White Cyphochilus insulanus beetles,exhibiting both environmental camouflage display and radiative cooling functions,serve as a good prototype for biomimetic fabrication.As inspired,this work presents a femtosecond(fs...White Cyphochilus insulanus beetles,exhibiting both environmental camouflage display and radiative cooling functions,serve as a good prototype for biomimetic fabrication.As inspired,this work presents a femtosecond(fs)laser-based biomimetic fabrication strategy that takes full use of the synthesized radiative cooling nanomaterials for a groundbreaking stimuli-responsive infrared(IR)impressionistic camouflage display.The proposed technique is capable of readily transforming various substrates(quartz glass and metals including Ti,Al,Zr,and W)into self-assembled porous networks(aerogels)consisting of oxygen-vacancy-rich oxide nanoparticles.Surprisingly,the emissions of all as-prepared porous particle-networks in the radiative-cooling long-wavelength infrared(LWIR)band are above 95%,with the SiO_(2) aerogels reaching a maximum of 99.6%.Benefiting from the far-from-equilibrium thermodynamic kinetics,metastable phases of anatase TiO_(2),tetragonal zirconia(t-ZrO_(2)),and monoclinic WO_(3)(Pc)are synthesizable,opening up opportunities for exploring their optical applications.Taking the low-temperature metastable phase WO_(3)(Pc)as representative for systematic studies,it is found that(1)the ratio WO_(3)(Pc)phase to that of room-temperature phase of WO_(3)(P2_(1)/n)can be tailored by modulation of processing parameters;(2)laser synthesized aerogels with hybrid phases of WO_(3)(Pc)and WO_(3)(P2_(1)/n)have a brighter visible whiteness,higher visible/nearinfrared(NIR)spectral selectivity than the natural prototype of white Cyphochilus insulanus beetles but with comparable LWIR emittance.White WO_(3) aerogel in situ deposited during flexibly fs laser artistic patterning can blur the painting features due to its radiative cooling effect,allowing a colorful impressionistic IR display in the heating mode.What's more,invisible painting features concealed by the white deposited WO_(3) aerogel are clearly/faintly distinguishable by introducing external stimuli of a human hand and sample heating,respectively,catalyzing progress in optical encryption and selectively stimuli-responsive decryption display in the infrared band.展开更多
With the aim of improving the fatigue properties of Mg alloy welded joints under cyclic loading,the effects of laser bionic treatment and ultrasonic impact bionic treatment on the fatigue crack growth(FCG)behavior of ...With the aim of improving the fatigue properties of Mg alloy welded joints under cyclic loading,the effects of laser bionic treatment and ultrasonic impact bionic treatment on the fatigue crack growth(FCG)behavior of AZ31B Mg alloy TIG-welded joints were studied and compared.The results show that bionic treatment refines the grains on the joint surface and improves the microhardness.In the crack stable growth stage,both bionic samples exhibit a lower FCG rate and a higher FCG resistance.The two bionic treatment methods reduce the probability of crack initiation and partially promote crack deflection,providing a new approach for improving the FCG behavior of welded joints.展开更多
In order to repair and reuse remaining quenching surface(RQS)divided into severely worn surface(SWun-S)and mildly worn surface(MWun-S)of abandoned gray cast iron guide rail,inspired by the bionic theory,varying forms ...In order to repair and reuse remaining quenching surface(RQS)divided into severely worn surface(SWun-S)and mildly worn surface(MWun-S)of abandoned gray cast iron guide rail,inspired by the bionic theory,varying forms of bionic units such as spot(Sp-S),striation(St-S),and reticulation(Re-S)were fabricated on RQS of gray cast iron through laser processing technology.Firstly,the microstructure,phase composition,and microhardness of bionic units and RQS were analyzed by optical microscopy as well as X-ray diffraction instrument and scanning electron microscopy,respectively.Secondly,the oil lubrication wear experiment was performed on homemade line reciprocating wear machine.The results demonstrated that the bionic units had a significant effect on improving wear resistance of RQS of abandoned guide rail due to the microstructure and higher hardness.In addition,the weight loss ratios of MWun-S,Sp-S,St-S,and Re-S samples were decreased by 36.72%,36.78%,62.26%,and 80.39%,respectively,compared with that of SWun-S sample.The mechanism of wear resistance enhancement was also discussed.展开更多
