Sn_(1−x)Er_(x)O_(2)(x=0%,8%,16%,24%)micro/nanofibers were prepared by electrospinning combined with heat treatment using erbium nitrate,stannous chloride and polyvinylpyrrolidone(PVP)as raw materials.The target produc...Sn_(1−x)Er_(x)O_(2)(x=0%,8%,16%,24%)micro/nanofibers were prepared by electrospinning combined with heat treatment using erbium nitrate,stannous chloride and polyvinylpyrrolidone(PVP)as raw materials.The target products were characterized by thermogravimetric analyzer,X-ray diffrotometer,fourier transform infrared spectrometer,scanning electron microscope,spectrophotometer and infrared emissivity tester,and the effects of Er^(3+)doping on its infrared and laser emissivity were studied.At the same time,the Sn_(1−x)Er_(x)O_(2)(x=0%,16%)doping models were constructed based on the first principles of density functional theory,and the related optoelectronic properties such as their energy band structure,density of states,reflectivity and dielectric constant were analyzed,and further explained the mechanism of Er^(3+)doping on SnO_(2)infrared emissivity and laser absorption from the point of electronic structure.The results showed that after calcination at 600℃,single rutile type SnO_(2)was formed,and the crystal structure was not changed by doping Er^(3+).The calcined products showed good fiber morphology,and the average fiber diameter was 402 nm.The infrared emissivity and resistivity of the samples both decreased first and then increased with the increase of Er^(3+)doping amount.When x=16%,the infrared emis-sivity of the sample was at least 0.71;and Er^(3+)doping can effectively reduce the reflectivity of SnO_(2)at 1.06μm and 1.55μm,when x=16%,its reflectivity at 1.06μm and 1.55μm are 50.5%and 40%,respectively,when x=24%,the reflectivity at 1.06μm and 1.55μm wavelengths are 47.3%and 42.1%,respectively.At the same time,the change of carrier concentration and electron transition before and after Er^(3+)doping were described by first-principle calculation,and the regulation mechanism of infrared emissivity and laser reflectivity was explained.This study provides a certain experimental and theoretical basis for the development of a single-type,light-weight and easily prepared infrared and laser compatible-stealth material.展开更多
At present, the most common micro/nano-scale fabri ca tion processes include the plane silicon process based on IC technology, stereo silicon process, LIGA, quasi-LIGA based on near ultra violet deep lithography, MEMS...At present, the most common micro/nano-scale fabri ca tion processes include the plane silicon process based on IC technology, stereo silicon process, LIGA, quasi-LIGA based on near ultra violet deep lithography, MEMS, energy beam etching and micro/nano-machining, etc. A common problem for t hese processes is the difficulty to fabricate arbitrary form for 3-dimensional micro/nano-parts, devices or mechanisms. To develop advanced MEMS manufacturin g technology, and to achieve fabrication of true 3-dimensional parts, devices or mechanisms, this paper proposes a nanofabrication technology for rapid proto typing of 3-dimensional parts, using plasma chemical vapor deposition (PCVD). This process can be describes as follows: A laser beam is produced by a low power, quasi molecule laser. It enters the vac uum chamber through a window, and is focused on with the substrate surface. A ga s in the chamber is ionized by the laser beam to produce PCVD on the substrate s urface, and forms a particle of the size of Ф100 nm (its thickness is about 100 nm). When the laser beam moves along X-axis, many particles form a line. Then the laser beam moves one step in Y-axis to form a new line. A plane is complete d by many lines. Then the substrate moves in Z-axis to form new plane. Eventu ally, many planes form a 3-dimensional component. Using available CAD/CAM softw are with this process, rapid prototyping of complex components can be achieved. A nanometer precision linear motor, such as that described in Chinese national p atent (patent No. ZL 98 2 16753.9), can be used to obtain the nanometer precisio n movements in the process. The process does not require mask, can be used for v arious rapid prototyping materials, to obtain high fabrication precision (its sc ale precision is 15 nm), and larger ratio of height to width of micro/nano-stru cture. It can find widespread applications in the fabrication of micro-mechani sm, trimming IC, and fabricating minilens, etc.展开更多
