Electron Beam Technology Research Articles

Obtaining a steel-based metal matrix composite by wire-feed additive electron beam manufacturing with the introduction of tungsten powder

Wire-feed electron-beam additive technology is used to produce samples of a composite material based on the 40Cr9Si2 steel by additionally introducing tungsten powder during printing. Controlling the feed of wire and powder makes it possible to form composite structures in the surface layers of the samples while maintaining the sample bulks with high strength and plasticity. The content of tungsten in the surface layer increases smoothly. This has a positive effect on the structure of the samples and prevents cracking or delamination at the boundary between the base metal and the surface layer. The tensile strength of the layers decreases with the introduction of tungsten in comparison with the bulk of the sample. In this case, the surface layers are characterized by a multiple increase in wear resistance, especially at elevated test temperatures.

ТЕХНОЛОГІЧНІ ОСОБЛИВОСТІ ОДЕРЖАННЯ СПЛАВІВ ТА ЛІГАТУР СИСТЕМИ TI–ZR–NB–SN В УМОВАХ ЕЛЕКТРОННО-ПРОМЕНЕВОЇ ЛИВАРНОЇ ТЕХНОЛОГІЇ

Electron beam casting technology is a unique method for obtaining cast products and semi-finished products from a wide range of titanium alloys. This technology can be very promissing in production of biocompatible titanium alloys for endoprosthesis. A particularly difficult and important task in this context is preparation of Ti-Zr-Nb-Sn system alloys with high strength and low modulus of elasticity. As a result of experimental development of specified alloys melt preparation technological modes, possibility of obtaining complex titanium alloys with a high content of zirconium and niobium was shown. It is also determined, that when the niobium content in the charge is more than 30 % wt. there is a decrease in the concentration of titanium and zirconium in the melt due to their freezing on the walls of the skull. As a result, there is a change in the chemical composition of the melt, the amount of niobium in which can exceed 50 % wt. Maximum amount of tin that can be assimilated in titanium-based melts under EBCT conditions is 5 % wt., and niobium-based melts are twice less. It has been proven that obtaining melts of Ti-Zr-Nb-Sn system with a precise chemical composition, using the chosen method, is a difficult and still unsolved problem, but due to the possibility of melting alloys with a high content of niobium and zirconium in its conditions, this method is effective in the production of master alloys and ingots for the production of powders used as raw materials for additive tmanufacturing. Keywords: titanium alloys for endoprosthesis, foundry production, Ti-Zr-Nb-Sn, electron-beam casting technology.

Effect of beam current of scanning electron beam on surface alloy layer of 20Cr steel

• The cross-sectional of the sample is composed of three parts: alloy layer, heat-affected zone and matrix. • The effect of beam current on the properties of alloy layer was studied. • A surface alloying method combining scanning electron beam and plasma thermal spraying is proposed. Scanning electron beam surface alloying can effectively improve the surface quality. In this paper, plasma thermal spraying technology and scanning electron beam technology are used to treat the surface of 20Cr steel. The effect of beam current on the microstructure, microhardness and wear resistance of alloy layer was studied. The results show that after alloying treatment, the cross-sectional structure of the sample is composed of three parts, the alloy layer, the heat-affected zone and the matrix. The microstructure of the alloy layer is acicular martensite, Fe-Ni solid solution, WC particles and a small amount of retained austenite. The microstructure of the heat-affected zone is mainly acicular martensite and lath martensite, the matrix structure is ferrite and pearlite. When the beam current reaches 12 mA, the surface hardness of the sample reaches the maximum (867HV), and the wear loss reaches the minimum (4.3 mg).

