Environmental friendly cutting fluids and cooling techniques in machining: a review

Atmospheric-pressure plasmas (APPs) have attracted great interest and have been widely applied in biomedical applications, as due to their non-thermal and reactive properties, they interact with living tissues, cells and bacteria. Various types of plasma sources generated at atmospheric pressure have been developed to achieve better performance in specific applications. This article presents an overview of the general characteristics of APPs and a brief summary of their biomedical applications, and reviews a wide range of these sources developed for biomedical applications. The plasma sources are classified according to their power sources and cover a wide frequency spectrum from dc to microwaves. The configurations and characteristics of plasma sources are outlined and their biomedical applications are presented.

https://iopscience.iop.org/article/10.1088/0963-0252/21/4/043001/pdf

Atmospheric-pressure plasma sources for biomedical applications

The generalization of the Local Density Approximation (LDA) method for the systems with strong Coulomb correlations is presented which gives a correct description of the Mott insulators. The LDA+U method is based on the model hamiltonian approach and allows to take into account the non-sphericity of the Coulomb and exchange interactions. parameters. Orbital-dependent LDA+U potential gives correct orbital polarization and corresponding Jahn-Teller distortion. To calculate the spectra of the strongly correlated systems the impurity Anderson model should be solved with a many-electron trial wave function. All parameters of the many-electron hamiltonian are taken from LDA+U calculations. The method was applied to NiO and has shown good agreement with experimental photoemission spectra and with the oxygen Kα X-ray emission spectrum.

http://absimage.aps.org/image/MAR06/MWS_MAR06-2005-007233.pdf

First-principles calculations of electronic structure and spectra of strongly correlated systems: the LDA+U method

Study on microstructure, mechanical properties and machinability of efficiently additive manufactured AISI 316L stainless steel by high-power direct laser deposition

Aluminum Metal Matrix Composites (MMCs) sought over other conventional materials in the field of aerospace, automotive and marine applications owing to their excellent improved properties. These materials are of much interest to the researchers from few decades. These composites initially replaced Cast Iron and Bronze alloys but owing to their poor wear and seizure resistance, they were subjected to many experiments and the wear behavior of these composites were explored to a maximum extent and were reported by number of research scholars for the past 25 years. In this paper an attempt has been made to consolidate some of the aspects of mechanical and wear behavior of Al-MMCs and the prediction of the Mechanical and Tribological properties of Aluminum MMCs.

/pdf/mechanical-and-tribological-behavior-of-particulate-4x05huiioi.pdf

Mechanical and Tribological Behavior of Particulate Reinforced Aluminum Metal Matrix Composites – a review

Owing to their shape memory effect and pseudoelasticity, NiTi shape memory alloys (SMAs) are widely used as functional materials. Mechanical processes particularly influence the final formation of the product owing to thermal softening and work-hardening effects. Surface integrity is an intermediate bridge between the machining parameter and performance of the product. In this study, experiments were carried out on turning NiTi SMAs at different cutting speeds, where surface integrity characteristics were analyzed. The results show that a higher cutting speed of 125 m/min is required to turn NiTi SMAs based on the evaluation of surface integrity. The degree of work hardening is higher at 15 m/min. Consequently, as a primary effect, work hardening appears on the plastic deformation of the machined samples, leading to dislocations and defects. As the cutting speed increases, the thermal softening effect exceeds work hardening and creates a smoother surface. A stress-induced martensitic transformation is considered during the turning process, but this transformation is reversed to an austenite from the X-ray diffraction (XRD) results. According to the differential scanning calorimetry (DSC) curves, the phase state and phase transformation are less influenced by machining. Subsequently, the functional properties of NiTi-SMAs are less affected by machining.

Surface integrity evolution of machined NiTi shape memory alloys after turning process

Broadband near-infrared (NIR) light-emitting diodes (LEDs) have important applications in non-destructive detection across agriculture, food, chemical and medical fields. LEDs coated with IR phosphors are widely used but have some shortcomings such as low efficiency, low brightness, short service life, and so on. Here, we propose a new strategy to solve the aforementioned problems by using the Cr3+:β-Ga2O3 single crystal as a transparent and conductive substrate with NIR fluorescent for the first time. The band structure and optical properties of the Cr3+:β-Ga2O3 crystal were calculated through density functional theory, and it was successfully grown by the edge-defined film-fed growth method. The crystal had a broad band absorption peak around 423 nm, which was located at the emitting band of the GaN LED. Broadband NIR emission from 600 nm to 850 nm with a peak maximum at 690 nm was found under the blue light excitation. Furthermore, the electrical properties of Cr3+:β-Ga2O3 were also studied by the Hall test. The spectral and electrical analyses indicate that Cr3+:β-Ga2O3 is promising in broadband NIR applications as a fluorescent substrate for vertical large current GaN LEDs. Combined with the advantages of low mismatch, transparency, conductivity and broadband NIR fluorescence, Cr3+:β-Ga2O3 provides a new strategy for high-brightness near-infrared broadband light sources.

