Excess Material Research Articles

Nickel-based alloy efficient milling with ceramic tool and experimental verification in closed impeller

Nickel-based alloys are a class of materials that possess exceptional properties, including superior corrosion, oxidation, and fatigue resistance. They are increasingly utilized in high-performance critical components, particularly in the fields of aerospace engines and gas turbines. Nickel-based alloys pose significant challenges during machining due to their high cutting forces and work hardening, leading to low machining efficiency, severe tool wear, and subpar surface quality of the machined parts. To address these challenges, an orthogonal cutting experiment was conducted on GH4061 alloy to evaluate the machining performance by using monolithic ceramic milling tools. The optimal cutting parameters combination for dry cutting of nickel-based alloys was determined. The surface quality was tested and analyzed, including surface micro structure, residual stress, and surface roughness. The machining experiment was conducted on GH4061 closed impeller. The results demonstrated that high-speed cutting was more effective than low-speed cutting in improving the surface quality of the machined part. In the rough processing, monolithic ceramic milling tools was used to quickly remove the excess material. The adhesive and diffusion effects mainly contributing to the wear of the monolithic ceramic tool in GH4061 milling. Average surface roughness 1.41 μm can be obtained through dry milling using a monolithic ceramic tool with cutting speed 602.88 m/min, cutting depth 0.3 mm, cutting width 6 mm and feed per tooth 0.03 mm/z, along with metal removal rate 5184 mm3/min. High cutting speed will resulting in relatively low residual stress in the surface layer as well as a lower thickness of the surface alternation layer. Finally, a physical GH4061 closed impeller was machined to verify the proposed milling method.

Role of submerged friction stir welding in reducing intermetallic growth and enhancing microstructure in dissimilar Al-Ti joints

The integrity of dissimilar Al-Ti welds during conventional friction stir welding (CFSW) is compromised by excessive material mixing, leading to thick intermetallic layers. Underwater friction stir welding (UWFSW) mitigates these effects by inhibiting material mixing due to lower thermal conditions. Scanning electron microscopy revealed substantial Ti particles, appearing as blocks and strips, within the stir zone during CFSW. Static recrystallization, driven by exothermic reactions between Ti blocks and the Al matrix, resulted in over 93% recrystallized grains along stir zone, 10.7% higher than in UWFSW. In contrast, UWFSW resulted in a finer dispersion of Ti particles with reduced density due to lower frictional heat. The average grain size at the Ti interface of CFSW was 1.0 μm, compared to 2.6 μm in UWFSW. The inhomogeneous distribution of Ti particles in CFSW led to uneven dislocation distribution and increased stress concentrations, while finer Ti particles in UWFSW promoted a uniform grain structure, enhancing joint strength to 267 MPa, 13.4% higher than CFSW. Additionally, the γ-fibre and basal fibre texture in UWFSW increased joint ductility. The study highlights UWFSW’s effectiveness in joining dissimilar metals, offering significant advantages for industries such as aerospace and automotive.

Monolithic dispersion engineered mid-infrared quantum cascade laser frequency comb

The high-power quantum cascade laser (QCL) frequency comb capable of room temperature operation is of great interest to high-precision measurement and low-noise molecular spectroscopy. While a significant amount of research is devoted to the longwave spectral range, shortwave 3–5 μm QCL combs are still relatively underdeveloped due to the excessive material dispersion. In this work, we propose a monolithic integrated multimode waveguide scheme for effective dispersion engineering and high-power-efficiency operation. Over watt-level output power at room temperature with a wall plug efficiency of 7% and robust dispersion reduction is achieved from a quantum cascade laser frequency comb at a wavelength approximately 4.6 μm. Narrow beatnote linewidth less than 1 kHz and clear dual-comb multiheterodyne comb lines manifest the coherent phase relation among the comb modes which is crucial to fast molecular spectroscopy. This monolithic dispersion engineered waveguide design is also compatible to an efficient active–passive optical coupling scheme and would open up a new research playground for ring comb and on-chip dual-comb spectroscopy.

