Edge Surface Research Articles

Regulating Grind-Induced Lattice Distortion for Nickel-Rich Cathodes by Annealing.

The commercialization of high-performance nickel-rich cathodes always awaits a cost-effective, environmentally friendly, and large-scale preparation method. Despite a grinding process normally adopted in the synthesis of the nickel-rich cathodes, lattice distortion, rough surface, and sharp edge transformation inevitably occurr in the resultant samples. In this work, an additional annealing process is proposed that aims at regulating lattice distortion as well as achieving round and smoother morphologies without any structural or elemental modifications. Such a structural enhancement is favored for improved lithium diffusion and electrochemical stability during cycling. Consequently, the annealed cathodes demonstrate a considerable enhancement in capacity retention, escalating from 68.7% to 91.9% after 100 cycles at 1C. Additionally, the specific capacity is significantly increased from 64 to 142mAhg-1 at 5C when compared to the unannealed cathodes. This work offers a straightforward and effective approach for reinforcing the electrochemical properties of nickel-rich cathodes.

Correlation between structural characteristics of edge selectively-oxidized graphite and electrochemical performances under fast charging condition

In the pursuit of ameliorating of the battery-performance degradation particularly during fast charging of lithium-ion batteries, we investigated the influence of surface-structural parameter of graphite. To explore the effect of the graphite surface state on the battery performance, we synthesized the edge selectively-oxidized graphite. The detailed analysis about the structural parameters of graphite samples revealed that the edge area increased from 3.41 to 4.26 m2 g−1 by oxidation process while preserving the specific surface area. Edge selectively-oxidized graphite samples showed the similar ratio between carbon and oxygen regardless of oxidized time, but the change of surface charge due to the different functional groups. The edge selectively-oxidized graphite exhibited a significantly improved capacity retention and rate performance compared with the bare graphite. Based on thorough examination about material properties and electrochemical responses, we corroborated a strong correlation among the electrochemical performance, edge surface area, and type of oxygen-based functional groups of graphite. Our study provides conclusive evidence that the surface nature of graphite plays a pivotal role in boosting the battery performance.

Influence of the cutting method on the fatigue life and crack initiation of non-oriented electrical steel sheets

The fatigue behavior of thin electrical steel sheets under cyclic loading is investigated in dependence on the edge surface. Therefore, four different edge conditions are compared, whereas the edge is either laser cut, shear cut, wire cut, or polished. Strain- and stress-controlled fatigue tests are performed to determine S-N curves in the low cycle regime as well as in the high cycle regime. Microstructural data is collected by non-contacting (optical) Profilometry, Nanoindentation, X-Ray Diffraction, and Electron Backscatter Diffraction to understand the differences in fatigue life by considering surface roughness, residual stresses, hardness, and microstructure. Shear cut specimens achieve the lowest fatigue life, while the other edge conditions reach relatively similar values in the LCF regime. Crack initiation is mainly intergranular in the case of defect-free edges. This tendency has a considerable influence on the observed fatigue behavior.

Mechanical enhancement of aluminum foam via in situ interfacial bonding

Aluminum foam (AF) has extensive application prospects due to its high specific strength and specific energy absorption. However, low compressive strength and plateau stress of AF limit their total energy absorption. This study introduces a combined way of melt foaming and infiltration casting for fabricating bi-continuous interpenetrating porous composites (BIPCs), which formed partial metallurgical bonding interfaces while ensuring three-dimensional mechanical bond constraints. Four types of three-dimensional structures were designed to reinforce AF. Mechanical behavior of AF and the composites under quasi-static compression was analyzed by combining compressive tests and the finite element method (FEM). The results showed that all reinforcements can efficiently improve the energy absorption of composites by preventing the expansion of cracks in aluminum foam. The structure reinforced along the body diagonal and the path of the center lines connecting the three pairs of parallel surfaces of the cube exhibited the best mechanical properties, whose energy absorption, specific energy absorption and specific compressive strength were 9.58, 3.48 and 2.89 times greater than those of AF, respectively. The critical stress of the rods to buckling and stretching failure of the four configurations were calculated. Results showed that large critical stresses tended to appear in the 1/4 and 1/2 round rods, which revealed that the fracture failure easily occurred at the intersection edges of plane surface and curved surface of struts.

