Laser Irradiation Method Research Articles

Ultra‐fast, selective, non‐melting, laser sintering of alumina with anisotropic and size‐suppressed grains

AbstractIn this paper, we report an ultra‐fast sintering phenomenon of alumina achieved by the scanning laser irradiation method. Using CO2 laser irradiation, we found that micrometer‐sized alumina powder (d50 = 1.2 µm) can be sintered close to full density within a few tens of seconds. The microstructure of laser‐sintered alumina was different from that of the furnace‐sintered alumina. The relative density and grain size of the laser‐sintered alumina gradually decreased from the center of the laser beam to the edge. Anisotropy of the grain size was measured along and perpendicular to the scanning direction. This anisotropy decreased as the scanning speed decreased from 0.1 mm/s to 0.01 mm/s. The sintering master curve of grain size versus relative density, which reflects the sintering mechanism, was found to be affected by the laser scanning speed. When the laser scanning speed was 0.1 mm/s, grain size suppression was found for the almost fully dense alumina. However, at lower scanning speed (e.g., 0.01 mm/s), there was significant grain growth in the regions where the relative density was greater than 90%. These results clearly indicate that alumina can be sintered, in the solid‐state, to a high density in a short time using scanning laser and the microstructure is different from the furnace‐sintered alumina.

Liquid‐Infused Slippery Stainless Steel Surface Prepared by Alcohol‐Assisted Femtosecond Laser Ablation

AbstractNepenthes‐inspired liquid‐infused slippery surface (LISS) attracts great attention because it can repel different kinds of liquid and shows great stability. However, the vast majority of LISSs are realized on polymer materials which limit the applications. Here, a kind of universal method to directly construct porous micro/nanostructures on any kind of materials to realize LISS is put forward. As an example, abundant micro/nanohole structures are built on stainless steel surface by alcohol‐assisted femtosecond laser ablation. Then, LISS is achieved on stainless steel, which shows slippery property to variety of liquid with different chemical composition. The velocity of water droplet slipping on LISS can be tuned by water droplet volume, LISS tilt angle, and lubricant type. Some potential applications of the LISS are demonstrated by some simple experiments. Flexible movement of magnetic water droplet is realized on the LISS by controlling magnetic field. The LISS shows good antifouling performance to green alga. Moreover, the porous structures are very stable in different harsh environments. This alcohol‐assisted femtosecond laser irradiation method successfully constructs porous micro/nanostructures on different kinds of materials. Thus, this work can promote the applications of LISS in droplet manipulation, microfluidics, antifouling surface, and so on.

A multiple laser-induced hybrid electrode for flexible triboelectric nanogenerators

A performance-enhanced TENG based on an Au-LIG hybrid electrode is fabricated by a simple and cost-effective multiple laser irradiation method.

Recent Progress of Black Silicon: From Fabrications to Applications.

Since black silicon was discovered by coincidence, the special material was explored for many amazing material characteristics in optical, surface topography, and so on. Because of the material property, black silicon is applied in many spheres of a photodetector, photovoltaic cell, photo-electrocatalysis, antibacterial surfaces, and sensors. With the development of fabrication technology, black silicon has expanded in more and more applications and has become a research hotspot. Herein, this review systematically summarizes the fabricating method of black silicon, including nanosecond or femtosecond laser irradiation, metal-assisted chemical etching (MACE), reactive ion etching (RIE), wet chemical etching, electrochemical method, and plasma immersion ion implantation (PIII) methods. In addition, this review focuses on the progress in multiple black silicon applications in the past 10 years. Finally, the prospect of black silicon fabricating and various applications are outlined.

One-step in-situ laser irradiation for unique flocculent carbon network-twined C/Si/SiC composite structure

Silicon-based materials with designed morphology and composite structure have received increasing interest in recent years due to the potential wide application for energy storage devices. However, these Si-based nanocomposites were usually synthesized and functionalized with other materials at a high temperature. Herein, one flocculent carbon network-twined C/Si/SiC nanocomposites were synthesized by a novel in-situ laser irradiation method using SiC targets as both a template and the source of C and Si. The fragmentation, decomposition and reshaping processes of bulk SiC to flocculent C/Si/SiC are simultaneously accomplished in one step, which can provide a more stable structure between epitaxial Si layer and C layer. What is more, due to the distinct laser-induced loose microstructure and flocculated carbon nanosheets, such nanocomposites exhibit a high specific surface area and hierarchically porous structure.

