The advancement of next-generation high-frequency communication systems and stealth detection technologies necessitate the development of efficient,multi-spectrum compatible shielding materials.However,the achievement...The advancement of next-generation high-frequency communication systems and stealth detection technologies necessitate the development of efficient,multi-spectrum compatible shielding materials.However,the achievement of simultaneous high efficiency and low reflectivity across microwave,terahertz,and infrared spectra remains a formidable challenge.Herein,a carbonized MXene/polyimide(C-MXene/PI)aerogel material integrating a spatially coupled hierarchically anisotropic structure with stepwise conductivity gradients was constructed.Electromagnetic waves propagate through the top-down vertical disordered horizontal architecture and progressive conductivity gradient of C-MXene/PI aerogel,undergoing stepwise absorption-dissipation-re-dissipation processes.The C-MXene/PI aerogel exhibits an average electromagnetic interference(EMI)shielding effectiveness of91.0 dB in X-band and a reflection coefficient of 0.40.In the terahertz frequency band,the average EMI shielding performance reaches66.2 dB with a reflection coefficient of 0.33.Furthermore,the heterolayered porous architecture of C-MXene/PI aerogels exhibits low thermal conductivity and reduced infrared emissivity,enabling exceptional infrared stealth capability across the 2-16μm wavelength spectrum.This study provides an feasible strategy for constructing low-reflectivity multi-spectrum compatible shielding materials.展开更多
SrTiO_(3)/ZnTiO_(3)heterolayered thin films were fabricated by spin coating Sr-Ti and Zn-Ti sol-gel precursors on fused silica substrate.The SrTiO_(3)and ZnTiO_(3)were coated alternatively to form ABAB heterolayered t...SrTiO_(3)/ZnTiO_(3)heterolayered thin films were fabricated by spin coating Sr-Ti and Zn-Ti sol-gel precursors on fused silica substrate.The SrTiO_(3)and ZnTiO_(3)were coated alternatively to form ABAB heterolayered thin films.The thickness of individual layers was tailored by controlling the coating layers.The structure characterization of the thin films showed independent structure of each layer while the microwave dielectric properties and optical band gaps can be tuned by changing the layer configuration.The effects of the layer configuration on the dielectric and optical properties were studied.展开更多
Tribological applications of polytetrafluoroethylene(PTFE)are often limited by technological complexity to overcome its poor wear resistance.Here,a PTFE/polyetheretherketone(PEEK)heterolayer(HL)was proposed and evalua...Tribological applications of polytetrafluoroethylene(PTFE)are often limited by technological complexity to overcome its poor wear resistance.Here,a PTFE/polyetheretherketone(PEEK)heterolayer(HL)was proposed and evaluated as a new solid lubrication solution.Pin-on-disk tribometry found the lowest friction coefficient(μ)of 0.031 and ultralow wear for the PEEK/HL under typical conditions.The friction coefficient of the HL surpasses those of the state-of-the-art polymeric coatings/composites by at least 200%,and approaches that of highly lubricated interfaces.Mechanistic investigations revealed multi-length physical and chemical heterogeneity of the HL that best facilitates a tribofilm with high subsurface stability and surface instability.The technological simplicity and robustness of the HL’s high lubricity make it a promising new type of solid lubrication toward greater reliability and longevity.展开更多
基金supported by the Fundamental Research Funds for the Central Universities under No.2024KQ130the National Natural Science Foundation of China(No.52373259)。
文摘The advancement of next-generation high-frequency communication systems and stealth detection technologies necessitate the development of efficient,multi-spectrum compatible shielding materials.However,the achievement of simultaneous high efficiency and low reflectivity across microwave,terahertz,and infrared spectra remains a formidable challenge.Herein,a carbonized MXene/polyimide(C-MXene/PI)aerogel material integrating a spatially coupled hierarchically anisotropic structure with stepwise conductivity gradients was constructed.Electromagnetic waves propagate through the top-down vertical disordered horizontal architecture and progressive conductivity gradient of C-MXene/PI aerogel,undergoing stepwise absorption-dissipation-re-dissipation processes.The C-MXene/PI aerogel exhibits an average electromagnetic interference(EMI)shielding effectiveness of91.0 dB in X-band and a reflection coefficient of 0.40.In the terahertz frequency band,the average EMI shielding performance reaches66.2 dB with a reflection coefficient of 0.33.Furthermore,the heterolayered porous architecture of C-MXene/PI aerogels exhibits low thermal conductivity and reduced infrared emissivity,enabling exceptional infrared stealth capability across the 2-16μm wavelength spectrum.This study provides an feasible strategy for constructing low-reflectivity multi-spectrum compatible shielding materials.
文摘SrTiO_(3)/ZnTiO_(3)heterolayered thin films were fabricated by spin coating Sr-Ti and Zn-Ti sol-gel precursors on fused silica substrate.The SrTiO_(3)and ZnTiO_(3)were coated alternatively to form ABAB heterolayered thin films.The thickness of individual layers was tailored by controlling the coating layers.The structure characterization of the thin films showed independent structure of each layer while the microwave dielectric properties and optical band gaps can be tuned by changing the layer configuration.The effects of the layer configuration on the dielectric and optical properties were studied.
基金support from the National Natural Science Foundation of China(51875153 and 51875152)the Fundamental Research Funds for the Central Universities(JZ2021HGPA0062).
文摘Tribological applications of polytetrafluoroethylene(PTFE)are often limited by technological complexity to overcome its poor wear resistance.Here,a PTFE/polyetheretherketone(PEEK)heterolayer(HL)was proposed and evaluated as a new solid lubrication solution.Pin-on-disk tribometry found the lowest friction coefficient(μ)of 0.031 and ultralow wear for the PEEK/HL under typical conditions.The friction coefficient of the HL surpasses those of the state-of-the-art polymeric coatings/composites by at least 200%,and approaches that of highly lubricated interfaces.Mechanistic investigations revealed multi-length physical and chemical heterogeneity of the HL that best facilitates a tribofilm with high subsurface stability and surface instability.The technological simplicity and robustness of the HL’s high lubricity make it a promising new type of solid lubrication toward greater reliability and longevity.
