The electrical conductivities of carbonaceous slate were measured using a complex impedance spectroscopic technique at 0.5−1.5 GPa and 423−973 K in the frequency range of 10-1 to 3.5×106 Hz. Experimental results indicate that the conductivities of carbonaceous slate slightly increased with increasing temperatures and pressures, respectively. At a certain temperature range, the conductivities of carbonaceous slate follow an Arrhenius relation. There are three Arrhenius relations for the conductivities of carbonaceous slate at a certain pressure. From high temperature range to low temperature range, the activation enthalpies for the conductivities of carbonaceous slate are found to be 0.02‒0.03 eV, 0.05‒0.06 eV, and 0.11‒0.13 eV, respectively. Electron conduction is proposed to be the conduction mechanism for carbonaceous slate at high temperatures and pressures. It is suggested that the unusually high conductivities of carbonaceous slate (0.1‒1 S/m) are associated to interconnected amorphous carbon. Furthermore, the electrical conductivities of carbonaceous rocks can be used to interpret the high-conductivity layers (HCLs) in the Earth’s interior.
{"title":"Experimental study on the electrical properties of carbonaceous slate: a special natural rock with unusually high conductivity at high temperatures and pressures","authors":"Wenqing Sun, Lidong Dai, Heping Li, Haiying Hu, Jian-jun Jiang, Changcai Liu","doi":"10.32908/hthp.v48.749","DOIUrl":"https://doi.org/10.32908/hthp.v48.749","url":null,"abstract":"The electrical conductivities of carbonaceous slate were measured using a complex impedance spectroscopic technique at 0.5−1.5 GPa and 423−973 K in the frequency range of 10-1 to 3.5×106 Hz. Experimental results indicate that the conductivities of carbonaceous slate slightly increased with increasing temperatures and pressures, respectively. At a certain temperature range, the conductivities of carbonaceous slate follow an Arrhenius relation. There are three Arrhenius relations for the conductivities of carbonaceous slate at a certain pressure. From high temperature range to low temperature range, the activation enthalpies for the conductivities of carbonaceous slate are found to be 0.02‒0.03 eV, 0.05‒0.06 eV, and 0.11‒0.13 eV, respectively. Electron conduction is proposed to be the conduction mechanism for carbonaceous slate at high temperatures and pressures. It is suggested that the unusually high conductivities of carbonaceous slate (0.1‒1 S/m) are associated to interconnected amorphous carbon. Furthermore, the electrical conductivities of carbonaceous rocks can be used to interpret the high-conductivity layers (HCLs) in the Earth’s interior.","PeriodicalId":12983,"journal":{"name":"High Temperatures-high Pressures","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69441332","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nickel is an important component in many alloys, so reliable surface tension data in the liquid phase are essential for simulation processes in the metal industry. First results for surface tension of liquid nickel from our working group by Aziz et al. [1], which led to one of the first publication on the topic of our Electromagnetic Levitation (EML) setup, delivered unusual high values compared to the literature, which itself covers a wide range. To find the reason for this behaviour the aim of this work was to investigate the surface tension of nickel samples from different suppliers at similar purity grades by the Oscillating Drop (OD) technique using the EML setup of the Thermophysics and Metalphysics Group at Graz University of Technology. Since no significant deviations between samples from different suppliers have been found, an extensive literature research according to various experimental and evaluation parameters has been performed. In the course of this investigation, the earlier obtained experimental data of Aziz et al. were re-evaluated. Due to gained awareness in evaluating the translational frequency in vertical direction, the mystery of these elevated surface tension results could be solved, so that in the end the originally obtained results of Aziz have been drastically decreased through re-evaluation.