Laser irradiation method to prepare polyethylene porous fiber membrane with ultrahigh xylene gas filtration capacity

In recent years, volatile organic compound (VOC) gases have caused potential harm to people's health. This study reveals the preparation of polyethylene porous fiber membrane with excellent low-concentration VOCs filtration performance via laser irradiation technology. A neodymium-doped yttrium aluminum garnet (Nd:YAG) pulsed laser beam was used to scan the laser-sensitive low-density polyethylene/carbon black (LDPE/CB) fibers prepared by nanolayer coextrusion in the air. The controllable thermal energy generated by laser irradiation makes the surface of the fiber membrane to produce a porous carbon layer in situ. Laser power and scanning speed are important parameters for controlling laser-induced carbonization. The results indicate that the rich "fluffy" carbon structures on the surface of the porous fiber membrane can efficiently adsorb xylene gas. This study can provide a positive reference for the large-scale preparation of polyolefin porous fiber membrane with VOCs filtration by simple and efficient laser irradiation method.

Effect of flame surface area of downward propagating flames induced by single and double laser irradiation on transition to parametric instability

The single laser irradiation ( SLI ) method was adopted to develop a double laser irradiation ( DLI ) method to investigate the effects of laser-induced structures of downward-propagating flames in a tube on the transition from primary acoustic instability to parametric instability . Previously, the SLI method was effectively used to study the interaction between acoustic oscillation and flame structure by controlling the shape of the flame front. The deformed cellular structure (either concave or convex) of the SLI -induced flame can transition from primary acoustic instability to parametric instability under certain conditions. We conducted experiments in the same combustion tube with C 2 H 4 /O 2 /CO 2 mixtures using both SLI and DLI for comparison. The DLI method forms double cellular structures, while SLI only forms single cellular structures on the flames. It was found that the DLI method was more effective than SLI in generating transition to parametric instability under same total laser power. Furthermore, a linear relationship was found between the area of the deformed structure (irrespective of its dimension) and the corresponding growth rate of acoustic pressure fluctuation during the propagation of the deformed flame. SLI - and DLI -induced deformed structures having the same deformed surface area demonstrate the same growth rate of thermo-acoustic instability regardless of the difference in ( ak ) 2 , where a is the amplitude and k is the wavenumber of the deformed structures, respectively. This factor described in the velocity coupling mechanism is important to reveal the growth rate of thermo-acoustic instability due to the variation in the flame surface area. The results revealed that the actual flame surface area, rather than ( ak ) 2 of the laser-induced downward-propagating flame structure, determines the transition in the presence of nonhomogeneous cell distribution induced by SLI and DLI . The total deformed surface area is a more comprehensive criterion for transition to parametric instability.

Surface Characteristics of Polymers with Different Absorbance after UV Picosecond Pulsed Laser Processing Using Various Repetition Rates.

We experimented with two polymer materials with different ultraviolet (UV) wavelength absorption characteristics, which are commonly used in flexible devices, by applying an ultrashort-pulsed laser of a 355-nm UV wavelength for 10 ps. The laser parameters studied were pulse repetition rate, laser irradiation method, and laser power condition. Previous studies using polyethylene terephthalate (PET), which does not exhibit linear absorption at a UV wavelength, have focused on processing trends resulting in minimal collateral damage around the laser-induced ablation. However, our results showed a trend of accumulating such damage irrespective of the laser parameters. Meanwhile, polyimide (PI) exhibited a completely different behavior depending on the laser parameters. At low pulse repetition rates, minimal collateral damage was observed, whereas at high repetition rates, the morphology varied considerably. The electrical characteristics of the laser-processed materials were found to be correlated with the variations in morphology. In the case of PI, such variations in electrical resistance and morphology indicated that the material was carbonized. The findings of this study are expected to provide a useful reference when selecting parameters for the laser processing of similar polymer materials.

