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Herein, we designed and prepared one cobalt–nitrogen-doped carbon (Co–N/C) nanoparticle catalyst with a metal–ligand cooperation (MLC) effect, where the MLC concept is significant in the catalytic hydrogenation reactions but limited to the homogeneous catalysts. The nanoparticles Co–N/C with the size of 138–172 nm catalyzed diverse organic reactions with high efficiency and selectivity, including the reductive formylation of nitroarenes with formic acid, C–N coupling between alcohols and amines, and selective hydrogenation of quinolines with H2. Detailed spectroscopic characterizations and controlled experiments revealed that the Co–N species is the catalytically active site. In addition, the recycled catalyst showed outstanding stability and reusability. Therefore, MLC is demonstrated to be effective in heterogeneous catalysts as well, paving the way to discover catalysts. [ABSTRACT FROM AUTHOR]

Aiming at radioactive cesium waste treatment, this work report a low-temperature immobilization method to convert Cs-polluted waste into pollucite. Results reveal that pollucite can be synthesized over a wide range of Cs content (36.5–53.2 wt.%) at 500 °C via the CsOH-Zeolite 4A-Silica gel system. The synthesized pollucite is composed of lamellar particles (0.8–2.5 μm) along with the agglomerates of small particles (0.1–0.3 μm) and Cs, Al, Si, O elements distribute uniformly on surface. Cs content and chemical stability analysis indicate 99.24% of Cs are immobilized and the leaching rate of Cs is on the order of 10–3 g/(m2 ·d). [ABSTRACT FROM AUTHOR]

In this study, strontium (Sr) contaminated zeolite was sintered at 1500 °C for 1 h, and the radionuclide was fixed into the glass matrix. The phase evolution, microstructure, morphology, mechanical property, and chemical durability were investigated. The results exhibited that the solid solubility limit of the glass solidified body could reach up to 72 wt%. Compared with other solidified forms of radioactive wastes, the glass matrix synthesized in this study has good mechanical properties and chemical durability. Therefore, high-temperature sintering is a potential method for disposing of the radioactively contaminated zeolite waste. [ABSTRACT FROM AUTHOR]

Zeolite, as a common adsorption material, should be safely treated after adsorbing different nuclear wastes. In this study, different types of simulated zeolite wastes were successfully immobilized based on the exploring result of suitable experiment conditions. Firstly, sintering temperature was selected based on TG‐DSC and phase results, which represented mainly as glassy phase. Then, the holding time was chosen through density and Vickers hardness results. For the sintering of zeolite, the suitable temperature is 1500℃ and the holding time is 1 h. Through the fitting process, FT‐IR results demonstrate that the main microstructures compose of sheet silicates. Three types of simulated zeolite wastes can successfully transform into matrix and all the waste contents were uniformly immobilized. Finally, SEM‐EDS results prove that the matrix is glass‐ceramic which can well immobilize the considered nuclear wastes. This work proposes the idea of treatment of zeolite adsorbed material as a potential nuclear waste glass‐ceramic matrix and the suitable conditions were also investigated. [ABSTRACT FROM AUTHOR]

The proper disposal of radioactively contaminated soil during the process of nuclear energy application has become the focus of attention. In this work, simulation Sr-contaminated soils could were successfully vitrified by microwave sintering. XRD and FESEM results show that the matrix has excellent glass morphology. The highest Vickers hardness and density values are 8.0 GPa and 3.10 g·cm−3. The NRSr after 14 days is less than 7.9 × 10–4 g·m−2·d−1, which shows the excellent chemical durability of glass. FT-IR and MD simulation results show that the matrix consists of [AlO4] and [SiO4]. [ABSTRACT FROM AUTHOR]

We reported a novel synthesis route to fabricate sulfonated aliphatic waterborne polyurethane dispersions (SWPU) only based on 2‐[(2‐aminoethyl) amino] ethane sulphonate sodium (AAS‐Na) by two‐step chain extension method with the assistance of acetone and water cosolvent. When AAS‐Na was added, only less than 50% of AAS‐Na was incorporated into polyurethane chain in the first‐step chain extension and the residual AAS‐Na formed molecular aggregates which were insoluble in acetone due to the high polarity of AAS‐Na. Subsequently, the mixture of acetone and water was added, the residual AAS‐Na aggregates dissolved, undertaking the further second‐step chain extension reaction, and the ultimate reaction conversion of AAS‐Na rose to more than 90%. The mechanism for acetone and water cosolvent to affect the preparation of SWPU dispersions was studied, as well as the water resistance, mechanical properties and hydrolysis resistance of as‐prepared SWPU dispersions. With the decrease of AAS‐Na content from 2.0% to 1.2%, the peak area of the melting peaks for SWPU films increased, as well as the water resistance. And the as‐prepared polyester SWPU exhibited good hydrolytic stability. [ABSTRACT FROM AUTHOR]

