Dual Phase Research Articles

A novel approach to modeling and experimenting a solar-fed H6 configuration for battery swapping stations in rural and commercial areas using a dual phase CLLC DC–DC resonant converter

In order to further the use of clean energy, the transition from internal combustion engine (ICE) vehicles to electric vehicles (EVs) was initiated globally. In the coming days, there will be a need for more EV charging stations in rural and commercial areas. The installation of new charging infrastructure for different vehicles with different voltage specifications in order to charge batteries are expensive with limited availability. Also fast charging is not possible in rural areas. To overcome this issue, the battery swapping station is a good option. In this paper, a new solar-powered dual-phase CLLC DC–DC resonant converter is proposed to test battery swapping. An equivalent circuit has been derived analytically, and the optimal design of the magnetic components for the proposed converter has been derived. Simulation has been carried out for the proposed system. The proposed system was tested with a prototype set-up of a 100 W lithium-ion battery bank of equal and unequal voltage levels in an open-loop condition using Analog Discovery-2. Introducing the H6 concept in the proposed converter has the features of low stress across switches, use of higher dc grid voltage, low switching losses due to the dual phase resonant compensation network, and a multi-port isolated output system. Apart from battery swapping applications it can be utilized for Energy Storage Solution [ESS].

Interphase Precipitation in Cold‐Rolled Dual‐Phase Steel Strip: Design and Challenges

In microalloyed steels, interphase precipitation involves the formation of precipitates at the ferrite/austenite interface during their transformation. The study on interphase precipitation has been ongoing since the 1970s and remains highly relevant today. While this metallurgical approach has been applied in various products of advanced steels, its application to cold‐rolled steels is still absent. This study presents a development of cold‐rolled dual‐phase (DP) steels strengthened by interphase‐precipitated carbides. A CALPHAD‐based approach is established to facilitate austenite to ferrite transformation coupled with interphase precipitation during simulated annealing for cold‐rolled DP steels. Further experimental investigations on the effects of V and Mo optimize the alloy composition, and the corresponding nano/microstructures are validated by transmission electron microscopy (TEM) and atom probe tomography. Besides, this work further addresses the impacts of interfacial segregation and microsegregation bands on the capability of interphase precipitation in the studied steels. In summary, this work charts a new pathway for the development of cold‐rolled DP steels strengthened by interphase‐precipitated carbides, advancing the realm of high‐strength steels.

Activating TiO2 through the Phase Transition-Mediated Hydrogen Spillover to Outperform Pt for Electrocatalytic pH-Universal Hydrogen Evolution.

Endowing conventional materials with specific functions that are hardly available is invariably of significant importance but greatly challenging. TiO2 is proven to be highly active for the photocatalytic hydrogen evolution while intrinsically inert for electrocatalytic hydrogen evolution reaction (HER) due to its poor electrical conductivity and unfavorable hydrogen adsorption/desorption behavior. Herein, the first activation of inert TiO2 for electrocatalytic HER is demonstrated by synergistically modulating the positions of d-band center and triggering hydrogen spillover through the dual doping-induced partial phase transition. The N, F co-doping-induced partial phase transition from anatase to rutile phase in TiO2 (AR-TiO2|(N,F)) exhibits extraordinary HER performance with overpotentials of 74, 80, and 142 mV at a current density of 10 mA cm-2 in 1.0 M KOH, 0.5 M H2SO4, and 1.0 M phosphate-buffered saline electrolytes, respectively, which are substantially better than pure TiO2, and even superior to the benchmark Pt/C catalysts. These findings may open a new avenue for the development of low-cost alternative to noble metal catalysts for electrocatalytic hydrogen production.

