Amorphous Steel Research Articles

Fe-based bulk metallic glass with high thermal stability and corrosion resistance

Fe-based metallic glass is prone to crystallization at high temperature due to its thermodynamic instability, resulting in the loss of many excellent properties. In this work, we developed a new Fe-based bulk metallic glass with high Cr and W refractory elements. The results show that the glass transition temperature Tg reaches 880 K. The very high thermal stability can result in the formation of Cr-Cr bonds, W-W bonds, and (Cr,W)-(C,B) bonds with stronger bond energy in Fe-based bulk metallic glass. Moreover, FeCrWCBY bulk metallic glass exhibits good corrosion resistance in 3.5 % NaCl and aqua regia solutions. The self-corrosion current density of FeCrWCBY bulk metallic glass in NaCl solution is only 8.4 × 10–7 A/cm2, much lower than the result of Fe48Cr15Mo14C15B6Y2, known as amorphous steel. The high thermal stability and excellent corrosion resistance are decoded in details from atomic bonding properties and passivation film characteristics.

Calcium nitrate effectively mitigates alkali–silica reaction by surface passivation of reactive aggregates

AbstractCalcium nitrate (CN: Ca(NO3)2) has been shown to mitigate alkali–silica reaction (ASR) in concrete. Such ASR mitigation has been suggested to be on account of precipitate (i.e., barrier or passivation layer) formation‐induced dissolution inhibition of reactive/dissolving aggregate surfaces. Herein, we examine the ability of CN to mitigate ASR across two cements (Type I/II and Portland Limestone Cement), for aggregates of varying reactivity, and across different types and dosages of SCMs (supplementary cementitious materials, i.e., amorphous steel slag and Class C and Class F fly ashes). Based on expansion measurements carried out as per ASTM C1260/C1567, it is observed that CN, as a function of dosage, substantively mitigates ASR in mortar formulations across aggregate types. Careful microstructural examinations, dissolution studies, and thermodynamic calculations indicate that CN induces the formation of C–S–H, portlandite (Ca(OH)2), and calcite (CaCO3) precipitate mixtures, which form on aggregate surfaces at the expense of typical ASR gels. Such precipitates create a dissolution barrier and inhibit ASR in both SCM‐free and SCM‐containing formulations. The outcomes indicate that CN is an efficient and cost‐effective ASR mitigation additive (∼$250–$600 per tonne), particularly in a time of dwindling fly ash supplies and unaffordable lithium prices (>∼$12 000 per tonne).

The Use of Polyimide as a Bonding Material to Improve the Mechanical Stability, Magnetic and Acoustic Properties of the Transformer Core Based on Amorphous Steel.

The constantly evolving electrification also entails an increase in requirements for the effective and efficient distribution of electricity with the lowest possible power losses. Such needs can be met by highly effective electrical devices, and one of them is a transformer whose main component is a magnetic core. Currently, one of the soft magnetic materials used alternatively for the production of transformer cores are amorphous metal strips with competitive losses. However, to successfully use these materials, a key problem must be solved: limited mechanical stability. The presented article describes the development and application of a polyimide-based binder for efficient bonding of an amorphous metal ribbon. The layered binder was characterized using confocal microscopy, scanning electron microscopy and Raman spectroscopy, and its anticorrosion and mechanical properties were examined. As a final step, a prototype of a toroidal magnetic core bonded with the binder was manufactured and subjected to the evaluation of no-load loss and the analysis of the emitted noise. It was confirmed that the proposed polyimide binder tremendously improved the mechanical stability while reducing core losses and audible noise.