Production of metal matrix composites based on aluminum-manganese bronze and nickel alloys by wire feed electron-beam additive manufacturing

Samples of composite materials based on BrAMts9-2 bronze with the introduction of the Udimet500 and Inconel625 nickel alloys were obtained by wire-feed electron-beam technology. The studies show that the structures of composites formed during printing, although fairly similar due to the same base of the alloys, have different features due to different combinations of alloying elements. The mechanical properties of the samples with the introduction of up to 15 % of the Udimet500 alloy are higher than those of the samples of the second material. With the introduction of 25 % of a nickel alloy, the strength is higher for the composite material samples with the introduction of the Inconel625 alloy. The microhardness of the samples with the introduction of 5 % of a nickel alloy is identical, the introduction of large volumes of a nickel alloy leads to the implementation of greater hardness in the samples with the introduction of the Inconel625 alloy due to the higher content of refractory materials. Relative elongation after rupture varies insignificantly for the samples of both types.

Attosecond electron-beam technology: a review of recent progress.

Electron microscopy and diffraction with ultrashort pulsed electron beams are capable of imaging transient phenomena with the combined ultrafast temporal and atomic-scale spatial resolutions. The emerging field of optical electron beam control allowed the manipulation of relativistic and sub-relativistic electron beams at the level of optical cycles. Specifically, it enabled the generation of electron beams in the form of attosecond pulse trains and individual attosecond pulses. In this review, we describe the basics of the attosecond electron beam control and overview the recent experimental progress. High-energy electron pulses of attosecond sub-optical cycle duration open up novel opportunities for space-time-resolved imaging of ultrafast chemical and physical processes, coherent photon generation, free electron quantum optics, electron-atom scattering with shaped wave packets and laser-driven particle acceleration. Graphical Abstract.

Treatment of oil-field produced wastewater by electron beam technology: Demulsification, disinfection and oil removal

The treatment of polymer-containing produced wastewater with high viscosity and emulsification is a challenging issue in the oilfield. In this paper, electron beam (EB) radiation technology was firstly applied to treat the real oilfield produced wastewater. The results showed that the viscosity of the produced wastewater decreased rapidly from initial 3.7 mPa s to 1.5 mPa s after EB radiation at absorbed dose of 1.0 kGy, then it gradually reached the level of pure water at 5.0 kGy. The produced wastewater was negatively charged and the absolute value of zeta potential diminished stepwise during EB radiation process, indicating that the stability of oil/water emulsion decreased. Radiation pretreatment contributed to the oil removal by coagulation. The efficiency of oil removal increased remarkably from 47% by coagulation alone to 85% with EB pretreatment at 1.0 kGy. Radiation is also effective to disinfect the three typical bacteria in oilfield wastewater, saprophytic bacteria (TGB), sulfate-reducing bacteria (SRB) and iron bacteria (IB). More than 99.8% of TGB, SRB and IB were killed at 1.0 kGy, and a complete inactivation was obtained at 2.5 kGy. Oxidation by ·OH radicals formed in water radiolysis is the major pathway to decrease the viscosity and kill the bacteria, while the direct action of EB radiation also plays a role. The members belonging to genera Thauera, Defluviimonas and Comamonadaceae were predominant in the produced wastewater, with a relative abundance of 40%, 19% and 16%. Based on PICRUSt analysis, the function genes related to metabolism exhibit the highest abundance (25%), which increased at 1.0 kGy, and then decreased at 10 kGy, suggesting that EB radiation at low dose might stimulate the bacterial activity.

Scanning electron beam surface strengthening of column-faced 45 steel

• Columnar surface strengthening by scanning electron beam technology. • The effect of curvature on the microstructure of the fusion zone is investigated. • The relationship between microhardness distribution and curvature is established. • The carbon content of the sub-surface is higher than that of the near surface. To conquer the shortcomings that the column-faced 45 steel is susceptible to wear and failure, scanning electron beam was conducted to strengthen it, the microstructure and microhardness of the modified layer under variable workpiece curvature were investigated. The results revealed that the modified layer was composed of fusion zone and heat-affected zone, the depth of the modified layer manifested an ascend tendency as the increment of curvature. Martensite dominates the modified layer, and the carbon content of martensite for the sub-surface is higher than that of the near surface, moreover, the grain size of martensite first reduced and then increased with increasing of curvature. The position of the maximum microhardness along the direction of depth as the curvature increases, and the maximum microhardness of 1/20 curvature is 688.26 HV, which is about 3.13 times that of the matrix. This study demonstrated the potential of using scanning electron beam to reinforce column-faced 45 steel.

