Fibrous porous ceramics are attractive for use as thermal insulation materials.However,the intrinsic brit-tleness of rigid materials has remained challenging and severely restricts their applications.Here,we demonstra...Fibrous porous ceramics are attractive for use as thermal insulation materials.However,the intrinsic brit-tleness of rigid materials has remained challenging and severely restricts their applications.Here,we demonstrated a facile method for fabricating elastic fibrous porous ceramics(EFPCs)with high com-pressive strength and low thermal conductivity through ordinary press filtration and subsequent heat treatment.The quasi-layered structure and the well-bonded bridging fibers between layers are the key points for the elasticity of EFPCs.The advanced EFPCs exhibited low density(∼0.126 g cm^(−3)),high com-pressive stress(∼0.356 MPa),and low thermal conductivity(∼0.026 W m^(−1) K^(−1)).Compared with rigid porous fibrous materials,the EFPCs had deformability and excellent shape recovery.In contrast to flexible materials,the EFPCs possessed high compressive stress,thus endowing them with good resistance to de-formation.The emergence of this fascinating material may provide new insights for candidate materials in thermal insulation and other fields.展开更多
The ultrasonic micro-arc oxidation(UMAO)was used to fabricate ceramic coatings on magnesium alloy.UMAO coatings were produced at 60 W input ultrasonic.The effects of the ultrasound on the microstructure,phase composit...The ultrasonic micro-arc oxidation(UMAO)was used to fabricate ceramic coatings on magnesium alloy.UMAO coatings were produced at 60 W input ultrasonic.The effects of the ultrasound on the microstructure,phase composition,elemental distribution and corrosion resistance of the coatings were extensively investigated by scanning electron microscopy(SEM),X-ray diffraction(XRD),energy-dispersive X-ray spectrometry(EDX)and electrochemical workstation.The results showed that ultrasound improved the homogeneous distribution of micro-porous structure.The coatings were mainly composed of MgO ceramic and small amount of calcium and phosphorus with porous structure.The Ca/P ratio of the coatings increased when 60 W ultrasonic was used.The corrosion potential in simulated body fluid(SBF)changed from1.583 V of bare magnesium alloy to -0.353 V of magnesium alloy coated under 60 W ultrasonic.The corrosion resistance of UMAO coatings was better than that of MAO coatings.展开更多
We present an experimental demonstration of ghost imaging of reflective objects with different surface roughness.The influence of the surface roughness, the transverse size of the test detector, and the reflective ang...We present an experimental demonstration of ghost imaging of reflective objects with different surface roughness.The influence of the surface roughness, the transverse size of the test detector, and the reflective angle on the signal-to-noise ratio(SNR) is analyzed by measuring the second-order correlation of the light field based on classical statistical optics. It is shown that the SNR decreases with an increment of the surface roughness and the detector's transverse size or a decrease of the reflective angle. Additionally, the comparative studies between the rough object and the smooth one under the same conditions are also discussed.展开更多
基金financially supported by the National Key Research and Development of China (No.2021YFB3400200)the National Natural Science Foundation of China (Nos.12090031 and 11602125)the Beijing Institute of Technology Research Fund Program for Young Scholars.
文摘Fibrous porous ceramics are attractive for use as thermal insulation materials.However,the intrinsic brit-tleness of rigid materials has remained challenging and severely restricts their applications.Here,we demonstrated a facile method for fabricating elastic fibrous porous ceramics(EFPCs)with high com-pressive strength and low thermal conductivity through ordinary press filtration and subsequent heat treatment.The quasi-layered structure and the well-bonded bridging fibers between layers are the key points for the elasticity of EFPCs.The advanced EFPCs exhibited low density(∼0.126 g cm^(−3)),high com-pressive stress(∼0.356 MPa),and low thermal conductivity(∼0.026 W m^(−1) K^(−1)).Compared with rigid porous fibrous materials,the EFPCs had deformability and excellent shape recovery.In contrast to flexible materials,the EFPCs possessed high compressive stress,thus endowing them with good resistance to de-formation.The emergence of this fascinating material may provide new insights for candidate materials in thermal insulation and other fields.
基金The authors are grateful for the supports from the National Natural Science Foundation of China(No.31070859)the Natural Science Foundation of Heilongjiang Province(No.ZD201008).
文摘The ultrasonic micro-arc oxidation(UMAO)was used to fabricate ceramic coatings on magnesium alloy.UMAO coatings were produced at 60 W input ultrasonic.The effects of the ultrasound on the microstructure,phase composition,elemental distribution and corrosion resistance of the coatings were extensively investigated by scanning electron microscopy(SEM),X-ray diffraction(XRD),energy-dispersive X-ray spectrometry(EDX)and electrochemical workstation.The results showed that ultrasound improved the homogeneous distribution of micro-porous structure.The coatings were mainly composed of MgO ceramic and small amount of calcium and phosphorus with porous structure.The Ca/P ratio of the coatings increased when 60 W ultrasonic was used.The corrosion potential in simulated body fluid(SBF)changed from1.583 V of bare magnesium alloy to -0.353 V of magnesium alloy coated under 60 W ultrasonic.The corrosion resistance of UMAO coatings was better than that of MAO coatings.
基金National Natural Science Foundation of China(NSFC)(61372102,61571183)Natural Science Foundation of Hunan Province(2017JJ1014)
文摘We present an experimental demonstration of ghost imaging of reflective objects with different surface roughness.The influence of the surface roughness, the transverse size of the test detector, and the reflective angle on the signal-to-noise ratio(SNR) is analyzed by measuring the second-order correlation of the light field based on classical statistical optics. It is shown that the SNR decreases with an increment of the surface roughness and the detector's transverse size or a decrease of the reflective angle. Additionally, the comparative studies between the rough object and the smooth one under the same conditions are also discussed.
