Preparation and property of self-sealed plasma electrolytic oxide coating on magnesium alloy

Plasma electrochemical oxidation (PEO) is a surface modification technology to form ceramic coatings on magnesium alloys However,its application is limited due to its defects.This work reports a novel preparation of in-situ sealing of PEO coatings by four-layer voltage and sol addition.The morphology and structure were characterized by scanning electron microscopy (SEM),energy dispersive X-ray spectroscopy (EDS),and X-ray diffractometer (XRD).Image-Pro Plus 6.0 was used to determine the porosity of the coating,which was decreased from 8.53%to 0.51%.Simultaneously,the coating thickness was increased by a factor of four.The anti-corrosion performance of each sample was evaluated using electrochemical tests,and the findings revealed that the corrosion current density of coatings (i_(corr)) of the samples were lowered from 9.152×10^(-2) to 6.152×10^(-4) mA·cm^(-2),and the total resistance (R_(T)) of the samples were enhanced from 2.19×10^(4) to 2.33×10^(5)Ω·cm^(2).The salt spray test used to simulate the actual environment showed that corrosion points appeared on the surface of the coating only at the 336 h.In addition,the mechanism of PEO self-sealing behavior was described in this article.

Experimental Verification and Research for the Distortion in the Integrated Frequency Responses of the High-Pressure Sealed Cabin and Magnetic Field Sensor

Although magnetotelluric sounding method applied to the land is advanced, there are many difficulties when it is applied to marine environment, one of which is how to lay magnetic field sensors down to the seafloor to complete measurements. To protect the magnetic field sensors from intense erosion and high pressure, suitable high-pressure sealed cabins must be designed to load them. For the consideration of magnetic measurement and marine operation, the sealed pressure cabin should be nonmagnetic and transportable. Among all optional materials, LC4 super.hard aluminum alloy has the highest performance of price/quality ratio to make the sealed pressure cabin. However, it does not mean that the high-pressure sealed cabin made using LC4 will be perfect in performance. In fact, because of its weak magnetism, the pressure cabin made using LC4 has distorting effect on frequency responses of the magnetic field sensors sealed in it. This distorting effect does not affect the use of the magnetic field sensor, but if we want to eliminate its effect, we should study it by experimental measurements. In our experiment tests, frequency sweep magnetic field as excitation signal was used, and then responses of the magnetic field sensor before and after being loaded into the high-pressure sealed cabin were measured. Finally, normalized abnormal curves for the frequency responses were obtained, through which we could show how the high-pressure sealed cabin produces effects on the responses of the magnetic field sensor. Experimental results suggest that the response distortion induced by the sealed pressure cabin appears on mid- and high-frequency areas. Using experimental results as standardization data, the frequency responses collected from seafloor magnetotelluric measurements can be corrected to restore real information about the seafloor field source.

Assessment of sealed fire states by fire characteristic

The paper presented assessment of sealed fire states in underground coal mines by so-called 'fire characteristic', which graphically described tendencies of fire gas components-oxygen, nitrogen, carbon dioxide, carbon monoxide and hydrocarbons-in time. In order to mark gas components tendencies in time the authors applied the time series analysis. The case studied confirmed, that analysis of fire gas components tendencies in time and their correlation allow to elicit proper conclusions about fire state assessment. Assessment of fire states based on single value of fire indexes without considering their trends in time and correlation between trends of gas components would give wrong results The suggested method can appropriately indicate fire states in a sealed area.

EIS Characterization of Sealed Anodic Oxide Films on Titanium Alloy Ti-10V-2Fe-3Al

Anodic oxide films grown on titanium alloy Ti-10V-2Fe-3Al in the solution of sodium tartrate, then sealed in boiling deionised water and calcium acetate solution were observed by using field emission scanning electron microscopy （FE-SEM）, and were chemically analysed by using energy dispersive spectroscopy （EDS）. Corrosion behaviour was investigated in a 3.5% sodium chloride solution, using electrochemical impedance spectroscopy （EIS）. The morphology of the anodic oxide films was dependent on the sealing processes. The surface sealed in calcium acetate solution presented a more homogeneous and smooth structure compared with that sealed in boiling deionised water. The corrosion resistance of the oxide films sealed in calcium acetate solution was better than that sealed in boiling deionised water.

A pressure-calibration method of wavelength modulation spectroscopy in sealed microbial growth environment

A new pressure-calibration method for calibrating the reduction of second harmonic(2f)amplitude caused by pressure broadening effect in sealed microbial growth environment is present.The new method combines with linewidth compensation and modulation depth compensation and makes the 2f amplitude accurately retrieve metabolic CO_(2) in microbial growth.In order to verify the method,a simulation experiment is developed,in which the increasing CO_(2) concentration leads to the increasing pressure.Comparing with the relation between the traditional 2f amplitude and gas concentration,there is a monotonous relation between the calibrated 2f amplitude and CO_(2) concentration,particularly,a linear relation is present when the CO_(2) concentration is replaced with the CO_(2) particle number.In terms of microbial measurement,the growth of Escherichia coli is measured,and the culture bottle is sealed during the microbial growth process.The experimental results show that,comparing to the microbial growth retrieved by traditional 2f amplitude,the calibrated 2f amplitude can accurately retrieve microbial growth in sealed environment.

