K. Kim, Kyoon Choi, Yoonsoo Han, S. Nahm, Sung-Min Lee
A cyclic fatigue test of SiCf/SiC ceramic matrix composites was conducted at 1400°C and compared to the monotonic tensile test. The specimens were prepared with an interface layer of pyrolytic carbon and densified through chemical vapor infiltration. In the monotonic tensile test, at 1400°C, the specimen fractured at a strain of 0.35% with a proportional limit stress of 175 MPa, showing a typical fiber pull-out. However, after a prolonged cyclic test with increasing stresses from 65 to 95 MPa, the specimen fractured brittlely with almost no fiber pull-out. The microstructure analysis of the fracture surface showed different oxidation levels with respect to fracture locations, indicating that the crack propagated during the cyclic fatigue test. Transmission electron microscopy analysis revealed that the interface layer of pyrolytic carbon was removed by oxidation and oxide layers were formed on both sides of the fiber and matrix at the later stage of the cyclic test, resulting in a strong interface between the fibers and matrix and brittle fracture during the cyclic test at 1400°C.
{"title":"High-temperature cyclic fatigue in air of SiCf/SiC ceramic matrix composite with a pyrolytic carbon interface","authors":"K. Kim, Kyoon Choi, Yoonsoo Han, S. Nahm, Sung-Min Lee","doi":"10.32908/HTHP.V50.1079","DOIUrl":"https://doi.org/10.32908/HTHP.V50.1079","url":null,"abstract":"A cyclic fatigue test of SiCf/SiC ceramic matrix composites was conducted at 1400°C and compared to the monotonic tensile test. The specimens were prepared with an interface layer of pyrolytic carbon and densified through chemical vapor infiltration. In the monotonic tensile test, at 1400°C, the specimen fractured at a strain of 0.35% with a proportional limit stress of 175 MPa, showing a typical fiber pull-out. However, after a prolonged cyclic test with increasing stresses from 65 to 95 MPa, the specimen fractured brittlely with almost no fiber pull-out. The microstructure analysis of the fracture surface showed different oxidation levels with respect to fracture locations, indicating that the crack propagated during the cyclic fatigue test. Transmission electron microscopy analysis revealed that the interface layer of pyrolytic carbon was removed by oxidation and oxide layers were formed on both sides of the fiber and matrix at the later stage of the cyclic test, resulting in a strong interface between the fibers and matrix and brittle fracture during the cyclic test at 1400°C.","PeriodicalId":12983,"journal":{"name":"High Temperatures-high Pressures","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69442225","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}
Single phase natural circulation loops are widely used passive systems in heat transfer applications. Since achievement of stable flow and highly efficient heat transfer is the main concern of recent studies, effects of geometry and the working fluid on the single phase natural circulation loops’ performance are getting attention. In this study, aspect ratio and pipe diameter effect on thermo-hydraulic performance of mini SPNCLs (SPNCmLs) has been investigated numerically by developing a 3D steady model. Water based Al2O3 nanofluid (1, 2, 3 vol. %) was used as a working fluid. Performance and characteristics of the loop for different working fluids is evaluated by using temperature distributions, mass flow rates and derived non-dimensional parameters. It is shown that pipe diameter effect on the heat transfer performance is more significant compared to aspect ratio. Moreover, nanofluids have higher temperatures and thus effectiveness values compared to water. In order to generalize the SPNCmL performance Num and Ress correlations were developed within the accuracy of ±10%.
