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Evaluation of surface roughness of metal films using plasmonic Fano resonance in attenuated total reflection
摘要： Attenuated total re?ection (ATR) by surface plasmon polariton (SPP) is a method for evaluating the dispersion relation of SPP from the position of a dip in the re?ection spectrum. However, recent studies have shown that the dips are displaced from SPP resonance because they are produced by a type of Fano resonance, i.e., the interference between the resonant re?ection process accompanied by resonant excitation of SPP and the direct re?ection process without resonant excitation. This result suggests that the system properties dif?cult to be achieved in the dispersion relation of SPP can be characterized using the ATR method. In this study, we investigate the effect of surface roughness due to nanosized dimples created in the initial stage of pitting corrosion on the ATR spectrum, from the viewpoint of Fano resonance. Using the temporal coupled-mode method, it is shown that the Fano resonance in ATR is caused by the phase change of direct re?ection because of the absorption on the metal surface, and the spectral shape is determined by this phase, along with the ratio of the external (radiative) decay rate to the total decay rate of the resonant mode. Moreover, it is clari?ed that the internal and external decay rates extracted from the ATR spectrum provide information on corrosion, such as the effective thickness of the metal ?lm and the randomness in dimple distribution.
关键词： surface plasmon resonance,Fano resonance,pitting corrosion,attenuated total re?ection,surface roughness
更新于2025-09-16 10:30:52
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Rapid crystallization of electrohydrodynamically atomized ZrO2 thin films by laser annealing
摘要： This paper aims to provide a simple and rapid fabricating method for solution-based ZrO2 thin films. The ZrO2 thin film was firstly deposited on a 316L stainless steel substrate by electrohydrodynamic atomization. Then the crystallization process was carried out by a 4W Nd:YAG laser with a wavelength of 1064 nm. The morphology, structure and evolution of chemical bonds (Zr and O) were evaluated by transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. After laser annealing, the O 1s (O-containing ions in ZrO2) fraction rose from 22.6 % to 51.1 %, and the principal tetragonal phase composition was obtained. The large temperature gradients that derived from the photothermal effect contribute to the fast crystallization during the laser treatments. The tribological and electrochemical corrosion experiments reveal that the laser crystallized films have significantly well wear and corrosion resistance, close to those of conventionally crystallized films. This fabricating method is simple, energy-saving and could achieve the spatially-resolved crystallization of films with a minimal temperature increase on the underlying substrates.
关键词： Laser annealing,ZrO2 thin films,Electrohydrodynamic atomization,Tribological and corrosion properties
更新于2025-09-16 10:30:52
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Microstructure and selected properties of boronized layers produced on C45 and CT90 steels after modification by diode laser
摘要： The paper presents the study results of macro- and microstructure, microhardness and corrosion resistance of C45 medium carbon steel and CT90 high carbon steel after diffusion boriding and laser modification by diode laser. It was found that the increase of carbon content reduced the thickness of boronized layer and caused change in their morphology. Diffusion boronized layers were composed of FeB and Fe2B iron borides. As a result of laser surface modification of these layers, the microstructure composed of three areas: remelted zone, heat affected zone (HAZ) and the substrate was obtained. Microhardness of laser remelting boronized layer in comparison with diffusion boronized layer was lower. The presence of HAZ was advantageous, because mild microhardness gradient between the layer and the substrate was assured. The specimens with laser boronized layers were characterized by better corrosion resistance than specimens without modified layer.
关键词： Laser remelting,Boronized layer,Corrosion resistance,Microstructure,Microhardness
更新于2025-09-16 10:30:52
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The microstructure and oxidation behavior of the N-doped modified layers on uranium surface prepared by pulsed laser irradiating
摘要： The N-doped modi?ed layer on uranium surface was prepared by pulsed laser irradiating in nitrogen atmosphere. The results of microstructure characterised by XRD, AES and XPS show that it is a composite layer with a gradual transition structure from UO2-xNy and uranium oxy-nitride (UNxOy) to UN and eventually to uranium from surface to interior. Initial oxidation behavior after sputtering for di?erent time illustrates that UNxOy with U 4f7/2 BE at 379.6 eV is inert under oxygen exposure. Further, the thermal stability study shows that the modi?ed layer exhibits excellent ability to prevent the O atoms from di?using into the interior at 423 K. Moreover, the corrosion protective properties of the N-doped modi?ed layers before and after thermal treatment were evaluated through potentiodynamic polarization tests. The results show that the N-doped modi?ed layer improved the corrosion protective properties of metallic uranium. The self-corrosive potential and self-corrosive current of the N-doped modi?ed layer are ?5.75 × 10?2 V vs. SCE and 1.37 × 10?7 A/cm2, while the values of metallic uranium were ?5.67 × 10?1 V vs. SCE and 8.08 × 10?7 A/cm2. After thermal treatment, its values are ?8.57 × 10?2 V vs. SCE and 4.83 × 10?8 A/cm2, indicating that the corrosion resistance of the N-doped modi?ed layer was further improved.