Method of analyzing vibration characteristics of armature system of hermetically sealed electromagnetic relay

Published research is minimal on vibration characteristics of hermetically sealed electromagnetic relay (EMR) ex- posed to mechanical environment. The vibration characteristics of armature system, link contact system with electromagnetic system will cause EMR malfunction. The nonlinear dynamics model of armature systems was studied by considering electro- magnetic attraction force and opposite mechanical force in this paper. Angular displacements of armature under different sinu- soidal vibration conditions are solved in order to obtain the failure mode result from armature system. Vibration tests showed the presented analyzing method is suitable for EMR. The conclusions are instructive for increasing vibration resistance of armature systems of EMR, and are significant for reliability design of switch apparatus.

Influence of the Gas Mixture Ratio on the Correlations Between the Excimer XeCl Emission and the Sealed Gas Temperature in Dielectric Barrier Discharge Lamps

For dielectric barrier discharge lamps filled with various gas mixture ratios, the correlations between the excimer XeCl* emission and the sealed gas temperature have been founded, and a qualitative explication is presented. For gas mixture with chlorine larger than 3%, the emission intensity increases with the sealed gas temperature, while with chlorine about 2%, the emission intensity decreases with the increase in the gas temperature, and could be improved by cooling water. However, if chlorine is less than 1.5%, the discharge appears to be a mixture mode with filaments distributed in a diffused glow-like discharge, and the UV emission is independent on the gas temperature.

Sealed model and computation of hazardous waste landfill high voltage DC leakage detection

According to the structural characteristics of hazardous waste landfill and the leakage current model of high voltage DC Landfill leakage detection, a sealed model is established detail. The detection layer of the hazardous waste landfill is considered as a sealed assumed that the source current flows through the leak entirely. The leak is regard and analyzed in space and it is ed as a positive current resource ＋ I located at the current entrance or a negative resource - I located at the current exit, which depends on the placement of the current supply. The electrical potential of an arbitrary in detection layer satisfies Poisson equation. The boundary condition is regarded as a natural bound- ary condition for the high resistivity of high density polyethylene （HDPE） membrane. Based on which a numerical calculation method is developed. Satisfactory agreement between experimental da- ta and simulated data validates the analysis. Parametric studies show that a larger horizontal distance between the power supply electrode and leak and a smaller distance between the detector electrodes and the detected liner are helpful to leak location. More parametric curves show that parameters leaks can be detected effectively with optimum selection of field survey.

Design and laboratory evaluation of fog-sealed chip seal on epoxy asphalt pavement for steel bridge deck

In order to improve the surface performace of epoxy asphalt pavement （EAP） for steel bridge deck, an epoxy asphalt chip seal （ ECS） covered by a cationic emulsified asphalt fog seal （i. e., fog-sealed chip seal） isproposed and a laboratory study is conducted to design and evaluate te fog-sealed chip seal. First, the evaluation indices and methods of te chip seal on steel bridge deck pavement were proposed. Secondly, the worst pavement conditions during te maintenance time were simulated by te small traffic load simulation system MMLS3 and the short-term aging test for minimizing the failure probability of chip seal. Finally, the design parameters of fog-sealed chip seal were determined by the experimental analysis and the performance of the designed fog-sealed chip seal was evaluated in thelaboratory. Results indicate that the proposed simulation method of pavement conditions is effective and the maximal load repetitions on the EAPslab specimen are approximately 925 300 times. Moreover, the designed fog-sealedchip sealcan provide a dense surface with sufficient skid resistance,aggregate-asphalt aahesive performance and interlayer shearing resistance.

Metal Sealing Performance of Subsea X-tree Wellhead Connector Sealer

The metal sealing performance of subsea X-tree wellhead connectors is crucial for the safety and reliability of subsea X-trees. In order to establish the theoretical relation between metal sealing ring＇s contact stress and its structural parameters and working pressure, a mechanical analysis method for double-cone sealing of high pressure vessels is applied in analyzing the metal sealing ring under the condition of preload and operation. As a result, the formula of the unit sealing load for the metal sealing ring under operation with residual preload is shown in this paper, which ensures that the metal sealing ring has an excellent sealing effect and can prevent the metal sealing ring from yielding. Besides, while analyzing the sealing process of the metal sealing ring, the change rule of contact stress and working pressure is concluded here, putting forward that the structural parameters of the metal sealing ring are the major factors affecting the change rule. Finally, the analytical solution through theoretical analysis is compared with the simulation result through finite element analysis in a force feedback experiment, and both are consistent with each other, which fully verifies for the design and calculation theory on metal sealing ring＇s contact stress and its structural parameters and working pressure deduced in this paper. The proposed research will be treated as an applicable theory guiding the design of metal seal for subsea X-tree wellhead connectors.