Fabrication of Superhydrophobic Ti-6Al-4V Surfaces with Single-Scale Micotextures by using Two-Step Laser Irradiation and Silanization.

Laser irradiation is a popular method to produce microtextures on metal surfaces. However, the common laser-produced microtextures were hierarchical (multiscale), which may limit their applicability. In this paper, a method of two-step laser irradiation, combining first-step strong ablation and sequentially second-step gentle ablation, was presented to produce micron-rough surface with single-scale microtextures. The effect of laser fluence on the Ti–6Al–4V surface morphology and wettability were investigated in detail. The morphology results revealed that the microtextures produced using this method gradually evolved from multiscale to single-scale meanwhile from microprotrusions to microholes with increasing the second-step laser fluence from 0.0 to 2.4 J/cm2. The wettability and EDS/XPS results indicated that attributing to the rich TiO2 content and micron roughness produced by laser irradiation, all the two-step laser-irradiated surfaces exhibited superhydrophilicity. In addition, after silanization, all these superhydrophilic surfaces immediately turned to be superhydrophobic with close water contact angles of 155–162°. However, due to the absence of nanotextures, the water-rolling angle on the superhydrophobic surfaces with single-scale microtextures distinctly larger than those with multiscale ones. Finally, using the two-step laser-irradiation method and assisted with silanization, multifunctional superhydrophobic Ti–6Al–4V surfaces were achieved, including self-cleaning, guiding of the water-rolling direction and anisotropic water-rolling angles (like the rice-leaf), etc.

Photon-generated carrier transfer process from graphene to quantum dots: optical evidences and ultrafast photonics applications

Graphene/III–V semiconductor van der Waals (vdW) heterostructures offer potential access to physics, functionalities, and superior performance of optoelectronic devices. Nevertheless, the lack of a bandgap in graphene severely restricts the controllability of carrier properties and therefore impedes its applications. Here, we demonstrate the engineering of graphene bandgap in the graphene/GaAs heterostructure via C and Ga exchange induced by the method of femtosecond laser irradiation (FLI). The coupling of the bandgap-opened graphene with GaAs significantly enhances both the harvest of photons and the transfer of photon-generated carriers across the interface of vdW heterostructures. Thus, as a demonstration example, it allows us to develop a saturable absorber combining a delicately engineered graphene/GaAs vdW heterostructure with InAs quantum dots capped with short-period superlattices. This device exhibits significantly improved nonlinear characteristics including <1/3 saturation intensity and modulation depth 20 times greater than previously reported semiconductor saturable absorber mirrors. This work not only opens the route for the future development of even higher performance mode-locked lasers, but the significantly enhanced nonlinear characteristics due to doping-induced bandgap opening of graphene by FLI in the vdW heterostructures will also inspire wide applications in photonic and optoelectronic devices.

The investigation of mechanical and thermal properties of super-hydrophobic nitinol surfaces fabricated by hybrid methods of laser irradiation and carbon ion implantation

Comparing with laser irradiation only, the laser ablation combined with chemical modification process is a widely used technique to obtain bio-inspired super-hydrophobic surface. However, the as-prepared surfaces may be polluted by toxic substance during chemical modification such as fluoroalkyl silane and stearic acid. The side effect of polluted functional surface on organisms and environment limited its application value. In this paper, a green and environmental-friendly super-hydrophobic surface was quickly fabricated on nitinol substrates through hybrid of nanosecond laser ablation and carbon ion implantation. The time that turning from super-hydrophilicity to super-hydrophobicity was only 16 h exhibiting high efficiency compared with pure laser processing. Surface morphology and chemical component were systematically investigated to reveal the formation mechanism of super-hydrophobicity in such short time. The mechanical abrasion tests implied that the mechanical properties of surface microstructure could be heightened after carbon ion implantation, showing the superior structure stability. It is noted that chemical modified super-hydrophobicity could be hardly destroyed under high temperature, and the thermal stability of this ion implanted super-hydrophobic surface was on a par with it. This hybrid method of laser irradiation and carbon ion implantation paves a green way for rapid fabrication super-hydrophobic surface on nitinol, which would have great application value in biomedicine and industry.

