50%diamond particle （5μm） reinforced 2024 aluminum matrix （diamond/2024 Al） composites were prepared by pressure infiltration method. Diamond particles were distributed uniformly without any particle clustering, ...50%diamond particle （5μm） reinforced 2024 aluminum matrix （diamond/2024 Al） composites were prepared by pressure infiltration method. Diamond particles were distributed uniformly without any particle clustering, and no apparent porosities or significant casting defects were observed in the composites. The diamond-Al interfaces of as-cast and annealed diamond/2024 Al composites were clean, smooth and free from interfacial reaction product. However, a large number of Al2Cu precipitates were found at diamond-Al interface after aging treatment. Moreover, needle-shaped Al2MgCu precipitates in Al matrix were observed after aging treatment. The coefficient of thermal expansion （CTE） of diamond/2024 Al composites was about 8.5×10-6 °C-1 between 20 and 100 °C, which was compatible with that with chip materials. Annealing treatment showed little effect on thermal expansion behavior, and aging treatment could further decrease the CTE of the composites. The thermal conductivity of obtained diamond/2024 Al composites was about 100 W/（m？K）, and it was slightly increased after annealing while decreased after aging treatment.展开更多
The NiCoCrAl alloy sheet was fabricated by electron beam physical vapor deposition technique and the effects of the heat treatment on the microstructure and tensile strength of the NiCoCrAl alloy sheet were investigat...The NiCoCrAl alloy sheet was fabricated by electron beam physical vapor deposition technique and the effects of the heat treatment on the microstructure and tensile strength of the NiCoCrAl alloy sheet were investigated. The heat treatment at 1050 °C is favorable to improve the interface bonding between the columnar structures due to the disappearance of the intergranular gaps. Comparing with the thin NiCoCrAl alloy sheet before heat treatment, the Ni3Al phase appears in the NiCoCrAl alloy sheet after heat treatment, which is favorable to improve the interface bonding between the columnar structures. The increase in the tensile strength and elongation is attributed to the improvement of the interface bonding between the columnar structures. The residual stress in the NiCoCrAl alloy sheet after heat treatment is reduced significantly, which also confirms that the interface bonding is improved by the heat treatment.展开更多
Laser-weldable Sip-SiCp/Al hybrid composites with high volume fraction （60%-65%） of SiC reinforcement were fabricated by compression moulding and vacuum gas pressure infiltration technology. Microscopic observation ...Laser-weldable Sip-SiCp/Al hybrid composites with high volume fraction （60%-65%） of SiC reinforcement were fabricated by compression moulding and vacuum gas pressure infiltration technology. Microscopic observation displayed that the Sip-SiCp/Al hybrid composites with bilayer structure were compact without gas pores and the intergradation between Sip/Al layer and SiCp/Al layer was homogeneous and continuous. Further investigation revealed that the Sip-SiCp/Al hybrid composites possessed low density （2.96 g/cm^3）, high gas tightness （1.0 mPa·cm^3）/s）, excellent thermal management function as a result of high thermal conductivity （194 W/（m·K） and low coefficient of thermal expansion （7.0×10^-6 K-1）. Additionally, Sip-SiCp/Al hybrid composites had outstanding laser welding adaptability, which is significantly important for electronic packaging applications. The gas tightness of components after laser welding （48 mPa·cm^3）/s） can well match the requirement of advanced electronic packaging. Several kinds of these precision components passed tests and were put into production.展开更多
This article studied experimentally the effect of multi-wall carbon nanotubes （MWCNTs） on the thermo physical properties of ionic liquid-based nanofluids. The nanofluids were composed of ionic liquid, 1-ethyl-3- met...This article studied experimentally the effect of multi-wall carbon nanotubes （MWCNTs） on the thermo physical properties of ionic liquid-based nanofluids. The nanofluids were composed of ionic liquid, 1-ethyl-3- methylimidazolium diethylphosphate [EMIM][DEP], or its aqueous solution[EMIM][DEP]（1） ＋ H20（2） and MWCNTs without any surfactants. The thermal conductivity, viscosity and density of the nanofluids were mea- sured experimentally. The effects of the mass fraction of MWCNTs, temperature and the mole fraction of water on the thermo physical properties of nanofluids were studied. Results show that the thermal conductivity of nanofluids increases within the range of 1.3%-9.7% compared to their base liquids, and have a well linear depen- dence on temperature. The viscosity and density of the nanofluids exhibit a remarkable increase compared with those of the base liquids. Finally, the correlation of the effective thermal conductivity and viscosity of the nanofluids was made using the models in the literatures.展开更多