Electron beam technology for Re-processing of personal protective equipment

Beginning with the outbreak of COVID-19 at the dawn of 2020, the continuing spread of the pandemic has challenged the healthcare market and the supply chain of Personal Protective Equipment (PPE) around the world. Moreover, the emergence of the variants of COVID-19 occurring in waves threatens the sufficient supply of PPE. Among the various types of PPE, N95 Respirators, surgical masks, and medical gowns are the most consumed and thus have a high potential for a serious shortage during such emergencies. Considering the unanticipated demand for PPE during a pandemic, re-processing of used PPE is one approach to continue to protect the health of first responders and healthcare personnel. This paper evaluates the viability and efficacy of using FDA-approved electron beam (eBeam) sterilization technology (ISO 11137) to re-process used PPE. PPEs including 3M N95 Respirators, Proxima Sirus gowns, and face shields were eBeam irradiated in different media (air, argon) over a dose range of 0–200 kGy. Several tests were then performed to examine surface properties, mechanical properties, functionality performance, discoloration phenomenon, and liquid barrier performance. The results show a reduction of filtration efficiency to about 63.6% in the N95 Respirator; however, charge regeneration may improve the re-processed efficiency. Additionally, mechanical degradation was observed in Proxima Sirus gown with increasing dose up to 100 kGy. However, no mechanical degradation was observed in the face shields after 10 times donning and doffing. Apart from the face shield, N95 Respirators and Proxima Sirus gown both show significant mechanical degradation with ebeam dose over sterilization doses (>25 kGy), indicating that eBeam technology is not appropriate for the re-processing these PPEs.

Microstructure and properties of mono-crystalline germanium enhanced by high-current pulsed electron beam

High current pulsed electron beam (HCPEB) technology was applied to irradiate the surface of mono-crystalline Ge wafers (Ge (100) and Ge (111)) with different orientations, and the microstructure and properties of the irradiated surface were analyzed in detail. The results show that after HCPEB irradiation, numerous molten pits and local microcracks were produced on the surface of mono-crystalline Ge, and the pit density decreased with the increase of irradiation pulses. TEM observations indicated that after irradiation, the defects are mainly vacancy group defects and dislocation rings, and Ge nanocrystals with uniform size distribution are produced. HCPEB irradiation also formed self-assembled nanostructures on the surface of Ge. Cross section TEM indicated that the 250 nm deep defect channels were under the quantum dots, which confirms the formation mechanism of self-assembled nanostructures. The photoluminescence results indicated that the irradiated mono-crystalline Ge still has blue emission properties, and the luminescence mechanism is the quantum confinement effect of Ge nanocrystals embedded in slightly oxidized or nitrided amorphous structures.

Treatment of hospital wastewater by electron beam technology: Removal of COD, pathogenic bacteria and viruses

The effective treatment of hospital sewage is crucial to human health and eco-environment, especially during the pandemic of COVID-19. In this study, a demonstration project of actual hospital sewage using electron beam technology was established as advanced treatment process during the outbreak of COVID-19 pandemic in Hubei, China in July 2020. The results indicated that electron beam radiation could effectively remove COD, pathogenic bacteria and viruses in hospital sewage. The continuous monitoring date showed that the effluent COD concentration after electron beam treatment was stably below 30 mg/L, and the concentration of fecal Escherichia coli was below 50 MPN/L, when the absorbed dose was 4 kGy. Electron beam radiation was also an effective method for inactivating viruses. Compared to the inactivation of fecal Escherichia coli, higher absorbed dose was required for the inactivation of virus. Absorbed dose had different effect on the removal of virus. When the absorbed dose ranged from 30 to 50 kGy, Hepatitis A virus (HAV) and Astrovirus (ASV) could be completely removed by electron beam treatment. For Rotavirus (RV) and Enterovirus (EV) virus, the removal efficiency firstly increased and then decreased. The maximum removal efficiency of RV and EV was 98.90% and 88.49%, respectively. For the Norovirus (NVLII) virus, the maximum removal efficiency was 81.58%. This study firstly reported the performance of electron beam in the removal of COD, fecal Escherichia coli and virus in the actual hospital sewage, which would provide useful information for the application of electron beam technology in the treatment of hospital sewage.