Fabrication of 3YSZ with single tetragonal phase by ultrafast high-temperature sintering

3 mol% yttria-stabilized zirconia (3YSZ) has been widely used as structural ceramics because of the high toughness of the tetragonal phase. However, since the conventional 3YSZ is sintered in the temperature range of the tetragonal-cubic phase coexistence region for several hours, Y3+ distributed inhomogeneously, and Y3+-rich regions undergo phase transformation into thermodynamically stable cubic phase. As a result, these 3YSZ usually exhibit tetragonal and cubic dual phases. Thus, suppressing the Y3+ redistribution during sintering is a key to prevent the phase transformation. Here, a fully dense 3YSZ with single tetragonal phase was successfully sintered by shorting sintering time using the ultrafast high-temperature sintering (UHS) method. The crystal structure, microstructure, and Y3+ distribution were investigated by XRD, SEM and STEM-EDS. We show that compared with the conventionally sintered 3YSZ, UHS effectively suppress Y3+ redistribution. The present results indicate UHS will be powerful to sinter ceramics in a non-equilibrium state.

A comparative study on resistance spot and laser beam spot welding of ultra-high strength steel for automotive applications

In this study, the effect of resistance spot welding (RSW) and laser beam spot welding (LBSW) processes on evolution of microstructure, load endurance capabilities, heat affected zone (HAZ) softening, and corrosion resistance of ultra-high-strength (UHSS) steel joints welded in lap joint design is investigated. The UHSS sheets of dual phase 1000 grade (UHSDP1000) having 1.20 mm thickness were joined using the RSW and LBSW parameters optimized by response surface methodology (RSM). The microstructural features of welding regions of RSW and LBSW joints were studied using optical microscopy (OM). The load endurance capabilities of RSW and LBSW joints were assessed using the tensile shear failure load (TSFL) and cross-tensile failure load (CTFL) tests. The ruptured surfaces of TSFL and CTFL tested samples were examined utilizing scanning electron microscopy (SEM). The microhardness distribution of divergent regions of RSW and LBSW joints was evaluated and imputed to the TSFL and CTFL failure of joints. The corrosion resistance of RSW and LBSW joints was analyzed using potentiodynamic corrosion and immersion corrosion tests. The RSW joints showed 183% and 62.79% greater TSFL and CTFL endurance capabilities than LBSW joints. The TSFL and CTFL endurance capabilities of LBSW joints are inferior to RSW joints due to the smaller load bearing area. It causes the stress concentration in FZ and HAZ of LBSW joints. The RSW joints and LBSW joints disclosed TSFL and CTFL failure in button pull out rupture mode with tearing of HAZ. The failure of RSW and LBSW joints in HAZ is due to the softening caused by martensitic tempering and coarsening of grains. The LBSW joints disclosed inferior resistance to corrosion than RSW joints due to the higher martensite content which contributes to greater fraction of favorable pitting sites and decreased corrosion resistance.

Valorization of oil palm empty fruit bunches into activated carbon: A mini-review

This paper aimed to comprehensively review the potential valorization of oil palm empty fruit bunches (OPEFBs) into activated carbon and its potential application. Activated carbon is carbon processed through dual phases, including carbonization and activation. Firstly, this process converts biomass into carbon thermally with zero to little oxygen conditions. Next, the carbon needs to be activated to stimulate the formation of pores and reduce impurities. The activated carbon’s quality is influenced by the activation process, which can be done physically, chemically, or physiochemically. Activated carbon has an amorphous structure and abundant internal pore structure, thus increasing the surface area. In Indonesia, the quality of active carbon is regulated by Indonesian National Standards or SNI 06-370-1995. The factors influencing the activation step include activator agent type, activator agent concentration, activation ratio and time, etc. . Generally, activated carbon can be widely applied to various sectors, such as agriculture (i.e., slow-released fertilizer, fertilizer, etc.), waste treatment (i.e., adsorbent, activator in anaerobic digestion/AD, bioremediation, etc.), gas purification, ceramic membrane, etc. However, further in-depth investigation is required to determine potential scaling-up and commercialization.

Heat Transfer Analysis of Memory Dependent Derivative in Biological Tissue Subjected to a Moving Heat Source

Abstract A new bioheat transfer equation is developed by introducing the memory-dependent derivative into dual phase lag model. The heat transfer process of memory dependent derivative in biological tissue under a moving heat source is studied. Besides, thermal conductivity is usually no longer constant at high temperature. The nonlinear temperature governing equation with considering variable thermal conductivity is formulated and the solutions are obtained by the methods of Kirchhoff and Laplace transformations. The influences of heat source velocity, variable thermal conductivity, relaxation time and kernel function on the variation of temperature are analyzed.

