1016/j.vacuum.2025.114153
Jianlong Chai , Dahuan Zhu , Zongxiao Guo , Baoguo Wang , Rong Yan , Rui Ding , Changjun Li , Binfu Gao , Chuannan Xuan , Zhiguang Wang , Junling Chen
Tungsten is a promising candidate material for plasma-facing components in future fusion reactors. An important issue is the irradiation-induced degradation of its mechanical properties and its typically superior thermal conductivity. In this study, tungsten was irradiated with 270 keV He+ to the damage levels of 0.7 dpa and 3.0 dpa at 500 °C and 800 °C. The overall distribution of the microstructure is observed and its evolutionary relationship with the micromechanics property is discussed. The study of the microstructure reveals that the increase in He + ion fluence leads to an increase in the density of bubbles, which conversely decreases with elevating temperature. Both ½ <111> and <100> loops have been identified in the current study, and ½ <111> loops will gradually transform into <100> loops as the temperature rises. The synergistic interaction between He bubbles and dislocation loops results in irradiation hardening, with the contribution of dislocation loops exceeding that of He bubbles. The increased presence of <100> loops at elevated temperatures further contributes to additional hardening increments. These findings help to understand the influence of bubble evolution and irradiation hardening behavior in tungsten, especially the contribution of different types of defects to hardening, and thus help to design new radiation resistant PFMs.
{"title":"Microstructure evolution and hardening of helium ion irradiated tungsten","authors":"Jianlong Chai , Dahuan Zhu , Zongxiao Guo , Baoguo Wang , Rong Yan , Rui Ding , Changjun Li , Binfu Gao , Chuannan Xuan , Zhiguang Wang , Junling Chen","doi":"10.1016/j.vacuum.2025.114153","DOIUrl":"10.1016/j.vacuum.2025.114153","url":null,"abstract":"<div><div>Tungsten is a promising candidate material for plasma-facing components in future fusion reactors. An important issue is the irradiation-induced degradation of its mechanical properties and its typically superior thermal conductivity. In this study, tungsten was irradiated with 270 keV He<sup>+</sup> to the damage levels of 0.7 dpa and 3.0 dpa at 500 <strong>°C</strong> and 800 <strong>°C</strong>. The overall distribution of the microstructure is observed and its evolutionary relationship with the micromechanics property is discussed. The study of the microstructure reveals that the increase in He <sup>+</sup> ion fluence leads to an increase in the density of bubbles, which conversely decreases with elevating temperature. Both ½ <111> and <100> loops have been identified in the current study, and ½ <111> loops will gradually transform into <100> loops as the temperature rises. The synergistic interaction between He bubbles and dislocation loops results in irradiation hardening, with the contribution of dislocation loops exceeding that of He bubbles. The increased presence of <100> loops at elevated temperatures further contributes to additional hardening increments. These findings help to understand the influence of bubble evolution and irradiation hardening behavior in tungsten, especially the contribution of different types of defects to hardening, and thus help to design new radiation resistant PFMs.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"235 ","pages":"Article 114153"},"PeriodicalIF":3.8,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143473980","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-19DOI: 10.1016/j.vacuum.2025.114158
Fu-Hua Sun , Zihao Zheng , Mingrui Liu , Jun Tan , Dongxia Tian , Fei Liu , Hong Li , Lun Yang , Xinyu Wang , Shifang Ma , Xiaolei Nie , Shaoqiu Ke
The high thermal conductivity of bulk thermoelectric (TE) materials is the main reason limiting the application field of bulk TE devices. The tetrahedrite (Cu12Sb4S13) is a kind of TE material with extremely low thermal conductivity. If the thermal conductivity can be further reduced, it is expected to expand the application field of bulk TE devices. Herein, some carbon-based nanoparticles (diamond, CNTs, B4C, and SiC) of different grain size are embedded into the Cu11.5Ni0.5Sb4S12.7 (CNSS) matrix by mechanical alloying and spark plasma sintering to enhance the TE performance. It is discovered that the Seebeck coefficient of CNSS/carbon-based nanoparticles nanocomposites remarkably increased while the total thermal conductivity significantly decreased because of the nanopores and new heterogeneous interface of CNSS/carbon-based nanoparticles induced by nanoscale carbon-based particles enhancing carrier and phonon scattering. As a result, the total thermal conductivity of the nanocomposites decreases from 1.36 Wm-1 K−1 to 0.93 W m−1 K−1 at 723 K with 0.2 vol% of SiC nanoparticles, decreasing 32 %. The maximum ZT reaches 1.0 at 723 K for the nanocomposite with 0.20 vol% of SiC, increasing 43 %. These results verify that the introduction of carbon-based nanoparticles is a promising method to improve the application of Cu12Sb4S13-based modules.
