Material Processing Applications Research Articles

Application of microwave in manufacturing technology: A review

In todays world due to wide experimentation of materials and wider application in various field and with introduction of reduced production or manufacturing costs, and processing lead times, newly developed processing technology is what is required with these advantages. The newly developed processing techniques should be such that it should be widely acceptable for all types of materials including metals, non-ferrous metals, non-metals etc. Such processing methods are many but microwave processing is one of the fastest and latest emerging manufacturing technology that has found new application in material joining, casting, heat treatment, cladding, sintering, machining and drilling. In comparison to other conventional processes, microwave processing of materials not only enhances the mechanical properties but also redues the defects and has certain economical advantage in power and time savings. In comparison to conventional processes, microwave processing due to hybrid and selective heating, the parts produced has more uniform, axial, cellular and homogeneous type of structure is obtained. It has found application in not only in food processing industry but wide application has been found in manufacturing industry. Though other processes are available in the industries like electric furnace and ohmic resistance heating but the microwave due to its properties like penetration radiation, controllable electric field distribution, rapid heating, selective heat, self limit reactions with advantage of lower environmental impact has been extensively used for industrial and material processing applications. This work describes the review focusses on technological advancement of microwave processing of materials and their application in manufacturing applications in industries.

Configuring microplasma for material process optimization

A microplasma can provide selective reactive reactions owing to its non-equilibrium nature. The non-equilibrium nature of plasma allows it to maintain highly energetic state of electrons keeping the gas temperature close to the room temperature and hence can be employed in the treatment of heat-sensitive materials as well, especially the bio-samples. Such plasmas have been used in applications like surface processing of magnesium, titanium and their alloys, production of carbon micro- and nano-structures, surface functionalization as well as modification of the mechanical properties of surfaces. However, the plasma processes are sensitive to the position of the surface placed in contact with plasma. The plasma potential and ion current density are important factors that determine the process outcome. In the present work, a DC powered microplasma source is considered to carry out numerical investigation of profile of the plasma parameters and ion current density at different positions within the plasma region. The effect of the presence of a conducting surface and a dielectric material on the plasma parameters is further studied in view of the material processing applications.

Evaluation of Selected Properties of Dielectric Barrier Discharge Plasma Jet.

In the technological processes requiring mild treatment, such as soft materials processing or medical applications, an important role is played by non-equilibrium plasma reactors with dielectric barrier discharge (DBD), that when generated in noble gases allows for the effective treatment of biological material at a low temperature. The aim of this study is to determine the operating parameters of an atmospheric pressure, radio-frequency DBD plasma jet reactor for the precise treatment of biological materials. The tested parameters were the shape of the discharge (its length and volume), current and voltage signals, as well as the power consumed by the reactor for various composition and flow rates of the working gas. To determine the applicability in medicine, the temperature, pH, concentrations of H2O2, NO2- and NO3- and Escherichia coli log reduction in the plasma treated liquids were determined. The obtained results show that for certain operating parameters, a narrow shape of plasma stream can generate significant amounts of H2O2, allowing for the mild decontamination of bacteria at a relatively low power of the system, safe for the treatment of biological materials.

Generating Ultralong-Superoscillation Nondiffracting Beams with Full Control of the Intensity Profile

Nondiffracting light beams receive substantial attention in various areas due to their properties of diffractionless propagation and achievable subwavelength beam size. Extending the propagation distance and compressing the beam size of nondiffracting beams are crucial to their practical applications. However, it remains challenging to achieve nondiffracting light beams with a subwavelength subdiffracting transverse size and a long propagation distance with controllable intensity profiles in both transverse and longitudinal directions. Here, we propose an optimization method to generate an ultralong-superoscillation nondiffracting light beam with full control of the beam intensity profile. A 45\ensuremath{\lambda}-long-superoscillation nondiffracting light beam, the transverse sizes of which are within the range of 0.37\ensuremath{\lambda}--0.4\ensuremath{\lambda} along the propagation axis, is experimentally demonstrated by a metalens based on continuous phase modulation using geometrical phase metasurfaces. Our method provides an attractive way to controllably generate ultralong-superoscillation nondiffracting beams on a subwavelength scale and might find fascinating applications in optical manipulation, materials processing, data storage, microscopy, and spectroscopy.