{"title":"Effect of geometrical parameters on the performance of nanofluid-based single phase natural circulation mini loops","authors":"N. Çobanoğlu, Mohmmad Alaboud, Z. H. Karadeniz","doi":"10.32908/hthp.v50.1019","DOIUrl":"https://doi.org/10.32908/hthp.v50.1019","url":null,"abstract":"Single phase natural circulation loops are widely used passive systems in heat transfer applications. Since achievement of stable flow and highly efficient heat transfer is the main concern of recent studies, effects of geometry and the working fluid on the single phase natural circulation loops’ performance are getting attention. In this study, aspect ratio and pipe diameter effect on thermo-hydraulic performance of mini SPNCLs (SPNCmLs) has been investigated numerically by developing a 3D steady model. Water based Al2O3 nanofluid (1, 2, 3 vol. %) was used as a working fluid. Performance and characteristics of the loop for different working fluids is evaluated by using temperature distributions, mass flow rates and derived non-dimensional parameters. It is shown that pipe diameter effect on the heat transfer performance is more significant compared to aspect ratio. Moreover, nanofluids have higher temperatures and thus effectiveness values compared to water. In order to generalize the SPNCmL performance Num and Ress correlations were developed within the accuracy of ±10%.","PeriodicalId":12983,"journal":{"name":"High Temperatures-high Pressures","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69442418","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}
Inverse heat transfer problems deal with the estimation of parameters or functions appearing in the mathematical formulation of problems in thermal sciences, by utilizing measurements of dependent variables of the formulation. Inverse problems are extremely useful for the indirect measurement of thermophysical properties, in particular for challenging situations involving high temperatures, where coupled multi-physics phenomena and nonlinearities must be taken into account. In this paper, basic inverse problem concepts are reviewed. Solution techniques within the Bayesian framework of statistics are briefly described and applied to two inverse problems related to the authors� experience on the estimation of thermophysical properties at high temperatures.
{"title":"Thermophysical characterization of materials at high temperatures by solving inverse problems within the Bayesian framework of statistics","authors":"P. Masson, H. Orlande","doi":"10.32908/hthp.v50.973","DOIUrl":"https://doi.org/10.32908/hthp.v50.973","url":null,"abstract":"Inverse heat transfer problems deal with the estimation of parameters or functions appearing in the mathematical formulation of problems in thermal sciences, by utilizing measurements of dependent variables of the formulation. Inverse problems are extremely useful for the indirect measurement of thermophysical properties, in particular for challenging situations involving high temperatures, where coupled multi-physics phenomena and nonlinearities must be taken into account. In this paper, basic inverse problem concepts are reviewed. Solution techniques within the Bayesian framework of statistics are briefly described and applied to two inverse problems related to the authors� experience on the estimation of thermophysical properties at high temperatures.","PeriodicalId":12983,"journal":{"name":"High Temperatures-high Pressures","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69442711","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. Failleau, N. Fleurence, O. Beaumont, R. Razouk, J. Hameury, B. Hay
The diffusivimeter of LNE has been modified by improving the inductive furnace used to heat the tested specimens in order to extend the operating temperature range up to 3000 �C. The temperature of specimen is one of the tricky parameters to be measured to ensure the relevance of the thermal diffusivity measurement and the associated uncertainty. At high temperature, radiation thermometers are used to determine the temperature of the specimens at which the thermal diffusivity measurements are performed. In addition to the periodic calibration of the radiation thermometers performed outside the experimental facility with black body sources, LNE proposes an in-situ verification method based on miniature high temperature fixed-point cells filled with metal-carbon eutectic alloys in order to detect and correct potential drift of the radiation thermometers between two out-of-process calibration operations. The proposed method enables high repeatable and reproducible temperature measurements on eutectic fixed-points (Pd-C, Pt-C and Ir-C) distributed in the range from 1500 �C to 2300 �C.