Unravelling Tool Edge Trajectory Patterns: Implications on Surface Roughness in End Milling Process

This study examines the effect of end milling on surface roughness in modern manufacturing. Mathematical equations simulate and analyse the tool edge trajectory of a two-flute end mill during end milling. The results are refined using MATLAB and watershed segmentation. An aluminium alloy flat bar is end-milled using a CNC milling machine for the experimental phase. Optical 3D surface measurements provide roughness data for analysis. The study shows that higher spindle speeds produce smoother surfaces with improved surface quality. The correlation matrix analysis highlights the significance of spindle speed in shaping surface roughness, and tool trajectories are associated with softer surfaces at elevated speeds for the spindle speed ranging between 1000 to 3500 rpm. The study offers valuable insights into the complex relationship between tool edge trajectories and surface roughness.

Osteology of the axial skeleton of Aucasaurus garridoi: phylogenetic and paleobiological inferences.

Aucasaurus garridoi is an abelisaurid theropod from the Anacleto Formation (lower Campanian, Upper Cretaceous) of Patagonia, Argentina. The holotype of Aucasaurus garridoi includes cranial material, axial elements, and almost complete fore- and hind limbs. Here we present a detailed description of the axial skeleton of this taxon, along with some paleobiological and phylogenetic inferences. The presacral elements are somewhat fragmentary, although these show features shared with other abelisaurids. The caudal series, to date the most complete among brachyrostran abelisaurids, shows several autapomorphic features including the presence of pneumatic recesses on the dorsal surface of the anterior caudal neural arches, a tubercle lateral to the prezygapophysis of mid caudal vertebrae, a marked protuberance on the lateral rim of the transverse process of the caudal vertebrae, and the presence of a small ligamentous scar near the anterior edge of the dorsal surface in the anteriormost caudal transverse process. The detailed study of the axial skeleton of Aucasaurus garridoi has also allowed us to identify characters that could be useful for future studies attempting to resolve the internal phylogenetic relationships of Abelisauridae. Computed tomography scans of some caudal vertebrae show pneumatic traits in neural arches and centra, and thus the first reported case for an abelisaurid taxon. Moreover, some osteological correlates of soft tissues present in Aucasaurus and other abelisaurids, especially derived brachyrostrans, underscore a previously proposed increase in axial rigidity within Abelisauridae.

Design and numerical analysis of a novel argon gas tube to reduce impurities in large size casting crystalline silicon furnace

A novel design of argon gas tube within the silicon casting system was developed employing pipe flow and side jet analysis, which facilitates horizontal ejection of argon gas along the silicon melt surface. The aim was to enhance control over gas flow velocity for removing impurities during large size silicon ingot (1400 kg) growth, with special attention on the edge region of ingot. It was found that the diameter of side-facing outlet holes, when oriented along the corner direction, is about 2 times of that along the side center direction, to achieve an extended jet distance reaching corner region. The gas flow and transport of SiO above the silicon melt surface were studied for the proposed gas tube configuration based on 3D numerical simulations. The simulation results reveal the correlation between argon flow rate and resultant gas velocity at the edge of melt surface, which is consistent with the theoretical analysis, particularly for moderate to high argon flow rates. The numerical simulations demonstrated that the proposed gas tube, equipped with eight optimized outlet holes, outperformed the conventional tube in extracting SiO from both central and corner regions above the silicon melt surface.

Effect of inhomogeneity on crack initiation for wear-resistant U75V rail treated by laminar plasma

The surface discrete hardening of laminar plasma (HLP) is an effective method of improving wear resistance for rails. While fracture failures on as-treated rail heads are still unavoidable and the related crack mechanism is unclear. As-treated U75V rail and untreated standard U75V rail were installed simultaneously on railway for comparison. The wear form and cracking mechanism of the rails after service are studied in detail. The results show that wear resistance of HLP-treated rail is improved dramatically compared with untreated ones. The wear depth of HLP-treated rail serviced for 9 months is still less than that of standard rail serviced for only 3 months. Central ablation induces overheated structures and hot cracks, resulting in cracks within the quenched area. Decarburized layer is the main reason for a ring-shaped reticular ferrite existing at the quenched area edge. Crack initiation at the interface is facilitated by the presence of reticulated ferrite and a non-uniform microstructure formed at the surface edge of the quenched area. These cracks propagate solely within the quenched area, preventing their propagation into the interior of the HLP-treated rail.