Research on magnetic field characteristics of amorphous alloy and grain‐oriented silicon steel hybrid magnetic circuit iron core

AbstractAmorphous alloy and grain‐oriented silicon steel are commonly employed as soft magnetic materials for the preparation of transformer cores, but both materials have their advantages and disadvantages. Using only silicon steel or amorphous alloy for the preparation of the core makes it difficult to achieve both high design density and low no‐load loss characteristics. In order to achieve the magnetic performance advantages of both amorphous alloy and silicon steel in transformer core development and application, the authors design and develop a kind of amorphous alloy and grain‐oriented silicon steel hybrid magnetic circuit core to explore the amorphous alloy and grain‐oriented silicon steel at different ratios under the magnetic properties of matching law. Based on the amorphous alloy and grain‐oriented silicon steel core magnetic performance comparison characteristics, the authors establish a core magnetic circuit model and design a hybrid magnetic circuit core structure with different material ratios. The hybrid magnetic circuit core model is simulated and analysed to obtain the magnetic density distribution of the hybrid magnetic circuit core. A number of hybrid magnetic circuit core experimental models are produced, and the use of a magnetic property measurement platform is made for the hybrid magnetic circuit core measurements, to reveal the magnetic performance matching law of the hybrid magnetic circuit core, providing a good solution for power distribution in the hybrid magnetic circuit.

Amorphous Core Distribution Transformer with Improved Efficiency and Low Loss for Power Sector Application

The amorphous transformer (AMTD) is an energy-efficient transformer that minimizes both airborne pollutants and the amount of energy required to create power. This research investigates the use of amorphous material in transformer construction rather than the usual silicon steel core. It outperforms silicon steel in terms of magmatic characteristics. Because of its high resistivity and low thickness, adopting amorphous as a transformer core instead of a traditional transformer can eliminate 70% of transformer no load losses. When deciding which transform to install and use in the electrical network, the total prices of silicon steel and amorphous steel are considered. The total owed cost (TOC) of any specific transformer is calculated by discounting future transformer losses (losses from both load and no load) to present value and leveling them across the transformer's lifetime. The characteristics of amorphous and conventional electrical cold-rolled grain-oriented(CRGO) materials were evaluated. Amorphous metal is a special type of alloy with an irregular molecular arrangement rather than a well-organized crystalline structure. Amorphous metal can be utilized for the transformer core to increase transformer efficiency. The material's increased magnetic characteristics and physical dimensions lead to much lower hysteresis and eddy current losses. Using amorphous metal cores can minimize transformer core loss by more than60 percent. High power-density transformers are in high demand in many applications where weight and available space are severely constrained, such as power electronics. While electromagnetic device weights and sizes normally decrease at higher frequencies, core loss may increase considerably.

Calculation of electromagnetic force and temperature distribution of amorphous transformers in different operating modes by finite element method

The study used the Finite element method (FEM) by ANSYS 3D software to calculate the distribution of electromagnetic force (EMF) and temperature on the high voltage and low voltage windings (HLVWs) of the amorphous steel core 3 phase transformer (ASCT) which has a power of 1000kVA –22/0.4kV under different load cases: No load, full load and short circuit (SC). The obtained results show the exact temperature distribution and location where the highest temperature is found on the HLVWs of ASCT. From the analysis of the temperature distribution on the HLVWs, it is shown that when the transformer falls into an SC fault, it causes the greatest EMF and thermodynamic force, causing extremely heavy consequences for the transformers. The obtained results help designers, manufacturers, and operators have the most suitable options to improve strength of SC and increase the life of the transformer.

Exploration of Key Technologies for Equipment Operation and Maintenance Based on New Power Systems

With the construction and development of the new generation of power system (thereafter, it is displaced with PS), intelligent power equipment is more widely used and higher requirements for the flexibility, controllability and safety of PS emerge. This article focused on the key technologies of equipment operation and maintenance (O&M) in the PS, aiming to improve the challenges faced by traditional PS through new energy power and intelligent PS. The article studied the development of new PS, analyzed intelligent PS from the perspectives of intelligent maintenance, online fault diagnosis and status monitoring and evaluation, compared the capacity of new energy equipment and simulated the wind PS simulation structure diagram. Setting the Longyangxia Hydropower Station as an instance, it explored the complementarity between solar and hydro energy in the hydropower station. By studying the service life of transformers in 50 PS of Longyangxia Hydropower Station, it was found that amorphous alloys and silicon steel were relatively excellent and a total of 8 rounds of power generation equipment in the PS passed the safety assessment. The article proposed a long-term maintenance research method for the key technologies of equipment O&M in the new PS, achieving precise management and efficient maintenance of equipment and ensuring safe and reliable operation of equipment under complex working conditions.