A stable LaB6 nanoneedle field-emission electron source for atomic resolution imaging with a transmission electron microscope

Field-induced electron emission offers the best performance point electron source for electron microscopes. Herewith we report a new cold field-emission point electron source utilizing a nanoneedle made of lanthanum hexaboride (LaB6) and its implementation in a spherical aberration-corrected transmission electron microscope (TEM). A sub-ångstrom resolution of 0.96 Å has been obtained with the TEM operated at an acceleration voltage of 60 kV and a smaller energy spread was also observed compared with the contemporary W(310) electron source. In particular, the LaB6 nanoneedle cold field-emission electron source required no thermal flashing for continuous operation of extended hours (>100 hours) while exhibiting and sustaining a high stability in emission current (<1%). We attribute the excellent performance of the LaB6 nanoneedle electron source to (i) a low work function of LaB6; (ii) excellent alignment of the nanoneedle emitter by the electron and ion dual-beam processing with nanoscale precision and (iii) robustness of the nanometric structure that suppressed mechanical vibrations of the LaB6 emitter even in a high electric field. This new LaB6 nanoneedle cold field-emission electron source enables stable high-resolution imaging in TEM and it will also benefit cryogenic electron microscopy, scanning electron microscopy, electron beam lithography, and other electron beam technologies.

Use of PtC Nanotips for Low-Voltage Quantum Tunneling Applications.

The use of focused ion and focused electron beam (FIB/FEB) technology permits the fabrication of micro- and nanometer scale geometries. Therefore, FIB/FEB technology is a favorable technique for preparing TEM lamellae, nanocontacts, or nanowires and repairing electronic circuits. This work investigates FIB/FEB technology as a tool for nanotip fabrication and quantum mechanical tunneling applications at a low tunneling voltage. Using a gas injection system (GIS), the Ga-FIB and FEB technology allows both additive and subtractive fabrication of arbitrary structures. Using energy dispersive X-ray spectroscopy (EDX), resistance measurement (RM), and scanning tunneling microscope (STM)/spectroscopy (STS) methods, the tunneling suitability of the utilized metal–organic material–platinum carbon (PtC) is investigated. Thus, to create electrode tips with radii down to 15 nm, a stable and reproducible process has to be developed. The metal–organic microstructure analysis shows suitable FIB parameters for the tunneling effect at high aperture currents (260 pA, 30 kV). These are required to ensure the suitability of the electrodes for the tunneling effect by an increased platinum content (EDX), a low resistivity (RM), and a small band gap (STM). The STM application allows the imaging of highly oriented pyrolytic graphite (HOPG) layers and demonstrates the tunneling suitability of PtC electrodes based on high FIB aperture currents and a low tunneling voltage.

Fiber-Optic Based Laser Wakefield Accelerated Electron Beams and Potential Applications in Radiotherapy Cancer Treatments

Ultra-compact electron beam technology based on laser wakefield acceleration (LWFA) could have a significant impact on radiotherapy treatments. Recent developments in LWFA high-density regime (HD-LWFA) and low-intensity fiber optically transmitted laser beams could allow for cancer treatments with electron beams from a miniature electronic source. Moreover, an electron beam emitted from a tip of a fiber optic channel could lead to new endoscopy-based radiotherapy, which is not currently available. Low-energy (10 keV–1 MeV) LWFA electron beams can be produced by irradiating high-density nano-materials with a low-intensity laser in the range of ~1014 W/cm2. This energy range could be useful in radiotherapy and, specifically, brachytherapy for treating superficial, interstitial, intravascular, and intracavitary tumors. Furthermore, it could unveil the next generation of high-dose-rate brachytherapy systems that are not dependent on radioactive sources, do not require specially designed radiation-shielded rooms for treatment, could be portable, could provide a selection of treatment energies, and would significantly reduce operating costs to a radiation oncology clinic.

