Morphology Of Holes Research Articles

Characteristics of stitching holes in plain-woven SiCf/SiC and its influence on tensile behavior

A certain number of stitching holes are randomly distributed in SiCf/SiC composites prepared by CVI method. The existence of these stitching holes disrupts the continuity of the internal fiber bundles and has a certain influence on the mechanical properties of the materials. In order to study the influence of stitching holes on the tensile behavior of plain-woven SiCf/SiC, this paper uses CT technology to scan the interior of plain-woven SiCf/SiC to obtain the morphology and distribution of the internal stitching holes. Then, cells containing stitching holes were modeled to study the influence of different characteristics of stitching holes on the tensile behavior of SiCf/SiC. Finally, the tensile behavior and damage process of the cell with stitching hole at the fracture location of the specimen and the cell with stitching hole near the fracture location were studied by modeling the specimen level cell with the thickness of the specimen. The conclusions are as follows: (1) A certain number of stitching holes were randomly distributed inside the specimen. The inclination angles of the stitching holes are mostly 70°–80°, and the radius of the stitching holes is mostly 0.25 mm–0.28 mm (2) The influence of stitching hole characteristics on the tensile behavior of plain-woven SiCf/SiC is as follows: Position > Hole radius > Inclination angle. Among the positional characteristics, the Type-Ⅱ model has the greatest influence on the weakening of the tensile behavior due to more pronounced stress concentration phenomenon. (3) The stitching hole at the edge of the specimen has the greatest influence on the weakening of the specimen strength and is accompanied by obvious stress concentration. In the section containing the stitching holes, the maximum local stresses in the fiber bundle and matrix are about 1.5 times that of the other two models, resulting in earlier damage initiation and faster accumulation.

Comparison of iron aluminide Fe3Al with armour steel in ballistic behaviour

Intermetallic aluminide compounds possess several potential advantages compared to alloyed steels, like enhanced oxidation resistance, lower density and the omittance of critical raw materials. Iron aluminides, compared to other transition metal–aluminides of TM3-Al type, although having a higher density compared to titan-aluminides, have a lower density compared to nickel-aluminides, but also a higher ductility than both alternatives, making this material potentially effective in ballistic protection application. Density–wise, this material may be a worthy alternative to armour steels, which was the aim of this study. Two materials, Fe3Al intermetallic compound (F3A-C) and Armox 500 armour steel were ballistically tested against tungsten-carbide (WC) armour-piercing ammunition, in accordance with STANAG 4569. After ballistic testing, microhardness and metallographic testing were performed, revealing differences in strain hardening, crack propagation mode and exit hole morphology. F3A-C ballistic resistance is similar to that of armour steel, in spite of the lower tensile and impact mechanical properties, relying on a considerably higher strain hardening rate, thermal properties and a lower density.

Computational Simulation of Monopile Scour under Tidal Flow Considering Suspended Energy Dissipation

Local scour around bridge foundations significantly impacts the stability and safety of marine structures. The development of scour holes adjacent to the pile foundations of sea-crossing bridges, influenced by tidal currents, involves multidimensional physical fields, multiscale coupling, and complex variations in marine loads. However, experimental models alone are inadequate for investigating the underlying mechanisms. Numerical simulation, a critical tool for studying local scour processes, faces the challenge of accurately modeling sediment transport, particularly under tidal flow conditions near pile foundations. To solve this challenge, this research considers the effect of reciprocating flow on sediment shear as well as its characteristic dissipation based on the immersed boundary method, introduces a reciprocating flow dissipation mechanism, and adds a momentum exchange term between the fluid and the sediment to derive a new controlling equation; a new tidal flow localized scour solver is ultimately constructed, termed TidalflowFOAM. The solver effectively simulates complex flow conditions under tidal currents, extending the modeling capabilities to more realistic three-dimensional bridge scour scenarios under combined wave and current conditions. Validation through cases reported in the literature and a series of controlled experiments, encompassing varying depths, flow velocities, and pile diameters, demonstrates the solver’s proficiency in capturing post-vortex data and accurately reflecting the influence of key factors on scour depth. However, the fidelity of the simulated scour hole morphology under tidal flow conditions behind the piles requires enhancement. The proposed numerical model for tidal flow conditions has high solution accuracy and can guide practical engineering applications.