Achieving a near-ideal silicon crystal neutron interferometer using submicrometer fabrication techniques

Perfect-crystal neutron interferometry, which is analogous to Mach-Zehnder interferometry, uses Bragg diffraction to form interfering neutron paths. The measured phase shifts can be used to probe many types of interactions whether it be nuclear, electromagnetic, gravitational, or topological in nature. For a perfect-crystal interferometer to preserve coherence, the crystal must possess a high degree of dimensional tolerance as well as being relatively defect-free with minimal internal stresses. In the past, perfect-crystal neutron interferometers have been produced by a two-step process. First, a resin diamond wheel would be used to remove excess material and shape the interferometer. Afterword, the crystal would be etched to remove surface defects and elevate strains. This process has had limitations in terms of repeatability and in maximizing the final contrast, or fringe visibility, of the interferometer. We have tested various fabrication and post-fabrication techniques on a single perfect-crystal neutron interferometer and measured the interferometer's performance at each step. Here we report a robust, nonetching fabrication process with high final contrast. For the interferometer used in this work, we achieved contrasts of greater than 90% several times and ultimately finished with an interferometer that has 92% contrast and a uniform phase distribution. Published by the American Physical Society 2024

Formation of concavities on the ends of parts manufactured on CNC skew rolling mills

This study investigates the problem of concavity formation on the ends of parts manufactured on CNC skew rolling mills. Numerical modeling and Taguchi method were used to determine the effects of the main parameters of skew rolling (i.e., forming angle, skew angle, reduction ratio, temperature, steel grade, dimeter ratio, velocity ratio) on the depth of concavities formed on the product ends. The simulations showed that the only parameter to have a significant impact on the concavity depth was the reduction ratio. The FEM results were then used to establish equations for calculating concavity depth and allowance for excess material with concavity. For more universality, the established equations took into account the billet diameter. The experimental validation showed high agreement between the numerical and the experimental concavity depths.

Characterization and simulation of AlSi10Mg reinforcement structures by direct energy deposition by means of laser beam and powder

Among metal additive manufacturing technologies, direct energy deposition (DED) processes have the advantage to be easily integrable in a manufacturing chain with other conventional technologies. This characteristic can be exploited by designing reinforcement structures to be added by DED onto pre-existing subcomponents to tailor the part’s mechanical properties while keeping the part lightweight. This study focuses on DED by means of laser beam and powder process optimization to improve material quality and geometrical accuracy of AlSi10Mg reinforcement structures while preventing excessive thermal deformations and material dilution into the substrate. These results are compared with finite elements numerical simulations of the deposition process, comprising thermo-elastic deformation and material deposition, to predict the bending and reinforcement of the processed substrate. In particular, the model includes the deterministic prediction of the deposition profile as a function of the process parameters and a few condition-specific coefficients: once calibrated, the model was used to compare the numerical and experimental residual deformation of the reinforced sample, obtaining promising agreement. The reinforcement provided to a 1.5 mm thick substrate by a single wall of deposited materials, with cross-sectional dimensions of 2 mm in width and 2.5 mm in height, was evaluated by three points bending. With the reinforcement on the tensile side of the stresses, the energy absorbed by the material plastic deformation increased by 2.4% as compared to the substrate alone, while with the reinforcement on the compression side of the stresses the energy absorption increased by 75.8% on average.

A comparative experimental study on abrasive flow machining vs flow peening GOV processes on Inconel 718

Inconel 718, a nickel-based super alloy, has a broad applications area from aerospace, medical and defence to traditional industries because of its high durability, corrosion resistance and elevated temperature performance. Unconventional surface treatment methods of abrasive flow machining (AFM) and shot peening (SP) are applied to improve the mechanical performance of Inconel 718. In this work, a new surface treatment process known as flow peening (GOV) already developed by combining the advantages of abrasive flow machining (AFM) and shot peening methods such as surface finishing and residual compressive stress generation respectively was applied experimentally for Inconel 718. The effects of process parameters for GOV and AFM processes on the surface quality of the specimens were experimentally investigated. White layer decrease, surface roughness decrease and material removal amount were discussed for both processes. The best surface quality with 0.56 μm Ra surface roughness value and material removal amount of 7.2 mg were obtained by GOV process while similar level of surface roughness value of 0.52 μm was obtained by removing 6648.03 mg material for AFM. When the AFM process was continued, the best values of 0.24 μm Ra was obtained removing excess material of 17,385.60 mg compared to the GOV process. Also, all these results were supported by SEM images.