{"title":"Metal-carbon eutectic high temperature fixed points for in-situ calibration of radiation thermometers","authors":"G. Failleau, N. Fleurence, O. Beaumont, R. Razouk, J. Hameury, B. Hay","doi":"10.32908/hthp.v50.1013","DOIUrl":"https://doi.org/10.32908/hthp.v50.1013","url":null,"abstract":"The diffusivimeter of LNE has been modified by improving the inductive furnace used to heat the tested specimens in order to extend the operating temperature range up to 3000 �C. The temperature of specimen is one of the tricky parameters to be measured to ensure the relevance of the thermal diffusivity measurement and the associated uncertainty. At high temperature, radiation thermometers are used to determine the temperature of the specimens at which the thermal diffusivity measurements are performed. In addition to the periodic calibration of the radiation thermometers performed outside the experimental facility with black body sources, LNE proposes an in-situ verification method based on miniature high temperature fixed-point cells filled with metal-carbon eutectic alloys in order to detect and correct potential drift of the radiation thermometers between two out-of-process calibration operations. The proposed method enables high repeatable and reproducible temperature measurements on eutectic fixed-points (Pd-C, Pt-C and Ir-C) distributed in the range from 1500 �C to 2300 �C.","PeriodicalId":12983,"journal":{"name":"High Temperatures-high Pressures","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69442405","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 vapor pressure in Bi: X (S, Se, Te): Br = 1: 1: 1 systems was measured by the static method using a membrane null manometer in the temperature range 300–1220 K and pressures 1–900 mm Hg. In the Bi-S-Br and Bi-Se-Br systems, the chemical interaction between the components begins at room temperature, and in the Bi-Te-Br system at 170 C. However, the formation of BiXBr ternary compounds going on only in the range of 350–400 C as a result of the interaction bismuth with chalcogen bromides according to the scheme X2Br2 (l) + 2Bi(s) → 2BiXBr (s). When heated above 400 C in the Bi-Te-Br system, above 420 and 460 C in the Bi-S-Br and Bi-Se-Br systems, the dissociation of ternary compounds going on according to the scheme 3BiXBr (l) → BiBr3 (vapor) + Bi2X3 (s). Based on the temperature dependences of the equilibrium constant of the reaction, the enthalpies and entropies of dissociation reactions are determined. The composition of the vapor after dissociation processes was defined.
Bi: X (S, Se, Te): Br = 1:1时的蒸气压:在温度范围为300-1220 K，压力范围为1 - 900 mm Hg的情况下，使用膜零压力计对1个体系进行静态测量。在Bi-S-Br和Bi-Se-Br体系中，组分之间的化学相互作用开始于室温，而在Bi-Te-Br体系中，组分之间的化学相互作用开始于170℃。BiXBr三元化合物的形成发生的范围只在350 - 400 C的交互与铋硫族元素根据计划X2Br2陈词滥调(l) + 2 bi (s)→2 BiXBr (s)。当加热超过400 C Bi-Te-Br系统,420和460 C以上Bi-S-Br和Bi-Se-Br系统,三元化合物的分离会根据方案3 BiXBr (l)→BiBr3(蒸汽)+ Bi2X3(年代)。根据反应的平衡常数的温度依赖性,解离反应的焓和熵是确定的。确定了解离过程后蒸汽的组成。
{"title":"Investigation of the interaction and composition of vapor in Bi: X(S, Se, Te): Br = 1: 1: 1 systems","authors":"Sona Кulieva, R. Agaeva, A. Mamedov","doi":"10.32908/hthp.v50.1017","DOIUrl":"https://doi.org/10.32908/hthp.v50.1017","url":null,"abstract":"The vapor pressure in Bi: X (S, Se, Te): Br = 1: 1: 1 systems was measured by the static method using a membrane null manometer in the temperature range 300–1220 K and pressures 1–900 mm Hg. In the Bi-S-Br and Bi-Se-Br systems, the chemical interaction between the components begins at room temperature, and in the Bi-Te-Br system at 170 C. However, the formation of BiXBr ternary compounds going on only in the range of 350–400 C as a result of the interaction bismuth with chalcogen bromides according to the scheme X2Br2 (l) + 2Bi(s) → 2BiXBr (s). When heated above 400 C in the Bi-Te-Br system, above 420 and 460 C in the Bi-S-Br and Bi-Se-Br systems, the dissociation of ternary compounds going on according to the scheme 3BiXBr (l) → BiBr3 (vapor) + Bi2X3 (s). Based on the temperature dependences of the equilibrium constant of the reaction, the enthalpies and entropies of dissociation reactions are determined. The composition of the vapor after dissociation processes was defined.","PeriodicalId":12983,"journal":{"name":"High Temperatures-high Pressures","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69442413","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 convective heat transfer characteristics of a Co0.5Zn0.5Fe2O4 nanofluid in the laminar flow region based on various concentrations are measured experimentally. The results indicate that the convective heat transfer coefficient increases with the concentration. The maximum heat transfer improved by 24.7% for the Co0.5Zn0.5Fe2O4 nanofluid at concentration 0.2wt% when the Reynolds number (Re) is 1600, compared with that of the base fluid (water/ethylene glycol (EG) = 80:20). Furthermore, the heat transfer improved by 3.6%, 16.2%, 22.5%, and 32.4% at concentrations of 0.025wt%, 0.05wt%, 0.1wt%, and 0.2wt%, respectively, when Re is 1400, compared with that of the base fluid (water/EG = 80:20). The convective heat transfer coefficient ratio of the Co0.5Zn0.5Fe2O4 nanofluid varied from 1.04 to 1.35. This means that the Co0.5Zn0.5Fe2O4 nanofluid had a larger heat transfer coefficient than the base fluid. Additionally, compared with that of the base fluid (water/EG = 80:20), the pressure drop of the Co0.5Zn0.5Fe2O4 nanofluid increased by 1.52%, 4.33%, 5.49%, and 7.32% at concentrations 0.025wt%, 0.05wt%, 0.1wt%, and 0.2wt%, respectively, when Re is 1600.
