Magnetic shielding of grain-oriented silicon steel was investigated. Ball scribing with spacing of 2 to 16 mm was performed at peak flux densities of 8.0 mT to 1.3 T. Magnetic shielding efficiency was calculated, incl...Magnetic shielding of grain-oriented silicon steel was investigated. Ball scribing with spacing of 2 to 16 mm was performed at peak flux densities of 8.0 mT to 1.3 T. Magnetic shielding efficiency was calculated, including absorption, reflection and inner multi-reflection shielding efficiencies. Magnetic shielding efficiency （MSE） increase ratios after different scribing spacing were compared, and thickness requirement to achieve absorption shielding of 50 dB was also calculated. The results show that magnetic shielding efficiencies of C711 and H668 silicon steels increase by 4.79 and 3.15 dB respectively after scribing of 16 mm. Before scribing, shielding efficiency of H668 steel was higher than that of C711 steel, while after scribing, both absorption and shielding efficiency gaps were largely abridged between C711 and H668 steels. Plate thickness of C711 steel could be reduced from 3.18 mm without scribing to 2. 20 mm after scribing of 16 mm. There is no apparent thickness reduction at lower flux densities; while the peak flux density is above 0.3 T, the shielding effect becomes apparent, and the thickness could be reduced from 2.28 mm without scribing to 1.70 mm with scribing spacing of 16 ram. Magnetizing process and its effect on variation of magnetic shielding were also analyzed.展开更多
This study introduces a simple and cost-effective approach for modifying large organic surfaces,facilitating robust adhesion between Au films and polymethyl methacrylate(PMMA)while retaining transparency to visible li...This study introduces a simple and cost-effective approach for modifying large organic surfaces,facilitating robust adhesion between Au films and polymethyl methacrylate(PMMA)while retaining transparency to visible light and effectively shielding against electromagnetic interference(EMI).The proposed surface modification method employs a cheap low-power conventional UV lamp to illuminate organic surfaces in an open environment,rending it convenient and applicable for surfaces ranging from small to massive,irrespective of size,shape and location.By subjecting transparent PMMA glass to a brief 20–30 min exposure to a 36 W UV lamp positioned 5 cm away from the sample surface,the PMMA surface is dramatically modified and the surface is turned from hydrophobic to hydrophilic,establishing a strong adhesion between PMMA and Au films.The resulting Au/PMMA glass exhibits remarkable transparency about 70%within the visible light spectrum,coupled with an impressive EMI shielding efficiency that surpasses 20 dB across a broad range of electromagnetic wavebands,encompassing the S,C,X and Ku bands that correspond to the wave frequencies of major electromagnetic pollution and crucial applications of 5G communication,credit card validation,radar systems,traffic control,etc.Various characterizations have been conducted,elucidating the underlying mechanisms.This study presents an important advancement,and the accessible and scalable nature of the large-scalable surface modification method has far-reaching implications across numerous industrial sectors and applications,in addition to transparent EMI shielding Au/PMMA glasses.展开更多
With the widespread popularity of electronic equipment and rapid development of wireless communication technology,electromagnetic shielding materials possessing thermal insulation properties can effectively block elec...With the widespread popularity of electronic equipment and rapid development of wireless communication technology,electromagnetic shielding materials possessing thermal insulation properties can effectively block electromagnetic radiation for ensuring normal operation of electronic equipment and human health,while providing heat insulation to improve energy efficiency and protect equipment from high temperatures.In this study,we employ covalent organic skeleton(COF)to optimize Ti_(3)C_(2)T_(x)MXene layers and successfully prepare MXene@COF heterostructures.This structure maintained the unique two-dimensional architecture of Ti_(3)C_(2)T_(x)MXene while preventing aggregation and self-stacking of MXene nanosheets through the outer COF layer.The modification increases material porosity and significantly enhances electrical conductivity.We incorporated the heterostructure into acrylamidegelatin hydrogels and controlled shielding efficiency by varying COF content.Results demonstrate that the MXene@COF-based hydrogel(15 mm p-pheny lenedi amine)exhibits high toughness,strong electromagnetic shielding capability,infrared stealth performance,and thermal insulation properties.In the X-band,mechanical tests show only 3 mm in thickness and 0.90 wt%MXene@COF content,electromagnetic shielding efficiency(EMI SE)of the material is as high as 37.52 dB,and the average total electromagnetic shielding(SE_(T))is 32.01 dB,the compressive stress is 20.85 MPa,the water content is 79.04%,and the electrical conductivity is 1.22 S m^(-1).These finding soffer new possibilities for developing COF-based electromagnetic shielding materials.展开更多