UV‐Triggered In Situ Formation of a Robust SEI on Black Phosphorus for Advanced Energy Storage: Boosting Efficiency and Safety via Rapid Charge Integration Plasticity

AbstractBlack phosphorus (BP) emerges as a highly promising electrode material for next generation of energy‐storage systems. Yet, its full potential is hindered by the instability of the solid‐electrolyte interphase (SEI) and the inflammability of its liquid systems. Here a pioneering UV‐induced in situ strategy is introduced for SEI construction, which leverages rapid electron supply to fracture sulfur‐dihalide bonds. This technique yields internal dihalide inorganic components and an external polymer segment, with any excess organic material being purged through pores. The (E)‐2‐chloro‐4‐((3′‐chloro‐4′‐hydroxyphenyl)diazinyl)phenyl acrylate (CA), with chlorine‐terminated groups, is initially in situ transformed into a flame‐retardant phenyl carboxylic acid (PCA), and then encapsulated within an ultrathin BP nanostructure, further nested in nitrogen (N), boron (B) co‐doped carbon (C) sheets that accommodate cobalt (Co) single atoms/nanoclusters (Co‐NBC). The Co‐NBC@BP@PCA construct demonstrates an impressive initial Coulombic efficiency (ICE) of 99.1% and maintains exceptional stabilities in terms of mechanical, chemical, and electrochemical performancecritical for prolonged cycle and calendar life. This research sheds light on the interplay between the rapid charge supply integrated in situ plasticity (RSIP) approach and the proactive establishment of an artificial SEI layer, offering profound insights into enhancing the durability and providing a solid foundation for advancements in energy storage technology.

Engineering of Interface Barrier in Hybrid MXene/GaN Heterostructures for Schottky Diode Applications.

The Fermi level position at the interface of a heterostructure is a critical factor for device functionality, strongly influenced by surface-related phenomena. In this study, contactless electroreflectance (CER) was utilized for the first time to investigate the built-in electric field in MXene/GaN structures with the goal of understanding the carrier transfer across the MXene/GaN interface. Five MXenes with high work functions were examined: Cr2C, Mo2C, V2C, V4C3, and Ti3C2. The physicochemical properties of the MXene/GaN structures were analyzed by using X-ray and UV photoelectron spectroscopies. It was shown that upon the coverage of the GaN surface by all investigated MXenes, a shift in the position of the surface Fermi level occurs, consequently raising the interface barrier. Additionally, the physicochemical stability of MXenes on the GaN surface was studied after annealing the structures at 750 °C. Our findings indicate that the annealing process increases the barrier height and the ionization energies of all studied structures. Furthermore, it has been shown that removing excess MXene material from the surface did not significantly impact the built-in electric field, emphasizing the robust physicochemical stability of the MXenes on the GaN surface. To validate the potential of engineering of MXene/GaN interface barrier, Schottky diodes with MXenes exhibiting the highest barrier height (Mo2C and V2C) were demonstrated.

At the Speed of Light: Recent Advances on Photocatalyzed Generation and Applications of Iminyl Radicals Promoted by Visible-light

: Nitrogen-positioned radicals are chemical entities that have a lengthier history than carbon ones and their high reactivity makes them invaluable. But, despite its power, much of its chemistry is still uncharted. Currently, developed methodologies to access nitrogen-positioned radicals, such as transition metal catalysis or visible-light photoredox methods through a single-electron transfer process, avoiding the use of harmful or toxic reagents, excess raw materials, solvents as well as pre-functionalization steps or extensive synthetic routes are in continuous progress. This revision aims to depict the recent advances in the field of iminyl-radicals’ syntheses, a special class of radicals placed on nitrogen, catalyzed by transition metals or photoredox techniques for the construction of C-N bonds and their synthetic applications. This work serves as a comprehensive guide for the scope of synthetic applications that this kind of radicals could have.

Research on ash accumulation surface measurement methods based on the dot laser principle

Dust collectors are essential environmental protection equipment in thermal power plants. However, in recent years, collapses caused by excessively high material levels in the ash hopper in dust collectors have increased frequently, resulting in serious casualties and significant economic losses. The level gauge of the ash hopper is a crucial device for detecting the material level in the ash hopper and plays a vital role in preventing the ash hopper from collapsing due to excessive material load. However, level gauges of the ash hopper currently in use have various problems. Laser-ranging technology is characterized by concentrated energy, a small divergence angle, and the ability to penetrate dust. We have proposed a new material-level measurement method based on the dot matrix laser ranging principle. This method utilizes dot-matrix laser ranging and visualizes the optimized measurement data to ultimately derive information about the material surface's morphology and level. A physical hopper model is used to conduct verification experiments on various material surface morphologies, material levels, and the material hanging on the hopper wall. The results indicate that this method can accurately identify the material level and the material hanging on the hopper wall, preventing false alarms due to “false material levels.”