Lubricity of chelated orthoborate-phosphonium ionic liquids on tetrahedral amorphous carbon and steel surfaces

In boundary lubrication, formation of tribofilms and subsequent friction and wear properties are strongly influenced by lubricant affinity to the lubricating surfaces. Ionic liquids (ILs), which are composed of ions, are expected to provide enhanced surface affinity compared to molecular liquids. This is also of interest for non-ferrous surfaces such as diamond-like carbon (DLC) coatings. DLC technology is widely utilised for sliding components, but DLC performance with conventional lubricants does not always fulfil the requirements. In this study, we compare lubricating performance of two non–halogenated ILs with a common cation, trihexyl(tetradecyl)phosphonium, but different anions, bis(oxalato)borate and bis(mandelato)borate, in the steel/steel and steel/DLC contacts. The tribofilms formed and their lubrication mechanism are investigated using a wide range of surface analysis techniques: Atomic Force Microscopy (AFM), nano-indentation, SEM-EDX and X-ray Photoelectron Spectroscopy (XPS). It is demonstrated that both ILs exhibited better lubricating performance than PAO oils of similar viscosity. It is also shown that the lubricating performance is controlled by the chemical stability of ILs, surface hardness and topography. The phosphonium bis(oxalato)borate IL exhibited excellent lubricity but its performance was adversely affected by the rough and very hard DLC surface that disrupted a delicate balance between the rates of tribofilm formation and removal. A higher chemical stability of the phosphonium bis(mandelato)borate IL facilitated formation of a non-sacrificial ionic tribofilm that reduced friction to a lower extent than the phosphonium bis(oxalato)borate IL but without accelerated tribochemical wear. The results demonstrate the potential for controlling lubrication properties by tuning functional groups of anion structure and subsequent chemical reactivity of ILs with lubricated surfaces.

アモルファス電磁鋼板の多層積層せん断加工における樹脂皮膜塗布の影響

Interfacial control plays a role in micro-punching an amorphous electrical steel sheet stack. The punching performance was compared between conventional and resin-coated sheets. Through the tensile loading test of resin-coated sheets, it was found that resin coating increased the interfacial friction between adjacent sheets. The punching load decreased in every five-layered stack specimen with an interfacial resin coating. In every punching experiment, punching- affected zones were mainly governed by cracking near the punched hole. Bending deformation was enhanced by interfacial friction to change the original shearing of the stack specimen.

Fine Piercing of Amorphous Electrical Steel Sheet Stack by Micro-/Nano-Textured Punch.

The periodic nanotexture was superposed to the micro-textured grooves on the side surface of the punch. These grooves with nanotextures were shaped to have parallel and vertical orientations to the punch stroke direction, respectively. A stack of five amorphous electrical steel sheets was punched out with these micro-/nano-textured punches. The process affected zone at the vicinity of the punched hole was analyzed by SEM (Scanning Electron Microscopy) and a three-dimensional profilometer. The punch surfaces were also observed by SEM to describe the debris particle adhesion on them. The dimensional change in each layer of the stack before and after perforation was measured to describe the punching behavior with the comparison to the punch diameter.

Property Evolution in Amorphous Steel Coatings by Different Thermal Spray Processes

Property Evolution in Amorphous Steel Coatings by Different Thermal Spray Processes

Analysis and optimization of speed regulation ability with field weakening of the stator hybrid laminated remanufactured motor

To improve the efficiency, a 13 kW used vehicle permanent magnet synchronous motor was remanufactured, whose stator core was replaced by a combination of amorphous alloy laminations and silicon steel laminations. But the speed regulation ability with field weakening of the remanufactured motor limits its development towards high speed direction. Taking the remanufactured motor as the object, based on the theory of speed regulation with field weakening, the maximum speed range was improved by increasing direct-axis inductance, and the structural optimization parameters affecting the direct-axis inductance were analysed. The two-dimensional inductance superposition method was proposed to calculate the direct-axis and quadrature-axis inductance of the remanufactured motor, and its accuracy and feasibility were verified by finite element simulation. The segmented structure of the V-type permanent magnet was used, and the motor structure was optimised from three aspects: the width and position of magnetic bridge and the magnetic pole implantation depth. The orthogonal experiments were designed to determine the best parameter combination. The results show that the direct-axis inductance of the optimised remanufactured motor is increased by 16.33%, and the performance of speed regulation with field weakening is improved significantly.