The perfluoroketone C5F10O, not only has good environmental compatibility, but also has excellent insulation properties and has the potential to replace SF6 in medium and low voltage switchgear. This paper focuses on the compatibility of C5F10O and its main decomposition products with the copper material inside the equipment and specifically constructs several adsorption models of C5F10O and its main decomposition products on a Cu (1 1 1) surface. The adsorption mechanism was studied from a system structure, electron density distribution and density of states perspective. The results showed that C5F10O mainly adsorbed chemically on the Cu surface through carbonyl oxygen atoms. Its maximum adsorption energy is −24.48 kcal mol−1, with electrons transferring from the copper surface to the adsorbed oxygen atom; and the adsorption energies of the main breakdown products CF4, C2F6, C3F8, C3F6, CF2O, C2F4O and CO2 with the surface are all less than −9.56 kcal mol−1. There is no obvious electron transfer between these decomposition gases and the copper surface, and thus, they belong to physical adsorption; while the adsorption energies of C3F6O, C2F4 and CO in the top, bridge and Hcc sites are respectively −9.661 kcal mol−1, −14.651 kcal mol−1 and −25.489 kcal mol−1, electrons on the copper surface transfer to the oxygen atom of C3F6O and carbon atoms of C2F4 and CO, forming stable chemical bonds, which belong to chemical adsorption. Through further analysis of the electron density of states, it is found that C5F10O and C3F6O bonded to the copper surface mainly by p orbitals on carbonyl oxygen atom and the pseudogaps are 3.2 eV and 2.5 eV. C2F4 and CO bonded to the copper surface by sp hybrid orbitals of carbon atoms, with a pseudogap of about 4 eV. Based on the above analysis, it can be seen that C5F10O and its main decomposition products C3F6O, C2F4 and CO have poor compatibility with metal copper. [ABSTRACT FROM AUTHOR]

How to use SF 6 decomposition feature component information to judge the form and degree of gas-insulated equipment (GIE) field discharge and overthermal faults quickly is a problem that remains unresolved. Based on the existing experimental data on SF 6 typical fault decomposition, this study considers the SF 6 decomposition mechanism under typical faults and uses the maximum correlation minimum redundancy criterion to filter out three decomposition feature components characterizing GIE typical fault attributes: SOF 2 +SO 2 , CF 4 , and SO 2 F 2. The weight of extracted feature components is optimized by the "area equivalence principle," and the triangle fault diagnosis method of the SF 6 decomposition component that is suitable for the rapid diagnosis of a GIE field is constructed. The diagnosis method is comprehensively tested using faulty data in different conditions, and the comprehensive recognition rate of lab tests reaches 96.2%. Results show that the constructed triangle fault diagnosis method of the SF 6 decomposition component can diagnose the internal fault nature of a GIE and identify the types of insulation defects that induce partial discharge faults. Moreover, the constructed method in this research is simple, effective, and suitable for field maintenance and online intelligent monitoring of GIE. [ABSTRACT FROM AUTHOR]

This study mainly aims to obtain the decomposition characteristics of SF6 under various degrees of negative partial discharge (PD) and establish a method for evaluating the internal PD fault for gas-insulated equipment (GIE). Thus, metal protrusion, a frequent insulation defect in DC GIE, was used in the study of PD characteristics from the initial discharge to the near breakdown process. Then, seven parameters for characterizing the development stage of PD were extracted, and the fuzzy C-means clustering algorithm was used for the categorization of PD into three degrees, namely, slight, medium, and severe. We performed SF6 decomposition experiments on the PD degrees to obtain the decomposition characteristics. Results show that the SF6 decomposition characteristics (formation and content variation of five characteristic components, namely, CF4, CO2, SO2F2, SOF2, and SO2) are closely related to PD status. Fuzzy comprehensive evaluation theory was used for the establishment of a PD fault status assessment model, which was based on SF6 decomposition characteristics. Then, we evaluated the collected samples, and the accuracy of the evaluation method was up to 87.5%. This paper lays the foundation for future comprehensive assessment and fault diagnosis of insulation status of DC GIE on the basis of SF6 decomposition characteristics. [ABSTRACT FROM AUTHOR]