Cryogenic and ultrasonic-assisted micro-drilling of printed circuit boards using high-frequency-amplitude spindle

Printed circuit boards (PCBs) are key components in computers, 5G, 6G, and other wireless communication devices. On the other hand, the manufacture of micro-holes in PCBs faces severe challenges. Conventional micro-drilling methods often encounter challenges such as poor surface quality and limited tool life. To overcome these issues, a novel micro-drilling method called cryogenic and ultrasonic-assisted micro-drilling (CUAMD) has been developed. This study compared four drilling methods to investigate the benefits of cryogenic and ultrasonic-assisted drilling in hybrid machining processes: conventional micro-drilling (CMD), cryogenic-assisted micro-drilling (CAMD), ultrasonic-assisted micro-drilling (UAMD), and cryogenic and ultrasonic-assisted micro-drilling (CUAMD). The experimental results unequivocally indicate that the utilization of cryogenic-assisted drilling leads to a significant reduction in cutting heat during the machining process. This not only contributes to an improvement in machining accuracy but also exerts a positive influence on tool life and surface morphology. Ultrasonic-assisted drilling separates chips into smaller volumes through high-frequency-vibration, effectively reducing the cutting forces. The high frequency of 38.25 kHz and high amplitude vibration of 5.16 μm of the ultrasonic spindle induced vibrations on the drill bit. Liquid nitrogen with a pressure and temperature of 28 kPa and − 196 °C, respectively, was used in the cryogenic-assisted method. The superior machining performance of the CUAMD approach was evaluated by comparing it to various methods, including cutting forces, tool flank wear, entrance/exit hole morphology, and chip formation. The CUAMD method avoids chip entanglement, suppresses burrs, and reduces the maximum cutting force, maximum torque, and exit hole damage factor Fd by 47.7 %, 56.1 %, and 42.5 %, respectively, compared with CMD.

Processing characteristics and ablation mechanism of CMC-SiCf/SiC by rotational thirteen-beam coupling nanosecond laser

Silicon carbide fiber reinforced silicon carbide ceramic matrix composite (CMC SiCf/SiC) has the advantages of high temperature resistance, corrosion resistance, high strength, low density, and oxidation resistance. It is a high-performance advanced material in aerospace, energy and other fields. However, due to its high hardness, brittleness and anisotropy of fiber structure, the research on application-oriented high-quality processing technology has become a hot issue. In this paper, a new process of rotational thirteen-beam coupling nanosecond laser processing of CMC-SiCf/SiC was studied. The rotational thirteen-beam coupling ablation experiments were carried out on CMC-SiCf/SiC workpiece. A laser beam is divided into thirteen beams and rotated around the beam center by using a beam splitter element. The morphology, structure and composition of ablation holes at different speeds were observed and analyzed by laser confocal microscope, scanning electron microscope, and X-ray energy dispersive spectrometer. It is found that the characteristics of rotational beam coupling have a significant effect on the laser ablation morphologies. The results show that the ablation region of CMC-SiCf/SiC is elliptical due to the fast heat transfer of fibers. The energy density distribution of the waist section of the Gaussian like beam after beam coupling is similar to the “W" shape, and the central energy is lower than the surrounding energy, and the ablation holes also show a similar “W" shape. With the increase of rotational speed, the hole depth first decreased and then increased, the hole diameter and roundness first increased and then decreased, and the hole section was “W" shaped. The ablation area can be divided into five parts: the white granular SiO2 solid coverage area, the recast layer, the lower recast layer, the molten layer, and the heat affected zone. The rotational characteristics will make the reaction intensity of the whole ablation area more uniform in the circumferential direction. The formation mechanism and element distribution of each part were explored. The research work in this paper will provide a new technical way for the high-performance application of CMC-SiCf/SiC.

