A water-conducting polyacrylamide/montmorillonite coating was prepared by solutionblending.The coating was coated on fiber and then composited with polymer to form a composite film material that used for water saving ...A water-conducting polyacrylamide/montmorillonite coating was prepared by solutionblending.The coating was coated on fiber and then composited with polymer to form a composite film material that used for water saving and tree planting in arid and desert regions.The coating＇s water-conducting characteristics and dynamic self-adjusting behavior were investigated by Fourier transform infrared（FTIR）spectroscopy,thermal analysis（TG-DTA）,and environmental scanning electron microscopy（ESEM）.The results showed that the coating＇s water-conducting rate increased but water-retention capacity weakened with increasing montmorillonite content.The water-loss rate was positively related to temperature and negatively related to soil moisture.Water potential greatly influenced the water-conducting rate of the coating during its water conduction process.When the coating was at a low water potential,the montmorillonite particles interconnected and water was conducted quickly via montmorillonite layers,whereas when the coating was at a high potential,the montmorillonite particles disconnected and water was conducted slowly via the swelled polyacrylamide net structure.The rate can be regulated by changing the proportion of polyacrylamide and montmorillonite to guarantee a reasonable water supply for trees and make trees easier to survive.Thus,the survival rate of trees can be increased and the use of water resources can be significantly reduced.展开更多
In order to improve the oxidation resistance of Ti Al alloy, silicide coatings were prepared by pack cementation method at 1273, 1323, and 1373 K for 1-3 hours. Scanning electron microscopy（SEM）, energy dispersive s...In order to improve the oxidation resistance of Ti Al alloy, silicide coatings were prepared by pack cementation method at 1273, 1323, and 1373 K for 1-3 hours. Scanning electron microscopy（SEM）, energy dispersive spectrometry（EDS） and X-ray diffraction（XRD） were employed to investigate the microstructures and phase constitutions of the coatings. The experimental results show that all silicon deposition coatings have multi-layer structure. The microstructure and composition of silicide coatings strongly depend on siliconizing temperatures. In order to investigate the rate controlling step of pack siliconizing on Ti Al alloy, coating growth kinetics was analyzed by measuring the mass gains per unit area of silicided samples as a function of time and temperature. The results showed that the rate controlling step was gas-phase diffusion step and the growth rate constant（k） ranged from 1.53 mg^2/（cm^4·h^2） to 2.3 mg^2/（cm^4·h^2）. Activation energy（Q） for the process was calculated as 109 k J/mol, determined by Arrhenius＇ equation： k = k0 exp[–Q/（RT）].展开更多
An in situ method was designed to measure a continuous open circuit potential （OCP） curve of AZ31 magnesium alloy and to observe the morphology variation of Ni-P coating during the process of the electroless plating...An in situ method was designed to measure a continuous open circuit potential （OCP） curve of AZ31 magnesium alloy and to observe the morphology variation of Ni-P coating during the process of the electroless plating. The deposition mechanism of the electroless Ni-P plating on AZ31 Mg alloy was studied by OCP curve, scanning electron microscopy （SEM）, and energy dispersion spectroscopy （EDS）. The process of electroless Ni-P plating contains the coating formation stage and the coating growth stage. The formation stage includes three procedures, i.e., the nucleation and growth of Ni crystallites, the extension of the coating in two-dimensional （2D） direction and the coalescence of the coating along three-dimensional （3D） direction. SEM investigations demonstrate that the spherical nodules of the Ni-P coating are not only formed during the coating growth stage, but also generated in the initial deposition stage of electroless Ni-P plating. The variation of the coating rates at different deposition stages corresponds to the deposition mechanism of their respective deposition stage.展开更多
基金Funded by the National Science Foundation of China(No.50772131)the National High-tech R&D Program of China(863Program)(No.2011AA322100)+1 种基金the Key Project of Chinese Ministry of Education(No.106086)the Fundmental Research Funds for the Central Universities(No.2010YJ05)
文摘A water-conducting polyacrylamide/montmorillonite coating was prepared by solutionblending.The coating was coated on fiber and then composited with polymer to form a composite film material that used for water saving and tree planting in arid and desert regions.The coating＇s water-conducting characteristics and dynamic self-adjusting behavior were investigated by Fourier transform infrared（FTIR）spectroscopy,thermal analysis（TG-DTA）,and environmental scanning electron microscopy（ESEM）.The results showed that the coating＇s water-conducting rate increased but water-retention capacity weakened with increasing montmorillonite content.The water-loss rate was positively related to temperature and negatively related to soil moisture.Water potential greatly influenced the water-conducting rate of the coating during its water conduction process.When the coating was at a low water potential,the montmorillonite particles interconnected and water was conducted quickly via montmorillonite layers,whereas when the coating was at a high potential,the montmorillonite particles disconnected and water was conducted slowly via the swelled polyacrylamide net structure.The rate can be regulated by changing the proportion of polyacrylamide and montmorillonite to guarantee a reasonable water supply for trees and make trees easier to survive.Thus,the survival rate of trees can be increased and the use of water resources can be significantly reduced.
基金Funded by the Natural Science Program for Basic Research in Key Areas of Shaanxi Province(2014JZ012)
文摘In order to improve the oxidation resistance of Ti Al alloy, silicide coatings were prepared by pack cementation method at 1273, 1323, and 1373 K for 1-3 hours. Scanning electron microscopy（SEM）, energy dispersive spectrometry（EDS） and X-ray diffraction（XRD） were employed to investigate the microstructures and phase constitutions of the coatings. The experimental results show that all silicon deposition coatings have multi-layer structure. The microstructure and composition of silicide coatings strongly depend on siliconizing temperatures. In order to investigate the rate controlling step of pack siliconizing on Ti Al alloy, coating growth kinetics was analyzed by measuring the mass gains per unit area of silicided samples as a function of time and temperature. The results showed that the rate controlling step was gas-phase diffusion step and the growth rate constant（k） ranged from 1.53 mg^2/（cm^4·h^2） to 2.3 mg^2/（cm^4·h^2）. Activation energy（Q） for the process was calculated as 109 k J/mol, determined by Arrhenius＇ equation： k = k0 exp[–Q/（RT）].
基金Project supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD), China
文摘An in situ method was designed to measure a continuous open circuit potential （OCP） curve of AZ31 magnesium alloy and to observe the morphology variation of Ni-P coating during the process of the electroless plating. The deposition mechanism of the electroless Ni-P plating on AZ31 Mg alloy was studied by OCP curve, scanning electron microscopy （SEM）, and energy dispersion spectroscopy （EDS）. The process of electroless Ni-P plating contains the coating formation stage and the coating growth stage. The formation stage includes three procedures, i.e., the nucleation and growth of Ni crystallites, the extension of the coating in two-dimensional （2D） direction and the coalescence of the coating along three-dimensional （3D） direction. SEM investigations demonstrate that the spherical nodules of the Ni-P coating are not only formed during the coating growth stage, but also generated in the initial deposition stage of electroless Ni-P plating. The variation of the coating rates at different deposition stages corresponds to the deposition mechanism of their respective deposition stage.