Development of method to design end-face synchronous motors made of amorphous steel using digital twin technology

Modern technologies of generative design and digital twins of electrical devices are based on the use of field models, as a rule, three-dimensional ones. Also, it is possible to solve design problems and to simulate accurately electrical machines and devices based on a set of 2D models of physical fields. Application of automatically generated field models in modern systems of engineering analysis during the design and optimization of electrical machines and devices makes it possible to get rid of many assumptions and outdated empirical and semi-empirical dependencies, as well as to reach a new methodological level of design theory, characterized by a unified approach to the calculation of various devices. Therefore, the purpose of this article is to develop a methodology to design a synchronous motor of an atypical design, based on the use of two-dimensional models of a stationary magnetic field at different design stages and allowing a solution to be obtained even in the absence of preliminary studies and recommendations. The finite element method is used implemented by means of the EMLib library (author's development), which allows calculating magnetic fields in a 2D formulation. Also, methods of the theory of synchronous machines and object-oriented programming in VBA in the MSExcel environment are used. Elements of digital twin technology and generative design are used while developing the methodology and design system. A method to design an end-face synchronous motor has been developed using automatically generated set of field models at the stages of choosing the height of a permanent magnet, calculating the parameters of an equivalent circuit, and an angular characteristic. Based on the popular MSExcel package, a system to design an end-face synchronous motor has been developed. The EMLib library has been implemented into the system, it allows using the results of calculating the magnetic field in the key design operations. The end-face synchronous motor has been designed and tested on the base of the developed system. The results of the research can be used during the development of methods to design electrical machines and devices of arbitrary, including non-standard design, for which approved algorithms for engineering analysis do not exist.

Compressive and Diagonal Tension Strengths of Masonry Prisms Strengthened with Amorphous Steel Fiber-Reinforced Mortar Overlay

A technique for strengthening masonry walls by plastering with amorphous steel fiber-reinforced mortar (ASFRM) is investigated through compressive and diagonal tension tests for masonry prisms. The vertical joint between masonry units was not completely filled with mortar to mimic poor workmanship, which is typically reflected in low-cost buildings. The test variables include the number and thickness of mortar overlays, fiber volume fraction, and additional reinforcement using glass fiber mesh or shear connectors. In most strengthened specimens, the ASFRM is not damaged but separated from the masonry prisms after its maximum strength is reached. Additional tests for the bond strength between the ASFRM overlay and masonry surface are conducted to evaluate its contribution to the strengthening effects. Based on experimental observations, equations for predicting the compressive and diagonal tension strengths of masonry prisms strengthened with ASFRM are proposed. The compressive strength can be predicted more accurately by considering the asymmetrical distribution of compressive stress when strengthening is performed on only one side. The diagonal tension strength after strengthening can be predicted by incorporating the contribution of the bond strength between the ASFRM overlay and masonry prism to the initial strength.

Femtosecond Laser Trimming with Simultaneous Nanostructuring to Fine Piercing Punch to Electrical Amorphous Steel Sheets.

A CVD (Chemical Vapor Deposition) diamond coated tungsten carbide (WC) and cobalt (Co) sintered alloy punch was trimmed by the femtosecond laser machining to sharpen its edge with about 2 μm and to simultaneously make nanostructuring to its side surface. In addition to the sharpened edge, its edge profile was formed to be homogeneous enough to reduce the damage layer width by piercing the electrical amorphous steel sheet stack. Each brittle sheet in the stacked work was damaged to have three kinds of defects by piercing; e.g., the droop-like cracking in the thickness and at the vicinity of hole, the wrinkling in peak-to-valley with partial cracking on the peaks, and the circumferential cracking. When using the WC (Co) punch with the inhomogeneous edge profile in the sharpened edge width, these three damages were induced into each sheet and the maximum damage width exceeded 80 μm. When using the punch with the sharpened edge and homogeneous edge profile, the wrinkling mode was saved and the total affected layer width was significantly reduced to less than 20 μm. Through the precise embossing experiments, this effect of punch edge profile condition to the induced damages was discussed with a statement on the nanostructuring effect on the reduction of damaged width in electrical amorphous steel sheets. The developed tool with the sharpened edge and homogenous edge condition contributes to the realization of a low iron loss motor with a reduced affected layer width.