Foundations of plasmas as ion sources

An overview of low temperature, partially magnetized ion sources is presented. This class of devices is broadly characterized by plasma densities below 1019 m−3, electron temperatures below 100 eV, and magnetic field strength tailored such that electrons are magnetized whereas ions are not. The overarching approach is pedagogical, targeting an audience that does not necessarily have an expertise in low temperature devices. A tutorial is presented on the basic physics of operation of common ion sources including an overview of standard methods for plasma generation and acceleration. Typical diagnostics and common uses of these plasma sources are also reviewed. Special attention is given to applications in plasma propulsion and materials processing. This class of ion sources is then discussed in the context of the current state of the field, key technical and scientific challenges, and future prospects.

Numerical optimization of non-equilibrium plasma source for surface processing of materials

Over the years, non-equilibrium plasma sources have emerged as a promising technology in surface processing of materials. Various strategies have been employed to make significant advancement in the technology. However, the process optimization is found to depend on different factors like power supply frequency, gas species and gas pressure. In order to control material processing outcome, it is necessary to control plasma parameters as per requirement. In the present work, a surface microwave generated non-equilibrium plasma source is proposed for material processing applications. The source comprises of rectangular waveguide system and a quartz tube, whose dimensions are optimized based on the electric field profile obtained within the plasma tube in the presence of the microwave (f = 2.45 GHz). Argon gas is allowed to flow through the discharge tube at a velocity of 10 m/s keeping its pressure at 1 torr. The microwave electric field within the discharge tube ionizes the argon gas medium resulting into plasma state whose properties are investigated using commercially available COMSOL Multiphysics® software. The inner surface of the discharge tube is then filled with dielectric beads (radius = 2 mm) and the effect of the dielectric constant on the plasma properties are studied. An investigation of ion flux at different positions in the plasma tube suggests that in the absence of dielectric beads, remote contact mode of operation can be preferred while in the presence of dielectric beads, direct contact mode of operation can be implemented. These results are of significance for direct as well as remote mode of surface processing of materials.

Application of Construction Waste Recycled Material Processing in Road Engineering

In order to promote the recycling of construction waste in China and reduce the cost of road engineering materials, this paper expounds on the technical indexes, road performance, durability, and the impact on the compressive strength of road engineering of construction waste recycled materials based on the analysis of the processing technology of construction waste recycled materials to provide reference for future research.

Self-starting high-order mode oscillation fiber laser.

In this paper, we proposed and demonstrated two kinds of all few-mode fiber lasers with self-starting high-order mode (HOM) oscillation. The fundamental mode can be completely suppressed by using a bandpass filter with a few-mode fiber pigtail. In the continuous-wave (CW) regime, the fiber laser directly oscillates in HOM with a signal-to-noise ratio as high as 70dB, and the slope efficiency is up to 46%. The self-starting HOM mode-locked pulse can be easily achieved by employing a saturable absorber. The HOM oscillation pulsed fiber laser stably operates at 1063.72nm with 3dB of 0.05nm, which can deliver cylindrical vector beams with a high mode purity of over 98%. To our knowledge, this is the first demonstration for self-starting HOM direct oscillation in stable CW and pulsed operation states without additional adjustment. This compact and stable HOM fiber laser with a simple structure can have important applications in materials processing, optical trapping, and spatiotemporal nonlinear optics. Moreover, this work may offer a promising approach to realizing high-power fiber laser with arbitrary HOMs stable output.

Development of an Atmospheric Pressure Plasma Jet Device Using Four-Bore Tubing and Its Applications of In-Liquid Material Decomposition and Solution Plasma Polymerization.

