The effect of rare earth doping on thermo-physical properties of lanthanum zirconate was investigated. Oxide powders of various compositions La2Zr2O7 were synthesized by coprecipitation-calcination method. High-temper...The effect of rare earth doping on thermo-physical properties of lanthanum zirconate was investigated. Oxide powders of various compositions La2Zr2O7 were synthesized by coprecipitation-calcination method. High-temperature dilatometer, DSC, and laser thermal diffusivity methods were used to analyze thermal expansion coefficient （TEC）, specific heat, and thermal diffusivity. The results showed that CeO2 doped pyrochlores La2（Zr1.8Ce0.2）2O7 and La1.7（DyNd）0.15（Zr0.8Ce0.2）2O7 had higher TEC than La2Zr2O7 and La1.7Dy0.3Zr2O7. La2（Zr1.8Ce0.2）2O7, La1.7Dy0.3Zr2O7, and La1.7（DyNd）0.15（Zr0.8Ce0.2）2O7 had lower thermal conductivity than undoped La2Zr2O7. The Dy2O3, Nd2O3, and CeO2 codoped composition showed the lowest thermal conductivity and the highest TEC. Thermo-physical results also indicated that TEC of rare earth oxide doped La2Zr2O7 ceramic was slightly higher than that of conventional ZrO2-8Wt.% Y2O3 （8YSZ）, and its thermal conductivity was lower than that of 8YSZ.展开更多
Geothermal exploration in northern Jordan is in juvenile phase. North eastern basaltic desert is expected to host, with other rock formations, a shallow geothermal field. For efficient geothermal potential evaluation,...Geothermal exploration in northern Jordan is in juvenile phase. North eastern basaltic desert is expected to host, with other rock formations, a shallow geothermal field. For efficient geothermal potential evaluation, a complete understanding of thermo-physical properties of deep reservoir rocks is of utmost importance. Due to the complex technical thermo-physical evaluations of basalts in depth, surficial basalts extending to the west were evaluated. Accordingly, six basaltic sub-flows from Al Hashimiyya were examined into their thermo-physical and mechanical properties. The flows represent the western extinction of large olivine basalt eruption. Different properties were evaluated for oven dried samples: thermal conductivity, permeability, porosity, density and specific heat capacity. In addition, basalts mechanical properties were examined: compressional wave velocity, unconfined compressive strength, indirect tensile strength and point load tests. The results were correlated in proportional patterns. They indicated that thermal conductivity of the studied basalts is dependent on porosity and permeability in parallel with mineral composition. It’s found that mechanical properties are controlled by porosity and permeability, too. The studied basalt properties exhibit slight deviation from the continental basalts thermo-physical and mechanical properties reported in the region. Thermal conductivity ranges between 1.89 and 1.32 W·m-1·K-1, whereas the porosity and permeability averages at 10.64% and 9.75899E-15 m2, respectively. Additionally, unconfined compressive strength averages at 104.9 Mpa and it’s almost 20 times higher than indirect tensile strength which ranges from 8.73 to 2.21 Mpa. As the samples were tested under laboratory conditions, in situ conditions will not be reflected by such values. At greater depth, temperature, pressure and hydrothermal activities will certainly affect rock properties. Micro fractures, whether it will be filled or not, will affect basalts properties, too. The results of this work will be used to develop a comprehensive thermo-physico-mechanical model, and improve the ability to predict rock properties at greater depths of Jordanian basalts.展开更多
