Epoxyaclay nanocomposites were prepared using two types of surface-treated montmorillonite (Closite 30B and Nanomer I28E). Wide angle X-ray scattering showed that all the nanocomposites had an ...intercalated structure. Improvements in tensile and fracture properties were found. The pure epoxy polymer was very brittle with a fracture energy, G c, of 131 J ma2. The addition of the nanoclays significantly increased the value of G c, up to 240 J ma2 for 5 wt% C30B. The toughening mechanisms acting in the nanocomposites were identified using scanning electron microscopy as crack deflection and plastic deformation of the epoxy matrix around the clay platelets following debonding. From electrical testing, the permittivity and loss angle of the nanocomposites decreased, and their breakdown strength increased as desired for insulation applications. The breakdown strength of the pure epoxy was found to be 11.7 kV mma1, while for a 2 wt% C30B nanocomposite, it increased to 14.7 kV mma1. It was concluded that the restriction of chain mobility inhibited electrical polarisation and thus decreased the permittivity and loss angle. The electrical damage zone was analysed using scanning electron microscopy. It was found that the higher resistance-to-surface degradation by partial discharges and the creation of a tortuous electrical path, which delayed the propagation of the electrical tree, were the main factors which improved the breakdown strengths of the nanocomposites.
This article proposed a new extended gate towards a source in AlGaN/GaN metal-oxide-semiconductor-high-electron-mobility transistors in order to increase breakdown voltage and reduce on-resistance. ...The TaN gate was isolated from the source by a 15 nm-thick RF-sputtered HfO sub( 2) gate insulator. A high breakdown voltage of 1410 V was measured as a result of the successfully blocked gate leakage current and surface passivation by the HfO sub( 2) gate insulator. The extended gate towards the source was an effective method to improve the on-resistance and drain current density by eliminating the gate-source space. The proposed device with the extended gate exhibited low specific on-resistance of 2.28 m Omega ...cm super( 2) while that of the MOS-HEMT with the conventional structure was 2.91 m Omega ...cm super( 2). Also, maximum drain current density at the V sub( GS) of 2 V was increased from 332 to 420 mA/mm by the proposed extended TaN gate.(ProQuest: ... denotes formulae/symbols omitted.)
Conditioning is an efficient technology to improve vacuum gap insulation, which is a collection of a series of breakdown events. Each breakdown event contains and be represented by one breakdown ...waveform with voltage and current. This paper aims to classify the vacuum breakdown during the conditioning based on deep learning with its advantages on image feature extraction and recognition. The differences among pulsed current induced breakdown (PB), field emission current induced breakdown (FEBD) and particle induced breakdown (PBD) during the pre-breakdown period and breakdown numbers during breakdown period in voltage and current could be extracted and recognited by deep learning. Thus, four kinds of breakdown waveforms PB, PBD1 (PBD with one or several breakdowns), PBD2 (PBD with continuous breakdowns) and FEBD are separated for deep learning to recognize and classify. The classification takes about 10 seconds for each breakdown waveform and its accuracy is above 84.7%. The validation is confirmed from different perspectives.
Device dimension scaling and process complexity have revealed new phenomena such as post-breakdown (BD) and variability issues in advanced technology nodes. Coupling of the first BD phenomena and ...their methodologies discussed in part I with the development of post-BD methodologies allows engineers to use device stress-data to accurately predict the product failure lifetime. The statistical modeling and new advances in understanding the root cause of variability issues have mitigated these seemingly uncontrollable "catastrophes" so that the scaling of the advanced technology process can continue its successful path forward. These two important aspects of dielectric BD will be reviewed in part II.
Vacuum breakdown mechanism evolution during the conditioning is important for vacuum interrupter insulation improvement. Traditionally, the breakdown mechanism can only be obtained after the ...conditioning, which requires the manual operation and classification step by step. It takes about 10 hours for one electrode pair with about 400 breakdowns. This paper proposes a new breakdown diagnosis method based on electrical measurement and deep learning recognition in conditioning. The voltage and current are measured and processed to be simplified breakdown waveforms, and the breakdown mechanism is classified through deep learning with simplified breakdown waveforms. The whole process of breakdown diagnosis is automatic with no manual operation. The results show that the new method accuracy has a close relationship with the train samples (above 77.81% at least), and it can diagnose breakdown during the conditioning, which takes about 5 seconds for one breakdown. The new method can make the breakdown diagnosis efficiency, real time and high accuracy.