In this study, we describe an atmospheric pressure plasma jet (APPJ) device made of four-bore tubing operable in inhospitable humid environments and introduce two potential applications of liquid material processing: decomposition of aqueous phosphorus compounds and solution-plasma polymerization. A four-bore tube was used as the plasma transfer conduit and two diagonal bores contained metal wires. In the proposed APPJ device, the metal wires serving as electrodes are completely enclosed inside the holes of the multi-bore glass tube. This feature allows the APPJ device to operate both safely and reliably in humid environments or even underwater. Thus, we demonstrate that the proposed electrode-embedded APPJ device can effectively decompose aqueous phosphorus compounds into their phosphate form by directly processing the solution sample. As another application of the proposed APPJ device, we also present the successful synthesis of polypyrrole nanoparticles by solution plasma polymerization in liquid pyrrole.

Femtosecond laser micromachining for stress-based figure correction of thin mirrors

The fabrication of a large number of high-resolution thin-shell mirrors for future space telescopes remains challenging, especially for revolutionary mission concepts such as NASA’s Lynx X-ray Surveyor. It is generally harder to fabricate thin mirrors to the exact shape than thicker ones, and the coatings deposited onto mirror surfaces to increase the reflectivity typically have high intrinsic stress that deforms the mirrors further. Since the rapid development of femtosecond laser technologies over the last few decades has triggered wide applications in materials processing, we have developed a mirror figure correction and stress compensation method using a femtosecond laser micromachining technique for stress-based surface shaping of thin-shell x-ray optics. We employ a femtosecond laser to selectively remove regions of a stressed film that is grown onto the back surface of the mirror, to modify the stress states of the mirror. In this paper, we present experimental results to create both isotropic and anisotropic stress states on thin flat silicon mirrors with thermal oxide ( S i O 2 ) films using femtosecond lasers. We show that equibiaxial stress can be generated through uniformly micromachined holes, while non-equibiaxial stress arises from the ablation of equally spaced troughs. We also present results from strength tests to show how this process minimally affects the strength of mirrors. These developments are beneficial to the high-throughput correction of thin-shell mirrors for future space-based x-ray telescopes.

Performance of plasma source and irradiation for optical properties improvement of gelatin/silver composite

AbstractThis article describes the design, development and operation of a plasma generator using nitrogen gas for various materials processing applications. It consists of two electrodes, anode and cathode, made of palladium rods of different diameters serve as the plasma source. The plasma between the anode and cathode was formed at different pressures using nitrogen gas. When compared the palladium electrodes to graphite ones, the discharge characteristics of palladium electrodes without and with Teflon insulators that covered all electrodes save the head were investigated. The discharge characteristics at the optimum anode‐cathode distance and the diameter of palladium electrodes without and with a Teflon insulator were compared. Also, the discharge characteristics for palladium and graphite electrodes at the optimum anode‐cathode distance and electrode diameter without and with Teflon insulator were compared. The gelatin/silver composite specimens (for solar cells) were exposed to nitrogen plasma at different intervals. The photoluminescence and ultraviolet‐visible spectra of these specimens were analyzed and the results appeared to show that the specimens were sensitive to the visible spectrum. Except plasma irradiation time of 360 s, when the optical band gap energy rose, the band gap decreased as nitrogen plasma irradiation times increased.

Study on preparation and wear resistance of NiCrBSi-WC/Co composite coatings by pulsed magnetic field assisted supersonic plasma spraying

Magnetic field-assisted material processing not only offers excellent mechanical properties of the material but also hinders the formation of defects because of its no contiguity to the material. In this work, the effect of the integration of magnetic field with ultrasonic plasma spraying technology to deposit composite coatings was investigated. NiCrBSi coatings with reinforced WC/Co ceramic particles were deposited using a 5T pulsed magnetic field-assisted supersonic plasma spraying process. The film integrity, mechanical properties, and wear resistance outperformed the traditional plasma spraying coating. The stirring effect caused by the pulsed magnetic field reduced the thermal stress and accelerated the solidification. Nickel-based coatings with a pulsed magnetic field exhibited better wear resistance and high bonding strength. It is attributed to the refinement of grain, even distribution of hard ceramic phase, and dense internal structure. This process opens a new gateway for developing advanced material processing and practical application of high-performance coatings.

