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The coating effect of 1,2-bis(triethoxysilyl)ethane (BTES) on carbonyl iron particles (CIPs) was enhanced by etching with hydrochloric acid (HCl) of various concentrations, and magnetorheological fluids (MRFs) with significantly improved dispersion stability were obtained. The microstructures, coating effect, and magnetism of CIPs were examined using scanning electron microscopy (SEM), automatic surface and porosity analysis (BTE), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and a vibrating sample magnetometer (VSM), respectively. Furthermore, the rheological properties and dispersion stability of the MRFs were assessed by a rotating rheometer and a Turbiscan Tower. The results show that as the HCl concentration increased, nanopores appeared on CIPs and then disappeared, and the specific surface area of the particles increased and then decreased. When the concentration of HCl was 0.50 mol/L, the number of nanopores and the specific surface area of particles changed sharply. Not only that, the coated mass of BTES increased greatly and the saturation magnetization of particles decreased sharply. As the coated mass increased, without a magnetic field, the viscosity and shear stress of the MRFs increased, especially when the coated mass was more than 2.45 wt.%; while under a magnetic field, the viscosity and shear stress decreased, and the sedimentation rate of the MRFs decreased from 0.13 to 0.01 mm/h. By controlling the concentration of HCl for etching, the coating effect of CIPs was greatly enhanced, and thus an MRF with superior shear stress and excellent dispersion stability was obtained, which is significant in basic research and MRF-related applications. [ABSTRACT FROM AUTHOR]

This study investigates the development and characterization of ceramic rod-reinforced TWIP (twinning-induced plasticity) steel matrix composites, produced using the lost foam casting technique. Mechanical tests revealed a substantial improvement in both flexural strength and ductility, with the composite demonstrating more than double the strength of unreinforced TWIP steel. Furthermore, a simple low-temperature heat treatment further enhanced these properties, increasing the flexural strength of the composite to 1023 MPa while also improving its ductility. The improvement in mechanical performance is attributed to the formation of additional twins in the TWIP steel matrix during deformation following heat treatment, which resulted in further strengthening of the matrix. [ABSTRACT FROM AUTHOR]

This study investigates the microstructural evolution and mechanical properties of high-nickel shipbuilding steel during thermal processing using high-temperature confocal laser-scanning microscopy (HTCLSM). An in situ observation of the heating and holding processes reveals critical insights into phase transformations, grain-growth behavior, and the formation of precipitates. The experimental results demonstrate that austenitization begins at approximately 700 °C, with significant grain-boundary nucleation. At 900 °C, the formation of black precipitates was observed, and their persistence up to temperatures exceeding 1000 °C was confirmed. Scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) analyses identified these precipitates as chromium carbides (Cr7C3), which significantly contribute to the material's strength. A comprehensive analysis using transmission electron microscopy (TEM) confirmed the presence and distribution of Cr7C3 within the grains and along grain boundaries. These findings provide a deeper understanding of the microstructural dynamics in high-nickel steels, guiding the optimization of heat-treatment processes to enhance mechanical properties for maritime applications. [ABSTRACT FROM AUTHOR]

This study investigated the fabrication and characterization of large ceramic-reinforced TWIP (twinning-induced plasticity) steel matrix composites using the lost-foam casting technique. Various ceramic shapes and sizes, including blocky, flaky, rod-like, and granular forms, were evaluated for their suitability as reinforcement materials. The study found that rod-like and granular ceramics exhibited superior structural integrity and formed strong interfacial bonds with the TWIP steel matrix compared to blocky and flaky ceramics, which suffered from cracking and fragmentation. Detailed microstructural analysis using scanning electron microscopy (SEM) and industrial computed tomography (CT) revealed the mechanisms influencing the composite formation. The results demonstrated that rod-like and granular ceramics are better for reinforcing TWIP steel composites, providing excellent mechanical stability and enhanced performance. This work contributes to the development of advanced composite structures with potential applications in industries requiring high-strength and durable materials. [ABSTRACT FROM AUTHOR]