Radio environment degrades significantly at Nan Shan 26 m Radio Telescope(NSRT) base due to new and upgraded electrical devices on-site and more establishment of surrounding radio communication services. How do we mit...Radio environment degrades significantly at Nan Shan 26 m Radio Telescope(NSRT) base due to new and upgraded electrical devices on-site and more establishment of surrounding radio communication services. How do we mitigate them effectively? Firstly, a quasi-real time Radio Frequency Interference(RFI) measurement method is employed for RFI detection and spectral analysis based on the layout for potential on-site interference areas and off-site radio communication services. Our investigation at the frequency bands for pulsar observations(1380–1700 MHz) indicates that transient interferences pose the greatest impact on observations. Then we use a portable RFI measurement system for interferences hunting at the NSRT, and the typical characteristics of interferences are analyzed. Secondly, based on the RFI characteristics, main interference sources in the observation room are shielded with shielding cabinets. The results from our shielding efficiency(SE) measurement and evaluation show that these methods work effectively.Furthermore, we propose a Radio Quiet Zone(RQZ) and the regulations for NSRT to mitigate off-site RFIs.展开更多
Particular properties of Ti2O and TiNx prepared by thermal decomposition were introduced. A precursor prepared by titanium powder reacting with oxalate acid was thermally decomposed in nitrogen atmosphere at 840℃ for...Particular properties of Ti2O and TiNx prepared by thermal decomposition were introduced. A precursor prepared by titanium powder reacting with oxalate acid was thermally decomposed in nitrogen atmosphere at 840℃ for 15 min, and relatively pure Ti2O was then obtained. Conductive TiNx was also prepared after altering reaction conditions. Samples were characterized by resistivity, X-ray powder diffraction, transmission electron microscope, Ultraviolet-Visible diffuse reflection, and electromagnetic shielding efficiency. The results indicate that both Ti2O and TiNx have good conductivity. Moreover, Ti2O shows a better solar photocatalytic activity and TiNx does well in the electromagnetic shield.展开更多
Transparent electromagnetic(EM)shielding glass with a metal mesh has significant potential for application in different fields of EM radiation and anti-EM interference light-transmitting observation windows.In particu...Transparent electromagnetic(EM)shielding glass with a metal mesh has significant potential for application in different fields of EM radiation and anti-EM interference light-transmitting observation windows.In particular,a transparent EM-shielding glass with a large-aspect-ratio metal mesh can effectively alleviate the contradictory problems of shielding effectiveness and light-transmission performance constraints.However,the fabrication of high-aspect-ratio metal meshes on glass substrates has problems such as high cost,complex processes,low efficiency,small area,and easy damage issues,which limit their application in the field of high-performance,transparent EM-shielding glass.Therefore,this paper proposes a composite additive manufacturing process based on electric-field-driven microjet 3D printing and electroplating.By fabricating metal meshes with an Ag-Cu core-shell structure on a glass substrate,EM-shielding glass with high shielding efficiency and light transmission can be manufactured without increasing the aspect ratio of the metal meshes.The prepared Ag-Cu composite metal mesh has excellent optoelectronic properties(period 250𝜇m,line width 10𝜇m,90.1%transmission at 550 nm visible light,square resistance 0.21Ω/sq),efficient electrothermal effect(3 V DC voltage can reach 189°C steady-state temperature),stable EM-shielding effectiveness(average shielding effectiveness 23 dB at X-band),and acceptable mechanical and environmental stability(less than 3%change in square resistance after 150-times adhesion test and less than 6%and 0.6%change in resistance after 72 h in acid and alkali environments,respectively).This method provides a new solution for the mass production of high-performance large-area transparent electric heating/EM-shielding glass.展开更多
基金Item Sponsored by National Natural Science Foundation of China(51174057,51274062)National High Technology Research and Development Program of China(2012AA03A503)
文摘Magnetic shielding of grain-oriented silicon steel was investigated. Ball scribing with spacing of 2 to 16 mm was performed at peak flux densities of 8.0 mT to 1.3 T. Magnetic shielding efficiency was calculated, including absorption, reflection and inner multi-reflection shielding efficiencies. Magnetic shielding efficiency （MSE） increase ratios after different scribing spacing were compared, and thickness requirement to achieve absorption shielding of 50 dB was also calculated. The results show that magnetic shielding efficiencies of C711 and H668 silicon steels increase by 4.79 and 3.15 dB respectively after scribing of 16 mm. Before scribing, shielding efficiency of H668 steel was higher than that of C711 steel, while after scribing, both absorption and shielding efficiency gaps were largely abridged between C711 and H668 steels. Plate thickness of C711 steel could be reduced from 3.18 mm without scribing to 2. 20 mm after scribing of 16 mm. There is no apparent thickness reduction at lower flux densities; while the peak flux density is above 0.3 T, the shielding effect becomes apparent, and the thickness could be reduced from 2.28 mm without scribing to 1.70 mm with scribing spacing of 16 ram. Magnetizing process and its effect on variation of magnetic shielding were also analyzed.