Performance optimization of PERC solar cells based on laser ablation forming local contact on the rear

Abstract To improve the photoelectric conversion efficiency (η) of the solar cell, a green wavelength (532 nm) laser source in a nanosecond range was used to ablate the passivated emitter and rear cell (PERC) to form the contact holes. If the laser ablation hole opening process was not set properly, the diameter or the external expansion of holes would be too large, causing the decline of the PERC performance. The Gaussian distribution of the laser is regulated by the output power (P o) and the repetition frequency (f rep) of the incident pulse laser, so that the optimized morphology of holes is obtained on the back of the PERC solar cells. After the contact holes are screen printed by the aluminum paste, the local back surface field is finally formed. The experimental results showed that the outward expansion decreases obviously with the increase of laser P o. Second, the spacing of the holes decreases with the increase of the laser f rep. It was found that under the laser P o of 33.0 W and f rep of 1,400 kHz, the η of the industrial PERC solar cells was the highest. The Quokka simulations indicated that small outward expansion, small diameter, and long spacing of holes would further decrease the recombination parameter in the rear surface. With the optimized morphology of contact holes and the low contact resistance, the PERC cell’s calculated V oc and η improvements were 6.5 mV and 0.48%, respectively, which was verified with experimental findings.

Hole formation mechanisms in double-sided laser drilling of Ti6Al4V-C/SiC stacked materials

This is the first investigation on the potential of doubled-sided laser drilling for hole making in Ti6Al4V-C/SiC, a hard-to-machine stacked structure that holds critical significance in high-temperature structural applications. While previous literature reported laser drilling-induced microstructural change in Ti6Al4V and C/SiC single sheets respectively, a comprehensive understanding of the melt pool formation process and its influence on hole morphology/quality is still lacking. The complexity increases when Ti6Al4V is coupled with C/SiC in a stacked structure, highlighting a significant yet understudied knowledge gap in understanding the intricate material interactions at the interface. Here we present a multifaceted study combining novel computational fluid dynamics (CFD) modeling approach with ablation mechanism investigation through advanced microstructure analysis. A hybrid CFD modeling strategy integrating volume of fluid method and level set method has been developed to successfully simulate the evolution of hole shape, recast layer formation, and melt pool flow behaviour in Ti6Al4V-C/SiC. This model provides comprehensive insights into molten pool dynamics under various laser drilling conditions, fostering a fundamental understanding of the mechanism that drives recast layer formation and influencing surface quality. To validate our modeling outcomes, extensive experimental investigations were undertaken across a range of laser drilling conditions. Whenever possible, samples were analysed using advanced materials characterization techniques, including scanning electron microscopy, energy dispersive spectroscopy, and electron backscatter diffraction, to elucidate the microstructural evolution within the recast layer and the formation of the heat-affected zone. Whenever possible, the results were also compared with single side drilled Ti6Al4V-C/SiC stacks, Ti6Al4V or C/SiC single sheets (i.e., the benchmark references). Our experimental findings align well with the modeling results, systematically illustrating that doubled-sided laser drilling of the stacked structure outperforms the conventional single-sided laser drilling in terms of hole morphology, surface roughness, and reduced recast layer formation. Despite these promising results, the proposed technology is currently limited to laboratory scales and lacks capacity in manufacturing certain parts with complex geometry. Future outlook has therefore been proposed with potential solution to address these challenges and enable real world applications in future.

Effect of PCD tool wear on surface morphology and material removal mechanisms in the micro-drilling of Cf/SiC composites: Experiment and simulation

This study investigates the polycrystalline diamond (PCD) tool's wear mechanism and the effect of tool wear on hole morphology in the micro-drilling of Cf/SiC composites. A 2D woven material model and tool wear model are created for the drilling simulation. The findings indicate that the wear mechanisms of the tools are mainly abrasive and adhesive. As the tool is worn, the quality of the hole entrance/exit and the shape accuracy deteriorate, and the surface roughness of the hole wall increases. Furthermore, a blunt cutting-edge radius shifts material removal from a shear effect to a compressive effect, transitioning from micro-brittle to macro-brittle removal. Notably, the simulation results approximately agree with the experimental results.