Al-high Si alloys were designed by the addition of Cu or Mg alloying elements to improve the mechanical properties. It is found that the addition of 1 wt.% Cu or 1 wt.% Mg as strengthening elements significantly impro...Al-high Si alloys were designed by the addition of Cu or Mg alloying elements to improve the mechanical properties. It is found that the addition of 1 wt.% Cu or 1 wt.% Mg as strengthening elements significantly improves the tensile strength by 27.2% and 24.5%, respectively. This phenomenon is attributed to the formation of uniformly dispersed fine particles(Al2Cu and Mg2Si secondary phases) in the Al matrix during hot press sintering of the rapidly solidified(gas atomization) powder. The thermal conductivity of the Al-50 Si alloys is reduced with the addition of Cu or Mg, by only 7.3% and 6.8%, respectively. Therefore, the strength of the Al-50 Si alloys is enhanced while maintaining their excellent thermo-physical properties by adding 1% Cu(Mg).展开更多
Solidification structure is critical in the control of the mechanical properties and quality during the continuous casting process. The thermo-physical properties of 13 Cr steel added some rare metals, such as Mo, V, ...Solidification structure is critical in the control of the mechanical properties and quality during the continuous casting process. The thermo-physical properties of 13 Cr steel added some rare metals, such as Mo, V, Nb, are measured to better understand the solidification structure of 13 Cr bloom. A computational model using CA-FE(cellular automation-finite element) method coupled with heat transfer model is developed to describe the solidification structure in continuous casting process. It is found that the calculated solidification structure is in good agreement with the observed data. The influence of casting speed and superheat on the solidification structure of the bloom is studied in detail. In order to obtain more equiaxed crystal ratio and low degree of the segregation in the bloom, the optimized casting speed 0.6 m/min and superheat less than 25 °C are determined for the caster. Using the optimized manufacturing parameters, these samples are 60% with the equiaxed zone ratio of 8%–10% and below the degree of segregation 1.05.展开更多
Biophysical studies were conducted on the action of laminin through membrane receptors of cancer cells. The results showed that variations occurred in the thermodynamic properties of membrane proteins,the mobility of ...Biophysical studies were conducted on the action of laminin through membrane receptors of cancer cells. The results showed that variations occurred in the thermodynamic properties of membrane proteins,the mobility of hydrocarbon chains of membrane lipids, and the permeability and transportation pathways of the membrane.展开更多
The mixed metal/metal sulphide(Ag@CoS)with reduced graphene oxide(rGO)nanocomposite(Ag@CoS/rGO)was synthesized for the possible electrode in supercapacitors.Ag@CoS was successfully deposited on the rGO nanosheets by h...The mixed metal/metal sulphide(Ag@CoS)with reduced graphene oxide(rGO)nanocomposite(Ag@CoS/rGO)was synthesized for the possible electrode in supercapacitors.Ag@CoS was successfully deposited on the rGO nanosheets by hydrothermal method,implying the growth of 2D Ag and CoS-based hexagonal-like structure on the rGO framework.The synthesized nanocomposite was subjected to structural,morphological and electrochemical studies.The XRD results show that the prepared nanocomposite material exhibits a combination of hexagonal and cubic phase due to the presence of CoS and Ag phases together.The band appearing at nearly 470.33 cm^−1 in FTIR spectra can be ascribed to the absorption of S—S bond in the Ag@CoS/rGO nanocomposite.The clear hexagonal structure was analysed by SEM and TEM with the grain sizes ranging from nanometer to micrometer.The electrode material exhibits excellent cyclic stability with a specific capacitance of 1580 F/g at a current density of 0.5 A/g without any loss of capacitive retention even after 1000 cycles.Based on the electrochemical performance,it can be inferred that the prepared novel nanocomposite material is very suitable for using as an electrode for electrochemical supercapacitor applications.展开更多