CDPNet: Cross-Modal Dual Phases Network for Point Cloud Completion

Point cloud completion aims at completing shapes from their partial. Most existing methods utilized shape’s priors information for point cloud completion, such as inputting the partial and getting the complete one through an encoder-decoder deep learning structure. However, it is very often to easily cause the loss of information in the generation process because of the invisibility of missing areas. Unlike most existing methods directly inferring the missing points using shape priors, we address it as a cross-modality task. We propose a new Cross-modal Dual Phases Network (CDPNet) for shape completion. Our key idea is that the global information of the shape is obtained from the extra single-view image, and the partial point clouds provide the geometric information. After that, the multi-modal features jointly guide the specific structural information. To learn the geometric details of the shape, we chose to use patches to preserve the local geometric feature. In this way, we can generate shapes with enough geometric details. Experimental results show that our method achieves state-of-the-art performance on point cloud completion.

2D/3D structure engineering of dual-phase Mo2C/MoO2-decorated rGO aerogels for electromagnetic waves absorption

The rational design of structure and regulation of composition in micro/nano-scale is of great significance for broadband absorbing properties of lightweight aerogels. Herein, the controllable dual phase Mo2C/MoO2-decorated rGO aerogels are prepared by designing the Mo-rGO precursor, which possesses heterostructure interfaces and three-dimensional structures. The dual-phase of Mo2C/MoO2 was controlled and nanoparticles were dispersed on the surface of graphene. The interconnected rGO sheets construct continuous network for electron transport, which facilitates conduction loss and multiple reflections inside the aerogel. The Mo2C/MoO2 nanoparticles decorated on rGO sheets contribute sufficient interfacial and dipole polarization, and improve the impedance matching and strengthen the loss capacity of electromagnetic waves. The as-prepared Mo2C/MoO2/rGO aerogel exhibits considerable electromagnetic wave absorption performance with a minimum reflection loss of −42.1 dB at 12.5 GHz and an effective absorption bandwidth of 5.6 GHz (10.6–16.2 GHz) at a thin thickness of 2.2 mm with a low density of 9.8 mg·cm−3. This Mo2C/MoO2/rGO aerogel would be a promising material for electromagnetic wave absorption in wide application fields, and it also provides a universal idea for constructing low-density broadband microwave absorption material by structural and composition engineering.

Spectrometer as a quantitative sensor for predicting the weld depth in laser welding

Spectrometers have been used for quality assessment or as auxiliary sensors in multisensor systems to record emissions at different wavelengths. This study developed a single-spectrometer sensor to quantitatively predict the laser penetration depth in Cu/Al overlap and dual-phase (DP) steel bead-on-plate welding joints. The spectrometer signals were sampled at 100 Hz, and an optical coherence tomography (OCT) sensor was used to estimate the in situ penetration depth. A one-dimensional (1D) convolution neural network (CNN) model was developed using the current step of the spectrometer signal. Furthermore, a two-dimensional (2D) CNN model was developed using 10 recent steps of the spectrometer signals. Consequently, 1732 and 3000 data points for DP steel and Al/Cu overlap welding were used for the penetration-depth modeling. Through model training, mean absolute errors of 22.67 and 52.96 µm were achieved for the Al/Cu overlap and DP steel welding, respectively, corresponding to approximately 1.5 % of the substrate thickness. The 2D-CNN models outperformed the 1D-CNN models for both material combinations. However, a slight delay was observed in the response of the models when confronted with abrupt output changes. This study confirmed that spectroscopy can serve as the sole quantitative sensing method for laser welding monitoring and control.