Effect of Decompression Hole Structure Design on Stress Inhomogeneity of Stainless Steel Base Force Transducers

In order to reduce the stress inhomogeneity of the stainless steel base force transducer, the force transducer structure with decompression holes of different depths and different hole morphologies is designed in this paper and compared with the traditional force transducer structure without decompression hole design. According to the finite element analysis theory, the stress inhomogeneity level under different pressures and different structures is tested using a simulation platform. When a flat-bottomed hole is used and the depth of the decompression hole is 7 mm, the stress inhomogeneity of the inner ring of the force measurement structure is 32.77% of the original scheme, and the stress inhomogeneity of the outer ring is 90.12% of the original scheme. The simulation results show that the use of a suitable decompression hole structure can help to reduce the stress inhomogeneity of the force measurement structure. This work provides a new idea in the field of sensor optimization.

Investigation of in-plane and out-of-plane micro-hole drilling on 2D-Cf/SiC composites

Carbon fiber-reinforced silicon carbide matrix composites (Cf/SiCs) are extensively utilized in the field of aviation and aerospace because of their superior mechanical qualities. However, it is difficult to machine high-quality small holes on them. To investigate the characteristics of micro-drilling on Cf/SiCs, the polycrystalline diamond (PCD) tool was used to machine holes on the in-plan and out-of-plan surfaces of Cf/SiC composites. The drilling force, the hole morphology and quality were explored. The mechanisms of material removal and tool wear were studied. The size effect during the micro-drilling process was also investigated. The outcomes showed that the out-of-plane drilling process yielded more thrust force and torque than the in-plane drilling process. The main forms of damage at the hole entrance and exit are tearing and burrs during in-plane drilling. The damage is mainly in the form of edge breaking caused by debonding and fracture of longitudinal fiber during out-of-plane drilling. The surface defects of the hole exit and entrance during out-of-plane drilling are fewer than those during in-plane drilling. The roundness errors of holes during in-plane drilling are fewer than those during out-of-plane drilling. Additionally, the surface roughness of the hole wall during in-plane drilling is less. Besides, brittle and ductile removal areas were observed at different fiber orientation angles (FOA). Furthermore, the rapid rise in specific cutting energy and the deterioration of surface quality when the feed rate is much smaller than the cutting edge proves the presence of the size effect. A new observation was that the abrasive wear of the flank face and chisel edge during out-of-plane drilling was more severe than that of in-plane drilling.

Modeling and surface morphological study in drilling of Al 2024 alloy

With concern to profuse usability of drilling operations in various industries, almost 1/3rd of the all the machining operations, the main focus is to obtain a proper quality of hole in less time at optimum cost. Aluminium alloy 2024 (Al 2024) is largely applied in various industries specially, aircraft, automotive, marine etc. because of its outstanding union towards strength, corrosion resistance, and weldability. Cutting time, cutting temperature and surface morphological investigation during drilling is very much necessary for obtaining a quality hole that has not been substantially researched so much. Therefore, a proper and thorough study of these responses is quite important regarding the hole quality. With this view, in this work, drilling of Al 2024 alloy is performed with three process parameters (input) viz. spindle speed (v), feed rate (f) and drill bit diameter (d) and performance parameters (output) as cutting time (s), cutting temperature (°C) and surface roughness (μm). Three different drill bit diameters of high speed steel (HSS) of size viz. 6 mm, 8 mm and 10 mm are used in drilling. Each process parameter has three levels. The surface morphological study is also conducted to know the depth of hole morphology details after drilling. To make the drilling operation environment friendly, it is performed in dry atmosphere. Using full factorial design, total 27 experiments are conducted. The experimental results showed that high spindle speed along with high feed rate decreases the cutting time, whereas it increases the cutting temperature. For better surface finish medium spindle speed along with low feed rate is recommended. From analysis of variance (ANOVA), all the three models developed for cutting time, cutting temperature and surface roughness are found statistically significant. Spindle speed and feed are the influential parameters to cutting time, cutting temperature and surface roughness. A mathematical model is developed using response surface methodology (RSM) to predict the responses cutting time, cutting temperature and surface roughness with better accuracy. The coefficient of determination (R2) for cutting time, cutting temperature and surface roughness is found as 96.65%, 95.88% and 93.65% respectively, which indicated that the developed models could be used for prediction with better accuracy. The morphological study shows that scratches, trenches, abrasive wear are visible on the hole surface. At high spindle speed surface grain refinement is observed more which causes a better surface finish.