{"title":"Enhanced thermoelectric properties in Cu12Sb4S13 tetrahedrite by incorporation of carbon-based nanoparticles","authors":"Fu-Hua Sun , Zihao Zheng , Mingrui Liu , Jun Tan , Dongxia Tian , Fei Liu , Hong Li , Lun Yang , Xinyu Wang , Shifang Ma , Xiaolei Nie , Shaoqiu Ke","doi":"10.1016/j.vacuum.2025.114158","DOIUrl":"10.1016/j.vacuum.2025.114158","url":null,"abstract":"<div><div>The high thermal conductivity of bulk thermoelectric (TE) materials is the main reason limiting the application field of bulk TE devices. The tetrahedrite (Cu<sub>12</sub>Sb<sub>4</sub>S<sub>13</sub>) is a kind of TE material with extremely low thermal conductivity. If the thermal conductivity can be further reduced, it is expected to expand the application field of bulk TE devices. Herein, some carbon-based nanoparticles (diamond, CNTs, B<sub>4</sub>C, and SiC) of different grain size are embedded into the Cu<sub>11.5</sub>Ni<sub>0.5</sub>Sb<sub>4</sub>S<sub>12.7</sub> (CNSS) matrix by mechanical alloying and spark plasma sintering to enhance the TE performance. It is discovered that the Seebeck coefficient of CNSS/carbon-based nanoparticles nanocomposites remarkably increased while the total thermal conductivity significantly decreased because of the nanopores and new heterogeneous interface of CNSS/carbon-based nanoparticles induced by nanoscale carbon-based particles enhancing carrier and phonon scattering. As a result, the total thermal conductivity of the nanocomposites decreases from 1.36 Wm<sup>-1</sup> K<sup>−1</sup> to 0.93 W m<sup>−1</sup> K<sup>−1</sup> at 723 K with 0.2 vol% of SiC nanoparticles, decreasing 32 %. The maximum <em>ZT</em> reaches 1.0 at 723 K for the nanocomposite with 0.20 vol% of SiC, increasing 43 %. These results verify that the introduction of carbon-based nanoparticles is a promising method to improve the application of Cu<sub>12</sub>Sb<sub>4</sub>S<sub>13</sub>-based modules.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"235 ","pages":"Article 114158"},"PeriodicalIF":3.8,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143464068","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-18DOI: 10.1016/j.vacuum.2025.114145
Wenbo Hu, Min Zhang, Xining Ma, Mingyue Lv, Xiaoyi Zhou
The influence of Mg doping concentration on the electronic structure, photoelectric and thermodynamic properties of Mg-doped β-Ga2O3 was systematically investigated using the GGA+U method based on density functional theory. The results show that Mg atoms preferentially substitute the Ga(2) atoms at octahedral sites, which is further supported by formation energy analysis. As the Mg doping concentration increases, both the lattice constants and volume show an increasing trend, while the β angle decreases. Mg doping introduces new impurity levels into the energy bands, leading to an increment of forbidden band-gap, and a 100 % spin polarization state appearing near the Fermi level. The covalent bond formed between Mg and O atoms displays strong ionic characteristics along with relatively weak bonding strength. Moreover, Mg doping causes a blue shift in the absorption edge together with the imaginary part of the dielectric constant. The heat capacity of β-Ga2O3 is enhanced with Mg doping, with Mg0.06Ga1.94O3 demonstrating optimal heat capacity characteristics. With the increase of Mg doping concentration, the free energy decline rate gradually increases, indicating an enhancement in the thermodynamic stability of β-Ga2O3. These findings provide valuable insights and deepen the understanding of Mg doping effects in β-Ga2O3.