Nanofluids(NFs) are nanotechnology-based colloidal suspensions fabricated by suspending nanoparticles(NPs) in a base liquid. These fluids have shown potential to improve the heat transfer properties of conventional he...Nanofluids(NFs) are nanotechnology-based colloidal suspensions fabricated by suspending nanoparticles(NPs) in a base liquid. These fluids have shown potential to improve the heat transfer properties of conventional heat transfer fluids. In this study we report in detail on fabrication, characterization and thermo-physical property evaluation of SiC NFs, prepared using SiC NPs with different crystal structures,for heat transfer applications. For this purpose, a series of SiC NFs containing SiC NPs with different crystal structure(α-SiC and β-SiC) were fabricated in a water(W)/ethylene glycol(EG) mixture(50/50 wt%ratio). Physicochemical properties of NPs/NFs were characterized by using various techniques, such as powder X-ray diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM),Fouriertransform infrared spectroscopy(FTIR), dynamic light scattering(DLS) and Zeta potential analysis.Thermo-physical properties including thermal conductivity(TC) and viscosity for NFs containing SiC particles(α- and β- phase) weremeasured. The results show among all suspensions NFs fabricated with α-SiC particles have more favorable thermo-physical properties compared to the NFs fabricated with β-SiC.The observed difference is attributed to combination of several factors, including crystal structure(β- vs. α-), sample purity,and residual chemicals exhibited on SiC NFs. A TC enhancement of ～20% while 14% increased viscosity were obtained for NFs containing 9 wt% of particular type of α-SiC NPs indicating promising capability of this kind of NFs for further heat transfer characteristics investigation.展开更多
Cu2ZnSnS4 (CZTS) and Cu2ZnSnSe4 (CZTSe) with optimum band gaps about 1.5 eV are important absorbers for solar cells. The elastic constants and the thermo-physical properties of the stannite-type CZTS and CZTSe are cal...Cu2ZnSnS4 (CZTS) and Cu2ZnSnSe4 (CZTSe) with optimum band gaps about 1.5 eV are important absorbers for solar cells. The elastic constants and the thermo-physical properties of the stannite-type CZTS and CZTSe are calculated by using density-functional theory (DFT) and the quasi-harmonic Debye model. The bonding strength along the [100] and [010] directions is the same to that along the [001] direction and the shear elastic properties of the {001} plane are anisotropic for CZTS and CZTSe. Both compounds exhibit ductile behavior due to their high ratio of bulk modulus to shear modulus (K/G). The values of thermal capacity are close to 200 J/(mol·K) at above 300 K, and the thermal expansion coefficients decrease with increasing pressure at same temperature. The entropy is variable by power-exponent, and the internal energy is almost linear with increasing temperature for CZTS and CZTSe. The Gibbs energy of CZTS is lower than that of CZTSe under same temperature and pressure. The Debye temperatures are 297 and 232 K, and Grneisen parameters are 2.36 and 2.37 for CZTS and CZTSe at 300 K, respectively.展开更多
Phase stability,elastic properties,thermo-physical properties,as well as electronic properties of hexa-（Mo,Cr,W）2C carbides were investigated by first-principles calculations.The results indicated that the Mo8C4,Mo7...Phase stability,elastic properties,thermo-physical properties,as well as electronic properties of hexa-（Mo,Cr,W）2C carbides were investigated by first-principles calculations.The results indicated that the Mo8C4,Mo7Cr1C4,Mo7W1C4,Mo6W2C4,and Mo6W1Cr1C4 are stable and the stability follows the sequence：Mo6W1Cr1C4〉Mo7W1C4〉Mo7Cr1C4〉 Mo6W2C4〉 Mo8C4.Mo6W1Cr1C4 shows the highest stability,deformation resistance and hardness.G/B（shear modulus/bulk modulus）and Poisson′s ratio of the stable hexa-（Mo,Cr,W）2C are all larger than 1.75 and 0.26,respectively,which indicates that they are all brittle.The anisotropies are mainly due to the different Vogit shear modulus/Reuss shear modulus;the mechanical anisotropy of Mo7Cr1C4 is the largest,and that of Mo8C4 is the smallest.Moreover,the obtained Debye temperatureΘDand heat capacity Cpindicate that Mo6W2C4 possesses the best thermal conductivity（ΘD=497.72K）,while Mo7Cr1C4 and Mo6W2C4possess the largest heat capacity when the temperature is in the range of 0-10 Kand larger than 10 K,respectively.From the electronic property analysis,the doped Cr and W atoms can not only participate in orbitals hybridization themselves but also enhance the orbitals hybridization between Mo and C atoms,which can reinforce the interatomic interactions.展开更多