基金financial supports from the National Youth Science Funds of China(Grant No.52302172)The State Key Program of National Natural Science of China(Grant No.52032004),。
文摘This study introduces a simple and cost-effective approach for modifying large organic surfaces,facilitating robust adhesion between Au films and polymethyl methacrylate(PMMA)while retaining transparency to visible light and effectively shielding against electromagnetic interference(EMI).The proposed surface modification method employs a cheap low-power conventional UV lamp to illuminate organic surfaces in an open environment,rending it convenient and applicable for surfaces ranging from small to massive,irrespective of size,shape and location.By subjecting transparent PMMA glass to a brief 20–30 min exposure to a 36 W UV lamp positioned 5 cm away from the sample surface,the PMMA surface is dramatically modified and the surface is turned from hydrophobic to hydrophilic,establishing a strong adhesion between PMMA and Au films.The resulting Au/PMMA glass exhibits remarkable transparency about 70%within the visible light spectrum,coupled with an impressive EMI shielding efficiency that surpasses 20 dB across a broad range of electromagnetic wavebands,encompassing the S,C,X and Ku bands that correspond to the wave frequencies of major electromagnetic pollution and crucial applications of 5G communication,credit card validation,radar systems,traffic control,etc.Various characterizations have been conducted,elucidating the underlying mechanisms.This study presents an important advancement,and the accessible and scalable nature of the large-scalable surface modification method has far-reaching implications across numerous industrial sectors and applications,in addition to transparent EMI shielding Au/PMMA glasses.
基金financially supported by the National Natural Science Foundation of China(No.52163001)Guizhou Provincial Science and Technology Program Project(Nos.Qiankehe Platform Talents-CXTD[2021]005,Qiankehe Platform Talents-GCC[2022]010-1,Qiankehe Platform TalentsGCC[2023]035,Qiankehe Platform Talents-CXTD[2023]003 and Qiankehe Platform Talents-KXJZ[2024]022)+3 种基金Guizhou Minzu University Research Platform(No.GZMUGCZX[2021]01)the Central Guided Local Science and Technology Development Funds Project(No.Qiankehe Zhong Yindi[2023]035)the Doctor Startup Fund of Guizhou Minzu University(No.GZMUZK[2024]QD77)Guizhou Province Special Fund for innovative capacity building of scientific research institutions(Nos.Qiankehe Fuqi[2023]001 and Qiankehe Fuqi[2024]002-1)
文摘With the widespread popularity of electronic equipment and rapid development of wireless communication technology,electromagnetic shielding materials possessing thermal insulation properties can effectively block electromagnetic radiation for ensuring normal operation of electronic equipment and human health,while providing heat insulation to improve energy efficiency and protect equipment from high temperatures.In this study,we employ covalent organic skeleton(COF)to optimize Ti_(3)C_(2)T_(x)MXene layers and successfully prepare MXene@COF heterostructures.This structure maintained the unique two-dimensional architecture of Ti_(3)C_(2)T_(x)MXene while preventing aggregation and self-stacking of MXene nanosheets through the outer COF layer.The modification increases material porosity and significantly enhances electrical conductivity.We incorporated the heterostructure into acrylamidegelatin hydrogels and controlled shielding efficiency by varying COF content.Results demonstrate that the MXene@COF-based hydrogel(15 mm p-pheny lenedi amine)exhibits high toughness,strong electromagnetic shielding capability,infrared stealth performance,and thermal insulation properties.In the X-band,mechanical tests show only 3 mm in thickness and 0.90 wt%MXene@COF content,electromagnetic shielding efficiency(EMI SE)of the material is as high as 37.52 dB,and the average total electromagnetic shielding(SE_(T))is 32.01 dB,the compressive stress is 20.85 MPa,the water content is 79.04%,and the electrical conductivity is 1.22 S m^(-1).These finding soffer new possibilities for developing COF-based electromagnetic shielding materials.