A Homopolymer of Xanthenoxanthene‐Based Polycyclic Heteroaromatic for Efficient and Stable Perovskite Solar Cells

AbstractHighly efficient perovskite solar cells typically rely on spiro‐OMeTAD as a hole transporter, achieving a 25.7 % efficiency record. However, these cells are susceptible to harsh 85 °C conditions. Here, we present a peri‐xanthenoxanthene‐based semiconducting homopolymer (p‐TNI2) with matched energy levels and a high molecular weight, synthesized nearly quantitatively through facile oxidative polymerization. Compared to established materials, p‐TNI2 excels in hole mobility, morphology, modulus, and waterproofing. Implementing p‐TNI2 as the hole transport layer results in n‐i‐p perovskite solar cells with an initial average efficiency of 24.6 %, rivaling 24.4 % for the spiro‐OMeTAD control cells under identical conditions. Furthermore, the p‐TNI2‐based cells exhibit enhanced thermostability at 85 °C and operational robustness.

A Homopolymer of Xanthenoxanthene-Based Polycyclic Heteroaromatic for Efficient and Stable Perovskite Solar Cells.

Highly efficient perovskite solar cells typically rely on spiro-OMeTAD as a hole transporter, achieving a 25.7 % efficiency record. However, these cells are susceptible to harsh 85 °C conditions. Here, we present a peri-xanthenoxanthene-based semiconducting homopolymer (p-TNI2) with matched energy levels and a high molecular weight, synthesized nearly quantitatively through facile oxidative polymerization. Compared to established materials, p-TNI2 excels in hole mobility, morphology, modulus, and waterproofing. Implementing p-TNI2 as the hole transport layer results in n-i-p perovskite solar cells with an initial average efficiency of 24.6 %, rivaling 24.4 % for the spiro-OMeTAD control cells under identical conditions. Furthermore, the p-TNI2-based cells exhibit enhanced thermostability at 85 °C and operational robustness.

Study on the rock-breaking characteristics of high-energy pulsed plasma jet for granite

Plasma jet rock-breaking technology, characterized by its high rock-breaking efficiency, low specific energy, and absence of mechanical wear, is one of the most promising methods for efficiently fracturing hard rock formations such as hot dry rock (HDR). This study designed a novel high-energy pulsed plasma power supply and pulsed gas supply system to achieve rock fracturing through the instantaneous high-temperature and thermal stress impact of the high-energy pulsed plasma jet on the rock surface. This paper conducted comparative experiments with a traditional constant plasma jet. The impact of crucial electrical parameters (peak current, valley current, frequency, and duty cycle) and rock initial temperature on the damage and fracturing patterns of granite was extensively investigated. Comprehensive evaluation criteria, including removal mass, diameter, depth, rate of penetration, and specific energy, were employed to study the effects meticulously. The results indicate that the pulsed plasma jet significantly enhances energy utilization, effectively reducing the occurrence of thermal melting. The specific energy decreased significantly by 54.74%, while the rate of penetration increased by 17.81%. Additionally, electrode wear was reduced by 50.06%, extending the lifespan of the plasma bit. Parametric analysis revealed that the peak current is the primary factor influencing the rock-breaking performance and efficiency. The valley current has minimal impact on hole morphology but significantly affects specific energy. Frequency and duty cycle can be adjusted to optimize the single-pulse energy, achieving the best specific energy and efficiency. Additionally, the rock temperature has a great influence on the breaking effect. The fracturing characteristics of granite were also analyzed from a microscopic level. Based on the experimental results, recommended parameters of pulsed plasma jet are provided for breaking granite. These findings offer guidance for high-energy pulsed plasma jet drilling of HDR.