关键词： Corrosion resistance,N-doped modi?ed layer,UNxOy,Microstructure,Pulsed laser irradiating
更新于2025-09-16 10:30:52
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Reducing the pitting susceptibility of AISI 304 stainless steel using a hybrid treatment of high-power diode laser and large pulsed electron beam irradiation
摘要： Large pulsed electron beam (LPEB) irradiation has been widely used for surface modification of metals, alloys, polymers, and composites due to its unique interaction mechanisms with materials. The rapid melting and resolidification processes during LPEB irradiation induce phase transformation at the resolidified layer, which enables a simultaneous improvement in mechanical characteristics and chemical stability of metals. However, the generation of craters during LPEB irradiation adversely affects surface quality. It is imperative to minimize crater formation following LPEB irradiation to mitigate pitting corrosion on the surface of stainless steel (SS). In this study, a hybrid surface modification approach using a high-power diode laser (HPDL) and LPEB is proposed to reduce the crater generation during LPEB irradiation. The size and density of craters generated during LPEB irradiation were effectively reduced following the HPDL-LPEB irradiation hybrid surface treatment. The decrease in extent of crater formation and phase transformation has enabled an improvement in corrosion resistance. The ability of the resolidified layer formed after the hybrid HPDL-LPEB irradiation to form a stable passive film shifts the pitting potential from less than 0 mV/SCE (for untreated 304 SS) to more than +800 mV/SCE, which reduced the depth of corroded pits by 75%. The hybrid HPDL-LPEB irradiation decreased non-metallic inclusions, extent of crater formation and the surface roughness, and improved the pitting corrosion and general corrosion resistance.
关键词： High power diode laser,Pitting corrosion,Electron beam,Microstructure,Corrosion resistance,Stainless steels
更新于2025-09-12 10:27:22
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Microstructure and properties of homogeneous Cu90Fe10 immiscible composites with nanotwins by laser powder deposition: Effect of spot size
摘要： To select the reasonable spot size during laser powder deposition (LPD), the homogeneous Cu90Fe10 immiscible composites were produced by LPD with different spot sizes (2 mm and 4 mm in diameter). The LPD-produced Cu90Fe10 immiscible composites deposited with different spot sizes display a similar microstructure composed of a-Fe/g-Fe and ε-Cu phases. A large amount of nanoscale Fe-rich particles is uniformly embedded within the Cu-rich matrix and the Cu-rich particles with nanotwins are distributed within the Fe-rich particles due to secondary liquid phase separation (SLPS). Moreover, some nanoscale FeCr grains (~20 nm) are precipitated within the Fe-rich particles. Both the averaged diameter and grain size of Fe-rich particles reduce with decreasing the spot size due to higher cooling rate. The immiscible composite produced with spot size of 2 mm exhibits higher microhardness and elastic modulus (1.9 GPa and 143.5 GPa respectively) than the corresponding ones for the counterpart with spot size of 4 mm (1.8 GPa and 142.6 GPa respectively) and Brass. As a result, the LPD-produced Cu90Fe10 immiscible composite deposited with spot size of 2 mm exhibits higher wear and corrosion resistance compared to that deposited with spot size of 4 mm.
关键词： Nanotwins,Wear,Laser powder deposition,Corrosion,Particle-reinforcement
更新于2025-09-12 10:27:22
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Experimental Study on the Effect of Dust Deposition on Photovoltaic Panels
摘要： In recent years, PV is considered to be one of the main way to solve the current energy crisis. PV is generally built in exposed areas such as deserts and wasteland. And the efficiency of power generation of PV is easy affected by the dust accumulated on it. The research expounds the "three factors" of the effect of dust on PV, namely shielding effect, temperature effect and corrosion effect, then an efficiency evaluation method for photovoltaic cells is proposed. Finally, the field experiments show that with the increase of dust density, the short-circuit current, open-circuit voltage, and output power of the PV both decrease. The dust with a density of 10 g/m2 can reduce the maximum power of the PV by about 34%. In the initial stage of PV dust accumulation, dust has the greatest impact on its output performance. In addition, the dust density and the conversion efficiency have better nonlinear correlation. As the dust accumulation density gradually increases, the PV conversion efficiency gradually decreases. When the dust density increases to a certain extent, the PV conversion efficiency tends to be stable.