{"title":"Surface tension of liquid nickel: Re-evaluated and revised data","authors":"Anna Werkovits, T. Leitner, G. Pottlacher","doi":"10.32908/HTHP.V49.855","DOIUrl":"https://doi.org/10.32908/HTHP.V49.855","url":null,"abstract":"Nickel is an important component in many alloys, so reliable surface tension data in the liquid phase are essential for simulation processes in the metal industry. First results for surface tension of liquid nickel from our working group by Aziz et al. [1], which led to one of the first publication on the topic of our Electromagnetic Levitation (EML) setup, delivered unusual high values compared to the literature, which itself covers a wide range. To find the reason for this behaviour the aim of this work was to investigate the surface tension of nickel samples from different suppliers at similar purity grades by the Oscillating Drop (OD) technique using the EML setup of the Thermophysics and Metalphysics Group at Graz University of Technology. Since no significant deviations between samples from different suppliers have been found, an extensive literature research according to various experimental and evaluation parameters has been performed. In the course of this investigation, the earlier obtained experimental data of Aziz et al. were re-evaluated. Due to gained awareness in evaluating the translational frequency in vertical direction, the mystery of these elevated surface tension results could be solved, so that in the end the originally obtained results of Aziz have been drastically decreased through re-evaluation.","PeriodicalId":12983,"journal":{"name":"High Temperatures-high Pressures","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69441601","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
G. Bracker, E. B. Baker, Jannatun Nawer, M. Sellers, A. Gangopadhyay, K. Kelton, X. Xiao, Jonghyun Lee, M. Reinartz, Stefan Burggraf, D. Herlach, M. Rettenmayr, D. Matson, R. Hyers
During containerless processing, the oscillating drop method can be used to measure the surface tension and viscosity of a levitated melt. Through containerless processing, reactive melts that cannot be measured through conventional methods can be accurately measured; however, the accuracy of this method is dependent on the internal flow within the drop. While laminar flow does not redistribute the momentum of the oscillations, turbulent flow does redistribute the momentum of the flow and, as a result, dominates the damping. As a result, it is important to understand the internal flow behavior and the factors that affect the flow during these experiments. Models are used for the indirect quantification and characterization of the internal flow using the experimental parameters and material properties. In some cases, such as Cu50Zr50, the flow is laminar over the full range of the experiment. In other cases, including Al75Ni25, the sample is dominated by turbulent flow at high temperatures and applied electromagnetic fields, but upon cooling, transitions to laminar flow. Additionally, cases exist in which the flow is fully turbulent over the range of interest and valid measurements using the oscillating drop method are not possible. During the design phase of the experiment, the experimental parameters should be modeled to characterize the flow behavior and ensure a clean experiment.
{"title":"The effect of flow regime on surface oscillations during electromagnetic levitation experiments","authors":"G. Bracker, E. B. Baker, Jannatun Nawer, M. Sellers, A. Gangopadhyay, K. Kelton, X. Xiao, Jonghyun Lee, M. Reinartz, Stefan Burggraf, D. Herlach, M. Rettenmayr, D. Matson, R. Hyers","doi":"10.32908/hthp.v49.817","DOIUrl":"https://doi.org/10.32908/hthp.v49.817","url":null,"abstract":"During containerless processing, the oscillating drop method can be used to measure the surface tension and viscosity of a levitated melt. Through containerless processing, reactive melts that cannot be measured through conventional methods can be accurately measured; however, the accuracy of this method is dependent on the internal flow within the drop. While laminar flow does not redistribute the momentum of the oscillations, turbulent flow does redistribute the momentum of the flow and, as a result, dominates the damping. As a result, it is important to understand the internal flow behavior and the factors that affect the flow during these experiments. Models are used for the indirect quantification and characterization of the internal flow using the experimental parameters and material properties. In some cases, such as Cu50Zr50, the flow is laminar over the full range of the experiment. In other cases, including Al75Ni25, the sample is dominated by turbulent flow at high temperatures and applied electromagnetic fields, but upon cooling, transitions to laminar flow. Additionally, cases exist in which the flow is fully turbulent over the range of interest and valid measurements using the oscillating drop method are not possible. During the design phase of the experiment, the experimental parameters should be modeled to characterize the flow behavior and ensure a clean experiment.","PeriodicalId":12983,"journal":{"name":"High Temperatures-high Pressures","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69441787","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The critical temperature and critical pressure are two important parameters to characterize a particular fluid. In this paper, we have studied the critical points of 24 binary mixtures containing hydrocarbon derivatives, carbon dioxide and alcohols. Computations were performed using the Heidemann-Khalil method, combined with the following equations of state (Eos): van der Waals (vdW), Soave-Redlich-Kwong (SRK) and Peng-Robinson (PR). The Newton-Raphson method was used to solve a set of nonlinear equations in three independent variables (molar fraction x, temperature T and volume V). Comparisons between predicted and available reference data are given to evaluate the accuracy of the thermodynamic model employed. The average absolute relative error (AARE) of the simulated data was less than 0.2% for critical temperature and 3% for critical pressure. A good agreement has been found between model prediction and reference data.