{"title":"Investigation of electronic structure, photoelectric and thermodynamic properties of Mg-doped β-Ga2O3 using first-principles calculation","authors":"Wenbo Hu, Min Zhang, Xining Ma, Mingyue Lv, Xiaoyi Zhou","doi":"10.1016/j.vacuum.2025.114145","DOIUrl":"10.1016/j.vacuum.2025.114145","url":null,"abstract":"<div><div>The influence of Mg doping concentration on the electronic structure, photoelectric and thermodynamic properties of Mg-doped β-Ga<sub>2</sub>O<sub>3</sub> was systematically investigated using the GGA+U method based on density functional theory. The results show that Mg atoms preferentially substitute the Ga(2) atoms at octahedral sites, which is further supported by formation energy analysis. As the Mg doping concentration increases, both the lattice constants and volume show an increasing trend, while the β angle decreases. Mg doping introduces new impurity levels into the energy bands, leading to an increment of forbidden band-gap, and a 100 % spin polarization state appearing near the Fermi level. The covalent bond formed between Mg and O atoms displays strong ionic characteristics along with relatively weak bonding strength. Moreover, Mg doping causes a blue shift in the absorption edge together with the imaginary part of the dielectric constant. The heat capacity of β-Ga<sub>2</sub>O<sub>3</sub> is enhanced with Mg doping, with Mg<sub>0.06</sub>Ga<sub>1.94</sub>O<sub>3</sub> demonstrating optimal heat capacity characteristics. With the increase of Mg doping concentration, the free energy decline rate gradually increases, indicating an enhancement in the thermodynamic stability of β-Ga<sub>2</sub>O<sub>3</sub>. These findings provide valuable insights and deepen the understanding of Mg doping effects in β-Ga<sub>2</sub>O<sub>3</sub>.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"235 ","pages":"Article 114145"},"PeriodicalIF":3.8,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143444394","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-18DOI: 10.1016/j.vacuum.2025.114134
Lexiang Yin , Chenyang Wang , Pei Li , Fanping Meng , Ping Zhu , Feng Huang , Fangfang Ge , Xuewen Xu , Peng Li
PVD coatings have limitations as corrosion-resistant coatings mainly because the rapid condensation resulting in insufficient atoms diffusion during the vapor deposition process leads to non-dense coating growth, preventing the coating from completely isolating corrosive agents. The mid-frequency Al target magnetron reactive sputtering method, by precisely controlling the O2 flow rate, has produced a nanocomposite coating consisting of nano-Al and amorphous Al2O3. During the corrosion process, the nano-Al gradually oxidizes, filling the pinholes, thus providing a self-healing effect that completely isolates the corrosive agents. This results in the coating exhibiting significantly improved corrosion resistance, enhancing the corrosion resistance by 10 orders of magnitude compared to 304 stainless steels.
{"title":"Self-healing behavior in high-deposition-rate sputtered Al·Al2O3 nanocomposite coatings for enhanced corrosion resistance","authors":"Lexiang Yin , Chenyang Wang , Pei Li , Fanping Meng , Ping Zhu , Feng Huang , Fangfang Ge , Xuewen Xu , Peng Li","doi":"10.1016/j.vacuum.2025.114134","DOIUrl":"10.1016/j.vacuum.2025.114134","url":null,"abstract":"<div><div>PVD coatings have limitations as corrosion-resistant coatings mainly because the rapid condensation resulting in insufficient atoms diffusion during the vapor deposition process leads to non-dense coating growth, preventing the coating from completely isolating corrosive agents. The mid-frequency Al target magnetron reactive sputtering method, by precisely controlling the O<sub>2</sub> flow rate, has produced a nanocomposite coating consisting of nano-Al and amorphous Al<sub>2</sub>O<sub>3</sub>. During the corrosion process, the nano-Al gradually oxidizes, filling the pinholes, thus providing a self-healing effect that completely isolates the corrosive agents. This results in the coating exhibiting significantly improved corrosion resistance, enhancing the corrosion resistance by 10 orders of magnitude compared to 304 stainless steels.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"235 ","pages":"Article 114134"},"PeriodicalIF":3.8,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143463389","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-18DOI: 10.1016/j.vacuum.2025.114140
Lei Ba , Haonan Yu , Rui Fu , Jing Wang , Renshu Yang
In this paper, the pure copper melt was purified by vacuum melting technology, and the purity and three-dimensional high-precision X-ray computed tomography morphology(3D-CT) changes of pore and inclusion defects were comprehensively observed. The total amount of impurity elements decrease from 178.74 ppm to 49.04 ppm, and the removal rate of impurity elements reached 72.6 %, the purity is improved from 3N to 4N. The hydrogen (H) content is reduced from 3.2 ppm to 0.9 ppm and the oxygen (O) content is reduced from 25.5 ppm to 11.7 ppm. The H and O contents are reduced by 71.9 % and 54.1 %, and the porosity and volume fraction of inclusion defects are reduced by 65.9 % and 52.2 %, respectively. In the vacuum melting process, the impurity elements are removed by volatilization, and the generation of inclusions can be reduced at the same time; H is precipitated to form hydrogen bubbles floating up to remove; O is formed into oxide inclusions gradually floating up to the surface of the melt. Vacuum melting technology can improve the purity of pure copper and greatly reduce the pore and inclusion defects in the cast billet.