Novel method to synthesis ZnO nanostructures via irradiation zinc acetate with a nanosecond laser for photocatalytic applications

In this study, a novel method to prepare ZnO nanostructures was proposed by irradiation zinc acetate with nanosecond laser in a liquid medium. Nd-YAG laser was used with energy of 180 mJ and 6000 pulses. As well as, the effects of using various liquids such as ethanol, deionized water, and ethylene glycol on the properties of the prepared ZnO were investigated. Structural, morphological, and optical properties were studied for all samples. Specifically, the X-ray diffractometer results revealed the presence of ZnO with hexagonal crystallization. Most importantly, as indicated by micrographs of scanning electron microscopy, the laser irradiation caused the immediate growth of ZnO nanorods in aqueous solution on the contrary of nanospheres which were grown in the other used solutions. Notably, the optical properties of the prepared ZnO showed that the highest absorption was obtained by ZnO nanospheres. Meanwhile, the energy gap was also studied and found to be between 3.5 and 3.59 eV. The incorporation of all these investigations provides a clear vision for growth mechanisms. This mechanism revealed the one-step growth of ZnO nanostructures with interesting properties that prepared by laser irradiation method. The splendid properties of nanorods structures enhance the photocatalytic performance of ZnO rather than spherical structures. The photocatalyst results revealed that the maximum decomposition of 5 ppm MB by the ZnO nanorods was greater than 98% which achieved after 40 min under UV light irradiation with a fixed catalyst concentration of 12 mg / L.

Laser-generated BiVO4 colloidal particles with tailoring size and native oxygen defect for highly efficient gas sensing

To alleviate the poor sensing performance of BiVO4, developing new strategies for the fabrication of unique device with improved sensing properties is very necessary and has great practical significance. In this work, size-tailored and uniform black BiVO4 colloids with abundant oxygen vacancy were synthesized by a unique method of pulsed laser irradiation of colloidal nanoparticles (PLICN). The corresponding laser irradiation effects on the sensing properties are comparatively investigated. The results indicate that the BiVO4 nanospheres with average size of 50 nm shows best sensing properties with high sensitivity, superior selectivity, low detection limit (44 ppb) to H2S at low working temperature (75 °C). Its sensing response is over 4 times higher when comparing with that of the raw material. Further investigation manifests that laser irradiation could induce quantity of the oxygen vacancy and decrease the resistance of the sensing device, which is mainly responsible for the enhanced sensing performance. Moreover, the density functional theories (DFT) calculations suggest that the oxygen vacancies can greatly decrease the surface absorption energy with enhanced H2S absorption capability on BiVO4 surface and lower the bader charger transfer from the absorbed H2S molecules to the BiVO4, thus enabling the implementation for the enhanced gas-sensing properties.

Thin Platinum Films Topology Formation on Ceramic Membranes

This article presents the technological aspects of experiments on the stable topological patterns formation from thin films of platinum on ceramic membranes. Platinum thin films were deposited by magnetron sputtering on a clean or pre-activated laser ceramics surface. After the deposition of platinum films, the method of various short-term laser irradiation was attempted to form a topological pattern. The results are discussed.

A Study on Debris Removal System Using Laser Pressure from Ground Stations

The amount of debris in space is increasing every year, and its effect on satellite missions is worsening. In this research, a method for removing debris using laser radiation pressure from a ground station is proposed. This method does not require a satellite to be launched to remove debris, and the system applied is less likely to be considered as a threat because it is relatively safe even if the laser erroneously irradiates another satellite, because the laser intensity is no more than 108 W/m2. However, the power applied to debris is small, such that it requires a great deal of time and energy to deorbit the debris. Therefore, this study aims to evaluate the feasibility of debris removal by laser radiation pressure from the view point of energy consumption and time. In addition, in order to increase feasibility of this method, a sub-optimized laser irradiation method for reducing the time and energy consumption required for removal is proposed. This study addresses how much energy and time is needed for a particular piece of debris to be removed by laser under three parameters: power of the laser, time that the laser is powered, and the location of laser station. By sub-optimizing these parameters, the energy needed to remove a particular piece of space debris within a particular time is minimized. Furthermore, a laser irradiation method for deorbiting multiple pieces of debris using multiple laser stations is discussed. This study contributes to show that the new debris removal method using laser radiation pressure from ground station can effectively and practically remove multiple debris in terms of time and energy cost.