EQUILIBRIUM PROBLEM FOR A TIMOSHENKO PLATE CONTACTING BY THE SIDE AND FACE SURFACES

A new model for a Timoshenko plate contacting by the side surface or the edge of the bottom surface (with respect to the chosen coordinate system) with a rigid obstacle of a given configuration is justified. The non-deformable obstacle is defined by a cylindrical surface, the generators of which are perpendicular to the middle plane of the plate, as well as by a part of the plane that is parallel to the middle plane of the plate. A corresponding variational problem is formulated as a minimization of an energy functional over a non-convex set of admissible displacements. The set of admissible displacements is defined taking into account a condition of fixing and a nonpenetration condition. The nonpenetration condition is given as a system of inequalities describing two cases of possible contacts of the plate and the rigid obstacle. Namely, these two cases correspond to different types of contacts by the plate side edge and by the edge of the plate bottom surface. The solvability of the problem is established. In particular case, when contact zones is previously known, an equivalent differential statement is found under the assumption of additional regularity for the solution to the variational problem.

Surface texturing, residual stresses and edge treatment of hardmetal tools by means of femtosecond pulsed laser

Laser induced periodic surface structures (LIPSS) have been produced at the surface of a WC-Co turning insert by femtosecond pulsed laser ablation. Wavelengths of approx. 500 nm have been obtained with a 1030 nm incident radiation and with a spot size of 30 μm. No thermal damage is induced by following this procedure, although a slight surface stress relaxation is detected as fluence increases. The higher material removal needed for chamfering operations requires accumulated fluences over 1 kJ/cm2. At lower energy densities, material removal is not completed. If fluence is increased by reducing the laser spot size, material removal is also inefficient since signicant amount of debris is accumulated on the irradiated areas. Best chamfering strategy involves the combination of relatively large spot sizes and fluences. Form factors (Κappa) of the chamfered cutting edges range from 4 to 10 although the laser is oriented at 45° of the rake face. Lower Κ values can be obtained by adjusting the laser focus along the machining process.

Surface reconstruction and cleavage of phyllosilicate clay edge by density functional theory

Phyllosilicate materials (e.g., smectite) have been proposed to act as a waste barrier within long-term deep geological repositories. Aside from longevity, these clay materials must also limit the mobility of radionuclides, which is achieved through intermolecular interaction involving clay basal planes and edge surfaces. We aim to contribute to the fundamental knowledge of clay edges by investigating surface reconstruction in a dehydrated context. Using density functional theory, surface reconstruction, charge redistribution, and formation energies have been explored for pyrophyllite edges resulting from thirteen terminations. Three primary reconstruction mechanisms were identified: (1) the displacement of Al into the tetrahedral layer, (2) proton shift, and (3) sub-surface reconstruction involving sub-surface -OH or apical O and surface Si. Reduction in overall relative bond deficiency and charge redistribution to becoming more bulk-like were found to be the main driving force for reconstruction. Formation energies were also determined with dispersion correction for dehydrated and hydrated surfaces. The presence of water terminating agents reduced energetic costs by approximately one order of magnitude and the inclusion of dispersion correction resulted in indistinguishable formation energies between different hydrated surfaces. Linear regression models were also explored to predict surface formation energies based on relative bond deficiency and charge. These models were able to identify the key contributions to the surface energy; however, due to the small dataset they were not found to be predictive.

The roles of edge-based and surface-based information in the dynamic neural representation of objects

We combined multivariate pattern analysis (MVPA) and electroencephalogram (EEG) to investigate the role of edge, color, and other surface information in the neural representation of visual objects. Participants completed a one-back task in which they were presented with color photographs, grayscale images, and line drawings of animals, tools, and fruits. Our results provide the first neural evidence that line drawings elicit similar neural activities as color photographs and grayscale images during the 175–305 ms window after the stimulus onset. Furthermore, we found that other surface information, rather than color information, facilitates decoding accuracy in the early stages of object representations and affects the speed of this. These results provide new insights into the role of edge-based and surface-based information in the dynamic process of neural representations of visual objects.

The role of applied potential on particle sizing precision in single-entity blocking electrochemistry

Blocking electrochemistry, a subfield of single-entity electrochemistry, enables in-situ sizing of redox-inactive particles. This method exploits the adsorptive impact of individual insulating particles on a microelectrode, which decreases the electrochemically active surface area of the electrode. Against the background of an electroactive redox reaction in solution, each individual impacting particle results in a discrete current drop, with the magnitude of the drop corresponding to the size of the blocking particle. One significant limitation of this technique is “edge effects”, resulting from the inhomogeneous flux of the redox species’ diffusion due to increased mass transport to the edge of the disk electrode surface. “Edge effects” cause increased errors in size detection, resulting in poor analytical precision. Here, we use computational simulations to demonstrate that inhomogeneous diffusional edge flux of quasi-reversible redox species is mitigated at lowered overpotentials. This phenomenon is further illustrated experimentally by lowering the applied potential such that the system is operating under a kinetically-controlled regime instead of a diffusion-limited regime, which mitigates edge effects and increases particle sizing precision significantly. In addition, we found this method to be generalizable, as the precision enhancement is not limited to geometrically spherical particles but also occurs for cubic particles. This work presents a simple, novel methodology for edge effect mitigation with general applicability across different particle types.