The use of SF6 gas decomposition components for the fault diagnosis of gas-insulated equipment (GIE) has received widespread attention and been extensively adopted by the power industry. However, the present focus is mainly on the use of a component type or absolute content for generating qualitative judgments on the existence of a fault, and the practical diagnosis method for field diagnosis is extremely lacking. In this paper, ten-year fault data were collected and analyzed. Decomposition components were extracted and combined, based on the decomposition characteristics of SF6, and enhancement factors were given to three component characteristic quantities using fuzzy C-means clustering algorithm. The component characteristic quantities that characterized the high-energy discharge fault, partial discharge, and partial over-thermal fault of the device were extracted: % (SOF2+SO2), % (9SO2F2), and % (5CO2). With adoption of these characteristic quantities as the coordinate axes of the triangle coordinate system, a triangle fault diagnosis method for field diagnosis of SF6 GIE was constructed. The diagnosis method was validated by a large number of experimental data and field failure data, and 128 of the 150 experimental samples were correctly recognized. Moreover, the test conditions did not considerably affect the diagnostic results of the method. This technique can provide a simple and effective field diagnostics technology for the power industry. [ABSTRACT FROM AUTHOR]

Fast interruption is vitally important in high-voltage direct current (HVDC) system to suppress the rapid increase of short current. In this paper, a multi-physics coupling simulation model of a high-speed electromagnetic repulsion mechanism (ERM) which is a part of HVDC breaker is proposed. The opening process with an electromagnetic buffer of ERM is investigated. The simulation results including forces, currents, displacements, and velocities are analyzed. Furthermore, a prototype of ERM is designed and developed. Results show that the efficacy of the proposed simulation methodologies is verified by the experimental results. The opening process of ERM could be divided into six stages. During an opening action, the impact of collision on the motion of ERM cannot be ignored. A good buffering effect can be achieved by reasonably setting the related parameters of the electromagnetic buffer. [ABSTRACT FROM AUTHOR]

The condition monitoring and fault diagnosis method based on decomposed component analysis (DCA) for SF6 gas‐insulated equipment, which mainly aiming at AC SF6 gas‐insulated equipment, has become a research hotspot. Therefore, SF6 positive DC partial discharge (PD) decomposition experiments under four typical insulation defects were conducted in this work. The result showed that there is a significant correlation between the generation rules of the five SF6 decomposition components (CF4, CO2, SO2F2, SOF2 and SO2) and the types of defects. The phenomenon was attributed to the variations in the properties of the four insulation defects. In addition, comparing with AC PD experiment, for the protrusion, contamination and gap defect models, the amounts and generation rates of the five characteristic decomposition components under positive DC are less than those under AC by the same defect; however, for the particles defect, it is by contrary. This could be attributed to the essential difference between AC PD and positive DC PD. Therefore, the theory of AC DCA could provide reference to construct DCA diagnostic model for DC SF6 gas‐insulated equipment, but cannot be applied mechanically. [ABSTRACT FROM AUTHOR]

Through his subversive thinking of Plato's cave metaphor, Martin Heidegger has restored to truth ( aletheia) its original significance. Then he bases the origin of art on its relation with truth. The so-called producing ( hersteUen) of the Earth and instituting ( aufsteUen) of the World is exactly the placing ( Stellen) and placing-together ( Ge-stell) of truth. A Heideggerian interpretation of Marcel Duchamp's " Fountain" wiil attest excellently to the validity of ready made art as the placing/stellen of truth. [ABSTRACT FROM AUTHOR]

To clarify the influence of pressure on SF6 decomposition under positive DC partial discharge (PD), SF6‐positive DC partial discharge decomposition experiments at different pressures were carried out. We found that the contents of SF6 primary decomposition products are proportional to E / P 3 / 2 exp − B d P / E. Keeping the chamber volume and external temperature constant, the difference of air chamber pressure means that the electronic mean free path is different. So, different pressures make a difference in the energy of free electrons obtained in a single flight, which results in the difference in the reaction rates of SF6 primary decomposition and further influences the formation of SF6 PD characteristic decomposition components. © 2018 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

