Steady TiO2 water-sol was prepared by peptization and the effects of pH value, temperature, concentration of colloid and peptizator on sol were investigated. Laser grain analyzer was used to verify nano-particles in t...Steady TiO2 water-sol was prepared by peptization and the effects of pH value, temperature, concentration of colloid and peptizator on sol were investigated. Laser grain analyzer was used to verify nano-particles in the sol. The photocatalytic degradation ratio and antibacterial property of nano-Ag/TiO2 thin-film on ceramics were used as the main index in addition to XRD analysis. The effect of film layers, embedding Ag+, annealing temperature and time on the degradation ratio and antibacterial property was studied. The temperature 30-80 ℃, pH 1.2-2.0, concentrations of 0.05-0.3 mol/L sol and 5% HNO3 would be the optimal parameters for the TiO2 water-sol preparation. The nano-Ag/TiO2 film of three layers with 3% AgNO3 embedded and treated at 350 ℃ for 2 h exhibits good performance. The elementary research on the kinetics of degradation shows that the reactions are on the first order kinetics equation.展开更多
Silver nano-particles with average diameter of about 60 nm were compacted in a high-strength mold under different pressures at 523 K to produce nano-structured Ag solid materials. The structure and characteristic of t...Silver nano-particles with average diameter of about 60 nm were compacted in a high-strength mold under different pressures at 523 K to produce nano-structured Ag solid materials. The structure and characteristic of the nano-structured Ag solid materials (NSS-Ag) were studied using X-ray diffraction (XRD), scanning electron microscope (SEM) and Raman spectrometer. The NSS-Ag could be used as highly efficient surface-enhanced Raman scattering (SERS) active substrates. The common probe molecules Rhodamine 6G (R6G, 1×10-10 mol/L) were used to test the SERS activity on these substrates at very low concentrations. It is found that the SERS enhancement ability is dependent on the density of NSS-Ag. When the relative density of NSS-Ag is 83.87%, the materials reveal great SERS signal.展开更多
The mechanical properties of magnesium matrix composties can be further improved by aging treatment. To study the aging behavior of SiC particles reinforced AZ61 magnesium matrix composites fabricated by ultrasonic me...The mechanical properties of magnesium matrix composties can be further improved by aging treatment. To study the aging behavior of SiC particles reinforced AZ61 magnesium matrix composites fabricated by ultrasonic method, an investigation has been undertaken by means of Vickers hardness measurement, scanning electron microscopy (SEM) and energy spectrum analyzing apparatus. The box-type heat treatment furnace was used in the study. The results showed that no discontinuous cellular precipitation is observed at the grain boundaries in the magnesium matrix of the composite while the Mg17Al12 preferentially precipitates in the matrix. The time to reach the peak hardness for AZ61 alloy or SiCp/AZ61 magnesium matrix composites is reduced with the increase of aging temperature. At the same temperature, the composite exhibit an accelerated aging manner but lower aging efficiency, compared with the unreinforced matrix alloy. The microhardness of the composite is higher than that of the unreinforced matrix alloy, because that the SiC particles distributes homogeneously in the matrix alloy under the ultrasonic processing condition.展开更多
Nano-silver/polyvinylpyrrolidone(PVP)composite materials were successfully synthesized bi-insitu from silver nitrate solution with N-vinyl pyrrolidone (NVP) monomer,containing neither initiator nor reductant, in ultra...Nano-silver/polyvinylpyrrolidone(PVP)composite materials were successfully synthesized bi-insitu from silver nitrate solution with N-vinyl pyrrolidone (NVP) monomer,containing neither initiator nor reductant, in ultraviolet irradiation conditions.The resultant Ag/PVP nanocomposites were characterized by infrared spectroscopy (FT-IR), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD).TEM show that nano silver particles are homogeneously dispersed in PVP polymer matrix, and the mean size of spherical silver particles is about 5 nm.The spectroscopy of XPS and FTIR showed that there is an interaction between nano silver not only with carbonyl oxygen but also with the nitrogen group within the NVP molecule through the p-π conjugation effect in the nano-silver/PVP composites system.展开更多
The thermal performance of nano fluid containing Ag NPs with different stabilizers was studied in detail. The wall temperature distributions of the heat pipe containing pure water and a small amount of PAN/Ag, PVP/Ag,...The thermal performance of nano fluid containing Ag NPs with different stabilizers was studied in detail. The wall temperature distributions of the heat pipe containing pure water and a small amount of PAN/Ag, PVP/Ag, L-cys/Ag, and OA/Ag were determined, respectively. With the addition of a small amount ofAg NPs in the pure water, the heat pipe wall temperature became lower than that of pipes filled with pure water. The efficiency under the same conditions was ranked as PVP/Ag 〉 L-cys/Ag 〉 PAN/Ag 〉 OA/ Ag. After adding a small amount of CNT in the mixture, the effect was enhanced further. As more CNT became dispersed in the working fluid, the opposite effect was observed. Therefore, the optimal amount is 4 mg/L CNT in nano-fluid. Ag nano fluid could form the multi-scaled surface with higher wettability and spreadability. The wettability of nano-fluid was improved with the addition of a small amount of CNT in the mixture. However, the spreadability of the mixture would decrease significantly in the presence of more CNT.展开更多
Theoretical dependence of the quantum yields on the size of Ag nano particle distribution from 0.8 nm to 37 nm embedded in BaO semiconductor is discussed. The calculation results show that the increase in Ag nano part...Theoretical dependence of the quantum yields on the size of Ag nano particle distribution from 0.8 nm to 37 nm embedded in BaO semiconductor is discussed. The calculation results show that the increase in Ag nano particle diameter leads to the increase of the quantum yield threshold and the emergence of the rough Gaussian form, the results also show that the greater increase in Ag nano particle diameter causes the emergence of the exact Gaussian form and makes the peaks rise up.展开更多
基金Projects(04GK2007,2007CK3075 ) supported by Industrial Key Project of Science and Technology of Hunan Province, China
文摘Steady TiO2 water-sol was prepared by peptization and the effects of pH value, temperature, concentration of colloid and peptizator on sol were investigated. Laser grain analyzer was used to verify nano-particles in the sol. The photocatalytic degradation ratio and antibacterial property of nano-Ag/TiO2 thin-film on ceramics were used as the main index in addition to XRD analysis. The effect of film layers, embedding Ag+, annealing temperature and time on the degradation ratio and antibacterial property was studied. The temperature 30-80 ℃, pH 1.2-2.0, concentrations of 0.05-0.3 mol/L sol and 5% HNO3 would be the optimal parameters for the TiO2 water-sol preparation. The nano-Ag/TiO2 film of three layers with 3% AgNO3 embedded and treated at 350 ℃ for 2 h exhibits good performance. The elementary research on the kinetics of degradation shows that the reactions are on the first order kinetics equation.