Freezing is the most common method used to preserve and minimize loss in quality of catfish during storage. Since freezing is a heat transfer process, the design and selection of freezing equipment require knowledge o...Freezing is the most common method used to preserve and minimize loss in quality of catfish during storage. Since freezing is a heat transfer process, the design and selection of freezing equipment require knowledge of thermophysical properties such as freezing temperature, enthalpy of freezing, unfreezable water and specific heat. Channel catfish thermophysical properties at freezing temperature were determined using differential scanning calorimetry. Using the combination of Raoult＇s law and Classius-Clapeyron equations, the amount of unfreezable （bound water） was estimated to be 0.129 g H20 g^-1 During freezing （or melting）, the specific heat increased from about 1.5 J g^-1 ℃^-1 to about 30.6 J g^-1 ℃^-1 It was found that freezing of catfish occur over a wide temperature range with the peak and incident freezing temperatures occurring at temperatures of-1.88 ℃ and -6.10 ℃, respectively. About 250 J g^-1 of heat have to be removed from catfish when it is to be frozen to -40 ℃. The implication is that any system that will be designed to freeze catfish must be able to remove 250 J g^-1 of heat.展开更多
A series of caprolactam ionic liquids(ILs) containing incorporated halide anions were synthesized.Their physical properties,such as melting points,heats of fusion and heat capacities,were measured by differential scan...A series of caprolactam ionic liquids(ILs) containing incorporated halide anions were synthesized.Their physical properties,such as melting points,heats of fusion and heat capacities,were measured by differential scanning calorimeter(DSC).The results indicate that these ionic liquids exhibit proper melting points,high value of heats of fusion,and satisfying heat capacities which are suitable for thermal energy storage applications.展开更多
Although the high diversity of plant species in the rupestrian fields has been primarily attributed to the existence of a set of distinct habitats, few studies support this assertion. The present study aimed to furthe...Although the high diversity of plant species in the rupestrian fields has been primarily attributed to the existence of a set of distinct habitats, few studies support this assertion. The present study aimed to further investigate the relationship between physical and chemical attributes of soils with the diversity of plant species in this unique ecosystem. The rupestrian field is a unique vegetation formation that covers some of the southeastern Brazilian mountains in the transition of the Atlantic rain forest and the Cerrado(savanna). Different habitats occur according to soil characteristics(e.g., presence of rocks, sand, fertility, hydrology, etc.). These attributes ultimately influence the vegetation that is highly adapted to the harsh edaphic and climatic mountain conditions. Five distinct habitats were studied by us: rocky outcrops, peat bogs, sandy bogs, quartz gravel fields, and "cerrado"(savanna). A floristic survey indicated that four families are found at greater frequency: Poaceae, Asteraceae, Cyperaceae, and Leguminosae. The greatest diversity of plant species was found in the rocky outcrops habitat, followed by cerrado, peat bog, quartz gravel grassland, and sandy bogs, respectively. The main difference in the floristic composition among these habitats was related to the dominant species. Trachypogon spicatus(Poaceae) was the most dominant species in the rocky outcrops, Axonopus siccus(Poaceae) in the peat bogs, Lagenocarpus rigidus(Cyperaceae) in the sandy bogs, Schizachyrium tenerum(Poaceae) in the cerrado, while Vellozia sp. 8(Velloziaceae) dominated the vegetation in the quartz gravel grassland. This study demonstrated that physical and chemical soil properties strongly related the diversity of plant species occurring in the different habitats of rupestrian fields.展开更多