To investigate the difference between the sulfur hexafluoride (SF6) decomposition characteristics initiated by two sorts of insulation defects — free metal particles and metal protrusion defects — under negative DC partial discharge (PD), SF6 decomposition data was obtained under different DC voltages on the basis of constructing a SF6 decomposition experimental platform. The differences between the characteristic components and the characteristic ratios of the two defects at the same discharge quantity and voltage were systematically analyzed. Results show that the two defects have significant differences in the type of decomposition components, the yield sizes of the components, and the changes in the component ratios. This paper proposed c(CF4 + CS2)/c(CO2) and c(CF4)/c(SO2F2) as the characteristic ratios to characterize the fault severity of the two defects, and their physical nature were revealed. The combination of the above ratios with the existing c(SO2F2)/c(SOF2 + SO2) can construct a feature quantity for identifying the two defects. [ABSTRACT FROM AUTHOR]

To study the correlation characteristics between SF6 decomposition components and discharge strength under negative DC partial discharge (PD) initiated by free metal particle defect, SF6 decomposition data were obtained under different voltages on the basis of constructing SF6 decomposition experimental platform. The variation law of SF6 decomposition components and characteristic ratios were systematically analyzed. The study shows that SF6 decomposes into CO2, SO2F2, SOF2, SO2, CF4, and a very small amount of CS2 under PD. The SOF2 concentration and its formation rate have the highest correlation with the PD discharge quantity among all components. The yield relationship of decomposition components is different at different discharge quantities. In addition, the fluctuation of each characteristic ratio is small after 72 h and can achieve a certain degree of steady state. c(CF4+CS2)/c(CO2) and the proposed c(SO2)/c(SO2F2) can be used as the fault severity characteristic ratio in free metal particle defect. [ABSTRACT FROM PUBLISHER]

Aimed to clarify the correlation characteristics between the internal partial discharge (PD) in the negative direct current (DC) gas‐insulated system (GIS) and gas pressure, and to establish an insulation fault diagnosis method based on decomposition component analysis, this study on PD decomposition of sulphur hexafluoride (SF6) was conducted under different pressures on the basis of constructing a SF6 decomposition experimental platform under DC PD. A stainless steel needle‐plate electrode was used to simulate the insulation defects of metal protrusions in GIS. SOF2, SO2 F2, CO2, SO2, and CF4 data generated from SF6 decomposition were obtained under different pressures. The variation law of component concentration and effective characteristic ratio with pressure were analysed in detail. In addition, a mathematical formula for pressure and decomposition components was deduced according to gas micro‐ionisation theory. The effective content and formation rate were defined to validate the relationship. Results show that the concentration of SF6 decomposition components decreased gradually with increasing pressure with a strong regularity. Furthermore, the relationship between pressure and component concentration derived from the theory can explain the relationship between the effective content of SF6 decomposition components and the effective formation rate and pressure variations. [ABSTRACT FROM AUTHOR]

Determination of the influence and mechanism of metallic materials on SF decomposition under direct current (DC) partial discharge is one of the key aspects to improve SF decomposition component analysis (DCA). In this study, three kinds of metallic materials, namely, aluminum, copper, and 18/8 stainless steel, were made into needle-plate electrons, and then used in the SF positive DC partial discharge decomposition experiments. The influences of metallic materials on the five main decomposition components (i.e., CF, CO, SOF, SOF, and SO) were determined by gas chromatography-mass spectrometry. Results showed no significant correlation among the contents of CO for the different kinds of metallic materials. However, the metallic materials considerably influenced the contents of the other four gases. The difference in SF decomposition characteristics for the different metal electrodes was mainly due to the difference in anti-halogenation ability of metals and the passive film. Therefore, the impacts of different metallic materials should be considered when using SF DCA for the condition monitoring and fault diagnosis of DC gas-insulated equipment. [ABSTRACT FROM AUTHOR]

To figure out the influence rules of trace H2O on SF6 decomposition characteristic components under spark discharge, a series of spark discharge decomposition experiments with various H2O contents were performed using needle-plate electrode to simulate metal protrusion insulation defect. The changing rules and mechanisms of five decomposition characteristic components were achieved quantitatively, indicating that no matter how much H2O was, there exist five main decomposition components: CF4, SOF2, SO2, SOF4 and SO2F2. The contents of the five decomposition components increased with the time extended, and resulting in the contents of SF6 spark decomposition components by the order: SOF2 > SO2F2 > SOF4 > SO2 > CF4. Additionally, the higher H2O content is, the stronger promoting effect on the generation of SO2F2, SOF2, SOF4 and SO2 is. [ABSTRACT FROM AUTHOR]