A series of strontium barium niobate-based borate system glass-ceramics with Gd sub(2)O sub(3) addition have been prepared by controlled crystallization method. The effect of Gd sub(2)O sub(3) ...addition on the microstructure, phase evolution and dielectric properties has been investigated. The results show that the addition of Gd sub(2)O sub(3) to the glass-ceramics changes the dielectric property and energy-storage density. Typically, the glass-ceramics with 0.5 mol% Gd sub(2)O sub(3) heat treated at 630 degree C/2 h + 800 degree C/3 h possesses a dielectric constant of 136, a breakdown strength of 1,075 kV/mm and energy-storage density of 6.94 J/cm super(3), which is suitable for the application in high energy-storage capacitors.
Physical evolution during pre-breakdown process of field emission induced breakdown (FEBD) reveals the mechanism how the breakdown is caused, which has theoretical significances for vacuum ...interrupter's insulation improvement. In this paper, an impulse voltage conditioning experiment is carried out between pure copper electrodes, and applied voltage and corresponding pre-breakdown current of FEBD are obtained. A Particle-in-Cell with Direct Simulation Monte Carlo (PIC-DSMC) model which considers two dimensions in space between electrodes and three dimensions in particles' velocity (2D3V) is proposed and established with the obtained experimental data. The distributions, densities and numbers of electrons, Cu neutrals and Cu + ions over pre-breakdown voltage are obtained to display the physical evolution during pre-breakdown process. The field emission current from the PIC-DSMC model is consistent with that measured from experiment, which validates the simulation method. It provides a novel insight into FEBD's pre-breakdown process through physical evolution between electrode gap.
Conditioning technology could increase the vacuum interrupter's insulation obviously, and the breakdown voltage or breakdown electric field of the conditioning saturation represents the final ...breakdown withstand capability. This article proposes a method with a breakdown electric field and breakdown time (BE-BT), both obtained from a breakdown voltage waveform, to diagnose conditioning saturation. The conditioning of the original electrode pair and pure metal electrode pair with impulse voltage is carried out. The results show that during the conditioning process, the breakdown electric field first increases and then reaches a final saturation, and the corresponding breakdown time first decreases and then reaches saturation. Before the conditioning saturation, the BE-BT showed a contrary trend, but they show the same trend during the conditioning saturation. Thus, the two parameters' first contrary and then the same trend could indicate the conditioning saturation precisely and efficiently. It has significant and meaningful guidance for industrial practice.
We propose an approach that utilizes the Delaunay triangulation to identify a robust/outlier-free subsample. Given that the data structure of the non-outlying points is convex (e.g. of elliptical ...shape), this subsample can then be used to give a robust estimation of location and scatter (by applying the classical mean and covariance). The estimators derived from our approach are shown to have a high breakdown point. In addition, we provide a diagnostic plot to expand the initial subset in a data-driven way, further increasing the estimatorsa efficiency.
Partial breakdown (PB) has been reported in breakdown of vacuum gaps in series but has not been fully understood. The objective of this article is to investigate the influence of PB on breakdown of ...vacuum gaps in series under lightening impulse voltages. Two commercial vacuum interrupters (VIs) of the same model were connected in series with various gap distance arrangements. Experimental results show that four breakdown types could be classified, i.e., repeatedly PB without final full breakdown of the series gaps (type I), two PBs before final full breakdown (type II), one PB before final full breakdown (type III), and no PB before final full breakdown (type IV). Breakdown voltage of the vacuum gaps in series decreases with the increasing difference between the two gaps and could be even lower than breakdown voltage of the larger gap alone. This is explained by analyzing the three stages of transients induced by a PB. A model was established to simulate transients induced by PB of the vacuum gaps in series. The simulated results could match the experimental results well. An evolution process from a PB to the four breakdown types was deduced. The influence of PB on insulation coordination and breakdown voltage of the vacuum gaps in series was analyzed according to the abovementioned analysis.
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