Temperature-dependent corrosion behaviour of the amorphous steel in simulated wet storage environment of spent nuclear fuels

Temperature dependence of corrosion behaviour in simulated wet storage conditions for spent nuclear fuels were investigated systematically by comparing SAM2X5 amorphous steel and 316 L SS. Results indicated that with elevating temperature, the passive current for the amorphous steel increased distinctly but without pitting corrosion. The sensitivity of the passive current with temperature for the amorphous steel was related to the reduction of Cr2O3 content and altered semiconductor characteristics for its passive film, and the prominent pitting resistance at higher temperatures was associated with the remarkably inhibited pit initiation by the uniform passive film and the suppressed stable growth of metastable pits.

Synthesis and characterization of silane based binder for the amorphous metal ribbon

Over the last few decades, amorphous steel has been gaining more and more interest as a key material for modern electrical transformers. Amorphous steel has already excellent electromagnetic properties, however, the efficiency of the transformer core can be further enhanced by the mechanical strengthening achieved by using a specially designed bonding material. Such an advanced material must combine numerous functionalities. Good surface adhesion is one of the most crucial characteristics of the binder.The presented work contains the results of research on synthesized double-layered binder based on the tetraethyl orthosilicate and 1,2-bis(triethoxysilyl)ethane and its binding properties to an amorphous metal substrate. The binder layers were deposited on an amorphous metal Metglas 2605 HB1M ribbon by dip coating method. A range of methods was used to examine the quality of the layers, its structure,thermal expansion coefficient and the forces causing delamination.The obtained results clearly evidence the studied hybrid layer made of tetraethyl orthosilicate and 1,2-bis(triethoxysilyl)ethane as a suitable, good quality binder for mechanical strengthening of electrical devices made of amorphous metal ribbon.

Topical Issues of the Technological Development of Advanced Electrical Steel Grade Production in Russia

The growing competition in the global steel market in the field of rolled products potentially implies an efficient, economical and environmentally friendly approach to the production of electrical steel. The following key elements of advanced strip steel casting are discussed: innovations in the use of cast strips for the production of the initial hot-rolled billet and cold-rolled steel from electrical anisotropic and isotropic steel, as well as amorphous steel strips for magnetic cores of electrical machines, which have been commercially applied in world practice.

고온에 노출된 비정질 강섬유 보강 고강도 콘크리트의 역학적 특성

고온에 노출된 비정질 강섬유 보강 고강도 콘크리트의 역학적 특성

Design of 3D-Printed Hybrid Axial-Flux Motor Using 3D-Printed SMC Core

Axial-flux permanent-magnet synchronous motors (AFPMSMs) have a higher torque density than radial-flux permanent-magnet synchronous motors (RFPMSMs); therefore, AFPMSMs are widely used in high-power and high-efficiency motors. However, in the case of AFPMSMs, three-dimensional production is limited, less mass production is available, and the production unit cost is high because the shape of the motor is implemented by rolling the amorphous electrical steel sheet or molding the soft magnetic composite (SMC) to manufacture the motor. Therefore, in this paper, a 3D-printed AFPMSM is proposed, which takes high torque density including the AFPMSM shoe to mold existing SMC into shape when producing the AFPMSM using 3D printing. Further, hybrid AFPMSM, which is made by heeding, is proposed. To reduce core loss with 3D-printed AFPMSM, the core loss of the proposed hybrid AFPMSM was compared to that of the target RFPMSM in this study. The 3D-printed AFPMSM showed a 48% increase in core loss compared to the target motor. However, the proposed hybrid AFPMSM reduced the ratio of the electrical steel sheet by more than 25% compared to 3D-printed AFPMSM. The validity of the proposed model was verified using the finite element method.