Traumatic Fracture Treatment: Calcium Phosphate Bone Substitute Case-Control Study in Humerus, Radius, Tibia Fractures-Assessing Efficacy and Recovery Outcomes.

To date, insufficient investigation has been carried out on the biocompatibility of synthetic bioactive bone substitute materials after traumatically induced bone fractures in clinical conditions. This study encompasses the safety, resorption, healing process, and complications of surgical treatment. Our current hypothesis posits that calcium phosphate-based bone substitutes could improve bone healing. In this retrospective case-control study, over 290 patients who underwent surgical treatment for acute fractures were examined. Bone defects were augmented with calcium phosphate-based bone substitute material (CP) in comparison to with empty defect treatment (ED) between 2011 and 2018. A novel scoring system for fracture healing was introduced to assess bone healing in up to six radiological follow-up examinations. Furthermore, demographic data, concomitant diseases, and complications were subjected to analysis. Data analysis disclosed significantly fewer postoperative complications in the CP group relative to the ED group (p < 0.001). The CP group revealed decreased risks of experiencing complications (p < 0.001), arthrosis (p = 0.01), and neurological diseases (p < 0.001). The fracture edge, the fracture gap, and the articular surface were definably enhanced. Osteosynthesis and general bone density demonstrated similarity (p > 0.05). Subgroup analysis focusing on patients aged 64 years and older revealed a diminished complication incidence within the CP group (p = 0.025). Notably, the application of CP bone substitute materials showed discernible benefits in geriatric patients, evident by decreased rates of pseudarthrosis (p = 0.059). Intermediate follow-up evaluations disclosed marked enhancements in fracture gap, edge, and articular surface conditions through the utilization of CP-based substitutes (p < 0.05). In conclusion, calcium phosphate-based bone substitute materials assert their clinical integrity by demonstrating safety in clinical applications. They substantiate an accelerated early osseous healing trajectory while concurrently decreasing the severity of complications within the bone substitute cohort. In vivo advantages were demonstrated for CP bone graft substitutes.

Numerical study of cooling photovoltaic panels with air exhausted from industrial systems: Comparisons and innovative configurations

Utilizing a cooling technique can help prevent overheating, which can have a detrimental impact on the performance of solar panels. Instead of using a water cooling system that requires a pump, an alternative method uses the return air from a Heating, Ventilating, and Air Conditioning (HVAC) system often utilized in industrial settings. An air cooling system that uses the HVAC system's return air was previously recommended by the co-authors of the current study. Using numerical methods, they carried out a feasibility analysis and showed how a variety of parameters, such as the convection coefficient and the flow type (natural or forced), might affect the output power (efficiency) of the system. As a continuation of the previous study, the present study examines two cooling scenarios to further their past findings. Three different configurations for external flow were tested: cooling the upper and lower surfaces of the PV with exhaust air, installing a vortex generator at the leading edge of the lower surface while relying on natural convection for the upper part, and installing a vortex generator on both the upper and lower surfaces. The efficiency of the PV system increases from 11 % to 18 % with an increase in cooling demand from 0 to 160 kW with solar radiation of 500 W/m2. Efficiency was improved by generating turbulent flow at the leading edge of the panel. While using an internal flow on the bottom surface, the system's efficiency increased as the PV module's length increased.