We explored the thermal decomposition characteristics of SF6 with partial overthermal fault in organic solid insulating materials. Results show that when organic solid insulating materials were around the fault point, the main overthermal decomposition characteristic products of SF6 were CS2, CO2, CF4, H2S, SO2F2, SOF2, and SO2. The difference in the generating reaction and degree of reaction of the seven decomposition components resulted in the complexity of concentration and growth regularity. Surface component analysis after the experiment showed that the thermode surface contained numerous S, O, C and F. Fe existed in the form of Fe2O3 and FeF2. The organic insulating materials added new elements, such as F and S, because HF and H2S easily reacted with O in the epoxy group. [ABSTRACT FROM AUTHOR]

Sulfur hexafluoride (SF₆) gas-insulated equipment (GIE) has been widely used in extra/ultra high voltage power transmission systems. During its operation, GIE inevitably experiences partial overthermal faults caused by poor contact. In this study, the SF₆ decomposition characteristic of partial overthermal faults was used to solve problems that cannot be detected effectively in GIE. First, a large number of experiments were conducted on an SF₆ overthermal decomposition system to obtain the overthermal decomposition characteristic of SF₆ below 400 °C. Then, from the perspective of the physical significance of engineering, three feature parameters, namely, total decomposition amount, effective formation rate, and ratio of characteristic components, were proposed to reveal the deterioration degree of the gas insulation medium as well as to represent the development trend and severity of a partial overthermal fault. Results show that total decomposition amount CT, CT1, and CT2 can depict the degradation degree of the GIE insulation medium and the carbonic metal structure caused by a partial overthermal fault, which can be a good index to differentiate partial overthermal fault temperatures. The effective formation rate of each characteristic component RRMS is closely related to temperature and can reflect the development trend of a partial overthermal fault. The feature ratio CO2/(SO₂F₂+SOF₄+SOF₂+SO₂+H2S) can reveal whether a partial overthermal fault involves organic insulation materials. H2S/(SO₂F₂+SOF₄) can depict the severity of a partial overthermal fault. Log10(SOF₂+SO₂)/(SO₂F₂+SOF₄) and its effective value TCRRMS3 can represent the deterioration degree of GIE and provide excellent correlation with the severity of a partial overthermal fault, and thus, it can be used to evaluate the severity of a partial overthermal fault quantitatively. [ABSTRACT FROM PUBLISHER]

This study examines how byproducts from thermal decomposition of sulfur fluoride (SF6) can be measured and applied to diagnose an overheating fault occurring in SF6 insulated equipment. Using a series of experiments performed on a SF6 thermal fault simulation system, the thermal decomposition characteristics of SF6 were obtained for temperatures below 400°C. Based on these results, the formation rate was extracted to indicate the progress of the thermal fault's development, and the characteristic component ratio was used to identify the type and severity of the thermal fault. The relationship of the fault temperature and the formation rate along with the correlation between the characteristic ratio and the fault temperature were studied. The results show that: the formation rate of the components effectively reflects the severity and development trend of the thermal fault; by integrating the IEC standard 60480‐2004, the obtained thermal fault maximum safe time (TMS) can accurately indicate the largest safe time when thermal fault happens; component characteristic ratios C(SO2)/C(SO2F2) and C(SO2F2+SOF4)/C(SOF2) can be used to evaluate whether the fault type is a thermal fault; and the thermal correlation ratio (TR) can be employed to recognize the temperature value from 300°C to 400°C. [ABSTRACT FROM AUTHOR]

To explore the influence mechanism of trace H2O on SF6 decomposition characteristics under partial thermal fault and establish the foundation of using SF6 thermal decomposition principle to diagnose the thermal fault of SF6 electrical equipment, a series of artificial thermal fault decomposition experiments with different H2O concentrations were conducted on the designed SF6 thermal decomposition experimental system. A trace water injector was used to control the content of trace H2O accurately and gas chromatograph, chromatography-mass spectrometry as well as Fourier transform infrared spectroscopy were used to measure decomposed components. Finally, the thermal decomposition characteristic under 340 ° was achieved. The analysis results indicate no matter how much H2O content is, SF6 can decomposes into many kinds of decomposition characteristics, such as CO2, SOF2, SO2, SOF4, SO2F2, H2S, HF. The concentrations of all these decomposition characteristics increase with the time extended, but change differently with the increase of H2O content, because H2O plays different role in the formation process of each decomposition characteristic components. The variation of H2O content not only affects the production of the decomposition characteristic components, but also makes SO2 and HF gradually evolved into the main characteristic components of SF6 thermal decomposition. In addition, the higher the H2O content is, the stronger the promoting effect on SO2 and HF is. [ABSTRACT FROM AUTHOR]