The current investigation focuses on the viscosity, coating weight, and surface characteristics of lost foam casting coatings, examining the effects of blade shape, stirring speed, and stirring time. A systematic analysis was conducted to determine how different stirring speeds and durations influenced coating weight and viscosity. The results indicate that the blade shape has a considerable impact on the uniformity and efficacy of the coating, with some designs being far more effective in reaching the optimal viscosity and coating weight through uniformly distributed mixing. Results were consistently obtained when stirring at 800–1200 rpm. It was demonstrated that while stirring speed significantly impacts coating deposition, it has small effect on viscosity. A stirring time of 30 min was found optimal for stabilizing coating weight and viscosity without significant variations. Drying at room temperature produced smoother surfaces with fewer cracks, whereas higher drying temperatures (50 °C) were associated with increased surface roughness and cracking. Crack analysis after drying revealed that coatings mixed with the tri-blade had the lowest tendency to crack, demonstrating its superior capability for even and thorough mixing. [ABSTRACT FROM AUTHOR]

This study explores the effects of the powder-to-liquid ratio on the performance characteristics of lost foam casting coatings. The investigation focuses on how variations in this ratio affect key properties, including apparent viscosity, shear thinning behavior, coating weight, and surface morphology. Through a series of controlled experiments, coatings were prepared with different powder-to-liquid ratios and assessed for their physical and application properties. The results indicate that increasing the powder-to-liquid ratio raises the apparent viscosity and modifies shear thinning behavior. Notably, ratios exceeding 2.0 result in a sharp increase in viscosity that impedes coating application. The optimal powder-to-liquid ratio was determined to be between 2.0 and 2.2, where coatings demonstrated enhanced uniformity, improved particle distribution, and superior surface morphology. Coating weight increased up to a ratio of 2.2 but decreased beyond this threshold due to excessive viscosity. Both microscopic and macroscopic analyses confirmed that a ratio of 2.0 to 2.2 strikes the best balance for coating performance. These findings underscore the importance of precise powder-to-liquid ratio control to optimize the quality of lost foam casting coatings, offering valuable insights for refining coating formulations and application techniques in industrial contexts. [ABSTRACT FROM AUTHOR]

This article focuses on the safety valve of pressure vessels, and a new ferrofluid sealing device for pressure vessel safety valves is developed based on a special magnetic circuit. A combined method of numerical calculation and experimental analysis is used to study the relationship between seal clearance, number of seals, pole slot width, pole tooth height, pole tooth width, and the sealing pressure of the ferrofluid sealing device. The research results show that seal clearance and pole tooth width have a significant impact on the sealing performance, and as the dimensions increase, the sealing pressure decreases. As the number of seals, pole tooth height, and slot width increase, the sealing performance initially improves and then decreases. This phenomenon is attributed to the increase in magnetic reluctance in the magnetic circuit. In experimental studies, when the excitation current of the electromagnet is 240 mA and the coil turns number 30, the sealing capacity is 61.22 kPa. When the excitation current is 200 mA and the coil turns number 80, the sealing capacity is 168.24 kPa. The experiments demonstrate the compensating ability of magnetic fluid seals in combination with safety valve seals, confirming that combined seals have higher reliability compared to conventional mechanical seals. [ABSTRACT FROM AUTHOR]

This paper introduces the prototype design, magnetic field analysis and experimental test of a double-rotating ferrofluid vane micropump with an embedded fixed magnet. The micropump is based on the working principle of a positive-displacement pump, as well as the magnetic characteristics and flow properties of magnetic fluid. Through the numerical analysis of the pump cavity magnetic field and the experimental test, the structural parameters of the micropump are optimized reasonably. The pumping flow and pumping height of the micropump were characterized at different driving speeds. The maximum pumping flow rate is approximately 410 μL/min, and the maximum pumping height is approximately 111.4 mm water column. The micropump retains the advantages of simple structure, easy manufacture, flexible control, self-sealing, self-lubrication, low heat production, etc., and can block the pumped liquid backflow. The resulting double-rotating ferrofluid blades can improve pumping efficiency and pumping capacity, and can improve pumping reliability and stability to a certain extent. [ABSTRACT FROM AUTHOR]

