The flow control valve, as a core component of the molecular beam epitaxy (MBE) system, determines the control performance of molecular flux in the deposition chamber and the stability of thin-film growth through its geometric precision, while the valve spool inclination angle can influence the molecular flux. This study combined experimental and simulation methods to systematically investigate the impact of different tilt angles on molecular flow. An experimental system consisting of an arsenic evaporation cell, a flow control valve, a cracker source, and a deposition chamber was constructed. A mass spectrometer was used to measure arsenic atom signals in the deposition chamber at different valve spool travel distances, and the background equivalent pressure (BEP) was calculated as a representation parameter for molecular flux. The experimental results show that the BEP increases linearly with the valve spool travel distance. However, when the travel exceeds 80%, the growth rate tends to plateau. On the simulation side, the influence of different valve spool structures and travel distances on the outlet pressure of the flow valve was analyzed based on the view factor model. The simulation results indicate that, under three different directional inclination angles, the outlet pressure decreases compared to the original structure when the valve spool travel is 1-2 mm, with a maximum reduction of 18.4%. At other travel distances, the outlet pressure increases, with a maximum increase of 6.09%. Moreover, as the travel distance continues to increase, the increase gradually diminishes and approaches zero. The larger the inclination angle, the greater the deviation of the outlet pressure from the original value. When the valve spool travel increases to 16 mm, this deviation gradually decreases and ultimately approaches zero.

Using a dual-chamber electron beam evaporation system and an improved bottomless alumina crucible, combined with a step-by-step evaporation process, the density and uniformity of aluminum films deposited by electron beam evaporation are significantly enhanced. Compared with the magnetron sputtering coating equipment, 1-micron-thick aluminum films were deposited on 4-inch silicon substrates. The resistivity, uniformity, reflectivity, and density of the films were tested. The results show that the aluminum films prepared by the improved electron beam evaporation technique outperform those deposited by magnetron sputtering in terms of resistivity, uniformity, and reflectivity, while there is no difference in density between the two methods. This research provides new evidence for revising the performance comparison between the two methods in preparing aluminum films.

Addressing the challenge of p-type doping in gallium oxide, this study prepared β-Ga₂O₃ films with varying nitrogen concentrations on Si and quartz substrates via radio-frequency magnetron sputtering. The effects of nitrogen doping on the structure, optical, and electrical properties were systematically investigated. The results indicated that nitrogen doping did not alter the fundamental crystal structure of β-Ga₂O₃ but significantly modulated its optical bandgap, which decreased from 4.92 to 4.78 eV with increasing N content. Hall-effect measurements revealed that nitrogen doping effectively tuned the carrier concentration and mobility, achieving a conversion from n-type to p-type conductivity at a specific doping level. Furthermore, photoelectric characterizations demonstrated a non-monotonic influence of nitrogen doping on the UV photoresponse of β-Ga₂O₃ metal-semiconductor-metal devices. Optimal nitrogen doping effectively enhanced the photo-to-dark current ratio and detection performance by suppressing dark current and optimizing carrier behavior.

Vacuum arc metallurgy is a core specialized metallurgical technology for the preparation of high-end specialty metal materials. Leveraging its unique advantages of low oxidation, low gas content, and high purity in a vacuum environment, it has become a fundamental process for the industrial production of key strategic materials such as titanium alloys, nickel-based superalloys, ultra-high-strength steels, and refractory metals. As two major core equipment in the field of vacuum arc metallurgy, the vacuum arc remelting furnace and the vacuum consumable shell furnace focus on large-quality ingot production and precision specialty casting, respectively, and are widely applied in critical sectors like aerospace, high-end equipment, nuclear power, and national defense. This paper systematically elucidates the working principles, equipment structures, and technical characteristics of these two core types of equipment, reviews the technological development and research status both domestically and internationally, analyzes the technical bottlenecks in the current processes of large-scale, precision, and intelligent development, summarizes advancements in key technologies such as power systems, arc control, solidification regulation, and vacuum assurance, and finally, based on the demands of the high-end materials industry, outlines the trends toward intelligent, large-scale, green, and integrated development of vacuum arc metallurgy equipment, providing theoretical references and technical support for the iterative upgrading and engineering application of specialized metallurgical equipment.