基金financial support received from the Shanghai Pujiang Program(23PJ1406500)。
文摘White Cyphochilus insulanus beetles,exhibiting both environmental camouflage display and radiative cooling functions,serve as a good prototype for biomimetic fabrication.As inspired,this work presents a femtosecond(fs)laser-based biomimetic fabrication strategy that takes full use of the synthesized radiative cooling nanomaterials for a groundbreaking stimuli-responsive infrared(IR)impressionistic camouflage display.The proposed technique is capable of readily transforming various substrates(quartz glass and metals including Ti,Al,Zr,and W)into self-assembled porous networks(aerogels)consisting of oxygen-vacancy-rich oxide nanoparticles.Surprisingly,the emissions of all as-prepared porous particle-networks in the radiative-cooling long-wavelength infrared(LWIR)band are above 95%,with the SiO_(2) aerogels reaching a maximum of 99.6%.Benefiting from the far-from-equilibrium thermodynamic kinetics,metastable phases of anatase TiO_(2),tetragonal zirconia(t-ZrO_(2)),and monoclinic WO_(3)(Pc)are synthesizable,opening up opportunities for exploring their optical applications.Taking the low-temperature metastable phase WO_(3)(Pc)as representative for systematic studies,it is found that(1)the ratio WO_(3)(Pc)phase to that of room-temperature phase of WO_(3)(P2_(1)/n)can be tailored by modulation of processing parameters;(2)laser synthesized aerogels with hybrid phases of WO_(3)(Pc)and WO_(3)(P2_(1)/n)have a brighter visible whiteness,higher visible/nearinfrared(NIR)spectral selectivity than the natural prototype of white Cyphochilus insulanus beetles but with comparable LWIR emittance.White WO_(3) aerogel in situ deposited during flexibly fs laser artistic patterning can blur the painting features due to its radiative cooling effect,allowing a colorful impressionistic IR display in the heating mode.What's more,invisible painting features concealed by the white deposited WO_(3) aerogel are clearly/faintly distinguishable by introducing external stimuli of a human hand and sample heating,respectively,catalyzing progress in optical encryption and selectively stimuli-responsive decryption display in the infrared band.
基金financially supported by the National Natural Science Foundation of China(No.51805235).
文摘With the aim of improving the fatigue properties of Mg alloy welded joints under cyclic loading,the effects of laser bionic treatment and ultrasonic impact bionic treatment on the fatigue crack growth(FCG)behavior of AZ31B Mg alloy TIG-welded joints were studied and compared.The results show that bionic treatment refines the grains on the joint surface and improves the microhardness.In the crack stable growth stage,both bionic samples exhibit a lower FCG rate and a higher FCG resistance.The two bionic treatment methods reduce the probability of crack initiation and partially promote crack deflection,providing a new approach for improving the FCG behavior of welded joints.
基金supported by Project 985-High Performance Materials of Jilin UniversityProject 985-Bionic Engineering Science and Technology Innovationdouble first-class project by Jilin Province and Jilin University(SXGJXX2017-14).
文摘In order to repair and reuse remaining quenching surface(RQS)divided into severely worn surface(SWun-S)and mildly worn surface(MWun-S)of abandoned gray cast iron guide rail,inspired by the bionic theory,varying forms of bionic units such as spot(Sp-S),striation(St-S),and reticulation(Re-S)were fabricated on RQS of gray cast iron through laser processing technology.Firstly,the microstructure,phase composition,and microhardness of bionic units and RQS were analyzed by optical microscopy as well as X-ray diffraction instrument and scanning electron microscopy,respectively.Secondly,the oil lubrication wear experiment was performed on homemade line reciprocating wear machine.The results demonstrated that the bionic units had a significant effect on improving wear resistance of RQS of abandoned guide rail due to the microstructure and higher hardness.In addition,the weight loss ratios of MWun-S,Sp-S,St-S,and Re-S samples were decreased by 36.72%,36.78%,62.26%,and 80.39%,respectively,compared with that of SWun-S sample.The mechanism of wear resistance enhancement was also discussed.