In order to produce the hear-resistant inner layer of hot-forging die, the plasma spraying and plasma re-melting and plasma spray welding were adopted. Substrate material was W6Mo5Cr4V2, including 10%, 20%, 30% tungst...In order to produce the hear-resistant inner layer of hot-forging die, the plasma spraying and plasma re-melting and plasma spray welding were adopted. Substrate material was W6Mo5Cr4V2, including 10%, 20%, 30% tungsten carbide （WC） ceramic powder used as coating material to obtain different Nickel-based WC alloys coating. Micro-structure and micro-hardness analysis of the coating layer are conducted, as well as thermophysical properties for the coating layer were measured. The experimental results show that the coating prepared with 70%Ni60, 30%WC powder has the best properties with plasma spray welding, in which the micro-hardness can achieve 900HV, meanwhile it can improve the thermal property of hot-forging die dramatically.展开更多
In order to produce the hear-resistant inner layer of hot-forging die, plasma spraying and plasma re-melting and plasma spray welding were adopted. Substrate material was W6Mo5Cr4V2, including 10%, 20%, 30% SiC cerami...In order to produce the hear-resistant inner layer of hot-forging die, plasma spraying and plasma re-melting and plasma spray welding were adopted. Substrate material was W6Mo5Cr4V2, including 10%, 20%, 30% SiC ceramic powder used as coating material to obtain different Ni-based SiC alloys coating. Micro-structure and micro-hardness analysis of the coating layer were followed, as well as thermophysical properties for the coating layer were measured. The experimental results show that the coating prepared with 70% Ni60, 30% SiC powder has best properties with plasma spray welding, in which the micro-hardness can achieve 1100 HV, meanwhile can improve the thermal property of hot-forging die dramatically.展开更多
In order to prepare heatresistant inner layer of hot-forging die, plasma spraying, plasma re- melting and plasma spray welding were adopted. Cr3C2 coatings of Ni-Based were prepared respectively with 10%, 20% and 30% ...In order to prepare heatresistant inner layer of hot-forging die, plasma spraying, plasma re- melting and plasma spray welding were adopted. Cr3C2 coatings of Ni-Based were prepared respectively with 10%, 20% and 30% Cr3C2 powder and W6Mo5Cr4V2 substrate. The coating microstructure analysis, the micro-hardness test, and the measurement of thermal parameters of coating were conducted. The experimental results show that the coating has the better thermo-physical property by using plasma spray welding method with the powder ratio of 90% Ni60 and 10% Cr3C2, and by this way the micro-hardness of coating can achieve 1100 HV.展开更多
基金supported by the Postdoctoral Foundation of China (20060400261)the Special Finance Scheme of Post Doctoral Foundation of China (200801350)
文摘The effect of rare earth doping on thermo-physical properties of lanthanum zirconate was investigated. Oxide powders of various compositions La2Zr2O7 were synthesized by coprecipitation-calcination method. High-temperature dilatometer, DSC, and laser thermal diffusivity methods were used to analyze thermal expansion coefficient （TEC）, specific heat, and thermal diffusivity. The results showed that CeO2 doped pyrochlores La2（Zr1.8Ce0.2）2O7 and La1.7（DyNd）0.15（Zr0.8Ce0.2）2O7 had higher TEC than La2Zr2O7 and La1.7Dy0.3Zr2O7. La2（Zr1.8Ce0.2）2O7, La1.7Dy0.3Zr2O7, and La1.7（DyNd）0.15（Zr0.8Ce0.2）2O7 had lower thermal conductivity than undoped La2Zr2O7. The Dy2O3, Nd2O3, and CeO2 codoped composition showed the lowest thermal conductivity and the highest TEC. Thermo-physical results also indicated that TEC of rare earth oxide doped La2Zr2O7 ceramic was slightly higher than that of conventional ZrO2-8Wt.% Y2O3 （8YSZ）, and its thermal conductivity was lower than that of 8YSZ.