Vertical 3D diamond field effect transistors with nanoscale gate-all-around

Recent studies have shown that diamond field effect transistors (FETs) have great potential in high-power and high-frequency electronics, exhibiting the maximum leakage current of 1.35 A·mm−1 and the breakdown voltage of 2 kV. However, there is still a lack of preliminary exploration on diamond FETs with a three-dimensional (3D) architecture, which has been evidenced as a promising approach to increase device performance and density for silicon transistors. In this paper, we present a systematic investigation of 3D vertical gate-all-around (GAA) diamond transistors, combined with numerical simulation, device fabrication and characterization of device performance. The p-type conductivity of the diamond channel in a transistor is obtained by Boron-ion implantation. Our numberical simulations address the close correlation of transfer characteristics of the 3D vertical GAA diamond transistors with the ion implanted impurities. In the device fabrication, we introduce the focused ion and electron beam technology for the electrode interconnections in the 3D devices. Finally, we demonstrate that the 3D vertical GAA diamond transistor exhibits the on-off ratio of 2.5 × 103, subthreshold swing of 334.3 mV·dec−1, and threshold voltage of 0.64 V. And the temperature dependence of transfer characteristics of the 3D devices indicates that 3D vertical GAA diamond transistors have potential application prospects in extreme environments such as high temperature.

Formation of FePt–MgO Nanocomposite Films at Reduced Temperature

The MgO nanolayer effect on the microstructure and magnetic characterizations added into Fe/Pt stacked films directly deposited onto MgO (001) single-crystal substrates at the reduced temperature of 380 °C using electron-beam technology was investigated in this present work. The nanograin isolation and exchange decoupling for the FePt–MgO system is attributed to the magnetic FePt isolated grains that originate from MgO atoms with a spreading behavior mostly along grain boundaries owing to its weaker surface energy than that of a single Fe or Pt element. The grain and domain size decreased when the MgO nanolayer was applied due to the interpenetration of MgO and created a strain-energy variation at the MgO/FePt interface. Measuring angular-dependent coercivity indicates a general trend of a domain-wall motion, and changes to the rotation of the reverse-domain model occurred as the MgO nanolayers were added into FePt films. The intergrain interaction is confirmed by the Kelly–Henkel plot, which shows that there is strong intergrain exchange coupling (positive δM type) between neighboring grains in the continuous Fe/Pt stacked films without MgO nanolayers. In addition, a negative δM type occurred when the Fe/Pt stacked films were added into MgO nanolayers, showing that the MgO nanolayer can be applied to adjust the force of intergrain exchange coupling between the adjacent FePt nanograins, and the addition of MgO nanolayers change into magnetic decoupling; thus, there was a formed dipole interaction in our claimed FePt–MgO composite structure of stacked ultrathin films at a reduced temperature of 380 °C.

Synthesis of nano-optical elements for zero-order diffraction 3D imaging

A method is proposed to compute and synthesize a microrelief to produce a new nano-optical element for forming 3D images with full parallax at the zero order of diffraction. The synthesis of nano-optical elements requires the use of multilevel structures. A method is developed for the first time to compute the phase function of such nano-optical elements. Optical security elements that produce the new security feature are synthesized using electron-beam technology. The accuracy of microrelief formation is 10 nm in terms of depth. A sample optical security element is manufactured, which when illuminated by white light, forms a 3D image at the zero order of diffraction. Photos and video of the new 3D visual effect exhibited by real optical elements are presented. The optical elements developed can be replicated using standard equipment employed for manufacturing security holograms. The new optical security feature is easy to control visually, safely protected against counterfeiting, and designed to protect banknotes, documents, ID cards, etc.