We put forward a protocolcombining laser treatment and acid etching to obtain multiscale micro/nano-texture surfaces of titanium alloy implant.Firstly,the operationalparameters of the laser were optimized to obtain an...We put forward a protocolcombining laser treatment and acid etching to obtain multiscale micro/nano-texture surfaces of titanium alloy implant.Firstly,the operationalparameters of the laser were optimized to obtain an optimum current.Secondly,the laser with the optimum operationalparameters was used to fabricate micro pits.Thirdly,multiple acid etching was used to clean the clinkers of micro pits and generate submicron and nanoscale structures.Finally,the bioactivity of the samples was measured in a simulated body fluid.The results showed that the micropits with a diameter of 150 μm and depth of 50 μm were built successfully with the optimized working current of 13 A.In addition,submicron and nanoscale structures,with 0.5-2 μm microgrooves and 10-20 nm nanopits,were superimposed on micro pits surface by multiple acid etching.There was thick and dense HA coating only observed on the multiscale micro/nano-textured surface compared with polished and micro-textured surface.This indicated that the multiscale micro/nano-texture surface showed better ability toward HA formation,which increased the bioactivity of implants.展开更多
Controllable fabrication of surface micro/nano structures is the key to realizing surface functionalization for various applications.As a versatile approach,ultrafast laser ablation has been widely studied for surface...Controllable fabrication of surface micro/nano structures is the key to realizing surface functionalization for various applications.As a versatile approach,ultrafast laser ablation has been widely studied for surface micro/nano structuring.Increasing research eforts in this feld have been devoted to gaining more control over the fabrication processes to meet the increasing need for creation of complex structures.In this paper,we focus on the in-situ deposition process following the plasma formation under ultrafast laser ablation.From an overview perspective,we frstly summarize the diferent roles that plasma plumes,from pulsed laser ablation of solids,play in diferent laser processing approaches.Then,the distinctive in-situ deposition process within surface micro/nano structuring is highlighted.Our experimental work demonstrated that the in-situ deposition during ultrafast laser surface structuring can be controlled as a localized micro-additive process to pile up secondary ordered structures,through which a unique kind of hierarchical structure with fort-like bodies sitting on top of micro cone arrays were fabricated as a showcase.The revealed laser-matter interaction mechanism can be inspiring for the development of new ultrafast laser fabrication approaches,adding a new dimension and more fexibility in controlling the fabrication of functional surface micro/nano structures.展开更多
The details of the special three-dimensional micro-nano scale ripples with a period of hundreds of microns on the surfaces of a Zr-based and a La-based metallic glass irradiated separately by single laser pulse are in...The details of the special three-dimensional micro-nano scale ripples with a period of hundreds of microns on the surfaces of a Zr-based and a La-based metallic glass irradiated separately by single laser pulse are investigated.We use the small-amplitude capillary wave theory to unveil the ripple formation mechanism through considering each of the molten metallic glasses as an incompressible viscous fluid.A generalized model is presented to describe the special morphology,which fits the experimental result well.It is also revealed that the viscosity brings about the biggest effect on the monotone decreasing nature of the amplitude and the wavelength of the surface ripples.The greater the viscosity is,the shorter the amplitude and the wavelength are.展开更多
We present a novel approach for tailoring the laser induced surface topography upon femtosecond(fs)pulsed laser irradiation.The method employs spatially controlled double fs laser pulses to actively regulate the hydro...We present a novel approach for tailoring the laser induced surface topography upon femtosecond(fs)pulsed laser irradiation.The method employs spatially controlled double fs laser pulses to actively regulate the hydrodynamic microfluidic motion of the melted layer that gives rise to the structures formation.The pulse train used,in particular,consists of a previously unexplored spatiotemporal intensity combination including one pulse with Gaussian and another with periodically modulated intensity distribution created by Direct Laser Interference Patterning(DLIP).The interpulse delay is appropriately chosen to reveal the contribution of the microfluidic melt flow,while it is found that the sequence of the Gaussian and DLIP pulses remarkably influences the surface profile attained.Results also demonstrate that both the spatial intensity of the double pulse and the effective number of pulses per irradiation spot can further be modulated to control the formation of complex surface morphologies.The underlying physical processes behind the complex patterns’generation were interpreted in terms of a multiscale model combining electron excitation with melt hydrodynamics.We believe that this work can constitute a significant step forward towards producing laser induced surface structures on demand by tailoring the melt microfluidic phenomena.展开更多