{"title":"Characteristics of forced convection heat transfer of Co0.5Zn0.5Fe2O4 during laminar flow in a tube","authors":"Y. Tong, Areum Lee, Honghyun Cho","doi":"10.32908/hthp.v50.1063","DOIUrl":"https://doi.org/10.32908/hthp.v50.1063","url":null,"abstract":"The convective heat transfer characteristics of a Co0.5Zn0.5Fe2O4 nanofluid in the laminar flow region based on various concentrations are measured experimentally. The results indicate that the convective heat transfer coefficient increases with the concentration. The maximum heat transfer improved by 24.7% for the Co0.5Zn0.5Fe2O4 nanofluid at concentration 0.2wt% when the Reynolds number (Re) is 1600, compared with that of the base fluid (water/ethylene glycol (EG) = 80:20). Furthermore, the heat transfer improved by 3.6%, 16.2%, 22.5%, and 32.4% at concentrations of 0.025wt%, 0.05wt%, 0.1wt%, and 0.2wt%, respectively, when Re is 1400, compared with that of the base fluid (water/EG = 80:20). The convective heat transfer coefficient ratio of the Co0.5Zn0.5Fe2O4 nanofluid varied from 1.04 to 1.35. This means that the Co0.5Zn0.5Fe2O4 nanofluid had a larger heat transfer coefficient than the base fluid. Additionally, compared with that of the base fluid (water/EG = 80:20), the pressure drop of the Co0.5Zn0.5Fe2O4 nanofluid increased by 1.52%, 4.33%, 5.49%, and 7.32% at concentrations 0.025wt%, 0.05wt%, 0.1wt%, and 0.2wt%, respectively, when Re is 1600.","PeriodicalId":12983,"journal":{"name":"High Temperatures-high Pressures","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69442504","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}
Magnetic nanofluids are colloids that contain magnetic nanoparticles dispersed in a base fluid. In the presence of the external magnetic field, they can be magnetized and manipulated. Moreover, their thermophysical properties may be tuned. Therefore, it is important to investigate the magnetization behaviour of them. For this purpose, magnetization behaviours of magnetite (Fe3O4)-water and maghemite (γ-Fe2O3)-water which are commonly used in the available literature were investigated by a vibrating sample magnetometer (VSM). Various samples with different volume concentrations for Fe3O4-water (1 and 2%) and γ-Fe2O3-water (1.1 and 2.2%) nanofluids were used in the measurements. The results indicated that γ-Fe2O3-water magnetic nanofluid has higher saturation magnetization values than Fe3O4-water magnetic nanofluid. The measurements also pointed out that as the volume concentration increases, the magnetization of both magnetic nanofluids increases as well.