In this study, phenomenological observations and the Kreuer interpretation of the origin of viscosity were used to develop a computational method for solving the turbulence problem of incompressible viscous Newtonian fluids based on extended Navier–Stokes (N–S) equations. The shear process in fluid flow was hypothesized to be accompanied by eddy formation, and the effects of eddies on the convection and diffusion were considered. The classical N–S equations were improved to obtain extended N–S equations. The extended equations are closed, and the sources of the velocity fluctuations are explicitly considered to be additional convection and diffusion. The extended equations are compatible with the classical N–S equations; thus, they can describe laminar and turbulent flows in a unified manner. In fluid flow simulations, the equations describing the mean flow quantities could be directly obtained from the extended N–S equations without any additional turbulence models. A numerical investigation was carried out to verify the extended equations by exploring the flow over a cube placed in a channel. The simulation results were compared with both the large eddy simulation and experimental results. [ABSTRACT FROM AUTHOR]

In this paper, the three-dimensional time-domain inversion of ground motions and its application are performed. The relationship between the incident wave time series and design ground motions is established, and the oblique incident wave time history is inverted. Subsequently, the free field is constructed based on the three-dimensional inversion of ground motions as an accurate solution. The errors based on the one- and two-dimensional inversions relative to the three-dimensional inversion are analyzed, and the errors with the incident angles, site sizes, and material parameters are revealed. Finally, the seismic responses of a canyon and an embankment dam with asphalt–concrete core are studied. The results show that the three-dimensional inversion of ground motions considers the oblique incidence angles, and the constructed three-dimensional nonuniform ground motions are more comprehensive. With regard to the core wall, the acceleration amplification effect obtained based on the three-dimensional inversion is the most significant, and the tensile failure area is the largest. Compared with the three-dimensional inversion, the tensile stress based on the two- and one-dimensional inversions is reduced by 57.1% and 20%, respectively. Therefore, the influence of the three-dimensional inversion on the seismic responses should be considered during the seismic designing of dams near faults. [ABSTRACT FROM AUTHOR]

The magnetic fluid seal (MFS) is a new type of sealing method that offers the advantages of no leakage and low wear. Hence, it is widely used in rotary seals in coal, chemical, and electric power fields. However, at high speeds, the degradation and even failure of the sealing performance severely limits the application of MFS in engineering. Therefore, this study designed a combined sealing device comprising a double screw seal and MFS and optimized the pressure resistance of the screw seal using an orthogonal test in combination with the response surface optimization method. Thus, the pressure resistance could be raised to 3.1 times that before optimization. The effect of the sealing gap on the sealing pressure of the MFS was analyzed by numerical simulation, and an optimal sealing gap value of 0.2 mm was obtained. The results of the verification test showed that the performance of the combined seal was significantly better than that of MFS alone. When sealing liquids, the pressure resistance of the combined seal reached 3.3 times that of the MFS at 3000 rpm, which indicates the application potential of MFS in high-speed working conditions. [ABSTRACT FROM AUTHOR]