临界温度和临界压力是表征某一流体特性的两个重要参数。本文研究了24种含烃衍生物、二氧化碳和醇的二元混合物的临界点。计算采用Heidemann-Khalil方法，结合以下状态方程(Eos): van der Waals (vdW)， Soave-Redlich-Kwong (SRK)和Peng-Robinson (PR)。采用牛顿-拉夫森方法求解了包含三个自变量(摩尔分数x、温度T和体积V)的一组非线性方程。将预测数据与现有参考数据进行比较，以评估所采用热力学模型的准确性。模拟数据的平均绝对相对误差(AARE)在临界温度和临界压力下分别小于0.2%和3%。模型预测结果与参考数据吻合较好。
{"title":"Critical behaviour of binary mixtures: Calculation by the Heidemann-Khalil method","authors":"H. Grine, H. Madani, Saida Fedali","doi":"10.32908/hthp.v48.799","DOIUrl":"https://doi.org/10.32908/hthp.v48.799","url":null,"abstract":"The critical temperature and critical pressure are two important parameters to characterize a particular fluid. In this paper, we have studied the critical points of 24 binary mixtures containing hydrocarbon derivatives, carbon dioxide and alcohols. Computations were performed using the Heidemann-Khalil method, combined with the following equations of state (Eos): van der Waals (vdW), Soave-Redlich-Kwong (SRK) and Peng-Robinson (PR). The Newton-Raphson method was used to solve a set of nonlinear equations in three independent variables (molar fraction x, temperature T and volume V). Comparisons between predicted and available reference data are given to evaluate the accuracy of the thermodynamic model employed. The average absolute relative error (AARE) of the simulated data was less than 0.2% for critical temperature and 3% for critical pressure. A good agreement has been found between model prediction and reference data.","PeriodicalId":12983,"journal":{"name":"High Temperatures-high Pressures","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69441101","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Vlaskin, A. Grigorenko, N. Chernova, S. Kiseleva, I. A. Lipatova, O. Popel, L. Dombrovsky
At present, microalgae are industrially produced mainly for the extraction of high-value products for food additives. At the same time, the microalgae possess also environmental advantages as it can be used for wastewater treatment, mitigation of industrial CO2 emissions as well as for oxygen production and atmospheric CO2 capturing. Due to increasing the environmental problems, it is reasonable to expand the “green” applications of microalgae and increase significantly their output. From this point of view, the problem of utilization of the microalgal biomass becomes more important and one of the most reliable ways to do it is a conversion of the biomass to a biofuel. It is expected that such a conversion can be implemented into the existing infrastructure for traditional hydrocarbons. In the case of microalgae, the hydrothermal liquefaction (HTL) with the production of bio-oil as a target product has attracted more attention in recent years because the bio-oil can be used in the existing refinery industry. The paper is also concerned with the use of microalgae to solve the environmental issues on the basis of HTL as a convenient and efficient method for the biomass-to-biofuel conversion. The known advantages of the HTL are the possible use of fresh microalgae just after harvesting, the processing of the whole biomass and high thermodynamic efficiency. In the paper it is shown that the latter is achieved due to the high HTL pressure that keeps the high-temperature potential of aqueous media after hydrothermal treatment and so creates the opportunity of more efficient heat recovery. The fundamental aspects of the process thermodynamics are discovered in the paper. It is shown that one of the main advantages of the process is provided by a combination of thermodynamic parameters. The problem of solar radiative transfer in photobioreactors with suspended microalgae and the desired thermophysical properties of the refined biofuels are also briefly discussed in the paper.