The surface functional groups and pyrolysis characteristics of lignite irradiated by microwave were comparatively studied to evaluate the feasibility of using industrial 915 MHz for lignite drying. The drying kinetics...The surface functional groups and pyrolysis characteristics of lignite irradiated by microwave were comparatively studied to evaluate the feasibility of using industrial 915 MHz for lignite drying. The drying kinetics, micro structure, chemical functional groups, re-adsorption properties, and pyrolysis characteristics of the dried coal were respectively analyzed. Results indicated that for typical Chinese lignite studied in this paper, 915 MHz microwave drying was 7.8 times faster than that of the hot air drying. After industrial microwave drying, the sample possessed much higher total specific surface area and specific pore volume than that of air dried sample. The oxygen functional groups and re-adsorption ratio of microwave irradiated coal decreased, showing weakened hydrophilicity. Moreover, during the pyrolysis of the coal dried by hot air and microwave, the yield of tar largely increased from 1.3% to 8.5% and the gas production increased correspondingly. The composition of the tar was also furtherly analyzed, results indicated that Miscellaneous hydrocarbons(HCs) were the main component of the tar, and microwave irradiation can reduce the fraction of polycyclic aromatic hydrocarbons(PAHs) from 26.4% to 22.7%.展开更多
基金Project (AWJ-M13-15) supported by the Open Fund of State Key Laboratory of Advanced Welding and Joining,Harbin Institute of Technology,China
文摘50%diamond particle （5μm） reinforced 2024 aluminum matrix （diamond/2024 Al） composites were prepared by pressure infiltration method. Diamond particles were distributed uniformly without any particle clustering, and no apparent porosities or significant casting defects were observed in the composites. The diamond-Al interfaces of as-cast and annealed diamond/2024 Al composites were clean, smooth and free from interfacial reaction product. However, a large number of Al2Cu precipitates were found at diamond-Al interface after aging treatment. Moreover, needle-shaped Al2MgCu precipitates in Al matrix were observed after aging treatment. The coefficient of thermal expansion （CTE） of diamond/2024 Al composites was about 8.5×10-6 °C-1 between 20 and 100 °C, which was compatible with that with chip materials. Annealing treatment showed little effect on thermal expansion behavior, and aging treatment could further decrease the CTE of the composites. The thermal conductivity of obtained diamond/2024 Al composites was about 100 W/（m？K）, and it was slightly increased after annealing while decreased after aging treatment.
基金Projects(51002019,91016024,51102031)supported by the National Natural Science Foundation of China
文摘The NiCoCrAl alloy sheet was fabricated by electron beam physical vapor deposition technique and the effects of the heat treatment on the microstructure and tensile strength of the NiCoCrAl alloy sheet were investigated. The heat treatment at 1050 °C is favorable to improve the interface bonding between the columnar structures due to the disappearance of the intergranular gaps. Comparing with the thin NiCoCrAl alloy sheet before heat treatment, the Ni3Al phase appears in the NiCoCrAl alloy sheet after heat treatment, which is favorable to improve the interface bonding between the columnar structures. The increase in the tensile strength and elongation is attributed to the improvement of the interface bonding between the columnar structures. The residual stress in the NiCoCrAl alloy sheet after heat treatment is reduced significantly, which also confirms that the interface bonding is improved by the heat treatment.
文摘Laser-weldable Sip-SiCp/Al hybrid composites with high volume fraction （60%-65%） of SiC reinforcement were fabricated by compression moulding and vacuum gas pressure infiltration technology. Microscopic observation displayed that the Sip-SiCp/Al hybrid composites with bilayer structure were compact without gas pores and the intergradation between Sip/Al layer and SiCp/Al layer was homogeneous and continuous. Further investigation revealed that the Sip-SiCp/Al hybrid composites possessed low density （2.96 g/cm^3）, high gas tightness （1.0 mPa·cm^3）/s）, excellent thermal management function as a result of high thermal conductivity （194 W/（m·K） and low coefficient of thermal expansion （7.0×10^-6 K-1）. Additionally, Sip-SiCp/Al hybrid composites had outstanding laser welding adaptability, which is significantly important for electronic packaging applications. The gas tightness of components after laser welding （48 mPa·cm^3）/s） can well match the requirement of advanced electronic packaging. Several kinds of these precision components passed tests and were put into production.