Broadband near-infrared Cr3+:β-Ga2O3 fluorescent single crystal grown by the EFG method

In this research work, the machinability of turning Hastelloy X with a PVD Ti-Al-N coated insert tool in dry, wet, and cryogenic machining environments is investigated. The machinability indices namely cutting force (CF), surface roughness (SR), and cutting temperature (CT) are studied for the different set of input process parameters such as cutting speed, feed rate, and machining environment, through the experiments conducted as per L27 orthogonal array. Minitab 17 is used to create quadratic Multiple Linear Regression Models (MLRM) based on the association between turning parameters and machineability indices. The Moth-Flame Optimization (MFO) algorithm is proposed in this work to identify the optimal set of turning parameters through the MLRM models, in view of minimizing the machinability indices. Three case studies by considering individual machinability indices, a combination of dual indices, and a combination of all three indices, are performed. The suggested MFO algorithm’s effectiveness is evaluated in comparison to the findings of Genetic, Grass-Hooper, Grey-Wolf, and Particle Swarm Optimization algorithms. From the results, it is identified that the MFO algorithm outperformed the others. In addition, a confirmation experiment is conducted to verify the results of the MFO algorithm’s optimal combination of turning parameters.

Optimization of Process Parameters for Turning Hastelloy X under Different Machining Environments Using Evolutionary Algorithms: A Comparative Study

In order to investigate hydrophilic recovery of hydrophobic treatment of cellulose fibers, ramie fibers are ethanol-pretreated followed by atmospheric pressure plasma jet (APPJ) treatment using helium as the treatment gas and age for up to 150 days in 20 °C and 65% relative humidity. Scanning electron microscopy shows the fiber surfaces of the ethanol-pretreated + APPJ-treated group of freshly prepared, aged for 30 days, and aged for 150 days are covered with polypropylene matrix after fiber pullout tests. X-ray photoelectron spectroscopy shows that the freshly prepared ethanol-pretreated + APPJ-treated group has a 31% reduction in atomic ratio of oxygen to carbon and maintains at a similar level even after 150 days of aging. Water contact angle measurement demonstrates that the wettability of fiber surface of the freshly prepared ethanol-pretreated + APPJ-treated group drastically decreases and remains at the same lever after aging. Interfacial shear strength test reveals that the interfacial adhesion be...

Aging of hydrophobized surfaces of ramie fibers induced by atmospheric pressure plasma treatment with ethanol pretreatment

In aerospace manufacture industry, cutting vibration is a key factor for surface quality and tool life during milling of thin-walled aluminum alloy parts, and the high-efficiency machining is limited seriously for this reason. In this research, the cutting layer’s deformation was inhibited to reduce cutting vibration by optimal design of cutting edge structure. Base on the observation and imitation of corn leaf’s teeth, the structure of groove and micro-blade of peripheral cutting edge was designed. The orthogonal cutting models were developed to analyze the cutting process by ABAQUS. Furthermore, comparative experiments of milling aluminum alloy 7050-T7451 were carried out to analyze the cutting force, vibration, surface roughness, and residual stress. The test and simulation results showed that the designed solid cemented carbide end mill based on bionics had a good effect for inhibiting the cutting layer’s deformation. The fluctuations of cutting force, cutting vibration, surface residual stress, and surface roughness were reduced effectively.

Jie Sun

Papers

Surface integrity evolution of machined NiTi shape memory alloys after turning process

Broadband near-infrared Cr3+:β-Ga2O3 fluorescent single crystal grown by the EFG method

Optimization of Process Parameters for Turning Hastelloy X under Different Machining Environments Using Evolutionary Algorithms: A Comparative Study

Aging of hydrophobized surfaces of ramie fibers induced by atmospheric pressure plasma treatment with ethanol pretreatment

Structural design of groove and micro-blade of the end mill in aluminum alloys machining based on bionics