{"title":"The hydrothermal liquefaction as a promising procedure for microalgae-to-biofuel conversion: A general review and some thermophysical problems to be solved","authors":"M. Vlaskin, A. Grigorenko, N. Chernova, S. Kiseleva, I. A. Lipatova, O. Popel, L. Dombrovsky","doi":"10.32908/hthp.v48.716","DOIUrl":"https://doi.org/10.32908/hthp.v48.716","url":null,"abstract":"At present, microalgae are industrially produced mainly for the extraction of high-value products for food additives. At the same time, the microalgae possess also environmental advantages as it can be used for wastewater treatment, mitigation of industrial CO2 emissions as well as for oxygen production and atmospheric CO2 capturing. Due to increasing the environmental problems, it is reasonable to expand the “green” applications of microalgae and increase significantly their output. From this point of view, the problem of utilization of the microalgal biomass becomes more important and one of the most reliable ways to do it is a conversion of the biomass to a biofuel. It is expected that such a conversion can be implemented into the existing infrastructure for traditional hydrocarbons. In the case of microalgae, the hydrothermal liquefaction (HTL) with the production of bio-oil as a target product has attracted more attention in recent years because the bio-oil can be used in the existing refinery industry. The paper is also concerned with the use of microalgae to solve the environmental issues on the basis of HTL as a convenient and efficient method for the biomass-to-biofuel conversion. The known advantages of the HTL are the possible use of fresh microalgae just after harvesting, the processing of the whole biomass and high thermodynamic efficiency. In the paper it is shown that the latter is achieved due to the high HTL pressure that keeps the high-temperature potential of aqueous media after hydrothermal treatment and so creates the opportunity of more efficient heat recovery. The fundamental aspects of the process thermodynamics are discovered in the paper. It is shown that one of the main advantages of the process is provided by a combination of thermodynamic parameters. The problem of solar radiative transfer in photobioreactors with suspended microalgae and the desired thermophysical properties of the refined biofuels are also briefly discussed in the paper.","PeriodicalId":12983,"journal":{"name":"High Temperatures-high Pressures","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69441165","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Liu Lili, Yuhan Jiang, Liwan Chen, Youchang Jiang, He Yelu, Liu Dingxing, Y. Wen
The electronic and thermal properties of LuNi2B2C were studied by performing density-functional theory (DFT) and density functional perturbation theory (DFPT). No virtual frequencies appear on the phonon spectrum, indicating that LuNi2B2C is dynamically stable in the tetragonal structure up to 30 GPa. The density of states at Fermi energy EF is nonzero and falls on the sharp peak, which is why LuNi2B2C has a high superconducting temperature. Moreover, the temperature and pressure dependences of bulk modulus, heat capacity at constant pressure and thermal expansion coefficient in a wide temperature (0-900 K) and pressure (0-30 GPa) ranges are presented in this study.