{"title":"Effect and mechanism of vacuum melting on impurity elements, pores and inclusions in pure copper","authors":"Lei Ba , Haonan Yu , Rui Fu , Jing Wang , Renshu Yang","doi":"10.1016/j.vacuum.2025.114140","DOIUrl":"10.1016/j.vacuum.2025.114140","url":null,"abstract":"<div><div>In this paper, the pure copper melt was purified by vacuum melting technology, and the purity and three-dimensional high-precision X-ray computed tomography morphology(3D-CT) changes of pore and inclusion defects were comprehensively observed. The total amount of impurity elements decrease from 178.74 ppm to 49.04 ppm, and the removal rate of impurity elements reached 72.6 %, the purity is improved from 3N to 4N. The hydrogen (H) content is reduced from 3.2 ppm to 0.9 ppm and the oxygen (O) content is reduced from 25.5 ppm to 11.7 ppm. The H and O contents are reduced by 71.9 % and 54.1 %, and the porosity and volume fraction of inclusion defects are reduced by 65.9 % and 52.2 %, respectively. In the vacuum melting process, the impurity elements are removed by volatilization, and the generation of inclusions can be reduced at the same time; H is precipitated to form hydrogen bubbles floating up to remove; O is formed into oxide inclusions gradually floating up to the surface of the melt. Vacuum melting technology can improve the purity of pure copper and greatly reduce the pore and inclusion defects in the cast billet.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"235 ","pages":"Article 114140"},"PeriodicalIF":3.8,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143444396","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper presents the results of an experimental-statistical examination of the change in characteristics of the Geiger-Müller (GM) counter under operating conditions. The impact of the number of registered pulses on the characteristics of the GM counter was investigated using an experimental method with low measurement uncertainty. The analyzed characteristics of the GM counter included the plateau width, plateau slope, characteristic steepness, and dead time. Additionally, the stability of the insulating properties of the GM counter tube's insulating gas was determined. The experiments were conducted on a laboratory model of the GM counting tube. The laboratory model was constructed in accordance with similarity laws for electrical discharges in gases and in relation to a commercial GM counting tube. During the experiments, diverse types of insulating gas were varied. A three-component mixture proved to be the optimal solution since it consists predominantly of argon, halogen quenching gas chlorine, and a small amount of electronegative gas sulfur hexafluoride.
{"title":"Stability of Geiger-Müller counter characteristics under operating conditions","authors":"Nenad Kartalović , Arbutina Dalibor , Alija Jusić , Uroš Kovačević","doi":"10.1016/j.vacuum.2025.114150","DOIUrl":"10.1016/j.vacuum.2025.114150","url":null,"abstract":"<div><div>This paper presents the results of an experimental-statistical examination of the change in characteristics of the Geiger-Müller (GM) counter under operating conditions. The impact of the number of registered pulses on the characteristics of the GM counter was investigated using an experimental method with low measurement uncertainty. The analyzed characteristics of the GM counter included the plateau width, plateau slope, characteristic steepness, and dead time. Additionally, the stability of the insulating properties of the GM counter tube's insulating gas was determined. The experiments were conducted on a laboratory model of the GM counting tube. The laboratory model was constructed in accordance with similarity laws for electrical discharges in gases and in relation to a commercial GM counting tube. During the experiments, diverse types of insulating gas were varied. A three-component mixture proved to be the optimal solution since it consists predominantly of argon, halogen quenching gas chlorine, and a small amount of electronegative gas sulfur hexafluoride.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"235 ","pages":"Article 114150"},"PeriodicalIF":3.8,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143444449","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-18DOI: 10.1016/j.vacuum.2025.114146
Yiming Ren , Junrong He , Zhenglong Hu , Yonghong Hu , Chunbo Hua , Li Xue
Manipulating interlayer twist angle represents a potent approach for tuning properties of layered two-dimensional crystals. However, limited attention has been given to explore the impact of twist angle on elastic properties. We employ first-principles calculations to investigate how twist angles affect the structure as well as mechanical and thermal characteristics of bilayer MoS2. The in-plane elastic constants of seven twisted structures are determined by fitting the stress-strain relationship linearly. The results indicate all structures exhibit both mechanical stability and elastic isotropy, with exceptional rigidity compared to other two-dimensional materials. Based on calculated elastic constants, the thermal parameters, including sound velocities, Grüneisen parameter, and Debye temperature are obtained. Moreover, we investigate how tuning the twist angle affects thermal conductivity and observe a decreasing trend with an increase in the moiré lattice constant due to the increase of acoustic branches. Notably, at twist angle of 60°, we find a thermal conductivity value of 93.57 Wm−1K−1, whereas at an angle of 9.43°, it reaches 9.09 Wm−1K−1, representing an approximate reduction of 90 % in the thermal conductivity. These findings offer valuable insights into understanding how twisting influences the properties of bilayer MoS2 and establish its potential as a promising material for thermoelectric devices.
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