Modelling of Pulsed Laser Ablation in Liquid via Monte Carlo techniques: The effect of laser parameters and liquid medium on the electron cloud

Pulsed Laser Ablation in Liquid (PLAL) is a method for nanoparticle synthesis in which electron clouds are involved in the ablation process by providing electron heating which increases ablation efficiency. To better understand and control PLAL, this process was modelled herein via the Monte Carlo technique and the pure jump algorithm approach. From this model, it was shown that picosecond lasers produce fewer electrons with lower kinetic energy density than femtosecond lasers within a typical material processing period that contains many pulses. It was found that photon energies of 100 eV resulted in a primary electron: secondary electron ratio of about 1 : 1.6 regardless of the number of simulated primary electrons. The maximum energy of the electron cloud during a 20 fs laser pulse with 100 eV photons was 0.05 keV regardless of the boundary condition (number of primary electrons). An increase in photon energy from 100 eV to 200 eV caused an increase of over 600% in electron cloud energy. Such an increase would be expected to have an influence on various materials processing applications. Repetition rates of 10–100 kHz were found to have no influence on the electron cloud dynamics originating from the related differences in temporal sequences.

Actively Q switched radially polarized Ho:YAG laser with an intra-cavity laser-written S-waveplate.

Nanosecond Q switched pulses and radial polarization are established stand-alone techniques for enhanced laser materials processing applications, but are generally challenging to achieve simultaneously at high average power levels. Here, we demonstrate a 20.6 W radially polarized Ho:YAG rod laser which has been actively Q switched in order to generate 515 μJ, 210 ns pulses at 2097 nm. By utilizing an ultra-low-loss spatially variant birefringent wave plate (S-waveplate) inside the laser cavity, the linearly polarized fundamental mode has been converted to a radially polarized donut-shaped beam with very high conversion efficiency.

Generating double focal spots by focusing a radially polarized double-ring-shaped beam with an annular classical axicon

Focusing properties of a radially polarized double-ring-shaped beam with an annular classical axicon are numerically investigated based on vector Debye theory. Double focal spots and a flat-topped beam can be generated by choosing appropriate values of the pupil to the beam ratio β, numerical aperture, and annular obstruction. The distance between the twin spots, their depth of focus and the depth of the flat-topped beam are considerably affected by numerical aperture and annular obstruction. These focal shapes may find applications in laser printing, multifocal microscopy, and material processing.

Integration of blue–green electroluminescence structure in mid-infrared hollow optical fiber for targeting invisible CO2 laser beam

Mid-infrared (IR) CO2 lasers have important applications in laser medicine and material processing. However, the CO2 laser beam is invisible to human eyes, it is not easy to accurately indicate the beam position in practical applications. In this work, we designed a PEDOT (Poly (3, 4-ethylenedioxythiophene))/ZnS: Cu/BaTiO3/Ag electroluminescence (EL) structure and integrated it at the output end of the mid-IR hollow optical fiber. The blue–green light can be output along with the CO2 laser beam in this EL structure integrated fiber, thus achieving the optical path indication and illumination of invisible laser beam. This work provides a possible guide for aiming the CO2 laser beam in the min-IR optical fiber.

Evaluation of thermal characteristics of laser induced heating of microfilm in relation to printed circuit board manufacturing