{"title":"Magnetization behaviour of Fe3O4–water and γ-Fe2O3–water magnetic nanofluids","authors":"R. Alsangur, S. Doğanay, A. Turgut, L. Çetin","doi":"10.32908/hthp.v50.995","DOIUrl":"https://doi.org/10.32908/hthp.v50.995","url":null,"abstract":"Magnetic nanofluids are colloids that contain magnetic nanoparticles dispersed in a base fluid. In the presence of the external magnetic field, they can be magnetized and manipulated. Moreover, their thermophysical properties may be tuned. Therefore, it is important to investigate the magnetization behaviour of them. For this purpose, magnetization behaviours of magnetite (Fe3O4)-water and maghemite (γ-Fe2O3)-water which are commonly used in the available literature were investigated by a vibrating sample magnetometer (VSM). Various samples with different volume concentrations for Fe3O4-water (1 and 2%) and γ-Fe2O3-water (1.1 and 2.2%) nanofluids were used in the measurements. The results indicated that γ-Fe2O3-water magnetic nanofluid has higher saturation magnetization values than Fe3O4-water magnetic nanofluid. The measurements also pointed out that as the volume concentration increases, the magnetization of both magnetic nanofluids increases as well.","PeriodicalId":12983,"journal":{"name":"High Temperatures-high Pressures","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69442770","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}
Regenerative heat exchangers, which increase the temperature of newly supplied air using the waste heat of exhaust gas, are installed in large thermal systems, such as thermal power plants and industrial boilers, to improve their thermal efficiency. These devices are also known as air preheaters, and the rotary regenerative type has been widely used. The heat transfer performance of a rotary regenerator is enhanced as the heat capacity, which is the product of the density and specific heat, increases rather than the thermal conductivity of heat exchanging plates (HEPs). Studies to replace the existing metal materials with polymers, which are resistant to corrosion and inexpensive, have garnered attention. In this study, the heat transfer performance of HEPs fabricated using polytetrafluoroethylene, Mono Cast nylon, stainless steel, and aluminum is experimentally compared using a laboratory-scale experimental setup. It is confirmed that the polymer materials have similar or larger effectiveness compared to metals within the experimental error.
{"title":"Evaluation of heat transfer performance of a laboratory-scale polymer rotary air preheater","authors":"Dae-hyun Kim, Jun‐Seok Oh, Sangcho Lee, D. Oh","doi":"10.32908/hthp.v50.1077","DOIUrl":"https://doi.org/10.32908/hthp.v50.1077","url":null,"abstract":"Regenerative heat exchangers, which increase the temperature of newly supplied air using the waste heat of exhaust gas, are installed in large thermal systems, such as thermal power plants and industrial boilers, to improve their thermal efficiency. These devices are also known as air preheaters, and the rotary regenerative type has been widely used. The heat transfer performance of a rotary regenerator is enhanced as the heat capacity, which is the product of the density and specific heat, increases rather than the thermal conductivity of heat exchanging plates (HEPs). Studies to replace the existing metal materials with polymers, which are resistant to corrosion and inexpensive, have garnered attention. In this study, the heat transfer performance of HEPs fabricated using polytetrafluoroethylene, Mono Cast nylon, stainless steel, and aluminum is experimentally compared using a laboratory-scale experimental setup. It is confirmed that the polymer materials have similar or larger effectiveness compared to metals within the experimental error.","PeriodicalId":12983,"journal":{"name":"High Temperatures-high Pressures","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69442177","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}
Thermophysical properties of the Al69.1Cu12.8Ag18.1 eutectic liquid alloy are of particular interest for support of self-and inter-diffusion studies. In the presented work, Al69.1Cu12.8Ag18.1-samples were processed contactlessly by electromagnetic levitation under microgravity conditions using the TEMPUS facility. The measurements were performed onboard the Airbus A310 Zero-G in parabolic flight campaigns. The oscillating-drop-method (ODM) was used for measurements of the viscosity via oscillations damping and surface tension via oscillations frequency. These were determined for temperatures in the range of 900–1500 K by analysis of the oscillation spectrum obtained from the electrical impedance. The latter was measured using the Sample Coupling Electronics. An Arrhenius-law η(T) ∝η∞ exp(Eη /RT) was used to fit the temperature-dependent viscosity data. The resulting fit parameters were η∞ = (0.632±0.160) mPas and activation energy of viscous flow Eη = (2.344±0.233) · 104 J/mol. A linear law γ(T) = γl + γT (T - Tm) was fit to the surface tension data yielding γl = (0.9013±0.02625) Nm−1 and γT = −(0.7462±0.2675)·10−4 Nm−1 K−1. The Kozlov-model was applied to determine the enthalphy of mixing as ΔHmix = -(18.576±0.018)kJ/mol.