Edge defect protection of graphitic carbon nanocages for stable potassium storage at low voltage

Graphitic nanocarbon possesses fast potassium storage capability at low voltage. However, a significant abundance of exposed edge surfaces and defects of graphitic nanocarbon would lead to a substantial number of irreversible reactions, thereby reducing the cyclic stability. Here, the edge defects of graphitic carbon nanocages (GCC) were protected by pitch-based disordered carbon shell to enhance the long-term cyclic stability. The mixture of GCC and pitch was compressed to ensure the full contact of the two components followed by carbonization at 1100 °C. The composite structure can protect the edge and defect of GCC to reduce the irreversible reactions. Moreover, the developed three-dimensional network can form interconnected paths to enhance the electron transfer. Benefiting from this structure, the composite anode achieves high reversible capacity below 1 V (214.1 mAh g−1 at 0.1 C) and high-rate (138.9 mAh g−1 at 1 C). Additionally, the composite anode exhibits higher cyclic stability (96.2% capacity retention from the first to the 80th cycle) than that of GCC (29.8%). This work presents a rational strategy to achieve the edge defect protection of graphitic nanocarbon, thereby facilitate the application of graphitic nanocarbon materials in potassium-ion batteries.

Micro-electro discharge machining characteristics of tungsten-copper for electronic devices

ABSTRACT Micro-machining involves the removal of small amounts of material by action other than that of a sharp-edged tool. The most common technique being electrical discharge machining (EDM). The material removal rate and edge definition of the finished product are based on different process parameters. This study is aimed to characterise micro-EDM process parameters for tungsten–copper and to achieve maximum material removal rate without affecting the edge definition and surface roughness while using smaller electrodes. Eight process parameters were studied for their influence on the material removal rate (MRR), surface roughness (Ra) and tool wear rate (TWR). Taguchi design of experiments was carried for 36 experimental runs. The ANOVA analysis showed that the MRR depends largely on voltage, energy and current, while the TWR depends on the energy and voltage. The surface roughness value (Ra) was influenced more by energy, incremental depth and the pulse width, thus differing from MRR and TWR. The optimum parameter set for higher MRR (10e-3 mm3/min) and lower Ra (0.13 µm) was deduced from regression analysis, and the confirmation tests showed less than 8 % deviation from the predicted values. The SEM studies showed greater depths of craters in the surface machined for higher MRR.

Analysis of size-dependent optoelectronic properties of red AlGaInP micro-LEDs.

We have theoretically investigated the size-dependent optoelectronic properties of InGaP/AlGaInP-based red micro-LEDs through an electro-optical-thermal coupling model. The model considers thermal effects due to current crowding near the electrodes, non-thermal efficiency droop due to electron leakage, and etch defects on the LED sidewall. Sidewall defects reduce the carrier concentration at the light-emitting surface's edge and exacerbate the current crowding effect. In addition, p-side electron leakage at high current densities is the leading cause of the efficiency droop of AlGaInP LEDs. In contrast, the effect of temperature on the overall efficiency degradation of LEDs is even more significant.

A new method to limit thermal energy required to de-ice the leading edge of a cylindrical surface

This paper experimentally investigates the effect of increasing ice thickness at a heater's edge on the thermal energy required to de-ice ice at the leading's edge. A correlation between ice thickness at the stagnation line and ice thickness at the heater edge is developed for the leading edge of a cylinder surface. An experimental approach is used to investigate whether the increase in ice thickness at the heater's edge is linked to the increase in ice thickness at the stagnation line. The de-icing investigation shows that as ice thickness at the heater's edge grows, the de-icing duration significantly increases. The results of this paper suggest that employing a correlation between the ice thickness at both the stagnation line and the heater's edge can help reduce the thermal energy required to remove ice from the leading edge of an airfoil or cylindrical surface.

Tuning intrinsic defects of Pt-based carbon supports by high-energy ball-milling for enhanced alkaline hydrogen evolution

Carbon materials are significant supports for catalysts, in which surface properties play a crucial role in catalytic performances. However, the correlation between the intrinsic defects of carbon supports and the alkaline hydrogen evolution reaction (HER) performance of catalysts is still unclear. Herein, graphite (G) was used as a model support to study the effect of intrinsic defects of carbon support on the HER performance. To this end, defect-enriched graphite supports were obtained by a simple high-energy ball-milling process. The affluent intrinsic defects (edge surfaces) in graphite supports served as active sites for the dispersion and anchoring of Pt nanoparticles for better electron transfer from Pt species to the support, leading to strong metal-support interactions. The resulting Pt-loaded on defect-enriched DG-30 (Pt/DG-30) delivered a lower overpotential of 46 mV at 10 mA cm−2 when compared to undecorated Pt/G (177 mV), indicating an excellent HER activity. Pt/DG-30 also showed superior stability due to the strong metal-support interactions between Pt nanoparticles and carbon support. In sum, significant insights into the rational optimization and regulation of intrinsic defects of carbon supports were provided for the preparation of new catalysts-modified carbon supports with enhanced HER performances.