Wettability is an important characteristic of solid surfaces. Enhancing the surface wettability is very important for improving the properties of materials. Superhydrophobic materials show good prospects for developme...Wettability is an important characteristic of solid surfaces. Enhancing the surface wettability is very important for improving the properties of materials. Superhydrophobic materials show good prospects for development in areas such as self-cleaning, anti-fog snow, anti-icing, and corrosion resistance. It has become a hot spot to develop a superhydrophobic surface with low surface free energy and good anti-adhesion properties. In this paper, nanosecond pulsed lasers were used to texture the nickel surface, and the different texturing speeds were changed. Combined with the ultrasonic treatment of low surface energy materials, nickel surfaces with different contact angles were obtained. The experimental results show that low surface energy substances can increase the contact angle of nickel surface but the extent of increase is limited. Laser microstructure induces micro & nanostructures. Ultrasonic action can adsorb certain low surface energy substances on the surface, greatly improving the hydrophobic properties of the surface, the contact angle with water up to 152? and the roll angle is less than 2?, and with the increase of the laser texturing speed, the contact angle of the nickel surface shows a decreasing trend.展开更多
The kind of micro-/nano-meter precision actuator in cludes a piezoelectric one, an electric deformation one, a magnetic deformation one, a mechanical one, and a mechanical and electrical one. This paper puts forw ard ...The kind of micro-/nano-meter precision actuator in cludes a piezoelectric one, an electric deformation one, a magnetic deformation one, a mechanical one, and a mechanical and electrical one. This paper puts forw ard a mechanical and electrical step actuator of nanometer precision, which cons ists of a step motor of large fine-dividing number of step angle, shaft couplin gs, a decelerator of large decelerating ratio, a screw mechanism and a pole of U shape, and has the minimum step displacement of 10 nm, the step displac ement precision of 1 nm, the step frequency of 4 kHz, the maximum loadability of 20 kg. In order to achieve the nano displacement of nano precision by this actu ator, the theoretical analysis of stress and strain must be made on the transmit ting course of nano displacement of the actuator, and their numerical simulation is done by computer. The paper establishes the constitutive equation of 3-D stress and the strain co ordinate equation of the composing system of the nanometer precision actuator. A s a result, the theoretical relation among stress and strain and displacement is set up. The torque of the step motor produces a thrust to transmit the displace ment of the above system of the parts and assemblies to output the needed nano d isplacement. In the case of concrete analysis and calculating, the comparing met hod of film-roof is applied to analyze and calculate the motor axis, decelerato r axes, the screw pole and the nut. The analysis method of plane stress and stra in is used to analyze and calculate the shaft couplings and gears. The analysis method of beam stress and strain is used to do the pole of U shape. These calcul ation is belong to the physical non-linear problem. Under the condition of smal l deformation, the analysis way of the finite element can be combined with the a bove analyses and calculations. The elementary analysis results show that the na nometer precision actuator can be applied in STM nanofabrication.展开更多
Three dimension free curves find wide applications in engineering. There is no problem to express them exactly mathematically, but th e reportage has not been done on the investigation of precision analysis of thre e-...Three dimension free curves find wide applications in engineering. There is no problem to express them exactly mathematically, but th e reportage has not been done on the investigation of precision analysis of thre e-dimension free curves nanofabrication. Nanofabrication Precision includes the geometrical precision and the precision of driving system (below simply cal led the system precision). This paper submits the precision analysis method of c urve normal vector to analyze geometrical precision. Take an aspherical surf ace for example, it can be fitted and constructed by tensor product parameter cu rves, such as linear drawing curves, straight veins curves, rotating curves, swe eping curves, DUCT curves and Geomap curves. Then the curves of the aspherical s urface is iterated and modified to select the best fitted curves of the aspheric al surface. Finally, the geometrical precision of perfect approximate aspherical surface fitting has been sought. This kind of geometrical fitting construction is very important. Another is the system precision, which contains axial position precision, line p recision, and twisting and swinging precision, etc. The paper adopts the theory of precision optimum match (Prof. Wang Er-qi first put forward in 19 83) to allocate precision optimumly. The minimum cost is used as an objective fu nction, and weight method matches the precision. To obtain the optimum match combination of the minimum cost design parameters and every composing element t olerance, the precision is iterated and sought optimumly to design the system op timumly. The theoretical analysis shows that it’s feasible to control three dim ension free curves nanofabrication within nanometer scale precision.展开更多