文摘Geothermal exploration in northern Jordan is in juvenile phase. North eastern basaltic desert is expected to host, with other rock formations, a shallow geothermal field. For efficient geothermal potential evaluation, a complete understanding of thermo-physical properties of deep reservoir rocks is of utmost importance. Due to the complex technical thermo-physical evaluations of basalts in depth, surficial basalts extending to the west were evaluated. Accordingly, six basaltic sub-flows from Al Hashimiyya were examined into their thermo-physical and mechanical properties. The flows represent the western extinction of large olivine basalt eruption. Different properties were evaluated for oven dried samples: thermal conductivity, permeability, porosity, density and specific heat capacity. In addition, basalts mechanical properties were examined: compressional wave velocity, unconfined compressive strength, indirect tensile strength and point load tests. The results were correlated in proportional patterns. They indicated that thermal conductivity of the studied basalts is dependent on porosity and permeability in parallel with mineral composition. It’s found that mechanical properties are controlled by porosity and permeability, too. The studied basalt properties exhibit slight deviation from the continental basalts thermo-physical and mechanical properties reported in the region. Thermal conductivity ranges between 1.89 and 1.32 W·m-1·K-1, whereas the porosity and permeability averages at 10.64% and 9.75899E-15 m2, respectively. Additionally, unconfined compressive strength averages at 104.9 Mpa and it’s almost 20 times higher than indirect tensile strength which ranges from 8.73 to 2.21 Mpa. As the samples were tested under laboratory conditions, in situ conditions will not be reflected by such values. At greater depth, temperature, pressure and hydrothermal activities will certainly affect rock properties. Micro fractures, whether it will be filled or not, will affect basalts properties, too. The results of this work will be used to develop a comprehensive thermo-physico-mechanical model, and improve the ability to predict rock properties at greater depths of Jordanian basalts.
基金financial support from the EU (Project Reference: 228882)Swedish Research Council (VR) for the project NanoHex (Enhanced Nano-fluid Heat Exchange)
文摘Nanofluids(NFs) are nanotechnology-based colloidal suspensions fabricated by suspending nanoparticles(NPs) in a base liquid. These fluids have shown potential to improve the heat transfer properties of conventional heat transfer fluids. In this study we report in detail on fabrication, characterization and thermo-physical property evaluation of SiC NFs, prepared using SiC NPs with different crystal structures,for heat transfer applications. For this purpose, a series of SiC NFs containing SiC NPs with different crystal structure(α-SiC and β-SiC) were fabricated in a water(W)/ethylene glycol(EG) mixture(50/50 wt%ratio). Physicochemical properties of NPs/NFs were characterized by using various techniques, such as powder X-ray diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM),Fouriertransform infrared spectroscopy(FTIR), dynamic light scattering(DLS) and Zeta potential analysis.Thermo-physical properties including thermal conductivity(TC) and viscosity for NFs containing SiC particles(α- and β- phase) weremeasured. The results show among all suspensions NFs fabricated with α-SiC particles have more favorable thermo-physical properties compared to the NFs fabricated with β-SiC.The observed difference is attributed to combination of several factors, including crystal structure(β- vs. α-), sample purity,and residual chemicals exhibited on SiC NFs. A TC enhancement of ～20% while 14% increased viscosity were obtained for NFs containing 9 wt% of particular type of α-SiC NPs indicating promising capability of this kind of NFs for further heat transfer characteristics investigation.
基金supported by the National Natural Science Foundation of China (No. 51075197)
文摘Cu2ZnSnS4 (CZTS) and Cu2ZnSnSe4 (CZTSe) with optimum band gaps about 1.5 eV are important absorbers for solar cells. The elastic constants and the thermo-physical properties of the stannite-type CZTS and CZTSe are calculated by using density-functional theory (DFT) and the quasi-harmonic Debye model. The bonding strength along the [100] and [010] directions is the same to that along the [001] direction and the shear elastic properties of the {001} plane are anisotropic for CZTS and CZTSe. Both compounds exhibit ductile behavior due to their high ratio of bulk modulus to shear modulus (K/G). The values of thermal capacity are close to 200 J/(mol·K) at above 300 K, and the thermal expansion coefficients decrease with increasing pressure at same temperature. The entropy is variable by power-exponent, and the internal energy is almost linear with increasing temperature for CZTS and CZTSe. The Gibbs energy of CZTS is lower than that of CZTSe under same temperature and pressure. The Debye temperatures are 297 and 232 K, and Grneisen parameters are 2.36 and 2.37 for CZTS and CZTSe at 300 K, respectively.
