Materials Science Forum Vol. 999

Abstract: To buffer the volume changes of silicon-based anode material and stabilize the solid-electrolyte-interface (SEI) layer formed in the electrolyte, a core-shell structure with VO₂ coating is newly designed. In this composite, the pitch modified spherical graphite serves as a core, and the Si particles are uniformly dispersed on its surface, then the VO₂ is synthesized in situ. The modified graphite/Si/VO₂ (Si@G@V) anode exhibits a reversible capacity of 1247 mAh g^-1 at the current density of 0.1 A g^-1 after 50 cycles, obtain a capacity retention of ~99%. The rate capability of ~320 mAh g^-1 at the current density of 10 A g^-1 is also obtained. The excellent cyclic stability and superior rate performance mainly attributed to the uniform dispersion of Si particles in the pitch modified spherical graphite, the core-shell structure of the material as well as the in-situ synthesis of VO₂. This simple synthesis process is of great significance to reduce the reunion and constrain the volume changes of silicon.

Abstract: Protein gel of soy was formed immediately during polymerization of aniline initiated by certain amount of FeCl₃. In order to obtain iron-doped carbon material, this composite was then carbonized at 700°C under nitrogen atmosphere for 5h. SEM, FT-IR, XRD, and isothermal desorption/adsorption technologies were employed to characterize morphology and structure of the material. Electrical capacitance of iron-doped carbon materials and performance of a prototype supercapacitor based on the material as its electrodes were measured by cyclic voltammetry, chronopotentiometry, and A.C. impedance respectively. Results show that morphology of as-obtained material is porous and hierachical, specific surface area of the material is 232.1m²/g, and specific capacitance of the material can reach 475.2F/g in 6 M KOH aqueous solution. Energy density and power density of the cell is 2.1Wh/kg and 2.0kW/kg, respectively. Capacity retention of the device is 100% after 5000 cycles at a current density of 2A/g. The above studies imply that this original iron-doped carbon material will have a good potential application in field of energy storage.

Abstract: Nickel-doped manganese dioxide (Ni-MnO₂) as electrode materials for supercapacitors were successfully prepared by one-step chemical liquid phase coprecipitation with the different nickel doped proportions. X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray fluorescence (XRF) were used to analyze the micro-structure, morphology and composition. And electrochemical properties were studied by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectrometry (EIS). The results revealed that MnO₂ synthesized in this work turned out to be δ-MnO₂ of homogeneous dispersion and excellent electrochemical properties. Specific capacitance of 300.85 F/g was achieved for the 2% Ni-doped MnO₂ at 2mV/s through cyclic voltammetry, and after 5000 circles the persistence rate of which still remained to 75%, exhibiting a preeminent advantage of stability and reversibility to naked MnO₂.

Abstract: After severe accident in the nuclear power station, it is necessary to remove the hydrogen timely for the purpose of preventing the containment integrity from breach. This report has investigated and studied the role of silver zeolite in the reaction of hydrogen and oxygen. According to the catalyst role, the principle test device for hydrogen removal with silver zeolite is provided. The force of natural circulation for principle test device is created by the Chimney Effect, which is the result of different density between the internal and external of the device. Also, this report suggests the flowing capability calculation method of up-thrust about the mixture gas passing through the catalyst layer of silver zeolite. The evaluation method of hydrogen removal efficiency with silver zeolite is described. Finally, this report gives the method of CFX numeric analog and the specific simulating steps for the layer of silver zeolite using for catalytic role.

Abstract: The irradiation embrittlement damage of reactor pressure vessel (RPV) steel is one of its primary failure mechanisms. In this work, neutron, ion and proton irradiation experiments were carried on the same commercial RPV steels with the same irradiation fluence under the same temperature of 292°C. Then the nano-indentation hardness tests were performed on the RPV steel before and after irradiation. The results show that the irradiation hardening effects are observed by means of nano-indentation technique under the above three irradiations, and the hardening features are basically the same. While the max variation and increase rate are obviously different between those irradiations. It is found that the main reason of the above differences are caused by different energies of irradiation energetic particles, resulting in different types and quantities of defects. The conclusions in this paper are helpful to select and compare different irradiation experiments to the research of RPV steels irradiation embrittlement damage.

Abstract: The manufacturing accuracy of the guide structure of the PWR control rod drive line (abbreviated as the drive line) is very important to ensure the accurate performance of the function of the drive line. In this paper, the technology of high speed laser welding is studied, and the parameters of low stress and high speed laser welding are obtained. The heat source of laser welding, the shrinkage of laser welding weld and the welding deformation of laser welding are modeled and analyzed. The deformation simulation technology of laser welding of driving line guide structure is established to provide theoretical guidance for the manufacture of laser welding of this part. The specific contents include: laser welding test and thermal cycle test, macroscopic weld forming, residual stress test, heat source model establishment and parameter determination, laser welding weld shrinkage model establishment and welding deformation prediction. Finally, the driving line guide structure welded by high speed laser uses Φ 10.26mm bar drop gauge at the speed of 4 × 5 m / min to pass freely at 0 °, 90 °, 180 °and 270 °, and the friction force is less than 88N. The drop bar gauge of Φ10.26 mm is used to pass freely through the driving line guide structure welded by high speed laser at the speed of 4 ~5 m/min at 0 °, 90°, 180° and 270°, and the friction force is less than 88N.

Abstract: In order to characterize the effect of solution treatment on the properties of Selective laser melting (SLM) 316L material for nuclear power field, the effects of different solution treatment conditions on the microstructure evolution and mechanical properties of 316L material were studied. The results show that 316L material is arc-shaped fish scale structure for as-deposited condition. After solution treatment at 1050 °C and 1150 °C respectively, the material microstructure recrystallizes and the arc boundary between layers disappears. The fracture characteristics is typical ductile fracture characteristic. Compared with temperature of 1050 °C, the material is fully recrystallized at 1150 °C and the microstructure uniformity is improved together with the anisotropy is obviously reduced, meanwhile, the formation of twin structure will be beneficial of improving the mechanical properties which has been demonstrated through metallographic analysis combined with characterization of mechanical performance.

Abstract: A 316L stainless steel instrument valve body which with complex internal flow passage and used for primary loop flow measurement in pressurized power plant along with test specimen were printed by selective laser melting. The optical metallography of specimen showed the microstructure transform to be uniform after heat treatment state. The residual stress test was tested on three different position on the valve body after heat treatment. The results showed that the valve body mainly had a surface residual compressive stress, and the max main stress was in a range of-367.27MPa to 34.97MPa which get higher along the building direction. Then the application performance of intergranular corrosion test and hydraulic test on the valve body showed a good performance and the result could meet the acceptance requirements of the construction rule.

Abstract: The development of materials for core components which can serve in high temperature corrosive environments for a long service time is crucial to realize high efficiency and high-burnup operation of advanced nuclear reactors. Alumina forming austenitic (AFA) alloy is a kind of promising materials with improved corrosion resistance as well as strength at elevated temperature. The progress on the composition design and characterization of AFA alloys are reviewed in this work for evaluation their potential applications in advanced nuclear reactors. AFA alloys without the addition of carbon have been fabricated. Microstructures were observed by SEM and TEM. Mechanical properties were measured at room temperature and high temperature.