基金Supported by the National Natural Science Foundation of China(51376036)
文摘This article studied experimentally the effect of multi-wall carbon nanotubes （MWCNTs） on the thermo physical properties of ionic liquid-based nanofluids. The nanofluids were composed of ionic liquid, 1-ethyl-3- methylimidazolium diethylphosphate [EMIM][DEP], or its aqueous solution[EMIM][DEP]（1） ＋ H20（2） and MWCNTs without any surfactants. The thermal conductivity, viscosity and density of the nanofluids were mea- sured experimentally. The effects of the mass fraction of MWCNTs, temperature and the mole fraction of water on the thermo physical properties of nanofluids were studied. Results show that the thermal conductivity of nanofluids increases within the range of 1.3%-9.7% compared to their base liquids, and have a well linear depen- dence on temperature. The viscosity and density of the nanofluids exhibit a remarkable increase compared with those of the base liquids. Finally, the correlation of the effective thermal conductivity and viscosity of the nanofluids was made using the models in the literatures.
文摘Al-high Si alloys were designed by the addition of Cu or Mg alloying elements to improve the mechanical properties. It is found that the addition of 1 wt.% Cu or 1 wt.% Mg as strengthening elements significantly improves the tensile strength by 27.2% and 24.5%, respectively. This phenomenon is attributed to the formation of uniformly dispersed fine particles(Al2Cu and Mg2Si secondary phases) in the Al matrix during hot press sintering of the rapidly solidified(gas atomization) powder. The thermal conductivity of the Al-50 Si alloys is reduced with the addition of Cu or Mg, by only 7.3% and 6.8%, respectively. Therefore, the strength of the Al-50 Si alloys is enhanced while maintaining their excellent thermo-physical properties by adding 1% Cu(Mg).
基金Projects(51274057,51474057) supported by the National Natural Science Foundation of ChinaProject(2012AA03A508) supported by the High-tech Research and Development Program of China
文摘Solidification structure is critical in the control of the mechanical properties and quality during the continuous casting process. The thermo-physical properties of 13 Cr steel added some rare metals, such as Mo, V, Nb, are measured to better understand the solidification structure of 13 Cr bloom. A computational model using CA-FE(cellular automation-finite element) method coupled with heat transfer model is developed to describe the solidification structure in continuous casting process. It is found that the calculated solidification structure is in good agreement with the observed data. The influence of casting speed and superheat on the solidification structure of the bloom is studied in detail. In order to obtain more equiaxed crystal ratio and low degree of the segregation in the bloom, the optimized casting speed 0.6 m/min and superheat less than 25 °C are determined for the caster. Using the optimized manufacturing parameters, these samples are 60% with the equiaxed zone ratio of 8%–10% and below the degree of segregation 1.05.
文摘Biophysical studies were conducted on the action of laminin through membrane receptors of cancer cells. The results showed that variations occurred in the thermodynamic properties of membrane proteins,the mobility of hydrocarbon chains of membrane lipids, and the permeability and transportation pathways of the membrane.
文摘The mixed metal/metal sulphide(Ag@CoS)with reduced graphene oxide(rGO)nanocomposite(Ag@CoS/rGO)was synthesized for the possible electrode in supercapacitors.Ag@CoS was successfully deposited on the rGO nanosheets by hydrothermal method,implying the growth of 2D Ag and CoS-based hexagonal-like structure on the rGO framework.The synthesized nanocomposite was subjected to structural,morphological and electrochemical studies.The XRD results show that the prepared nanocomposite material exhibits a combination of hexagonal and cubic phase due to the presence of CoS and Ag phases together.The band appearing at nearly 470.33 cm^−1 in FTIR spectra can be ascribed to the absorption of S—S bond in the Ag@CoS/rGO nanocomposite.The clear hexagonal structure was analysed by SEM and TEM with the grain sizes ranging from nanometer to micrometer.The electrode material exhibits excellent cyclic stability with a specific capacitance of 1580 F/g at a current density of 0.5 A/g without any loss of capacitive retention even after 1000 cycles.Based on the electrochemical performance,it can be inferred that the prepared novel nanocomposite material is very suitable for using as an electrode for electrochemical supercapacitor applications.
