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To investigate the separation of Ni(II) impurity and the refining of the electrolyte for magnesium electrolysis, the electrochemical behavior of the Ni(II) impurity in the MgCl2–KCl–NaCl melt at 973 K has been studied using several techniques, including cyclic voltammetry (CV), square wave voltammetry (SWV), and chronoamperometry (CA). Based on the analysis of the CV and SWV curves, it can be inferred that the reduction of Ni(II) in the MgCl2–KCl–NaCl melt at the tungsten electrode exhibits a quasi-reversible reaction. This reaction involves the transfer of a pair of electrons in a single step. The diffusion coefficient was determined at 973 K to be 3.84 × 10−5 cm2 s−1 through the semi-integral method, with the activation energy for diffusion was found to be 45.81 kJ mol−1. The reaction rate constant for the Ni(II) redox reaction was determined to be approximately 10−3 cm s−1 using the Nicholson method. This value suggests that the reaction fall within the quasi-reversible range, as defined by the Matsuda–Ayabe standard. The results obtained from the CA technique have demonstrated that the deposition of nickel on the tungsten electrode occurs through an instantaneous nucleation process, which is primarily controlled by diffusion. [ABSTRACT FROM AUTHOR]

Based on the decorrelation calculation of diffusion ultrasound in time-frequency domain, this paper discusses the repeatability and potential significance of Disturbance Sensitive Zone (DSZ) in time-frequency domain. The experimental study of Barely Visible Impact Damage (BVID) on Carbon Fiber Reinforced Polymer (CFRP) is carried out. The decorrelation coefficients of time, frequency, and time-frequency domains and DSZ are calculated and compared. It has been observed that the sensitivity of the scattered wave disturbance caused by impact damage is non-uniformly distributed in both the time and frequency domains. This is evident from the non-uniform distribution of the decorrelation coefficient in time-domain and frequency-domain decorrelation calculations. Further, the decorrelation calculation in the time-frequency domain can show the distribution of the sensitivity of the scattered wave disturbance in the time domain and frequency domain. The decorrelation coefficients in time, frequency, and time-frequency domains increase monotonically with the number of impacts. In addition, in the time-frequency domain decorrelation calculation results, stable and repetitive DSZ are observed, which means that the specific frequency component of the scattered wave is extremely sensitive to the damage evolution of the impact region at a specific time. Finally, the DSZ obtained from the first 15 impacts is used to improve the decorrelation calculation in the 16-th to 20-th impact. The results show that the increment rate of the improved decorrelation coefficient is 10.22%. This study reveals that the diffusion ultrasonic decorrelation calculation improved by DSZ makes it feasible to evaluate early-stage damage caused by BVID. [ABSTRACT FROM AUTHOR]

The utilization of reclaimed asphalt mixture, which combines old asphalt reclaimed material (RAP) with new aggregate, holds significant environmental benefits. However, the road performance of this mixture can decline due to the degradation of the old asphalt components. In this study, the shape characteristics of both old and new aggregates were analyzed using IPP6.0 software. Notably, the roundness of old aggregates within the 9.5–16 mm range exhibited the most substantial wear. Consequently, an investigation was conducted on the road performance implications of incorporating 30% RAP and its associated impact on aggregate roundness. The research findings indicated that there was minimal disparity in roundness between new and old aggregates within the particle size range of 4.75 mm to 9.5 mm. Nevertheless, as the proportion of old aggregates exceeding 9.5 mm increased, the recycled asphalt mixture exhibited reduced low-temperature and high-temperature performance, as well as diminished water stability. [ABSTRACT FROM AUTHOR]

Surface residual stress is made on the aero-engine blades by shot peening to improve the fatigue life of the blades. As the service time increases, the surface residual stress is decreasing due to thermomechanical relaxation and the centrifugal load caused by high-speed rotation. Therefore, the surface residual stress detection is of great importance for predicting the remaining life of aero-engine blades. Up to now, efficient and non-contact detection of surface residual stress is still a challenge. In this paper, an active thermal deformation excitation (ATDE) method for surface residual stress is proposed. According to the thermal deformation theory, the thermal deformation of the material is positively correlated with the surface residual stress, and by measuring the thermal deformation the surface residual stress can be detected and evaluated. The theoretical deformation model was established, and simulation models with different surface residual stresses were constructed. A detection system was proposed to detect the blade deformation with different surface residual stresses. Results show that there was a linear relationship between the blade deformation and the surface residual stress from −636 Mpa to −1403 Mpa. [ABSTRACT FROM AUTHOR]

Polyvinylidene fluoride (PVDF)-based dielectric energy storage materials have the advantages of environmental friendliness, high power density, high operating voltage, flexibility, and being light weight, and have enormous research value in the energy, aerospace, environmental protection, and medical fields. To investigate the magnetic field and the effect of high-entropy spinel ferrite (Mn0.2Zr0.2Cu0.2Ca0.2Ni0.2)Fe2O4 nanofibers (NFs) on the structural, dielectric, and energy storage properties of PVDF-based polymers, (Mn0.2Zr0.2Cu0.2Ca0.2Ni0.2)Fe2O4 NFs were prepared via the use of electrostatic spinning methods, and (Mn0.2Zr0.2Cu0.2Ca0.2Ni0.2)Fe2O4/PVDF composite films were prepared via the use of the coating method. The effects of a 0.8 T parallel magnetic field, induced for 3 min, and the content of high-entropy spinel ferrite on the relevant electrical properties of the composite films are discussed. The experimental results show that, structurally, the magnetic field treatment causes the originally agglomerated nanofibers in the PVDF polymer matrix to form a linear fiber chain with different fiber chains parallel to each other along the magnetic field direction. Electrically, the introduction of the magnetic field enhanced the interfacial polarization, and the (Mn0.2Zr0.2Cu0.2Ca0.2Ni0.2)Fe2O4/PVDF composite film with a doping concentration of 10 vol% had a maximum dielectric constant of 13.9, as well as a low energy loss of 0.068. The high-entropy spinel ferrite (Mn0.2Zr0.2Cu0.2Ca0.2Ni0.2)Fe2O4 NFs and the magnetic field influenced the phase composition of the PVDF-based polymer. The α-phase and γ-phase of the cohybrid-phase B1 vol% composite films had a maximum discharge energy density of 4.85 J/cm3 and a charge/discharge efficiency of 43%. [ABSTRACT FROM AUTHOR]

Energy depletion is one of the significant threats to global development. To increase the usability of clean energy, the energy storage performance of dielectric materials must be urgently enhanced. Semicrystalline ferroelectric polymer (PVDF) is the most promising candidate for the next generation of flexible dielectric materials thanks to its relatively high energy storage density. In this work, high-entropy spinel ferrite (La0.14Ce0.14Mn0.14Zr0.14Cu0.14Ca0.14Ni0.14Fe2O4) nanofibers (abbreviated 7FO NFs) were prepared by the sol-gel and electrostatic spinning methods, then blended with PVDF to prepare composite films using the coating method. A magnetic field was used to control the orientation distribution of the high-entropy spinel nanofibers in the PVDF matrix. We investigated the effects of the applied magnetic field and the content of high-entropy spinel ferrite on the structure, dielectric, and energy storage properties of the PVDF substrate films. The 3 vol% 7FO/PVDF film treated in a 0.8 T magnetic field for 3 min exhibited a good overall performance. The maximum discharge energy density was 6.23 J/cm3 at 275 kV/mm and the efficiency was 58% with 51% β -phase content. In addition, the dielectric constant and dielectric loss were 13.3 and 0.035, respectively, at a frequency of 1 kHz. [ABSTRACT FROM AUTHOR]