文摘Phase stability,elastic properties,thermo-physical properties,as well as electronic properties of hexa-（Mo,Cr,W）2C carbides were investigated by first-principles calculations.The results indicated that the Mo8C4,Mo7Cr1C4,Mo7W1C4,Mo6W2C4,and Mo6W1Cr1C4 are stable and the stability follows the sequence：Mo6W1Cr1C4〉Mo7W1C4〉Mo7Cr1C4〉 Mo6W2C4〉 Mo8C4.Mo6W1Cr1C4 shows the highest stability,deformation resistance and hardness.G/B（shear modulus/bulk modulus）and Poisson′s ratio of the stable hexa-（Mo,Cr,W）2C are all larger than 1.75 and 0.26,respectively,which indicates that they are all brittle.The anisotropies are mainly due to the different Vogit shear modulus/Reuss shear modulus;the mechanical anisotropy of Mo7Cr1C4 is the largest,and that of Mo8C4 is the smallest.Moreover,the obtained Debye temperatureΘDand heat capacity Cpindicate that Mo6W2C4 possesses the best thermal conductivity（ΘD=497.72K）,while Mo7Cr1C4 and Mo6W2C4possess the largest heat capacity when the temperature is in the range of 0-10 Kand larger than 10 K,respectively.From the electronic property analysis,the doped Cr and W atoms can not only participate in orbitals hybridization themselves but also enhance the orbitals hybridization between Mo and C atoms,which can reinforce the interatomic interactions.
基金Funded by the National Natural Science Foundation of China(No.50675165)the National Key Technology R&D Program(No.2006BAF02A29)
文摘In order to produce the hear-resistant inner layer of hot-forging die, the plasma spraying and plasma re-melting and plasma spray welding were adopted. Substrate material was W6Mo5Cr4V2, including 10%, 20%, 30% tungsten carbide （WC） ceramic powder used as coating material to obtain different Nickel-based WC alloys coating. Micro-structure and micro-hardness analysis of the coating layer are conducted, as well as thermophysical properties for the coating layer were measured. The experimental results show that the coating prepared with 70%Ni60, 30%WC powder has the best properties with plasma spray welding, in which the micro-hardness can achieve 900HV, meanwhile it can improve the thermal property of hot-forging die dramatically.
基金Funded by the National Natural Science Foundation of China (No. 50675165)
文摘In order to produce the hear-resistant inner layer of hot-forging die, plasma spraying and plasma re-melting and plasma spray welding were adopted. Substrate material was W6Mo5Cr4V2, including 10%, 20%, 30% SiC ceramic powder used as coating material to obtain different Ni-based SiC alloys coating. Micro-structure and micro-hardness analysis of the coating layer were followed, as well as thermophysical properties for the coating layer were measured. The experimental results show that the coating prepared with 70% Ni60, 30% SiC powder has best properties with plasma spray welding, in which the micro-hardness can achieve 1100 HV, meanwhile can improve the thermal property of hot-forging die dramatically.
文摘In order to prepare heatresistant inner layer of hot-forging die, plasma spraying, plasma re- melting and plasma spray welding were adopted. Cr3C2 coatings of Ni-Based were prepared respectively with 10%, 20% and 30% Cr3C2 powder and W6Mo5Cr4V2 substrate. The coating microstructure analysis, the micro-hardness test, and the measurement of thermal parameters of coating were conducted. The experimental results show that the coating has the better thermo-physical property by using plasma spray welding method with the powder ratio of 90% Ni60 and 10% Cr3C2, and by this way the micro-hardness of coating can achieve 1100 HV.