基金supported by the Key Research and Development Program of Hebei Province(No.21351501D)A Provincial and Ministerial Scientific Research Project(LJ20212C031165)Basic Frontier Science and Technology Innovation Project of Army Engineering University of PLA(KYSZJQZL2210)。
文摘Sn_(1−x)Er_(x)O_(2)(x=0%,8%,16%,24%)micro/nanofibers were prepared by electrospinning combined with heat treatment using erbium nitrate,stannous chloride and polyvinylpyrrolidone(PVP)as raw materials.The target products were characterized by thermogravimetric analyzer,X-ray diffrotometer,fourier transform infrared spectrometer,scanning electron microscope,spectrophotometer and infrared emissivity tester,and the effects of Er^(3+)doping on its infrared and laser emissivity were studied.At the same time,the Sn_(1−x)Er_(x)O_(2)(x=0%,16%)doping models were constructed based on the first principles of density functional theory,and the related optoelectronic properties such as their energy band structure,density of states,reflectivity and dielectric constant were analyzed,and further explained the mechanism of Er^(3+)doping on SnO_(2)infrared emissivity and laser absorption from the point of electronic structure.The results showed that after calcination at 600℃,single rutile type SnO_(2)was formed,and the crystal structure was not changed by doping Er^(3+).The calcined products showed good fiber morphology,and the average fiber diameter was 402 nm.The infrared emissivity and resistivity of the samples both decreased first and then increased with the increase of Er^(3+)doping amount.When x=16%,the infrared emis-sivity of the sample was at least 0.71;and Er^(3+)doping can effectively reduce the reflectivity of SnO_(2)at 1.06μm and 1.55μm,when x=16%,its reflectivity at 1.06μm and 1.55μm are 50.5%and 40%,respectively,when x=24%,the reflectivity at 1.06μm and 1.55μm wavelengths are 47.3%and 42.1%,respectively.At the same time,the change of carrier concentration and electron transition before and after Er^(3+)doping were described by first-principle calculation,and the regulation mechanism of infrared emissivity and laser reflectivity was explained.This study provides a certain experimental and theoretical basis for the development of a single-type,light-weight and easily prepared infrared and laser compatible-stealth material.
文摘At present, the most common micro/nano-scale fabri ca tion processes include the plane silicon process based on IC technology, stereo silicon process, LIGA, quasi-LIGA based on near ultra violet deep lithography, MEMS, energy beam etching and micro/nano-machining, etc. A common problem for t hese processes is the difficulty to fabricate arbitrary form for 3-dimensional micro/nano-parts, devices or mechanisms. To develop advanced MEMS manufacturin g technology, and to achieve fabrication of true 3-dimensional parts, devices or mechanisms, this paper proposes a nanofabrication technology for rapid proto typing of 3-dimensional parts, using plasma chemical vapor deposition (PCVD). This process can be describes as follows: A laser beam is produced by a low power, quasi molecule laser. It enters the vac uum chamber through a window, and is focused on with the substrate surface. A ga s in the chamber is ionized by the laser beam to produce PCVD on the substrate s urface, and forms a particle of the size of Ф100 nm (its thickness is about 100 nm). When the laser beam moves along X-axis, many particles form a line. Then the laser beam moves one step in Y-axis to form a new line. A plane is complete d by many lines. Then the substrate moves in Z-axis to form new plane. Eventu ally, many planes form a 3-dimensional component. Using available CAD/CAM softw are with this process, rapid prototyping of complex components can be achieved. A nanometer precision linear motor, such as that described in Chinese national p atent (patent No. ZL 98 2 16753.9), can be used to obtain the nanometer precisio n movements in the process. The process does not require mask, can be used for v arious rapid prototyping materials, to obtain high fabrication precision (its sc ale precision is 15 nm), and larger ratio of height to width of micro/nano-stru cture. It can find widespread applications in the fabrication of micro-mechani sm, trimming IC, and fabricating minilens, etc.