<i>In-situ</i> Laser Ultrasonics Measurements of Ferrite Formation during Stepped Cooling of A 0.1C-2Mn Dual Phase Steel

<i>In-situ</i> Laser Ultrasonics Measurements of Ferrite Formation during Stepped Cooling of A 0.1C-2Mn Dual Phase Steel

Circulating power flow restricted operation of the isolated bi-directional dual-active bridge DC-DC converter for battery charging applications

This paper presents the Non-Circulating Power Flow (NCPF) enabled Dual Active Bridge (DAB) converter controller strategy. The proposed DAB controller eliminates the non-circulating power flow for all the four conventional modulation algorithms, i.e., Single Phase Shift (SPS), Extended Phase Shift (EPS), Dual Phase Shift (DPS) and Triple Phase Shift (TPS) modulation schemes. This leads to lesser current stress and power loss across the DAB converter switches due to reduced peak inverse current. The proposed controller strategy finds various applications, such as in a Solid-State Transformer (SST) enabled microgrid, or for Electric Vehicle (EV) Energy Storage Unit (ESU: battery, supercapacitor) integrations, etc. The proposed NCPF operation reduces battery (and supercapacitor) current stress by upto 71.8 %, and improves operative environment, thus fostering its health and lifecycle. In NCPF mode, if the rating of installed switches (current and voltage ratings) remains unchanged, its power transfer capability is marginally reduced by mere 10.0 %. In addition to this, the operating range (i.e., controlling range of phase shift (Φ) and modulation index (m)) remains unaffected. This paper summarizes the DAB NCPF operation in restricted power flow mode as a function of Φ and m through 3-D and 4-D graphs. Finally, working of NCPF DAB is tested via both simulation and hardware platforms. Comparative results are shown for conventional and proposed modulation schemes on hardware platform, to showcase the elimination of circulating current in both forward and reverse DAB operating modes. It is inferred that proposed controller is worthy of real-world implementations.

Influence of changing loading directions on damage in sheet metal forming

The impact of the stress state on damage evolution, fracture behavior, and product performance is well understood for proportional loading. However, many complex sheet forming operations involve non-proportional loading, which affect the material's hardening and fracture characteristics. This study investigates the influence of a loading direction change on damage evolution in a dual phase steel DP800. Specimens are pre-strained by tensile tests and subsequently loaded in either the same or orthogonal direction to the initial pre-strain direction by additional tensile tests and bending tests. Damage quantification by scanning electron microscopy reveals lower damage evolution after an orthogonal change of loading direction in contrast to monotonic loading directions. The load paths, defined as a history of triaxiality and Lode parameter during loading, are identified numerically under consideration of kinematic hardening. Since kinematic hardening leads to higher triaxialities after orthogonal changes, the load path is not the dominant influence on damage. A possible explanation for the experimental results is the void characteristics after tensile load. After the pre-straining in tensile test, voids are oriented orthogonally to the tensile direction and located between hard martensitic phases. The influence of this morphology on subsequent void growth is illustrated by a simulation verifying that an orthogonal change of loading direction results in void shrinkage, while monotonic loading directions lead to further void growth.

Effect of W on the Mechanical Properties and Tribological Behavior of CoCrFeNiWx Compositionally Complex Alloy

Introducing the hard second phase into soft matrix and reducing the grain size are key strategies to enhance the strength and wear performance of metallic alloys. Herein, to investigate the effect of hard second phase on the mechanical properties and tribological behavior of face‐centered‐cubic (FCC) CoCrFeNi compositionally complex alloy (CCA), a series of ultrafine‐grained CoCrFeNiWx (x = 0, 0.3, 0.5, and 1.0) CCAs with varying W contents are fabricated. The results show that the single FCC CCA transforms to the dual phase of FCC and μ phase after addition of W. With increasing W content, the hardness and yield strength show a linear increase due to the additional solid solution strengthening and secondary phase strengthening, but the fracture strain shows an opposite trend. Dry sliding wear tests show that both coefficients of friction and wear rates decrease with the W content. The wear mode changes from abrasive wear for CoCrFeNi CCA to multiple wear modes of abrasive wear, oxidative wear, and fatigue wear for W‐containing CCAs. These results suggest that adding W into the FCC CCA matrix could strengthen the FCC alloy and simultaneously improve wear performance.