{"title":"Electronic and thermal properties of LuNi2B2C under pressure","authors":"Liu Lili, Yuhan Jiang, Liwan Chen, Youchang Jiang, He Yelu, Liu Dingxing, Y. Wen","doi":"10.32908/hthp.v48.779","DOIUrl":"https://doi.org/10.32908/hthp.v48.779","url":null,"abstract":"The electronic and thermal properties of LuNi2B2C were studied by performing density-functional theory (DFT) and density functional perturbation theory (DFPT). No virtual frequencies appear on the phonon spectrum, indicating that LuNi2B2C is dynamically stable in the tetragonal structure up to 30 GPa. The density of states at Fermi energy EF is nonzero and falls on the sharp peak, which is why LuNi2B2C has a high superconducting temperature. Moreover, the temperature and pressure dependences of bulk modulus, heat capacity at constant pressure and thermal expansion coefficient in a wide temperature (0-900 K) and pressure (0-30 GPa) ranges are presented in this study.","PeriodicalId":12983,"journal":{"name":"High Temperatures-high Pressures","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69441483","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
D. Chebykin, H. Heller, I. Saenko, G. Bartzsch, R. Endo, O. Volkova
The role of B2O3 as a fluxing agent for developing fluoride free fluxes has been accentuated in the recent years. Therefore, knowledge about thermophysical properties of the oxide are essential to find the optimal chemical composition of the mold fluxes. In the present study, the density and thermal conductivity of B2O3 were measured by means of the buoyancy method, the maximal bubble pressure (MBP) method and the hot-wire method in the temperature range of 295–1573 K. The results are discussed in the context of the chemical stability of the B2O3 as well as the effect of glass transition on the thermal conductivity. The density of the B2O3 decreases non-linearly with increasing temperature in the temperature range of 973–1573 K. The MBP method was successfully applied for the density measurements with a viscosity up to 91 Pa.s. The thermal conductivity of the B2O3 in the solid and molten states increases with increasing temperature. Based on the Kittel’s equation, the temperature dependence of the thermal conductivity through the glass transition temperature of B2O3 was discussed.
{"title":"Effect of glass transition: density and thermal conductivity measurements of B2O3","authors":"D. Chebykin, H. Heller, I. Saenko, G. Bartzsch, R. Endo, O. Volkova","doi":"10.32908/hthp.v49.801","DOIUrl":"https://doi.org/10.32908/hthp.v49.801","url":null,"abstract":"The role of B2O3 as a fluxing agent for developing fluoride free fluxes has been accentuated in the recent years. Therefore, knowledge about thermophysical properties of the oxide are essential to find the optimal chemical composition of the mold fluxes. In the present study, the density and thermal conductivity of B2O3 were measured by means of the buoyancy method, the maximal bubble pressure (MBP) method and the hot-wire method in the temperature range of 295–1573 K. The results are discussed in the context of the chemical stability of the B2O3 as well as the effect of glass transition on the thermal conductivity. The density of the B2O3 decreases non-linearly with increasing temperature in the temperature range of 973–1573 K. The MBP method was successfully applied for the density measurements with a viscosity up to 91 Pa.s. The thermal conductivity of the B2O3 in the solid and molten states increases with increasing temperature. Based on the Kittel’s equation, the temperature dependence of the thermal conductivity through the glass transition temperature of B2O3 was discussed.","PeriodicalId":12983,"journal":{"name":"High Temperatures-high Pressures","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69441725","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Shahzad, M. Kashif, T. Munir, M. A. Shakoori, M. He, S. Bashir, Q. Islam
A modified Evan-Gillan homogenous perturbed scheme was employed to measure the thermal response and corresponding normalized plasma thermal conductivity (λ0) of strongly coupled dusty plasmas (SCDPs). Homogenous perturbed molecular dynamics (HPMD) approach was employed to analyze the efficiency and compared the obtained outcomes of perturbed heat flux vector to the outcomes computed through equilibrium molecular dynamics (EMD) approach. Our new outcomes show that the thermal response of heat energy current through HPMD and EMD approaches is an excellent agreement with each other for SCDPs at much low value of normalized external perturbation (F*). The obtained HPMD simulations demonstrate that the presented approach provides good outcomes with fast convergence and small system size for low-tointermediate plasma couplings (Γ) at very weak F*. It was found that the measured plasma λ0 outcomes at nearly equilibrium weak F* (= 0.00005) are in reasonable agreement with earlier results obtained from EMD, homogenous and inhomogeneous nonequilibrium molecular dynamics simulations and theoretical predictions and generally overpredicted the plasma λ0 by ~1%–~24% depending on the arrangement of plasma parameters (Г, к). It was shown that the HPMD is an excellent approach to calculate the plasma λ0 and to recognize the elementary patterns in 3D SCDPs.
