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In this study, laser cleaning of blue and red polyurethane paint on aluminum alloy surface were investigated by using a nanosecond pulsed laser at 1.8, 3.2 and 8.0 J/cm 2 . The surface topography after laser cleaning was analyzed by confocal laser scanning microscope (CLSM) and field emission scanning electron microscopy (SEM), and the paint removal process was recorded by high-speed camera (HSC) and spectrophotometer. It was found that the cleaning results and phenomena of the two paints were significantly different. After cleaned at 1.8 J/cm 2 , the blue residual paint is a uniform and flat paint layer while the red residual paint presents a loose mesh morphology. Although both red paint and blue paint could be removed at 3.2 and 8.0 J/cm 2 , the surface of the substrate shows different topography. It could be observed by HSC that the blue paint detached from the substrate by being vaporized and the red paint was disintegrated into pieces and ejected from the substrate. This phenomenon was caused by the difference in the absorption coefficient of the two paints to the laser. To illustrate this, an energy distribution model was established considering Beer-Lambert’s law and the temperature distribution of paint and thermal stress of substrate were calculated. Under laser irradiation, blue paint was more likely to be ablated and vaporized, while red paint was subject to greater thermal stress. For blue paint removal, vaporization, spallation and combustion are the dominated mechanisms and the red paint was mainly erupted by thermal stress of substrate.

The rapid development of neuro-inspired computing demands synaptic devices with ultrafast speed, low power consumption, and multiple non-volatile states, among other features. Here, a high-performance synaptic device is designed and established based on a Ag/PbZr 0.52 Ti 0.48 O 3 (PZT, (111)-oriented)/Nb:SrTiO 3 ferroelectric tunnel junction (FTJ). The advantages of (111)-oriented PZT (~1.2 nm) include its multiple ferroelectric switching dynamics, ultrafine ferroelectric domains, and small coercive voltage. The FTJ shows high-precision (256 states, 8 bits), reproducible (cycle-to-cycle variation, ~2.06%), linear (nonlinearity <1) and symmetric weight updates, with a good endurance of >10 9 cycles and an ultralow write energy consumption. In particular, manipulations among 150 states are realized under subnanosecond (~630 ps) pulse voltages ≤5 V, and the fastest resistance switching at 300 ps for the FTJs is achieved by voltages <13 V. Based on the experimental performance, the convolutional neural network simulation achieves a high online learning accuracy of ~94.7% for recognizing fashion product images, close to the calculated result of ~95.6% by floating-point-based convolutional neural network software. Interestingly, the FTJ-based neural network is very robust to input image noise, showing potential for practical applications. This work represents an important improvement in FTJs towards building neuro-inspired computing systems. Brain-inspired computing demands high-performance synapses. Here, the authors report a subnanosecond ferroelectric tunnel junction with 256 conductance states, 10 9 endurance, and 5.3 fJ/bit energy consumption, satisfactory to build synaptic devices.

Inspired by the micro-papillae structure on the lotus leaf surface, this study employed a nanosecond pulsed laser with a wavelength of 1064 nm to fabricate circular micro-dimple arrays with different spacings (15 μm, 10 μm, 5 μm, 3 μm) on X65 steel surfaces. The evolution behavior of the microstructure from “separated” to “intersected” and its influence on the surface morphology were systematically investigated. The sample morphology was analyzed using scanning electron microscopy (SEM). The results indicate that as the spacing decreases, the micro-dimples gradually evolve from an independent distribution to a continuous network of groove-protrusion composite structures, with a significant enhancement in the thermal accumulation effect. This study successfully achieved the controllable fabrication of micro-nano structures on the X65 steel surface, providing an experimental basis for its application in biomimetic functional surfaces such as hydrophobic and drag-reducing surfaces.

Steel, aluminum, and copper have widespread applications in manufacturing railway structures and components, bridges, automobiles, battery systems, and electronics. Different surface treatment processes have been carried out to increase these material’s functional ability. Laser ablation is one of the laser processing technologies employed to modify the surface properties of various materials. Limited work is carried out on laser ablation of steel SM490A irradiated with a nanosecond pulsed laser. Furthermore, no study was reported on the comparative analysis between SM490A, aluminum (Al), and copper (Cu). The objective of the present study is to determine the ablation threshold and single-shot ablation of SM490A, Al, and Cu using a nanosecond pulsed laser in ambient air conditions. Scanning electron microscopy (SEM) has been performed to measure the ablated crater width to determine the ablation threshold of the materials. The study also investigates the effect of laser parameters on the ablation process on different surface roughness of the materials. It was observed that surfaces with higher roughness have a higher ablation threshold than those with minimum surface roughness. The study’s outcomes show the influence of laser shots on the ablation thresholds of the material. The results show that Cu has a higher threshold fluence than Al and SM490A, while SM490A has minimum threshold fluence at single-shot ablation. The study explains the laser ablation mechanism for different materials.

In this study, we conducted an investigation into the heterogeneous bonding process of glass and copper using a nanosecond pulsed laser for laser transmission welding. Our research focused on examining various processing parameters and the influence of focal plane positions on bonding quality. To evaluate weld strength, we employed both pull-tensile separation force (PTSF) and shear-tensile separation force (STSF) measurements. The analysis of fracture and separation results encompassed detailed examinations of weld morphology, microstructure, elemental composition, and phase configuration. The results revealed that increasing the laser welding energy initially enhanced the weld strength until it reached a saturation point. This saturation point was attributed to the formation of voids or cracks, leading to residual stress within the weld zone due to non-uniform hot spots in the molten area during processing. Among the different focal plane positions tested, positioning it below the glass/copper interface yielded the highest weld strength. The maximum achieved bond strength was above 10 MPa, demonstrating the feasibility of cost-effective pulsed laser welding for copper-to-glass applications. Moreover, the weld strength obtained using STSF surpassed that of PTSF. This discrepancy arises from the fact that PTSF separation led to fractures at the weld seam-glass boundary, leaving the weld seam on the copper plate. In contrast, STSF resulted in separation along the weld-copper interface, leaving the weld seam on the glass sheet. In-depth analysis through SEM and EDS elucidated that Cu and SiO 2 underwent intra-mixing and inter-particle diffusion in the molten pool during welding. HR-TEM and SAED observations unveiled the presence of polycrystalline copper nanoparticles, copper oxides, and an amorphous Cu–O-Si region at the weld interface. This amorphous region significantly contributed to the robust bonding between copper and glass.

Currently, SiC particle–reinforced aluminum matrix (SiCp/Al) materials are extensively utilized in industries. However, during the cutting process, the extrusion of the cutting tool onto the materials induces a significant stress concentration phenomenon, subsequently increasing tearing of the Al matrix as well as pull-out and fracture of the SiC particles. These phenomena can lead to severe cutting tool wear. Nanosecond pulsed laser–assisted cutting has been chosen for 45% volume fraction SiCp/Al to improve the cutting tool wear. The cutting simulation and experiments are used to analyze the types of cutting tool wear. The adjustment of pulsed laser power (0–50 W) and pulse width (0–100 ns) can effectively mitigate the cutting tool wear by inducing a thermal softening effect. The simulation and experimental results demonstrate that the utilization of the pulsed laser enhances the plastic deformation of the Al matrix and mitigates the fracture of the SiC particles, thereby potentially reducing abrasive wear on the cutting tools. The increase in pulse width and pulsed laser frequency may result in enhanced adhesive wear on the rake surface under elevated temperature conditions. Therefore, by adjusting the pulsed laser parameters, the interaction between the cutting tool and Al matrix as well as SiC particles can be improved during the cutting process, thereby reducing the cutting tool wear.