The emerging field of microelectronics has expeditiously developed over recent decades, owing to the development of novel materials and state-of-the-art fabrication technologies, as it offers crucial solutions to specific and complicated challenges. Laser systems are effectively utilized in material processing applications due to their inherent capabilities that provide rapid, quality and flexibility to reduce production costs involved. Microelectronics manufacturing basically comprises circuit boards (printed circuit boards), semiconductor, IC wafers are a few applications where laser system has been employed over traditional manufacturing technologies. In the viewpoint of the importance of the application of laser in the arena of microelectronics, the present research work is dedicated to evaluate the thermal characteristics developed in laser heating of microfilm (printed circuit board). During the operation of laser heating on the substrate surface, the quantity of material removal is largely dependent on the high temperature induced by the laser. The parametric laser-substrate interaction phenomena are the prime deciding factor for the successful accomplishment of the manufacturing operation. From the literature review, it has been observed that not much concentration has been given to the application of non-Fourier’s model though it is specifically suited for microscale heat transfer. This research paper theoretically investigates the thermal characteristics (peak temperature, temperature distribution curvature, pulse time, optical penetration depth, time of laser exposure, laser absorption radius and so on) by employing non-Fourier’s heat conduction model with pulse laser heat source. The theoretical estimation will be validated by the existing experimental research outcomes. The present research paper might be an asset for deciding the design of process variables and protocols in terms of laser-based manufacturing in the arena of microelectronics.

Microwave radiation technique for the isolation of Sunn Hemp natural fiber in the application of material processing

Experimental works have been done on Sunn Hemp fiber and its reinforced composite to investigate various properties. Sunn Hemp fiber is modified physically by a multimode microwave oven (2.45 Hz) at the power of 160W–800W with 120W with varying time from 2 to 10 min with 4 min of interval. The fiber and composite properties are characterized structurally and physically. An increase in crystallinity and crystallite size in treated fiber is observed in X-Ray Diffraction (XRD) study, where Fourier Transmission Infrared (FTIR) shows no change in basic crystallinity in fiber. Morphology of treated fiber shows fibrillation and rough surface, but a higher treatment makes the fiber brittle and carbonized. Change in hydrophilicity from contact angle study and crosslinking density from equilibrium swelling theory affects the flexural and tensile properties of treated composites.

Comparative Study of Plasma Torch Characteristics Using Air and Carbon Dioxide

The plasma torch is the key component of the thermal plasma-assisted material processing system. Particularly, direct current (dc) nontransferred arc plasma torch is widely used in high-temperature material processing applications. The characteristics of the thermal plasma jet emanating from the plasma torch depend on many factors, including arc current, type of plasma forming gas, gas flow rates, gas injection configuration, torch geometry, and so on. This experimental study focuses on the comparison between the effects of CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> and air on the arc voltage, electrothermal efficiency, and specific enthalpy of the plasma torch operated at the atmospheric pressure. For this purpose, a low-power dc plasma torch consisting of a rod-type thoriated tungsten cathode and the copper anode was customized. CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> and air were used as the plasma forming gases along with a feeble amount of argon (15 lpm). The plasma torch was operated over a wide range of current (100–175 A) with fixed gas flow rates. The <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$I$ </tex-math></inline-formula> – <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$V$ </tex-math></inline-formula> characteristics and the electrothermal efficiency of the plasma torch were measured, and results were compared. The maximum electrothermal efficiency and specific enthalpy of the plasma torch when operated with CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> were reported as 70% and 1900 KJ/Kg, respectively, which is higher than the same torch operated with air as the plasma forming gas. The electron number density and electron temperature of the air and CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> plasma jet were measured by optical emission spectroscopy (OES). The calculated electron number density and electron temperature of the plasma jet with CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> were <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2.89\times 10\,\,^{\mathrm{ 16}}$ </tex-math></inline-formula> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−3</sup> and 8598 K, respectively, which is higher than air plasma jet. It was found that CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> has a stronger influence than air on the arc voltage fluctuation, electrothermal efficiency, and operating regime of the plasma torch.

Stabilisation of transverse mode purity in a radially polarised Ho:YAG laser using machine learning

Radially polarised solid-state lasers offer attractive improvements in materials processing applications, but selection and stabilisation of the appropriate radially polarised mode is much more challenging than for the fundamental mode. Here, we demonstrate automated stabilisation of a radially polarised Ho:YAG laser by utilising laser mode analysis computed from a convolutional neural network. The neural network predicts the transverse modal content from single plane intensity images with high accuracy on timescales of a few milliseconds, permitting real-time self-adjustment of the laser cavity. Radially polarised emission has been maintained across a 30 W range of pump power, with the stabilisation of other arbitrary laser modes using the same neural network also demonstrated.