{"title":"Studies of weak external force on thermal conductivity of complex liquids using homogenous perturbed simulations","authors":"A. Shahzad, M. Kashif, T. Munir, M. A. Shakoori, M. He, S. Bashir, Q. Islam","doi":"10.32908/hthp.v49.943","DOIUrl":"https://doi.org/10.32908/hthp.v49.943","url":null,"abstract":"A modified Evan-Gillan homogenous perturbed scheme was employed to measure the thermal response and corresponding normalized plasma thermal conductivity (λ0) of strongly coupled dusty plasmas (SCDPs). Homogenous perturbed molecular dynamics (HPMD) approach was employed to analyze the efficiency and compared the obtained outcomes of perturbed heat flux vector to the outcomes computed through equilibrium molecular dynamics (EMD) approach. Our new outcomes show that the thermal response of heat energy current through HPMD and EMD approaches is an excellent agreement with each other for SCDPs at much low value of normalized external perturbation (F*). The obtained HPMD simulations demonstrate that the presented approach provides good outcomes with fast convergence and small system size for low-tointermediate plasma couplings (Γ) at very weak F*. It was found that the measured plasma λ0 outcomes at nearly equilibrium weak F* (= 0.00005) are in reasonable agreement with earlier results obtained from EMD, homogenous and inhomogeneous nonequilibrium molecular dynamics simulations and theoretical predictions and generally overpredicted the plasma λ0 by ~1%–~24% depending on the arrangement of plasma parameters (Г, к). It was shown that the HPMD is an excellent approach to calculate the plasma λ0 and to recognize the elementary patterns in 3D SCDPs.","PeriodicalId":12983,"journal":{"name":"High Temperatures-high Pressures","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69441813","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
High quality kutnohorite CaMn(CO3)2 single crystals up to 100 μm in size were successfully achieved under high pressure-temperature (P-T) conditions. Electron microprobe analyses revealed the average wt% of CaO was 25.98% and that of MnO was 32.88%, correspondingly well to the ideal formula of Ca1.0Mn1.0(CO3)2. Accurate crystalline structural data were determined from single-crystal X-ray diffraction (XRD), with the R3 space group and R3c space group used to refine the crystal structure of CaMn(CO3)2. The Ca-O and Mn-O bond lengths were slightly different when using the R3 space group, which were clearly distinguished from those in the dolomite structure. Therefore, R3c is the most probable space group for the CaMn(CO3)2 crystal structure. Thermogravimetric (TG) analysis and differential scanning calorimetry (DSC) showed that CaMn(CO3)2 decomposed from 620–750 °C, but only one endothermic peak was observed during the decomposition process. It indicated that the octahedral units in CaMn(CO3)2 have the same thermal stability due to the complete miscibility of Ca and Mn. The results of single crystal XRD and thermal analysis provided direct evidence that CaMn(CO3)2 has a calcitetype structure, not dolomite-type layered structure, which was in good agreement with the rigid model of rhombohedral carbonates.