关键词： Temperature effect,Corrosion effect,Conversion efficiency,Shielding effect
更新于2025-09-12 10:27:22
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Parametric study of laser welding of copper to austenitic stainless steel
摘要： Welding of copper to stainless steel is challenging because of sharp difference in thermophysical properties of materials and the presence of miscibility gap in Fe-Cu system. The parametric study of continuous Yb:YAG laser welding between copper and austenitic stainless steel 316L has been performed. The influence of laser power, welding speed and beam offset from joint line on weld composition, microstructure and tensile properties was studied. The corrosion behaviour of the welds was evaluated in 0.1M NaCl with the potentiostatic pulse testing method, salt fog and immersion tests. In function of copper dilution in the melted zone, different types of microstructure were observed: homogenous solid solution (≥2 at.% Cu), copper-rich net between austenite cells (2-5 at.% Cu) and formation of Cu-rich droplets (> 20 at.% Cu). Selective corrosion of Cu-rich microstructures took place in the melted zone. Tensile properties of the welds were determined by the formation of heat-affected zone in solid copper, where ductile fracture took place.
关键词： stainless steel,copper,corrosion,laser,dissimilar welding
更新于2025-09-12 10:27:22
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Fatigue Strength of Laser Beam Welded Steel-Aluminium Joints Considering Variable Amplitude Loading and Corrosive Environment
摘要： Hybrid material combinations of steel and aluminium are currently being joined by explosive welding in ship design, in order to reduce fuel consumption and increase transport weight. As an alternative to the elaborate and expensive explosive welding, a replacement for steel-aluminium adapters by means of laser beam welding in a lap joint configuration is being aimed at. Therefore, a laser beam welding process has been developed and optimised with regard to the different melting points and coefficients of thermal expansion of the materials as well as the formation of intermetallic phases due to the limited solubility of the elements. The characteristic of the weld seam, which is the result of a melt pool through the steel into the aluminium material, has a major impact on the quasi-static and cyclic strength of the joint. Especially the weld width and penetration depth have been identified as main influencing parameters. In the end, the developed laser beam welding process under spectroscopic control of the penetration depth is validated by fatigue investigations of lap joints and compact designed adapters. In addition to the fatigue strength under constant amplitude loading (CAL), the fatigue performance under variable amplitude loading (VAL) is particularly promising, even though the scatter increases from CAL to VAL and a linear damage accumulation is not applicable. A change in the fracture behaviour is explained by the intensity of the loading. Finally, the corrosion fatigue behaviour is shown by constant amplitude loading in a corrosive environment with a sodium chloride solution of 5 %, which causes a strength reduction from high cycle to long life fatigue.
关键词： steel-aluminium joint,ship building,corrosion fatigue,explosion welding,laser beam welding,lap joint,corrosive environment,ship design,constant amplitude loading,variable amplitude loading,compact adapter,fatigue assessment
更新于2025-09-12 10:27:22
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Effect of energy parameters of pulsed laser welding of Zr-1%Nb alloy on metal contamination with gases and properties of welds
摘要： Effect of pulsed laser welding parameters (pulse energy and duration, frequency, welding speed and, as a result, overlapping factor) on properties of E110 (Zr-1%Nb) alloy welds is presented. Butt welded joints of two identical plates with a thickness of 0.5 mm were investigated. EDS analysis of a surface layer of the welds was done, initial hydrogen concentration in the weld metal was measured and influence of absorbed gases (oxygen, nitrogen, carbon and hydrogen) on tensile strength, microhardness, hydrogen absorption rate and corrosion resistance of the welds was evaluated. The weld metal contained initial hydrogen concentration within the limits set by standards. However, mixing argon flows with atmospheric gases caused the weld metal contamination with oxygen, nitrogen and carbon. As a result, inclusions of complex chemical composition and surface branching microcracks were formed. They were stress raisers where weld failures occurred. Furthermore, it was the reason of increased hydrogen absorption rate and decreased corrosion resistance of the weld metal. The obtained results showed that absence of discoloration on surfaces of the welded joints did not guarantee metal purity and, as a consequence, required performance properties. Future research is required to determine the optimal overlapping factor; shielding gas compositions (Ar, He or their mixture) and flow rates; configuration and inclination angle of nozzles as well as distance from the nozzles to the weld zone.
关键词： Pulsed laser welding,Metal contamination,Corrosion resistance,Hydrogen content,Zirconium alloy,Hydrogen absorption rate
更新于2025-09-12 10:27:22