基金Supported by Chinese Academy of Sciences(CAS)“Light of West China” ProgramThe National Natural Science Foundation(11973077,11473061)The Operation,Maintenance and Upgrading Fund for Astronomical Telescopes and Facility Instruments,budgeted from the Ministry of Finance of China(MOF)and administrated by the CAS
文摘Radio environment degrades significantly at Nan Shan 26 m Radio Telescope(NSRT) base due to new and upgraded electrical devices on-site and more establishment of surrounding radio communication services. How do we mitigate them effectively? Firstly, a quasi-real time Radio Frequency Interference(RFI) measurement method is employed for RFI detection and spectral analysis based on the layout for potential on-site interference areas and off-site radio communication services. Our investigation at the frequency bands for pulsar observations(1380–1700 MHz) indicates that transient interferences pose the greatest impact on observations. Then we use a portable RFI measurement system for interferences hunting at the NSRT, and the typical characteristics of interferences are analyzed. Secondly, based on the RFI characteristics, main interference sources in the observation room are shielded with shielding cabinets. The results from our shielding efficiency(SE) measurement and evaluation show that these methods work effectively.Furthermore, we propose a Radio Quiet Zone(RQZ) and the regulations for NSRT to mitigate off-site RFIs.
基金financially supported by the Science Fund from Tongji University (No. 1380219042)
文摘Particular properties of Ti2O and TiNx prepared by thermal decomposition were introduced. A precursor prepared by titanium powder reacting with oxalate acid was thermally decomposed in nitrogen atmosphere at 840℃ for 15 min, and relatively pure Ti2O was then obtained. Conductive TiNx was also prepared after altering reaction conditions. Samples were characterized by resistivity, X-ray powder diffraction, transmission electron microscope, Ultraviolet-Visible diffuse reflection, and electromagnetic shielding efficiency. The results indicate that both Ti2O and TiNx have good conductivity. Moreover, Ti2O shows a better solar photocatalytic activity and TiNx does well in the electromagnetic shield.
基金supported by National Natural Science Foundation of China(Grant No.52175331)Shandong Provincial National Natural Science Foundation of China(Grant Nos.ZR2020ZD04,ZR2022ME014,ZR2022QE077)Support Plan for Outstanding Youth Innovation Team in Universities of Shandong Province of China(Grant No.2020KJB003).
文摘Transparent electromagnetic(EM)shielding glass with a metal mesh has significant potential for application in different fields of EM radiation and anti-EM interference light-transmitting observation windows.In particular,a transparent EM-shielding glass with a large-aspect-ratio metal mesh can effectively alleviate the contradictory problems of shielding effectiveness and light-transmission performance constraints.However,the fabrication of high-aspect-ratio metal meshes on glass substrates has problems such as high cost,complex processes,low efficiency,small area,and easy damage issues,which limit their application in the field of high-performance,transparent EM-shielding glass.Therefore,this paper proposes a composite additive manufacturing process based on electric-field-driven microjet 3D printing and electroplating.By fabricating metal meshes with an Ag-Cu core-shell structure on a glass substrate,EM-shielding glass with high shielding efficiency and light transmission can be manufactured without increasing the aspect ratio of the metal meshes.The prepared Ag-Cu composite metal mesh has excellent optoelectronic properties(period 250𝜇m,line width 10𝜇m,90.1%transmission at 550 nm visible light,square resistance 0.21Ω/sq),efficient electrothermal effect(3 V DC voltage can reach 189°C steady-state temperature),stable EM-shielding effectiveness(average shielding effectiveness 23 dB at X-band),and acceptable mechanical and environmental stability(less than 3%change in square resistance after 150-times adhesion test and less than 6%and 0.6%change in resistance after 72 h in acid and alkali environments,respectively).This method provides a new solution for the mass production of high-performance large-area transparent electric heating/EM-shielding glass.