基金Funded by the National Natural Science Foundation of China(51175306 and 51575320)the Tai Shan Scholar Foundation(TS20130922)the Fundamental Research Funds for the Central Universities(2014JC020)
文摘We put forward a protocolcombining laser treatment and acid etching to obtain multiscale micro/nano-texture surfaces of titanium alloy implant.Firstly,the operationalparameters of the laser were optimized to obtain an optimum current.Secondly,the laser with the optimum operationalparameters was used to fabricate micro pits.Thirdly,multiple acid etching was used to clean the clinkers of micro pits and generate submicron and nanoscale structures.Finally,the bioactivity of the samples was measured in a simulated body fluid.The results showed that the micropits with a diameter of 150 μm and depth of 50 μm were built successfully with the optimized working current of 13 A.In addition,submicron and nanoscale structures,with 0.5-2 μm microgrooves and 10-20 nm nanopits,were superimposed on micro pits surface by multiple acid etching.There was thick and dense HA coating only observed on the multiscale micro/nano-textured surface compared with polished and micro-textured surface.This indicated that the multiscale micro/nano-texture surface showed better ability toward HA formation,which increased the bioactivity of implants.
基金support by the National Key Research and Development Program of China(No.2017YFB1104300)the National Natural Science Foundation of China(Nos.51575309 and 51210009)the Tsinghua University Initiative Scientifc Research Program(No.2018Z05JZY009).
文摘Controllable fabrication of surface micro/nano structures is the key to realizing surface functionalization for various applications.As a versatile approach,ultrafast laser ablation has been widely studied for surface micro/nano structuring.Increasing research eforts in this feld have been devoted to gaining more control over the fabrication processes to meet the increasing need for creation of complex structures.In this paper,we focus on the in-situ deposition process following the plasma formation under ultrafast laser ablation.From an overview perspective,we frstly summarize the diferent roles that plasma plumes,from pulsed laser ablation of solids,play in diferent laser processing approaches.Then,the distinctive in-situ deposition process within surface micro/nano structuring is highlighted.Our experimental work demonstrated that the in-situ deposition during ultrafast laser surface structuring can be controlled as a localized micro-additive process to pile up secondary ordered structures,through which a unique kind of hierarchical structure with fort-like bodies sitting on top of micro cone arrays were fabricated as a showcase.The revealed laser-matter interaction mechanism can be inspiring for the development of new ultrafast laser fabrication approaches,adding a new dimension and more fexibility in controlling the fabrication of functional surface micro/nano structures.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.10572002,10732010,and 11332002)
文摘The details of the special three-dimensional micro-nano scale ripples with a period of hundreds of microns on the surfaces of a Zr-based and a La-based metallic glass irradiated separately by single laser pulse are investigated.We use the small-amplitude capillary wave theory to unveil the ripple formation mechanism through considering each of the molten metallic glasses as an incompressible viscous fluid.A generalized model is presented to describe the special morphology,which fits the experimental result well.It is also revealed that the viscosity brings about the biggest effect on the monotone decreasing nature of the amplitude and the wavelength of the surface ripples.The greater the viscosity is,the shorter the amplitude and the wavelength are.
基金support by the European Union’s Horizon 2020 research and innovation program through the project BioCombs4Nanofibres(Grant Agreement No.862016)。
文摘We present a novel approach for tailoring the laser induced surface topography upon femtosecond(fs)pulsed laser irradiation.The method employs spatially controlled double fs laser pulses to actively regulate the hydrodynamic microfluidic motion of the melted layer that gives rise to the structures formation.The pulse train used,in particular,consists of a previously unexplored spatiotemporal intensity combination including one pulse with Gaussian and another with periodically modulated intensity distribution created by Direct Laser Interference Patterning(DLIP).The interpulse delay is appropriately chosen to reveal the contribution of the microfluidic melt flow,while it is found that the sequence of the Gaussian and DLIP pulses remarkably influences the surface profile attained.Results also demonstrate that both the spatial intensity of the double pulse and the effective number of pulses per irradiation spot can further be modulated to control the formation of complex surface morphologies.The underlying physical processes behind the complex patterns’generation were interpreted in terms of a multiscale model combining electron excitation with melt hydrodynamics.We believe that this work can constitute a significant step forward towards producing laser induced surface structures on demand by tailoring the melt microfluidic phenomena.