Taking the double-walled core barrel of a certain type of hot isostatic pressing (HIP) furnace as the research object, this study investigates the influence of the equal shear stress pre-stressed steel wire winding layer on the buckling failure behavior of the core barrel based on the cylindrical buckling theory. Two numerical simulation methods, namely elastic prestressed buckling analysis and elastoplastic prestressed buckling analysis were adopted. The critical external pressure for buckling obtained from the simulations is compared and verified with the analytical value derived from the classical Bresse-Bryan formula. The results show that there is a significant deviation between the analytical value of the Bresse-Bryan formula and the numerical simulation results, with the analytical value being excessively high, which fails to accurately characterize the actual external pressure-bearing capacity of the core barrel. Compared with the results of the elastic pre-stressed buckling analysis and the analytical value, the calculation results of the elastoplastic pre-stressed buckling analysis exhibit the highest agreement with the actual bearing characteristics. Further investigations into the effects of interlayer gap, slip effect, and water-cooling groove structure of the double-walled barrel on the critical external pressure for buckling reveal that an increase in interlayer gap, a decrease in interfacial friction coefficient, and the presence of water-cooling grooves all lead to a decrease in the critical external pressure for buckling of the core barrel. The research results of this paper may provide theoretical support and engineering design guidance for the external pressure buckling failure analysis of pre-stressed steel wire-wound core barrel structures.

Vacuum levitation melting furnaces offer advantages such as contactless heating, high purity, and low pollution, making them widely used in the preparation of high-performance metal materials. However, the complex nonlinear relationships between multi-physics coupling and process parameters within them make precise control difficult for traditional methods that rely on experience and experimentation. This paper constructs a mechanistic model based on thermodynamics and electromagnetics. By combining historical operating data to modify boundary conditions and parameters, it created a digital twin of the melting process, achieving dynamic modeling and updating that was consistent between the virtual and the real. Furthermore, a physicalinformed machine learning approach was introduced to train an AI-powered process parameter prediction model under physical boundary constraints. The AI-predicted parameters were applied to actual melting, and the resulting data was used to inversely optimize the mechanistic and AI models, forming a closed-loop co-evolutionary frame work. This approach significantly improves the accuracy and prediction reliability of the mechanistic model, enabling adaptive process control and intelligent production. It transcends the limitations of traditional empirical control and purely data-driven models to construct a novel intelligent control paradigm integrating interpretable mechanisms and AI adaptability. This approach provides an effective solution for the digital twinning and intelligent upgrading of high-end vacuum metallurgical equipment, as well as for overall technological advancement in the industry.

High-nitrogen steels (HNS) exhibit exceptional strength-toughness combinations, corrosion resistance, and high-temperature stability, making them critically valuable for applications in aerospace, energy equipment, and high-end manufacturing sectors. Pressurized electroslag remelting (PESR) is currently the core industrial process for producing HNS. A key technical challenge in PESR lies in maintaining dynamic equilibrium between the cooling water pressure in the mold and the internal gas pressure within the furnace chamber during melting, thereby preventing mold deformation or even catastrophic failure caused by excessive pressure differentials. This paper systematically reviews the current methods for HNS production and the state-of-the-art development of PESR technology. It focuses on analyzing the technical requirements of the gas-water pressure balance system and compares two dominant design approaches: independent control and interlinked control. Furthermore, the paper discusses critical design considerations for piston-cylinder mechanisms, emphasizing that increasing the effective piston area, enhancing machining precision, and selecting wear- and corrosion-resistant materials are essential for achieving high sealing integrity and precise pressure control. The findings provide theoretical support and technical reference for the independent development of high-performance domestic PESR equipment.

Aiming at the problems of temperature stability and uniformity existing in the sintering process of tantalum powder in high-temperature and high-vacuum heat treatment furnace, this study proposes a new temperature calibration method based on the volume shrinkage characteristics of the anode block of tantalum electrolytic capacitors. By pressing tantalum anode blocks of specific specifications （1 g tantalum powder, with a diameter of 6 mm and a pressing density of 5.5 g/cm³）, under the sintering conditions of 1 500~2 000℃, a volume shrinkage ratio control model was established in combination with the 3σ principle of the Gaussian distribution. The experimental results show that this method can effectively monitor the temperature deviation in the front, middle and rear areas of the furnace. When the volume shrinkage ratio exceeds the confidence interval, it indicates that the thermocouple is attenuated and needs to be replaced in a timely manner. Compared with the traditional temperature calibration method using temperature measuring rings, this method has the characteristics of strong temperature adaptability and high precision （within ±5℃）, and can provide a reliable basis for the optimization of the sintering process of capacitor-grade materials of tantalum powder.