Tailored design of novel Co0-Coδ+ dual phase nanoparticles for selective CO2 hydrogenation to ethanol

Catalytic hydrogenation of CO2 to ethanol is a promising solution to address the greenhouse gas (GHG) emissions, but many current catalysts face efficiency and cost challenges. Cobalt based catalysts are frequently examined due to their abundance, cost-efficiency, and effectiveness in the reaction, where managing the Co0 to Coδ+ ratio is essential. In this study, we adjusted support nature (Al2O3, MgO-MgAl2O4, and MgO) and reduction conditions to optimize this balance of Co0 to Coδ+ sites on the catalyst surface, enhancing ethanol production. The selectivity of ethanol reached 17.9 % in a continuous flow fixed bed micro-reactor over 20 mol% Co@MgO-MgAl2O4 (CoMgAl) catalyst at 270 °C and 3.0 MPa, when reduced at 400 °C for 8 h. Characterisation results coupled with activity analysis confirmed that mild reduction condition (400 °C, 10 % H2 bal N2, 8 h) with intermediate metal support interaction favoured the generation of partially reduced Co sites (Coδ+ and Co0 sites in single atom) over MgO-MgAl2O4 surface, which promoted ethanol synthesis by coupling of dissociative (CHx*)/non-dissociative (CHxO*) intermediates, as confirmed by density functional theory analysis. Additionally, the CoMgAl, affordably prepared through the coprecipitation method, offers a potential alternative for CO2 hydrogenation to yield valuable chemicals.

Virtual laboratory enabled constitutive modelling of dual phase steels

Accurate and efficient characterization and modelling of deformation responses are critically essential in the development of advanced metal forming processes. This work presents a virtual laboratory enabled constitutive framework for modelling complex deformation responses of dual phase (DP) steels under complex stress states, based on multi-phase full-field crystal plasticity (CP) and advanced phenomenological modelling. In the CP based virtual testing method, kinematic hardening and degradation of elastic modulus are modelled in particular to improve the capability for describing evolving microstructure induced mechanical responses of DP steels. The workflow of this framework is completely built and numerically implemented, including (i) representative volume element (RVE) generation based on microstructure characterization, (ii) identification of multiphase CP model parameters, (iii) prediction of elastic modulus degradation, (iv) prediction of yield stresses and plastic potentials in uniaxial tension and biaxial tension with various stress ratios, and (v) prediction of stress–strain curves in reverse tension compression. Using DP780 and DP980 as case materials, the corresponding physical experiments are conducted to verify the accuracy of the virtual tests, showing a good agreement between the virtual and experimental approaches. Both experimental and virtual tests are used to calibrate advanced phenomenological constitutive models that include non-linear elasticity, anisotropic yielding, and kinematic hardening. The calibrated models are implemented into the finite element (FE) codes to predict complex deformation and springback behaviours of DP780 and DP980 sheets in U-bending processes. In comparison with forming experiments of U-channel parts, the virtually calibrated models are validated and show good performance in predicting deformation and springback behaviours, providing a high capability for process analysis. The findings support that the virtual laboratory enabled modelling approach could be a substitute for extensive, expensive, and hard-to-access physically mechanical experiments required in the model calibration for a more effective and efficient analysis of metal forming processes.

Effect of thermal diffusivity on Rayleigh waves in human tissue

This work examines the nature of human tissue under the context of dual phase lag thermoelastic diffusion theory using the principle of propagation of Rayleigh wave along the stress free, thermally insulated/isothermal, and impermeable/isoconcentrated conditions. The governing equations for the tissue are formed by considering the third-order approximation of Taylor’s expansion for the modified Fourier’s law of heat conduction and modified Fick’s law of mass diffusion in terms of phase lag parameters. The irrational secular equations of Rayleigh waves are derived, which are then rationalized to extract their complex roots. The phase speeds and the attenuation coefficients are evaluated from these complex roots. The variation of these phase speeds and attenuation coefficients are plotted graphically against angular frequency for two significant modes. The behavioral patterns of displacement components, temperature, and concentration fields are computed and are expressed graphically. The paths of the particle motion are represented graphically. Some results of published articles are recovered from the present formulation to validate our results.