基金Project(10804101) supported by the National Natural Science Foundation of ChinaProject(2007CB815102) supported by the National Basic Research Program of ChinaProject(2007B08007) supported by the Science and Technology Development Foundation of Chinese Academy of Engineering Physics
文摘Silver nano-particles with average diameter of about 60 nm were compacted in a high-strength mold under different pressures at 523 K to produce nano-structured Ag solid materials. The structure and characteristic of the nano-structured Ag solid materials (NSS-Ag) were studied using X-ray diffraction (XRD), scanning electron microscope (SEM) and Raman spectrometer. The NSS-Ag could be used as highly efficient surface-enhanced Raman scattering (SERS) active substrates. The common probe molecules Rhodamine 6G (R6G, 1×10-10 mol/L) were used to test the SERS activity on these substrates at very low concentrations. It is found that the SERS enhancement ability is dependent on the density of NSS-Ag. When the relative density of NSS-Ag is 83.87%, the materials reveal great SERS signal.
基金financially supported by the National Natural Science Foundation of China(Grant No.50765005)supported by the Innovative Group of Science and Technology of Colleges,Jiangxi Province,China(00008713)
文摘The mechanical properties of magnesium matrix composties can be further improved by aging treatment. To study the aging behavior of SiC particles reinforced AZ61 magnesium matrix composites fabricated by ultrasonic method, an investigation has been undertaken by means of Vickers hardness measurement, scanning electron microscopy (SEM) and energy spectrum analyzing apparatus. The box-type heat treatment furnace was used in the study. The results showed that no discontinuous cellular precipitation is observed at the grain boundaries in the magnesium matrix of the composite while the Mg17Al12 preferentially precipitates in the matrix. The time to reach the peak hardness for AZ61 alloy or SiCp/AZ61 magnesium matrix composites is reduced with the increase of aging temperature. At the same temperature, the composite exhibit an accelerated aging manner but lower aging efficiency, compared with the unreinforced matrix alloy. The microhardness of the composite is higher than that of the unreinforced matrix alloy, because that the SiC particles distributes homogeneously in the matrix alloy under the ultrasonic processing condition.
文摘Nano-silver/polyvinylpyrrolidone(PVP)composite materials were successfully synthesized bi-insitu from silver nitrate solution with N-vinyl pyrrolidone (NVP) monomer,containing neither initiator nor reductant, in ultraviolet irradiation conditions.The resultant Ag/PVP nanocomposites were characterized by infrared spectroscopy (FT-IR), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD).TEM show that nano silver particles are homogeneously dispersed in PVP polymer matrix, and the mean size of spherical silver particles is about 5 nm.The spectroscopy of XPS and FTIR showed that there is an interaction between nano silver not only with carbonyl oxygen but also with the nitrogen group within the NVP molecule through the p-π conjugation effect in the nano-silver/PVP composites system.
基金Funded by the Program of Introducing Talents of Discipline to Universities(No.B13009)
文摘The thermal performance of nano fluid containing Ag NPs with different stabilizers was studied in detail. The wall temperature distributions of the heat pipe containing pure water and a small amount of PAN/Ag, PVP/Ag, L-cys/Ag, and OA/Ag were determined, respectively. With the addition of a small amount ofAg NPs in the pure water, the heat pipe wall temperature became lower than that of pipes filled with pure water. The efficiency under the same conditions was ranked as PVP/Ag 〉 L-cys/Ag 〉 PAN/Ag 〉 OA/ Ag. After adding a small amount of CNT in the mixture, the effect was enhanced further. As more CNT became dispersed in the working fluid, the opposite effect was observed. Therefore, the optimal amount is 4 mg/L CNT in nano-fluid. Ag nano fluid could form the multi-scaled surface with higher wettability and spreadability. The wettability of nano-fluid was improved with the addition of a small amount of CNT in the mixture. However, the spreadability of the mixture would decrease significantly in the presence of more CNT.
文摘Theoretical dependence of the quantum yields on the size of Ag nano particle distribution from 0.8 nm to 37 nm embedded in BaO semiconductor is discussed. The calculation results show that the increase in Ag nano particle diameter leads to the increase of the quantum yield threshold and the emergence of the rough Gaussian form, the results also show that the greater increase in Ag nano particle diameter causes the emergence of the exact Gaussian form and makes the peaks rise up.