Highly sensitive and reproducible SERS substrates with binary colloidal crystals (bCCs) based on MIM structures

Surface-enhanced Raman scattering (SERS) is a powerful molecular vibrational spectrum characterization method, and has shown promising applications in surface science, life science, environmental monitoring, etc. Developing new simple processes to fabricate low-cost substrates is an essential prerequisite to promote and strengthen the practical application of the SERS technique. For this purpose, the present work reports on the development of a metal/insulator/metal (MIM) structure combined with polystyrene (PS) binary colloidal crystals (bCCs) based on nanosphere self-assembly and electron-beam evaporation technologies. The PS bCCs are used to form a dielectric layer sandwiched between a bottom Ag reflection layer and an upper Ag shell layer. Compared with single-sized colloidal spheres, the PS bCCs exhibit considerably richer morphologies and structures. In addition, the closely packed Ag shell arrays enhance the density of electromagnetic field “hot spots” thus increasing the SERS activity. The PS bCCs-based MIM substrate could achieve an enhancement factor (EF) of 1.10 × 108 and an ultralow detection limit for the Rhodamine 6G (R6G) molecule of about 10−14 M. The results demonstrate that the proposed substrates with a facile fabrication strategy, low cost, large area and high sensitivity have high potential applications of SERS sensors for bio- and chemical molecular analysis.

Investigations on the Microstructure of an Aluminium Nitride Layer and Its Interface with the Aluminium Substrate (Part I)

In principle, the plasma nitriding of Al based substrates is a well-known process, though it remains extremely challenging from both the technological point of view and the aspect of stress loading conditions. In order to improve the latter, a duplex treatment consisting of plasma nitriding and subsequent surface remelting using electron beam technology was employed. The focus of this paper (part I) was on the characterisation of the initial microstructure after plasma nitriding. This should create the basis for a better understanding of the processes taking place or changes in the subsequent duplex treatment. This was done with the help of high-resolution imaging and analysis tools in the scanning and transmission electron microscope as well as XPS analyses. Special attention was paid to the nitriding mechanism at the interface as a function of the local microstructural constituents of the hypereutectic Al alloy substrate (Al solid solution, primary silicon, and intermetallic phases). While the main part of the nitride layer formed consisted of AlN and small fractions of pure Al in the diffusion paths, other nitrides and oxides could also be detected in the area of the interface.

First full-scale application of electron beam technology for treating dyeing wastewater (30,000 m3/d) in China

Electron beam technology has been widely investigated for the degradation of recalcitrant organic pollutants in water and wastewater in laboratory scale. However, it needs verification in practical application for long-term operation. Strikingly, for the first time, we have successfully applied electron beam technology to treat the actual dyeing wastewater in capacity of 30,000 m3/d in Jiangmen city, Guangdong Province, China. The continuous monitoring data of the effluent water quality showed that electron beam technology can be used as advanced treatment process to effectively improve the removal efficiency of COD and color. The effluent COD of electron beam unit stayed between 20 and 50 mg/L when the influent COD ranged from 180 to 280 mg/L, and the color of the treated dyeing wastewater decreased to about 10 times. The operational cost of whole wastewater treatment processes was about 2.0–2.5 ¥/m3, including electron beam unit. Based on the monitoring data of more than one year's operation, it can be concluded that electron beam technology could provide a solution for refractory industrial wastewater treatment, which is a high efficient and cost-effective advanced treatment process.

Electron Beam Technology Coupled to Fenton Oxidation for Advanced Treatment of Dyeing Wastewater: from Laboratory to Full Application

Electron Beam Technology Coupled to Fenton Oxidation for Advanced Treatment of Dyeing Wastewater: from Laboratory to Full Application