Transient response of a spherical cavity with a partially sealed shell embedded in viscoelastic saturated soil

Based on Biot’s wave equation, this paper discusses the transient response of a spherical cavity with a partially sealed shell embedded in viscoelastic saturated soil. The analytical solution is derived for the transient response to an axisymmetric surface load and fluid pressure in Laplace transform domain. Numerical results are obtained by inverting the Laplace transform presented by Durbin, and are used to analyze the influences of the partial permeable property of boundary and relative rigidity of shell and soil on the transient response of the spherical cavity. It is shown that the influence of these two parameters is remarkable. The available solutions of permeable and impermeable boundary without shell are only two extreme cases of this paper.

Protection Performance of Plasma Sprayed Al_(2)O_(3)-13 wt%TiO_(2) Coating Sealed with an Organic-inorganic Hybrid Agent

An organic-inorganic hybrid sealing agent was fabricated and used in the plasma sprayed Al_(2)O_(3)-13 wt%TiO_(2)coating,and conventional silicone agent was also used for comparison.Protection performance of the coatings was comprehensively evaluated based on both anti-corrosion and anti-biofouling properties.The results reveal that the sealing treatment is remarkably useful to decrease the porosity of the coating,and the porosity of the coating sealed with the hybrid agent is only 0.035%.Immersion corrosion test and Tafel polarization test reveal that the sealed coating with the hybrid agent exhibits a better corrosion resistance by compared with the coating sealed with silicone agent.The corrosion current density i_(corr) of the hybrid agent sealed coating is only 0.7×10^(-6)A·cm^(-2).Moreover,anti-biofouling tests both in the outdoor analogue hydraulic environment and in the natural marine environment prove that the mentioned novel coating presents a better combination of corrosion resistance and anti-biofouling property by compared with the other coatings,and it could be used as a protection of metal components in the marine environment.

Direct measurement of oxygen consumption rates from attached and unattached cells in a reversibly sealed, diffusionally isolated sample chamber

Oxygen consumption is a fundamental component of metabolic networks, mitochondrial function, and global carbon cycling. To date there is no method available that allows for replicate measurements on attached and unattached biological samples without compensation for extraneous oxygen leaking into the system. Here we present the Respiratory Detection System, which is compatible with virtually any biological sample. The RDS can be used to measure oxygen uptake in microliter-scale volumes with a reversibly sealed sample chamber, which contains a porphyrin-based oxygen sensor. With the RDS, one can maintain a diffusional seal for up to three hours, allowing for the direct measurement of respiratory function of samples with fast or slow metabolic rates. The ability to easily measure oxygen uptake in small volumes with small populations or dilute samples has implications in cell biology, environmental biology, and clinical diagnostics.

Contact Pressure between the Outside Surface of the Sealer and Cylinder Wall

Character of contract pressure distribution between the outside surface of the sealing material and rigid cylinder wall depending on geometrical sizes and mechanical properties of a sealer under its unilateral compression, is defined. The magnitude of the axial load for achieving tightness is determined. The dependence between the magnitude of the axial load necessary for achieving tightness and geometrical sizes is determined. It is shown that with a decrease in the height of the sealing element, the axial load necessary for achieving tightness greatly increases. Threshold height of the sealer, above which contact pressure depends little on the magnitude of the axial load, is defined. The stress-strain state of the sealing element is defined with regard to viscous-elastic properties of its material. It is shown that this greatly influences its sealing ability.

Molecular Orientation Effect of Heat-Sealed PP Film on Peel Strength and Structure

Heat sealing properties are optimized by controlling temperature, pressure and dwell time, while film strength depends on the drawn ratio and the molecular orientation of the film. However, heat seal strength of polymer films with high drawn ratio shows lower peel strength, because the adhesion of films needs a higher heat sealing energy for molecular orientation relaxation at heat sealing. In the present study, polypropylene films with a drawn ratio of 1.0×, 1.5×, and 2.5× are heat sealed by using the heat sealing technique. The heat sealing condition is set to heat sealing time 1.0 s, sealing pressure 0.2 MPa, and heat sealing temperature 145°C. The effect of drawn ratio and stabilization temperature of PP films for peel strength are investigated using T-Peel test, DSC, FT-IR, and Raman spectroscopy. As a result, it is found that the peel strength is decreased with increasing the drawn ratio and stabilization temperature of PP films. The difference of ?H and melting point from the result of DSC measurement are exhibited for 1.5× drawn ratio film as compared with 2.5× one. In addition, FT-IR imaging and Raman line mapping reveal the influence and variation of high order structure for heat sealed parts of the drawn PP films.

