The pollution characteristics of Cd,Cr,Cu,Zn,Ni and Hg in agricultural soil around coal mining area were studied. After longterm mining activity,the soil around mining area was polluted by 6 elements to different degr...The pollution characteristics of Cd,Cr,Cu,Zn,Ni and Hg in agricultural soil around coal mining area were studied. After longterm mining activity,the soil around mining area was polluted by 6 elements to different degrees. Especially for Cd,its concentration was 3. 2times that of the National Soil Environmental Quality Standard Ⅱ. The values suggest that the contamination degree from strong to weak in soil is in the order of Hg > Cu > Cr > Zn > Ni > Cd. BCR sequential extraction results show that the order of average percentage about weak acid soluble fraction( F1) is that Cd > Ni > Zn > Cu > Hg > Cr,the order of 6 heavy metals available fraction( F1 + F2 + F3) is that Cu( 56. 89) > Cd( 50. 95) > Ni( 41. 52) > Zn( 35. 06) > Hg( 23. 04) > Cr( 4. 88). The RAC results indicate that soils were in a moderate potential ecological risk by pollution of Cd,and at the same time,Cu,Zn,Ni,Hg should be noted.展开更多
To solve the pollution problem of insulators on ultra-high voltage DC transmission lines,superhydrophobic coatings were presented and their pollution deposit morphology and pollution flashover voltage in electric fiel...To solve the pollution problem of insulators on ultra-high voltage DC transmission lines,superhydrophobic coatings were presented and their pollution deposit morphology and pollution flashover voltage in electric field were studied by an artificial pollution deposit system.The experimental results show that the pollution on the surface of super-hydrophobic coating is distributed in clusters,which inhibits the chain distribution on the surface of silicone rubber and improves the pollution flashover voltage.Secondly,the competition mechanism of the pollution flashover on the superhydrophobic coating surface was found.This competition mechanism can lead to the failure of the insulation performance of the superhydrophobic coating in severely polluted environments.Finally,a pollution flashover model of superhydrophobic coating is proposed to explain the competition mechanism,which is affected by pollution and the discrete droplets.The conclusions of this study can provide an experimental and theoretical basis for the application of the superhydrophobic coating in the field of UHV DC external insulation.展开更多
Carbon/aluminium(C/Al)composites have the advantages of low density and high electrical conductivity,which have potential applications in aerospace,rail transportation and other fields.However,the unstable bonding of ...Carbon/aluminium(C/Al)composites have the advantages of low density and high electrical conductivity,which have potential applications in aerospace,rail transportation and other fields.However,the unstable bonding of the C/Al interface and significant thermal expansion differences have resulted in risks of the composites'failure once suffering from severe thermal shock.In this work,the C/Al composites were prepared by the pressure impregnation method,and silicon(Si)was added to overcome the problems of C/Al non-wettability and thermal expansion differences.The effects of mass fractions of doped silicon on the mechanical properties,electrical conductivity and thermal shock resistance of C/Al composites were also examined.Results show that the formed SiC interlayer has effectively enhanced the interfacial bonding and reduced the differences in the thermal expansion coefficient of each component.As a result,the thermal shock resistance of the composites has been remarkably improved,and the flexural strength could remain 90%of the original level after the thermal shock test,compared with 50%of that without Si doping.展开更多
基金Supported by Project for Social Development of Guizhou Province(SY20103013)
文摘The pollution characteristics of Cd,Cr,Cu,Zn,Ni and Hg in agricultural soil around coal mining area were studied. After longterm mining activity,the soil around mining area was polluted by 6 elements to different degrees. Especially for Cd,its concentration was 3. 2times that of the National Soil Environmental Quality Standard Ⅱ. The values suggest that the contamination degree from strong to weak in soil is in the order of Hg > Cu > Cr > Zn > Ni > Cd. BCR sequential extraction results show that the order of average percentage about weak acid soluble fraction( F1) is that Cd > Ni > Zn > Cu > Hg > Cr,the order of 6 heavy metals available fraction( F1 + F2 + F3) is that Cu( 56. 89) > Cd( 50. 95) > Ni( 41. 52) > Zn( 35. 06) > Hg( 23. 04) > Cr( 4. 88). The RAC results indicate that soils were in a moderate potential ecological risk by pollution of Cd,and at the same time,Cu,Zn,Ni,Hg should be noted.
基金National Natural Science Foundation of China,Grant/Award Numbers:51837009,51907168Excellent Youth Foundation of Si’chuan Scientific Committee of China,Grant/Award Number:2020JDJQ0039。
文摘To solve the pollution problem of insulators on ultra-high voltage DC transmission lines,superhydrophobic coatings were presented and their pollution deposit morphology and pollution flashover voltage in electric field were studied by an artificial pollution deposit system.The experimental results show that the pollution on the surface of super-hydrophobic coating is distributed in clusters,which inhibits the chain distribution on the surface of silicone rubber and improves the pollution flashover voltage.Secondly,the competition mechanism of the pollution flashover on the superhydrophobic coating surface was found.This competition mechanism can lead to the failure of the insulation performance of the superhydrophobic coating in severely polluted environments.Finally,a pollution flashover model of superhydrophobic coating is proposed to explain the competition mechanism,which is affected by pollution and the discrete droplets.The conclusions of this study can provide an experimental and theoretical basis for the application of the superhydrophobic coating in the field of UHV DC external insulation.
基金National Natural Science Foundation of China,Grant/Award Numbers:52077182,51837009,U19A20105Fundamental Research Funds for the Central Universities,Grant/Award Number:2682018CX17+1 种基金National Rail Transit Electrification and Automation Engineering Technology Research ProjectChengdu Guojia Electrical Engineering Co.Ltd,Grant/Award Number:NEEC-2018-B06。
文摘Carbon/aluminium(C/Al)composites have the advantages of low density and high electrical conductivity,which have potential applications in aerospace,rail transportation and other fields.However,the unstable bonding of the C/Al interface and significant thermal expansion differences have resulted in risks of the composites'failure once suffering from severe thermal shock.In this work,the C/Al composites were prepared by the pressure impregnation method,and silicon(Si)was added to overcome the problems of C/Al non-wettability and thermal expansion differences.The effects of mass fractions of doped silicon on the mechanical properties,electrical conductivity and thermal shock resistance of C/Al composites were also examined.Results show that the formed SiC interlayer has effectively enhanced the interfacial bonding and reduced the differences in the thermal expansion coefficient of each component.As a result,the thermal shock resistance of the composites has been remarkably improved,and the flexural strength could remain 90%of the original level after the thermal shock test,compared with 50%of that without Si doping.