{"title":"Kutnohorite CaMn(CO3)2 crystal growth at high pressure-temperature","authors":"Rui Li, Lin Li, J. Bai, Wen Liang, Hongfeng Tang","doi":"10.32908/hthp.v49.831","DOIUrl":"https://doi.org/10.32908/hthp.v49.831","url":null,"abstract":"High quality kutnohorite CaMn(CO3)2 single crystals up to 100 μm in size were successfully achieved under high pressure-temperature (P-T) conditions. Electron microprobe analyses revealed the average wt% of CaO was 25.98% and that of MnO was 32.88%, correspondingly well to the ideal formula of Ca1.0Mn1.0(CO3)2. Accurate crystalline structural data were determined from single-crystal X-ray diffraction (XRD), with the R3 space group and R3c space group used to refine the crystal structure of CaMn(CO3)2. The Ca-O and Mn-O bond lengths were slightly different when using the R3 space group, which were clearly distinguished from those in the dolomite structure. Therefore, R3c is the most probable space group for the CaMn(CO3)2 crystal structure. Thermogravimetric (TG) analysis and differential scanning calorimetry (DSC) showed that CaMn(CO3)2 decomposed from 620–750 °C, but only one endothermic peak was observed during the decomposition process. It indicated that the octahedral units in CaMn(CO3)2 have the same thermal stability due to the complete miscibility of Ca and Mn. The results of single crystal XRD and thermal analysis provided direct evidence that CaMn(CO3)2 has a calcitetype structure, not dolomite-type layered structure, which was in good agreement with the rigid model of rhombohedral carbonates.","PeriodicalId":12983,"journal":{"name":"High Temperatures-high Pressures","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69441897","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jannatun Nawer, Xiao Xiao, M. SanSoucie, D. Matson
Loss of mass due to evaporation during molten metal levitation processing significantly influences the evaluation of density, viscosity and surface tension during thermophysical property measurement. Since there is no direct way to track the evaporation rate during the process, this paper describes a mathematical approach to track mass loss and quantify any changes in alloy composition as a function of time and temperature. The Ni-based super alloy CMSX-4 Plus (SLS) was investigated and a model was developed to predict the dynamic loss of mass with time and track the potential for composition shifts throughout each thermal cycle based on the Langmuir’s equation for ideal solution behavior. Results were verified by post-test chemical analysis of key elemental constituents including Al, Cr, Ti, and Co where the error in composition for each element was less than 1% when the activity of aluminum in solution was fixed at zero – effectively eliminating evaporation of aluminum for ground-based electrostatic levitation (ESL) testing in vacuum. This model predicts the mass evaporation for Al and Co within ±6 % errors for CMSX-4 plus samples processed in ESL. Application of this technique to the space tests using the ESA ISS-EML facility shows that by conducting experiments in an inert shielding-gas environment, composition shifts due to differential relative evaporation become negligible and the composition is maintained within the desired limits. By tracking overall mass loss during testing the influence of evaporation on density measurements is discussed.
金属液悬浮过程中由于蒸发造成的质量损失对热物性测量中密度、粘度和表面张力的评定有显著影响。由于在此过程中没有直接的方法来跟踪蒸发速率，因此本文描述了一种数学方法来跟踪质量损失并量化合金成分随时间和温度的变化。以镍基高温合金CMSX-4 Plus (SLS)为研究对象，基于理想溶液行为的Langmuir方程，建立了一个模型来预测质量随时间的动态损失，并跟踪每个热循环过程中成分变化的可能性。通过对Al, Cr, Ti和Co等关键元素成分的测试后化学分析验证了结果，当铝在溶液中的活度固定为零时，每个元素的组成误差小于1%，有效地消除了真空中地面静电悬浮(ESL)测试中铝的蒸发。该模型预测在ESL中处理的CMSX-4 +样品的Al和Co的质量蒸发误差在±6%以内。在利用欧空局国际空间站- eml设施进行的空间试验中应用这一技术表明，通过在惰性屏蔽气体环境中进行实验，由于差异相对蒸发引起的成分变化可以忽略不计，并且成分保持在所需的限度内。通过跟踪测试过程中的总质量损失，讨论了蒸发对密度测量的影响。
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