Study of Plasma Arc Underwater Penetration Processes in Steel Structures Covered with Non-conductive Materials

Recently, plenty of offshore platforms have faced decommissioning. Offshore steel structures covered with rust, mud, and barnacles require suitable cutting methods for their removal. The non-transferred plasma arc is highly efficient in cutting both conductive and non-conductive materials and is expected to play an important role in offshore demolition operations. This work aims to investigate the underwater penetration process of non-transferred plasma arcs on steel structures covered with non-conductive substances. The workpiece consisted of a 5 mm cement layer and a 10 mm steel plate, whose removal mass and hole morphology were recorded at several moments. It was found that the hole of the cement layer was larger than that of the steel plate, while the mass removal rate of the steel plate was much higher than that of the cement layer. The hole in the cement layer gradually changes from an inverted cone to a drum, and the hole in the steel plate is always an inverted cone. A combined heat source model with time variation is proposed based on the experimental results, and a 2D axisymmetric simulation model is developed. The error between the simulated and experimental hole dimensions was within 3.1%, proving that the proposed heat source model can reflect the heat process of the workpiece well.

High-speed projectile perforation of nickel-based Inconel 718 superalloy plates: Experiments and modeling

Understanding ballistic behavior of structural materials is important for their applications in aeronautical and astronautical industries. We investigate perforation of 2-mm thick Inconel 718 superalloy plates by spherical stainless steel 304 projectiles with high-speed photography at impact velocities ranging from 548 ms−1 to 1360 ms−1. Postmortem target samples are characterized with optical metallography, scanning electron microscopy and electron backscatter diffraction as regards bullet hole morphology and deformation. Grain refinement and shear banding are the main microstructural deformation modes near the bullet holes. Shear dominated deformation and tension–shear dominated deformation of target material occur sequentially in bullet hole along the impact direction. The morphologies of bullet holes and postmortem projectiles are obtained from the experiments and simulations. The effect of projectile deformation on ballistic behavior of the target is investigated. On the basis of dimensional analysis, a quadratic relation is derived between the energy absorption ratio of target and the dimensionless postmortem projectile diameter, along with a phenomenological model that can well predict projectile residual velocities.

Comparative Study of Percussion Drilling in Glasses with a Femtosecond Laser in Single Pulse, MHz-Burst, and GHz-Burst Regimes and Optimization of the Hole Aspect Ratio.

In this contribution, we present a comparative study on top-down drilling in sodalime glass, with a femtosecond laser operating in single-pulse, MHz-burst and GHz-burst modes, respectively. We investigate the hole depth, drilling rate, and hole morphology for these three regimes while keeping the same experimental conditions. We demonstrate that, for both burst regimes, the burst length has to be adapted for optimizing the hole depth. In the GHz-burst regime, the lower the ablation rate the longer the holes. The three drilling regimes lead to different hole morphologies, where the GHz-burst mode results in the best hole quality featuring glossy inner walls and an almost cylindrical morphology. Furthermore, we obtain crack-free holes, the deepest measuring 3.7 mm in length and 25 µm in entrance diameter corresponding to an aspect ratio of 150, which is the highest aspect ratio reported thus far with femtosecond GHz-burst drilling to the best of our knowledge.