文摘Freezing is the most common method used to preserve and minimize loss in quality of catfish during storage. Since freezing is a heat transfer process, the design and selection of freezing equipment require knowledge of thermophysical properties such as freezing temperature, enthalpy of freezing, unfreezable water and specific heat. Channel catfish thermophysical properties at freezing temperature were determined using differential scanning calorimetry. Using the combination of Raoult＇s law and Classius-Clapeyron equations, the amount of unfreezable （bound water） was estimated to be 0.129 g H20 g^-1 During freezing （or melting）, the specific heat increased from about 1.5 J g^-1 ℃^-1 to about 30.6 J g^-1 ℃^-1 It was found that freezing of catfish occur over a wide temperature range with the peak and incident freezing temperatures occurring at temperatures of-1.88 ℃ and -6.10 ℃, respectively. About 250 J g^-1 of heat have to be removed from catfish when it is to be frozen to -40 ℃. The implication is that any system that will be designed to freeze catfish must be able to remove 250 J g^-1 of heat.
基金Supported by the National Natural Science Foundation of China （21176010, 20706005）.
文摘A series of caprolactam ionic liquids(ILs) containing incorporated halide anions were synthesized.Their physical properties,such as melting points,heats of fusion and heat capacities,were measured by differential scanning calorimeter(DSC).The results indicate that these ionic liquids exhibit proper melting points,high value of heats of fusion,and satisfying heat capacities which are suitable for thermal energy storage applications.
文摘Although the high diversity of plant species in the rupestrian fields has been primarily attributed to the existence of a set of distinct habitats, few studies support this assertion. The present study aimed to further investigate the relationship between physical and chemical attributes of soils with the diversity of plant species in this unique ecosystem. The rupestrian field is a unique vegetation formation that covers some of the southeastern Brazilian mountains in the transition of the Atlantic rain forest and the Cerrado(savanna). Different habitats occur according to soil characteristics(e.g., presence of rocks, sand, fertility, hydrology, etc.). These attributes ultimately influence the vegetation that is highly adapted to the harsh edaphic and climatic mountain conditions. Five distinct habitats were studied by us: rocky outcrops, peat bogs, sandy bogs, quartz gravel fields, and "cerrado"(savanna). A floristic survey indicated that four families are found at greater frequency: Poaceae, Asteraceae, Cyperaceae, and Leguminosae. The greatest diversity of plant species was found in the rocky outcrops habitat, followed by cerrado, peat bog, quartz gravel grassland, and sandy bogs, respectively. The main difference in the floristic composition among these habitats was related to the dominant species. Trachypogon spicatus(Poaceae) was the most dominant species in the rocky outcrops, Axonopus siccus(Poaceae) in the peat bogs, Lagenocarpus rigidus(Cyperaceae) in the sandy bogs, Schizachyrium tenerum(Poaceae) in the cerrado, while Vellozia sp. 8(Velloziaceae) dominated the vegetation in the quartz gravel grassland. This study demonstrated that physical and chemical soil properties strongly related the diversity of plant species occurring in the different habitats of rupestrian fields.
基金Supported by the National Natural Science Foundation of China(51621005)the Fundamental Research Funds for the Central Universities(2017FZA4013)
文摘The surface functional groups and pyrolysis characteristics of lignite irradiated by microwave were comparatively studied to evaluate the feasibility of using industrial 915 MHz for lignite drying. The drying kinetics, micro structure, chemical functional groups, re-adsorption properties, and pyrolysis characteristics of the dried coal were respectively analyzed. Results indicated that for typical Chinese lignite studied in this paper, 915 MHz microwave drying was 7.8 times faster than that of the hot air drying. After industrial microwave drying, the sample possessed much higher total specific surface area and specific pore volume than that of air dried sample. The oxygen functional groups and re-adsorption ratio of microwave irradiated coal decreased, showing weakened hydrophilicity. Moreover, during the pyrolysis of the coal dried by hot air and microwave, the yield of tar largely increased from 1.3% to 8.5% and the gas production increased correspondingly. The composition of the tar was also furtherly analyzed, results indicated that Miscellaneous hydrocarbons(HCs) were the main component of the tar, and microwave irradiation can reduce the fraction of polycyclic aromatic hydrocarbons(PAHs) from 26.4% to 22.7%.