Due to the complexity of working conditions and physical fields, the clearance flow field of the magnetic fluid sealing device for the main shaft of hydraulic turbine has always been a difficult point in the research of magnetic fluid seal. To study the flow characteristics of magnetic fluid in the clearance of the magnetic fluid sealing device for the main shaft of a hydraulic turbine, a numerical model of the flow field in the seal clearance of the main shaft was established and verified through experiments. The influence of the seal clearance, the width of the pole tooth, the height of the pole tooth and the width of the pole tooth slot on the flow of the magnetic fluid was studied by numerical calculation. The results show that the magnetic fluid near the pole tooth is not affected by the structural parameters and basically remains stationary. When the seal clearance is less than 0. 6 mm, the magnetic fluid in the clearance basically does not flow. When the seal clearance exceeds 0. 6 mm, the magnetic fluid near the pole slot and permanent magnet increases with the increase of the seal clearance, and the speed increases linearly. The flow of magnetic fluid near the pole tooth slot and permanent magnet decreases with the increase of the width of the pole tooth, and the velocity decreases linearly at first, decreases sharply at the width of the pole tooth from 3. 0 mm to 3. 5 mm, and finally tends to be stable. With the gradual increase of the height of the pole teeth and the width of the pole tooth slot, the magnetic fluid flow near the pole teeth and the permanent magnet will weaken. The magnetic fluid velocity near the pole teeth and slots will decrease sharply at the the height of the pole tooth from 1. 0 mm to 3. 5 mm and the width of the pole teeth from 3. 0 mm to 12 mm and finally become stable, while the magnetic fluid velocity near the permanent magnet has been decreasing linearly. [ABSTRACT FROM AUTHOR]

The widths and shapes of sealing interfaces are key indicators for characterizing the sealing stability of dynamic and static magnetic fluid seals. In this study, the interface of a magnetic fluid seal was numerically simulated and changes in the interfacial shape and width were tested and verified using a magnetic fluid seal device. The results showed that the pressure resistance decreased with an increase in seal clearance, and the magnetic fluid seal interface generated a small leakage channel. Following the complete formation of the leakage channel, the static seal gradually failed. During failure, the interface width of the magnetic fluid became narrow. At a certain pressure, the maximum pressure resistance decreased as a function of the rotational speed. Compared with a static seal, more small leakage channels and bubbles were generated. In constant conditions, such as fixed sealing clearance speed during dynamic and static sealing, the change in the width of the magnetic fluid interface of the dynamic seal was 5–7 times that of the static seal. [ABSTRACT FROM AUTHOR]

Ferrofluid micropumps have become an important development in the field of micropumps because of their self-sealing, self-lubricating, and integral properties. To further explore the relationship between pumping velocity and pumping period, in this study, an overlapping grid technology is coupled with a model with six degrees of freedom to perform numerical analyses on the inlet- and outlet-velocity pulsation characteristics of a micropump. The results show that the inlet and outlet velocities of the micropump are periodic and region-dependent and are not affected by backpressure and rotating speed. The rotating speed determines the pumping speed of the micropump, and the ratio of the rotating speeds under two working conditions is equal to the ratio of the pumping speeds. In a laminar flow range, where the Reynolds number is 8, the outlet velocity exhibited a small lateral pulsation (of 10−4 orders of magnitude). The backpressure and pumping fluid at the outlet pressurized by the micropump are key factors that induce the backflow of the micropump. To solve the backflow problem, a double-piston micropump structure that is effective in restraining backflow, without requiring additional mechanical devices, and retains the compactness and simplicity of the micropump is proposed. [ABSTRACT FROM AUTHOR]

The canned motor pump is a device in one of the most important loops in the nuclear power plant system and key technology research project, of which the seismic requirements shall be checked by Category A. It is required that the structural integrity and electric drive assembly performability of the unit can be ensured during or after operating basic earthquake (OBE) or safe shutdown earthquake (SSE). The author uses Ansys software workbench module to carry out appearance-based three-dimensional modeling, finite element meshing, intrinsic mode analysis, and carry out structural overall element analysis and calculation considering dead weight load and earthquake spectrum load. The results show that the unit major structure rotary and static parts, gear system, bearing parts, bolt and screw strengths meet the requirements and the structure maintains integrity, the relative deformation of the unit rotary and static parts shall be less than the specified value of gap among them, so as to keep the performability and not interfere with the operation. The appearance–based seismic analysis method not only can ensure the calculation accuracy, but also can greatly reduce the workload in calculation and checking, has a certain learning value.