A safety state identification method based on the vacuum degree arc energy coupling model is proposed to address the problem of transformer oil carbonization caused by sealing failure of vacuum arc extinguishing chamber. By analyzing the diffusion characteristics of metal vapor in the vacuum arc extinguishing chamber （pressure≤10^-4 Pa）, a synergistic criterion for ultraviolet radiation, vibration signals, and acetylene growth rate is established. According to the Markov constraint conditions of the transformer vacuum on-load tap changer, the average resistance in the topology circuit of the tap changer is defined, and the electrical stress equation of the tap changer is solved to complete the electrical stress analysis of the transformer vacuum on-load tap changer. Using the electrical stress equation, the transient impulse component and sensitive frequency band component of the tap changer are extracted, and the electrical stress equation of the tap changer is derived to solve the safe state threshold of the switch operation and achieve the identification of the safe state of the transformer vacuum on-load tap changer operation. The results show that effectively determining the real-time voltage regulation status of transformer vacuum on-load tap changers based on vibration signals and power signals is beneficial for ensuring the accuracy of switch operation status recognition results.

To overcome the limitations of current ferroptosis monitoring methods for tumor cells-namely poor real-time performance and high invasiveness-a label-free, non-contact dynamic monitoring approach was developed by integrating high-vacuum conditions with piezoelectric resonance principle. A piezoelectric resonator with a high quality factor (Q>10⁴) was designed, and a resonant sensing system with an ultimate vacuum level of 10^-4 Pa and a leakage rate below 10^-8 Pa·m³/s was established. Ferroptosis was induced in tumor cell models, during which resonance frequency shifts, damping changes, and mass-loading responses were recorded in real time. Signal features were extracted via Fourier transform and principal component analysis. The experimental results demonstrate that high vacuum significantly suppresses gas damping and thermal noise, thereby enhancing resonance sensitivity. Within 60 minutes of induction, frequency shifts exceeded 18.1 Hz and damping variations reached 21.0%, both highly correlated with intracellular ROS levels and iron ion concentrations (R²=0.81). Regression analysis revealed a nonlinear increase in Q-value with decreasing pressure, identifying 10^-3 Pa as the optimal vacuum window for sensing performance. By enhancing Q-factor and reducing background interference, the high-vacuum chamber enables the sensor to capture changes in cellular vibration modes, achieving high-precision, non-invasive, and label-free dynamic detection of ferroptosis at the cellular level. This work expands the applicability of vacuum-enabled biosensing technologies and provides a novel platform for tumor diagnosis and therapeutic monitoring.

Using glass fibers and phase change microcapsules with different ratios and ingredients as raw materials, energy storage fiber-reinforced vacuum insulation panel (VIP) composite core materials were prepared via a wet forming process. As the content of phase change powder increased from 0% to 45%, the thermal conductivity, affected by solid-state heat conduction, rose from 2.61 mW/(m·K) to 4.84 mW/(m·K). Among these, the core material containing 37℃ phase change material demonstrated the best comprehensive performance (2.84 mW/(m·K)). By reducing the thickness of the single-layer core material from 2 mm to 0.8 mm, the thermal conductivity was significantly reduced to 2.22 mW/(m·K). Vacuum degree had a significant impact on performance. The performance was stable when the internal pressure was lower than 100 Pa and a sharp rise in thermal conductivity otherwise. Although the introduction of phase change materials slightly increased the initial internal pressure, it effectively suppressed the increase in internal pressure during the static period, improving the long-term service stability of the board. This energy storage fiber-reinforced VIP, while maintaining excellent thermal insulation performance, endowed the core material with heat storage and temperature regulation functions, demonstrating significant application value in the field of energy conservation and consumption reduction.

To suppress oxidation defects induced by laser cladding under atmospheric conditions, vacuum laser cladding was employed to fabricate 316L stainless steel coatings. The effects of vacuum degree (from low to high) on the microstructure and properties of the coatings were systematically investigated. The results indicated that with increasing vacuum degree (i.e., decreasing oxygen content), oxide inclusions in the coatings are significantly reduced and the grains are markedly refined: the primary dendrite arm spacing decreases from 14.52 μm under atmospheric conditions to 5.84 μm at a high vacuum level of 10^-1 Pa. Meanwhile, the porosity of the coating was reduced from 2.85% at atmospheric environment to 0.12%, and the crack density continuously decreased with increasing vacuum degree, approaching zero at 10^-1 Pa. Owing to the synergistic effects of microstructural purification and grain refinement, the microstructural integrity of the coatings is significantly improved, providing a structural basis for the enhancement of mechanical performance and service durability. This study demonstrates that controlling the vacuum degree is an effective approach to optimizing the quality of laser-cladded coatings and provides a reference for the vacuum fabrication of high-performance coatings.