A variable diameter spiral path planning strategy for large eccentricity variable curvature rotating parts with focus on thickness and performance control in cladding

When laser cladding rotating parts that have large eccentricity and variable curvature, first-order discontinuities in the cladding path and fluctuations in the real-time scanning speed are common problems. These issues cause significant inhomogeneities in the cladding thickness and localized excessive material accumulation. This not only leads to unstable mechanical properties of the cladding layer but also results in a significant waste of cladding materials during subsequent precision machining. In response, this paper introduces a cladding method that employs a variable diameter constant linear velocity spiral path and establishes models for dynamic vector and angle conversion, constant linear velocity optimization, and cladding path data conversion. This approach enables consistent control over the real-time scanning speed and defocus distance during laser cladding of parts with large eccentricity and variable curvature. A comparison of the experimental results from spiral path cladding, variable linear velocity and variable diameter spiral cladding, and constant linear velocity variable diameter spiral cladding revealed that the latter method achieves a more uniform cladding layer thickness, with a maximum deviation of only 0.036 mm. The microstructure primarily consists of cellular structures, demonstrating improved consistency. Samples were taken from three different cladding methods, and hardness tests were performed on the cross-sections of the cladding layers.

A multi-scale method for the study of deep drying of ethylene with 3A zeolite

Coal-based ethanol to ethylene (ETE) is an emerging production pathway with the advantages of a short construction period, high product purity, and few by-products. N2 is commonly used in industry to regenerate zeolites during the ETE process, with the problems of excessive material consumption, energy consumption and environmental pollution. To solve this problem, this paper proposed a method of using the ethylene product as regeneration gas to regenerate the zeolite and recover the desorbed gas. In this work, we adopted a multi-scale simulation method combining microscale apparent diffusivity and macroscale mass transfer models. Reactive force field and molecular dynamics (ReaxFF-MD) were used to obtain an equation for the diffusion coefficient versus temperature. The start-up of the twin-tower temperature and pressure swing adsorption (TPSA) process was simulated using Computational Fluid Dynamics (CFD). The TPSA process achieved an outlet water content below 5 ppm, fulfilling the process specifications.

Detection and removal of excess materials in aircraft wings using continuum robot end-effectors

Detection and removal of excess materials in aircraft wings using continuum robot end-effectors

Enhanced wear resistance and strength synergy in Ti3AlC2 MAX through in-situ synthesis of nano TiB2 heterostructure

The rapid development of science and technology poses the core parts and techniques of industrial tribo-systems facing more stringent situations like high temperature exceeding 600 °C. For this case, solid lubrication materials are required to possess high strength, low friction coefficient and high wear resistance over a wide temperature range. However, achieving such “strong wearable yet lubricated” materials have proven challenging. Here we report a unique reinforced strategy for lubricated Ti3AlC2 MAX ceramic by in-situ synthesis of nano TiB2 heterostructure, which results in a superior high temperature strength and lubrication simultaneously excess other traditional solid-lubrication materials. Such TiB2/Ti3AlC2 composite employs a high level of compressive strength (1120 MPa ∼ 1368 MPa), wear resistance (<10‐5 mm3/(N∙m)) and low friction coefficient (<0.4) at even 800 °C. We show that its unusual properties stem from the introduction of TiB2 nanocrystalline densified and strengthened the Ti3AlC2 matrix thus to ensure the high strength. Meanwhile, the TiB2 also undergoes rapid oxidation along high temperatures friction, resulting in the formation of a continuous and smooth lubricative tribofilm containing solid lubricant B2O3, leading to exceptional solid lubrication effect at high temperature. Our finding provides a potential material portfolio and a new design strategy for high temperature solid-lubricative applications.

Tree Mortality, Biome Shifts, and Living Sustainably to Halt Human-Caused Climate Change

Human-caused climate change has caused extensive tree mortality across West Africa and the western United States and biome shifts around the world. Reducing excessive material consumption by people offers a solution to halt climate change and risks to trees.