Numerical simulation and experimental study on the interaction between a convex ring PDC bit and rock

To address the problems of low rock-breaking efficiency and high energy consumption of polycrystalline diamond compact (PDC) bits in hard formations of deep well sections, a convex ring PDC bit is proposed that alters the stress distribution law of the smooth bottom hole of a conventional PDC bit and forms a double-order stress state of the bottom-hole rock. The interaction law between the convex ring PDC bit and rock is explored by combining numerical simulation and experiment. The numerical simulation of conventional PDC bit and convex ring PDC bits is conducted using the discrete element method. The simulation results show that the stress concentration occurs at the convex ring of the new drill bit, resulting in multiple main cracks and facilitating volume crushing. The surrounding compressive stress ring formed by the new drill bit exhibits obvious pressure differences, which can effectively induce the penetration of cracks. The location and size of the convex hull structure have an important influence on the rock's damage law. The experimental results show that the potholes in the bottom hole morphology of the new bit are significantly larger than those of the conventional bit, and the formed cuttings are a factor of 1–2.5 larger than those of the conventional bit. The new PDC bit has a critical WOB, when the WOB exceeds the critical value, the mechanical specific energy of the new bit is lower than that of the conventional bit, and the ROP is higher than that of the conventional bit, it has better rock-breaking efficiency. These research results should provide a theoretical basis for the application and promotion of the new convex ring PDC bit.

Investigation on the Coaxial-Annulus-Argon-Assisted Water-Jet-Guided Laser Machining of Hard-to-Process Materials.

In this study, the novel coaxial-annulus-argon-assisted (CAAA) atmosphere is proposed to enhance the machining capacity of the water-jet-guided laser (WJGL) when dealing with hard-to-process materials, including ceramic matrix composites (CMCs) and chemical-vapor-deposition (CVD) diamond. A theoretical model was developed to describe the two-phase flow of argon and the water jet. Simulations and experiments were conducted to analyze the influence of argon pressure on the working length of the WJGL beam, drainage circle size, and extreme scribing depth on ceramic matrix composite (CMC) substrates. A comparative experiment involving coaxial annulus and helical atmospheres revealed that the coaxial annulus atmosphere disrupts the water jet proactively, while effectively maintaining the core velocity within the confined working length and enhancing the processing capability of the WJGL beam. Single-point percussion drilling experiments were performed on a CMC substrate to evaluate the impact of machining parameters on hole morphology. The maximum depth-to-width ratio of the groove and depth-to-diameter ratio of the hole reached up to 41.2 and 40.7, respectively. The thorough holes produced by the CAAAWJGL demonstrate superior roundness and minimal thermal damage, such as fiber drawing and delamination. The average tensile strength and fatigue life of the CMCs specimens obtained through CAAAWJGL machining reached 212.6 MPa and 89,463.8 s, exhibiting higher machining efficiency and better mechanical properties compared to femtosecond (194.2 MPa; 72,680.2 s) and picosecond laser (198.6 MPa; 80,451.4 s) machining. Moreover, groove arrays with a depth-to-width ratio of 11.5, good perpendicularity, and minimal defects on a CVD diamond were fabricated to highlight the feasibility of the proposed machining technology.

Near-IR intracellular Pd0/Pd2+ triggered de-allylation switch based on self-assembled perylene diimide

In this report, we have synthesized and characterized novel dibromo allyl substituted perylene diimide (PDI-BA) for the selective detection of palladium species. PDI-BA showed solvatofluorism properties and can be used for mapping of moisture content (>5%) in CH3OH. The near-IR emission of PDI-BA was selectively disturbed by Pd0/Pd2+ species at concentrations as low as 17.2 nM and 286 nM, respectively. The PDI-BA showed ratiometric absorbance (A732nm/A548nm) changes upon addition of Pd0/Pd2+ with limit of detection as low as 97.3 nM/284 nM associated with color change from pink to green. Interestingly, no reducing agent is required for the Pd2+ induced de-allylation process. In the aggregated state (80% water), PDI-BA is 55 times more sensitive for Pd0 in comparison to its monomeric state (20% water). We further demonstrated the applications of PDI-BA for intracellular (L929 live cells) and pharmaceutical sample detection of Pd0 and Pd2+ species. The self-assembled aggregates of PDI-BA with morphology of holes disintegrates into spherical structures as confirmed by DLS and AFM techniques.