{"title":"Contactless measurement of temperaturedependent viscosity and surface tension of liquid Al69.1Cu12.8Ag18.1 eutectic alloy under microgravity conditions using the oscillating-drop-method","authors":"M. Beckers, M. Engelhardt, S. Schneider","doi":"10.32908/HTHP.V50.1031","DOIUrl":"https://doi.org/10.32908/HTHP.V50.1031","url":null,"abstract":"Thermophysical properties of the Al69.1Cu12.8Ag18.1 eutectic liquid alloy are of particular interest for support of self-and inter-diffusion studies. In the presented work, Al69.1Cu12.8Ag18.1-samples were processed contactlessly by electromagnetic levitation under microgravity conditions using the TEMPUS facility. The measurements were performed onboard the Airbus A310 Zero-G in parabolic flight campaigns. The oscillating-drop-method (ODM) was used for measurements of the viscosity via oscillations damping and surface tension via oscillations frequency. These were determined for temperatures in the range of 900–1500 K by analysis of the oscillation spectrum obtained from the electrical impedance. The latter was measured using the Sample Coupling Electronics. An Arrhenius-law η(T) ∝η∞ exp(Eη /RT) was used to fit the temperature-dependent viscosity data. The resulting fit parameters were η∞ = (0.632±0.160) mPas and activation energy of viscous flow Eη = (2.344±0.233) · 104 J/mol. A linear law γ(T) = γl + γT (T - Tm) was fit to the surface tension data yielding γl = (0.9013±0.02625) Nm−1 and γT = −(0.7462±0.2675)·10−4 Nm−1 K−1. The Kozlov-model was applied to determine the enthalphy of mixing as ΔHmix = -(18.576±0.018)kJ/mol.","PeriodicalId":12983,"journal":{"name":"High Temperatures-high Pressures","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69442444","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}
Daeho Kim, Jae-Myung Park, S. Nahm, Sang-Hocuk Lee
Nickel-based superalloys have been widely used for various high-temperature and high-pressure applications such as gas-turbines, power plants, and boiler housings. In this study, we report new experimental results for thermophysical properties of René N5 alloy in a temperature range of room temperature to 1000 °C. Especially, specimens of René N5 alloy were studied in directions [001] and [111] from the same batch of commercial alloy bar. Thermal diffusivity, specific heat capacity, thermal conductivity, and coefficient of thermal expansion (CTE) with correction data of density were evaluated for each measurement method, and detailed data are provided in tables. Thermal conductivity of the [001] alloy had a higher trend than that of the [111] alloy, with relative deviation of 0.7% to 4.8%. Coefficient of thermal expansion values showed good agreement (within 5.3%) and had a curve similar to that of the specific heat capacity. All thermophysical property results were described and compared with those of single crystal alloy of CMSX-4, René N5 and conventional cast René 80 of reference data. The microstructures of alloys [001] and [111] of René N5 were observed by SEM and found to have phase of γ/γ′, which affects the thermophysical properties.
{"title":"Thermophysical properties of nickel-based single crystal of René N5","authors":"Daeho Kim, Jae-Myung Park, S. Nahm, Sang-Hocuk Lee","doi":"10.32908/hthp.v50.1085","DOIUrl":"https://doi.org/10.32908/hthp.v50.1085","url":null,"abstract":"Nickel-based superalloys have been widely used for various high-temperature and high-pressure applications such as gas-turbines, power plants, and boiler housings. In this study, we report new experimental results for thermophysical properties of René N5 alloy in a temperature range of room temperature to 1000 °C. Especially, specimens of René N5 alloy were studied in directions [001] and [111] from the same batch of commercial alloy bar. Thermal diffusivity, specific heat capacity, thermal conductivity, and coefficient of thermal expansion (CTE) with correction data of density were evaluated for each measurement method, and detailed data are provided in tables. Thermal conductivity of the [001] alloy had a higher trend than that of the [111] alloy, with relative deviation of 0.7% to 4.8%. Coefficient of thermal expansion values showed good agreement (within 5.3%) and had a curve similar to that of the specific heat capacity. All thermophysical property results were described and compared with those of single crystal alloy of CMSX-4, René N5 and conventional cast René 80 of reference data. The microstructures of alloys [001] and [111] of René N5 were observed by SEM and found to have phase of γ/γ′, which affects the thermophysical properties.","PeriodicalId":12983,"journal":{"name":"High Temperatures-high Pressures","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69442301","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}
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