Consumerism in Modern Times: Necessity and Significance

Consumerism and literature have a complex relationship. Literature often critiques and reflects on consumer culture, revealing its impact on individuals and society. Works like "Fight Club" and "American Psycho" satirize excessive materialism, while "The Great Gatsby" and "The Catcher in the Rye" portray the emptiness of wealth and status. Other authors, like Don DeLillo and Thomas Pynchon, explore the effects of consumerism on human relationships and identity. Literature also explores the commodification of art and culture, as seen in "The Secret Life of Things" and "The Brief Wondrous Life of Oscar Wao". Additionally, authors like Dave Eggers and George Saunders examine the consequences of consumerism on individuals and society, highlighting issues like inequality and environmental degradation. Through these works, literature provides a platform for critique and reflection, encouraging readers to reevaluate their relationship with consumer culture and its values. By exploring the complexities of consumerism, literature inspires critical thinking and sparks important conversations about the role of material goods in our lives.

Iatrogenic Root Perforations: Case Report

Root perforation, a connection between the root canal system and tooth surface, is a common cause of endodontic therapy failures. Caused by pathological conditions or operative errors, it can occur during access cavities, root canal preparation, or post-preparation. A 28-year-old patient was diagnosed with a vestibular medium-sized infra-osseous perforation during root post realization. Despite no systemic disorders, the patient showed physiologic movement and was slightly sensitive to pressure. A flap surgical treatment was chosen to remove excess material and enable tissue regeneration. Biodentine® was used to prevent future discolorations. The patient underwent an intrasulcular incision, flap raised, cavity cleaned, disinfected, revised, and sealed using an anterior Schilder plugger. Root perforations are common errors caused by factors like anatomy, caries, pulp calcifications, and intracanal posts. Diagnosis is based on clinical signs, radiographic examinations, and imaging techniques. The prognosis depends on preventing bacterial infection. The ideal reparation material should stimulate bone formation, be biocompatible, maintain sealing, and not disintegrate in tissue fluid. Equivalent materials like Biodentine® offer advantages in protocol, antibacterial power, and bioactive properties. Radicular perforations, a significant dental issue, can be prevented through early management using modern techniques and clinical training, ensuring long-term success in endodontic treatments.

Optimization of Material Utilization by Developing a Reliable Design Criterion for Tool Construction in Cross-Wedge Rolling

The massive forming industry in Germany produces around 1.4 million parts every year, which are mainly used in safety-relevant areas such as the automotive industry. The production of these parts requires a considerable amount of energy, much of which remains unused and causes high CO2 emissions. An efficient approach to reduce these emissions and improve material utilization is cross-wedge rolling, which enables efficient material utilization but is limited by the so-called Mannesmann effect, which leads to unwanted material defects. This paper describes the development and validation of a safe design criterion for cross-wedge rolling tools in order to avoid material damage caused by the Mannesmann effect and thus increase resource efficiency in forging. Based on simulation-supported investigations and experimental tests, process maps are created for various materials. The validation is carried out both in an experimental test facility with real tools and in an industrial production facility, which leads to a significant reduction in excess material and CO2 emissions. The results show that the full resource potential of cross-wedge rolling can be exploited by optimizing process parameters and tool geometries.

Impact of Cobalt Addition on Single-Crystal Li1+x(Ni0.6Mn0.4)1−xO2 Cathode Material Performance

Nickel and manganese-based layered oxides with a nickel content ranging from 50% to 80% are promising cathode materials for high-energy density lithium-ion batteries. However, these materials face challenges such as poor rate capability and limited cycling stability. The addition of excess lithium can mitigate these issues to some extent. This study examines the impact of incorporating small amounts of cobalt (5% or 10%) into these materials through an “all-dry” synthesis approach in stoichiometric and excess lithium-containing compositions. Results indicate that adding even these small amounts of cobalt decreases the cation mixing, improves crystallinity, reduces electronic resistance, and influences the morphology depending on whether nickel or manganese is replaced. The materials can accommodate up to 15% excess lithium without significant surface impurities. The addition of cobalt further enhances the rate capability of the material in excess lithium materials, but increasing cobalt content tends to compromise cycling stability when the materials are cycled up to 4.4 V. Materials in which 5% cobalt replaces nickel still exhibit superior rate capability and cycling performance compared to materials without cobalt. Therefore, incorporating small amounts of cobalt can positively impact the performance of Li1+x(Ni0.6Mn0.4)1−xO2 materials, offering a balance between improved rate capability and cycling stability.