瑞典能源局为建设SEALER原型堆提供资助

【世界核新闻网站2022年2月15日报道】瑞典能源局近日决定向瑞典模块化反应堆公司(Swedish Modular Reactors)提供9900万瑞典克朗(约1060万美元)资金,支持在奥斯卡港核电厂(拥有3座沸水堆,其中2座已永久关闭)建设铅冷模块化小堆SEALER的电热非核原型堆。该原型堆拟于2024年投运,将运行5年时间,用于在高温熔融铅的环境中测试并验证相关材料和技术。

STUDY ON PERFORMANCE OF COMPOSITE JOURNAL BEARING SEALED AND LUBRICATED WITH FERROFLUID

The theoretical computation model of the composite journal bearing sealed and lubricated with ferrofluid is established The oil film pressure distribution,temperature field and heat conduction equation of the bearing liner are jointly calculated The static and dynamic properties of the bearing under condition of different eccentricities and ratios of width to diameter are obtained and discussed The results show the feasibility of this type of bearing for smaller eccentricities and width to diameter ratios,and that the oil film temperature,which is more subject to be influenced by the rotating speed,is higher than that of the bearing with leakage flow The key problem of the further development and application of the bearing is to design more reasonable and effective types of seal structures

Catastrophic Failure Assessment of Sealed Cabin for Ultra large Manned Spacecraft in M/OD Environment

Hypervelocity impacts of Micrometeoroid and Orbital Debris(M/OD)may lead to catastrophic failure of long-term flight manned spacecraft in orbit.Risk assessment for manned spacecraft in M/OD environment is of great significance for the safety of human space missions.For typical catastrophic failure modes of manned spacecraft such as gas-leakage-induced astronaut hypoxia,sealed cabin fracture,and spacecraft breakup,catastrophic failure assessment method using critical perforation diameters and critical crack lengths of sealed cabins and critical fragment size of spacecraft breakup as failure criteria are proposed.In addition,corresponding modules of catastrophic failure assessment were developed and integrated with Meteoroid and Orbital Debris Assessment and Optimization System Tools,providing an effective assessment tool for researching on the safety of manned spacecraft.On the basis of which,catastrophic failure evaluation of sealed cabin for a specific ultralarge manned spacecraft in the M/OD environment was conducted,providing references for on-orbit mission safety evaluation.

Sealing capacity evaluation of underground gas storage under intricate geological conditions

Evaluating underground gas storage(UGS)sealing capacity is essential for its safe construction and operational efficiency.This involves evaluating both the static sealing capacity of traps during hydrocarbon accumulation and the dynamic sealing capacity of UGS under intensive gas injection and withdrawal,and alternating loads.This study detailed the methodology developed by Sinopec.The approach merges disciplines like geology,geomechanics,and hydrodynamics,employing both dynamic-static and qualitative-quantitative analyses.Sinopec's evaluation methods,grounded in the in situ stress analysis,include mechanistic studies,laboratory tests,geological surveys,stress analysis,and fluid-solid interactions.Through tests on the static and dynamic sealing capacity of UGS,alongside investigations into sealing mechanisms and the geological and geomechanical properties of cap rocks and faults,A geomechanics-rock damage-seepage mechanics dynamic coupling analysis method has been developed to predict in situ stress variations relative to pore pressure changes during UGS operations and evaluate fault sealing capacity and cap rock integrity,thereby setting the maximum operational pressures.Utilizing this evaluation technique,Sinopec has defined performance metrics and criteria for evaluating the sealing capacity of depleted gas reservoirs,enabling preliminary sealing capacity evaluations at UGS sites.These evaluations have significantly informed the design of UGS construction schemes and the evaluation of fault sealing capacity and cap rock integrity during UGS operations.

Effect of Fluid-Structure Interaction on Sealed Flow Field and Leakage Rate Based on Computational Fluid Dynamics

This paper addresses the issue of reciprocating compressors staggered labyrinth seal structure. The internal flow field of sealed structure, the displacement of cylinder and piston for different tooth profile angles are analyzed synchronously using FLUENT software, and the effects of fluid-structure interaction on the performance of the labyrinth seal are revealed. The results indicate that with the growth of tooth profile angle, the leakage rate of labyrinth seal tends to decrease first, and then increase. The results of fluid-structure interaction analysis are close to those of actual engineering. The effect of fluid-structure interaction makes tiny deformation in calculation mesh of piston and cylinder structure, and the coupling interaction affects the performance of the labyrinth seal.