Dielectric, electric, and magnetic response of modified bismuth ferrite-based double perovskites for NTC-thermistor application

Owing to the variation of the characteristics due to the cationic substitution of diverse elements at both A and B sites, the new polycrystalline double perovskite BaBiFeMnO6, synthesized via a cost-efficient solid-state reaction route. Initial structural refinement by Rietveld analysis reveals material crystallised in dual phases i.e. monoclinic and orthorhombic. The respective cell parameters for monoclinic as well as orthorhombic phases are a = 5.5881 Å, b = 5.6541 Å, c = 7.9186 Å with cell angles α = γ = 900 and β = 89.90810 and a = 5.4807Å, b = 5.3583Å, c = 7.4045Å and refined angles are α = β = γ = 900 respectively. The microstructural interpretation of the present sample reflects a non-uniform distribution of the grains with an average grain size of 2.97 μm with a mean crystalline size of 342.65 nm. The Fourier-Transform Infrared Spectroscopy (FTIR) graph indicated that the sample belongs to the perovskite family. The impedance measurement was carried out in a selected frequency and an assigned temperature range to investigate the electrical features of the material which suggested the non-Debye type relaxation and negative temperature coefficient of resistance (NTCR). Furthermore, the thermistor constant (β) and temperature coefficient of resistance (TCR) contributed to investigating the NTCR characteristic of the sample under NTC-type thermistor applications. The room temperature dielectric constant is 1707.67 with a minimal tangent loss of 0.7069 at 100Hz frequency has been estimated by fitting the dielectric data by utilizing the Havrilliak-Negami function. The polarization (P) induced due to the maximum applied electric field of 1.287 kV is studied from the hysteresis loop plotted between them. The hysteresis loop indicates the ferroelectric property of the material with a lossy nature. The room temperature remnant magnetization (2Mr) of 0.4424 emu/g and coercivity (2Hc) of 6.2 kOe have been estimated from the M ∼ H loop. The potentiality of the material to be used as a viable candidate in various energy storage devices and supercapacitors is suggested by all of the characterisations in conjunction with the high value of εr i.e. ∼80000 at 300 °C for the lower frequency.

Uncovering the mechanism of the LME susceptibility for the galvanized and electrogalvanized DP 1180 steels

Zn-based coatings generally protect dual-phase (DP) 1180 advanced high-strength steel in automobiles from corrosion. However, liquid metal embrittlement (LME) tends to occur in Zn-coated DP 1180 steel during resistance spot welding. In this study, the LME phenomena of the galvanized (GI) and electrogalvanized (EG) DP 1180 steels were compared based on the LME susceptibility evaluation standard. For DP 1180 steel coated with GI, the maximum length of the LME crack was approximately 121.2 μm at the shoulder of the welding spot. In contrast, for the specimen coated with EG, the maximum length of the LME crack was 792.6 μm at the center of the welding spot. Owing to the different galvanizing processes, the microstructure differed during annealing, thereby influencing the occurrence of the LME. Furthermore, the microstructural observations indicated that the protection of the interfacial oxide layer in the GI specimen could prevent the formation of the LME to some extent. Therefore, the presence of the interfacial oxide layer could account for the different LME susceptibilities of the GI and EG DP 1180 steels.

Development of a lead-free colossal dielectric material barium bismuth ferrous oxide for electronic devices

Ceramic materials are promising for the ever-increasing demand in next-generation electronic devices. In this regard, we report the development and characterizations (structural, microstructural surface, dielectric, transport, impedance, resistive and current-voltage properties) of a novel complex material Ba3Bi2Fe2O9. Preliminary investigation of the X-ray diffraction (XRD) pattern shows the dual phase nature (cubic and tetragonal phase). The analysis of the Williamson-Hall plot illustrates the average crystallite size and micro-lattice strain are 91.37 nm and 0.002, respectively. The scanning electron microscopic spectrum examines the microstructural surface interface analysis, fractal study and topographic roughness (using the standard ISO25178). The analysis of Maxwell-Wagner dielectric dispersion, relaxation, and transport mechanisms are investigated utilizing dielectric, impedance, and conductivity spectrum accumulated within the experimental frequency (1 kHz–1 MHz) and temperature (298 K–373 K) range. The energy band of intrinsic and ionization regions with different frequencies (1 kHz and 10 kHz) indicates the semiconducting behavior of the material. The presence of non-Ohmic and space charge limited conduction (SCLC) mechanisms is investigated by the varistor constant β1 and β2. The thermistor constant (β) is determined to be 1683.13, and the temperature coefficient of resistance (TCR) is −0.00903, which may be suitable for wearable NTC thermistors and other related device applications.