Tensile strength prediction of orthogonal CFRP under high intensity CW laser irradiation

Considering the two most important factors, delamination and tensile strength temperature dependence, a tensile strength prediction model for orthogonal carbon fiber reinforced polymer (CFRP) under continuous wave (CW) laser irradiation is proposed. In the prediction model, delamination was judged by the thermal data recorded by a thermal imager. In order to eliminate the influence of heating rate on the tensile strength temperature dependence parameters, a two-sided laser irradiation method was proposed to test the tensile strength temperature dependence of CFRP. Furthermore, according to the temperature distribution in the thickness direction of the T700/E44 CFRP specimen and the tensile strength temperature dependence, the tensile strength for orthogonal CFRP under CW laser irradiation was calculated. The results show that the prediction model can reflect the decreasing process of tensile strength with laser irradiation, especially in the cases of high intensity laser irradiation and high tensile load. This research can make a reference for the tensile strength prediction of composite materials in high intensity CW laser irradiation and pre-tension loading conditions.

Experimental studies on joinability of zircaloy and SiC/SiC composite with titanium powder

AbstractAs for the enhanced accident tolerant fuel cladding for the advanced light‐water reactor, silicon carbide fiber reinforced silicon carbide matrix composite (SiC/SiC composite) is expected as a potential replacement of the current Zircaloy fuel cladding due to its many superiorities, where it is a key issue to develop the endcap seal of SiC/SiC composite cladding. In this research, based on the calking method, the fiber laser irradiation method was employed for sealing the endcap of SiC/SiC composite tube by Zircaloy tube, where the titanium micro‐powder was packed in the slit manufactured on the outer surface of SiC/SiC composite tube. By applying the laser beam irradiation to the outer surface of Zircaloy tube circumferentially, the mechanical calking joint was successfully fabricated. In addition, it is revealed that the good adhesion between Zircaloy and SiC/SiC composite was partially produced as the result of the generation of all proportional solid solution between titanium and zirconium. Moreover, the examinations about the slit shape influences indicate that the narrow hook slit seems to be the best type of silt for holding the titanium powder during the laser irradiation, where the width of slit should be narrower than that of laser irradiation line.

Laser Synthesized Bi-functional Hybrid Catalyst Oxygen-defective Co3O4−x/N-Graphene for Oxygen Electrode Reactions

A hybrid of oxygen-defect-abundant Co3O4−x nanoparticles and graphene was successfully synthesized by a simple one-step laser irradiation method, and N atoms were introduced into the graphene by su...

Ultrafast synthesis of SiC@graphene nanocomposites by one-step laser induced fragmentation and decomposition

Carbides with high strength and chemically inert have unique optical and electrical properties, but widely used and controllable wet chemical methods are unsuitable for the synthesis of their nanocomposites because of the ultrahigh melting point. In this paper, we demonstrate one novel, simple and ultrafast laser irradiation method to synthesize ultrafine SiC@graphene nanocomposites. Both the fragmentation and spheroidization of bulk SiC flakes and surface covered by 1–3 graphene layers are accomplished in the one-step laser irradiation process.

Fabrication of a silica-based complex Fourier-transform integrated-optic spatial heterodyne spectrometer incorporating 120° optical hybrid couplers.

We demonstrate a silica-based planar waveguide spatial heterodyne spectrometer incorporating 120° optical hybrid 3×3 MMI couplers as the output couplers in 32 MZIs, which enabled us to derive the spectrum without use of the previously reported dynamic phase shifting. The free spectral range was 640GHz, and the spectral resolution was 14GHz. We used a CO2 laser irradiation method to calibrate the light powers from all the output ports of the couplers and to measure the optical phases and amplitudes at the individual MZIs. We solved the resultant system of three linear equations at each MZI and performed a complex Fourier transformation to derive a narrowband light spectrum. The background noise level of the retrieved spectrum was 0.05 with respect to the peak even when no window function was applied.