文摘Wettability is an important characteristic of solid surfaces. Enhancing the surface wettability is very important for improving the properties of materials. Superhydrophobic materials show good prospects for development in areas such as self-cleaning, anti-fog snow, anti-icing, and corrosion resistance. It has become a hot spot to develop a superhydrophobic surface with low surface free energy and good anti-adhesion properties. In this paper, nanosecond pulsed lasers were used to texture the nickel surface, and the different texturing speeds were changed. Combined with the ultrasonic treatment of low surface energy materials, nickel surfaces with different contact angles were obtained. The experimental results show that low surface energy substances can increase the contact angle of nickel surface but the extent of increase is limited. Laser microstructure induces micro & nanostructures. Ultrasonic action can adsorb certain low surface energy substances on the surface, greatly improving the hydrophobic properties of the surface, the contact angle with water up to 152? and the roll angle is less than 2?, and with the increase of the laser texturing speed, the contact angle of the nickel surface shows a decreasing trend.
文摘The kind of micro-/nano-meter precision actuator in cludes a piezoelectric one, an electric deformation one, a magnetic deformation one, a mechanical one, and a mechanical and electrical one. This paper puts forw ard a mechanical and electrical step actuator of nanometer precision, which cons ists of a step motor of large fine-dividing number of step angle, shaft couplin gs, a decelerator of large decelerating ratio, a screw mechanism and a pole of U shape, and has the minimum step displacement of 10 nm, the step displac ement precision of 1 nm, the step frequency of 4 kHz, the maximum loadability of 20 kg. In order to achieve the nano displacement of nano precision by this actu ator, the theoretical analysis of stress and strain must be made on the transmit ting course of nano displacement of the actuator, and their numerical simulation is done by computer. The paper establishes the constitutive equation of 3-D stress and the strain co ordinate equation of the composing system of the nanometer precision actuator. A s a result, the theoretical relation among stress and strain and displacement is set up. The torque of the step motor produces a thrust to transmit the displace ment of the above system of the parts and assemblies to output the needed nano d isplacement. In the case of concrete analysis and calculating, the comparing met hod of film-roof is applied to analyze and calculate the motor axis, decelerato r axes, the screw pole and the nut. The analysis method of plane stress and stra in is used to analyze and calculate the shaft couplings and gears. The analysis method of beam stress and strain is used to do the pole of U shape. These calcul ation is belong to the physical non-linear problem. Under the condition of smal l deformation, the analysis way of the finite element can be combined with the a bove analyses and calculations. The elementary analysis results show that the na nometer precision actuator can be applied in STM nanofabrication.
文摘Three dimension free curves find wide applications in engineering. There is no problem to express them exactly mathematically, but th e reportage has not been done on the investigation of precision analysis of thre e-dimension free curves nanofabrication. Nanofabrication Precision includes the geometrical precision and the precision of driving system (below simply cal led the system precision). This paper submits the precision analysis method of c urve normal vector to analyze geometrical precision. Take an aspherical surf ace for example, it can be fitted and constructed by tensor product parameter cu rves, such as linear drawing curves, straight veins curves, rotating curves, swe eping curves, DUCT curves and Geomap curves. Then the curves of the aspherical s urface is iterated and modified to select the best fitted curves of the aspheric al surface. Finally, the geometrical precision of perfect approximate aspherical surface fitting has been sought. This kind of geometrical fitting construction is very important. Another is the system precision, which contains axial position precision, line p recision, and twisting and swinging precision, etc. The paper adopts the theory of precision optimum match (Prof. Wang Er-qi first put forward in 19 83) to allocate precision optimumly. The minimum cost is used as an objective fu nction, and weight method matches the precision. To obtain the optimum match combination of the minimum cost design parameters and every composing element t olerance, the precision is iterated and sought optimumly to design the system op timumly. The theoretical analysis shows that it’s feasible to control three dim ension free curves nanofabrication within nanometer scale precision.