Vacuum conditions (10-1 000 Pa) induce unique gas-liquid interface behavior and mass transfer processes in porous medium, significantly affecting multiple-phase fluid flow efficiency and the structural response of the medium. There is a complex relationship between multiphase flow in porous medium and geomechanical deformation processes; particularly in environments with active seismic faults, this relationship is a key factor, influencing the safety and stability of underground engineering projects such as geological carbon dioxide storage. This study proposesd a novel coupled model that incorporated gas slip effects, low-pressure adsorption-desorption kinetics, and dynamic contact angle equations to reveal the feedback mechanisms between gas-liquid interface evolution and multiple-phase fluid flow under vacuum suction. By quantifying the regulatory roles of equivalent osmotic pressure and low-pressure gradients on capillary force reconstruction and interfacial mass transfer, a dynamic evolution model of pores and fractures was established. This model enables high-precision simulation of low-pressure zone propagation, gas-phase channel formation, and matrix contraction during vacuum extraction. The results indicate that increasing the vacuum to 500 Pa increases the gas-liquid interface migration rate, widens the solid-liquid contact angle, and significantly optimizes the dewatering efficiency. At a higher vacuum degree (200 Pa), the interfacial migration rate accelerated further, and the dewatering efficiency approached a steady state within 10 minutes, far outperforming the results under lower vacuum conditions. This conclusion indicates that increasing the vacuum, by reducing residual pressure within the pores, restructuring capillary force equilibrium, and enhancing the interfacial advancement rate, can be a key factor in achieving efficient dewatering and low residual saturation, providing direct evidence for the parameter optimization of vacuum dewatering processes. This model provides theoretical support for vacuum dehydration technology, the design of porous filtration media, and surface treatment processes.

When constant vacuum field is used for cleaning slender lumen instruments, the axial vacuum attenuation amplitude reaches 0.015~0.02 MPa due to the influence of conductivity limitation, which causes the uneven distribution of boiling mass transfer and the residual rate of pollutants at the end of lumen exceeds 25%, and restricts the development of current lumen cleaning technology. Therefore, an actively programmable dynamic vacuum field was proposed and established in this study. By utilizing gradient compensation, rate regulation, and temporal matching, this approach effectively resolves the mass transfer limitations arising from the passive adaptation of conventional static vacuum fields. Based on the difference of conductance of four typical cavities, a dynamic vacuum parameter design method was established, and a quantitative model of desorption rate and mass transfer uniformity was constructed by combining multi-field coupling simulation and experimental verification. The results show that, compared with the traditional constant vacuum method, the dynamic vacuum field can control the vacuum fluctuation in the whole cavity to 0.003 MPa, with a decrease of 70%-76%, the desorption rate of four kinds of cavity pollutants exceeds 90%, and the flow rate and volumetric mass transfer coefficient of cleaning solution are increased by 100%-135.7% and 33%-35%, respectively. The goodness-of-fit of the quantitative models were all over 0.9, and the average relative error was less than 4.2%.

Aiming at the problems that the traditional gravity drainage system is prone to clogging due to freezing and failure caused by low air pressure in high-altitude and cold tunnels, the adaptive design and vacuum stability research of the vacuum drainage system in extreme environments were carried out. The system design method introducing air pressure, temperature and seepage correction factors was constructed. The pump efficiency environmental correction model and the zonal redundancy layout strategy were proposed, and the field deployment and operation monitoring were completed in the plateau tunnel. Based on the SCADA platform, a coupled response model of vacuum degree and environmental parameters was established, including seal degradation, increased flow resistance and pump efficiency fluctuations as the dominant disturbance mechanisms. The results show that the gauge pressure inside the pipeline can be stably maintained within -75 to -60 kPa, with a fluctuation of less than 3.5 kPa, and the maintenance rate is over 98% under extremely cold conditions. The control test verified the significant improvement effect of the sealing structure and thermal control measures on the steady-state operation of the system. The research systematically established the design theory and operation control method of vacuum drainage suitable for high-altitude and cold environments, providing theoretical references for tunnel drainage projects in cold regions.