As a mechanical vacuum pump, dry vacuum pump has the advantages of wide pumping speed range, no oil in the pumping chamber, no friction of components, low energy consumption and corrosion resistance. It has become the preferred vacuum acquisition equipment in microelectronics, semiconductor, precision machining, new energy equipment and other industries at present, because there is no oil or other working medium in the pump chamber, and it can provide a relatively clean vacuum environment. In this paper, the application scenarios of dry vacuum pump in semiconductor preparation and new energy equipment manufacturing industry are briefly described. The product characteristics of some dry vacuum pumps are explained. The development space and challenges of domestic dry vacuum pump industry are summarized.

Based on the geometrical characteristics of screw vacuum pump rotor and the internal leakage model of screw vacuum pump, a mathematical model of the internal working process of the screw vacuum pump is established. With the help of MATLAB software, the fourth-order Runge-Kutta method is used to solve each differential equation as the initial condition repeatedly, and an application program that can quickly calculate the pumping speed curve of the screw vacuum pump is designed according to the MATLAB/GUI interface. The program is used to predict and calculate the pumping speed curve of a variety of screw vacuum pumps, and it is improved according to the results of the examples.

The Knudsen pump, a type of micro-pump, is widely used in microelectromechanical systems (MEMS). The paper proposes a ratchet-type Knudsen pump with varied surface accommodation coefficients. The gas flow characteristics of this pump are simulated numerically by using the direct simulation Monte Carlo (DSMC) method. The results show that surface accommodation characteristics significantly influence the flow field and gas separation features. Distinct surface reflection characteristics give rise to varying thermally induced flow mechanisms within the Knudsen pump. The primary thermally induced flow in the Knudsen pump at α_n=σ_t=0 of the inclined edge of the triangle is the radiometric flow, which is advantageous for gas separation. At α_n=σ_t=1 of the triangular inclined edge, the primary thermally induced flow is the thermal edge flow, which is not clearly advantageous for gas separation. The velocity difference and diffusion velocity difference between He and Xe are greatest near the upper vertex of triangular ratchet at α_n=σ_t=0 of the triangular inclined edge, while the differences are greatest near the left vertex of triangular ratchet at α_n=σ_t=1. Moreover, the flow velocity and diffusive velocity increase as the gas becomes lighter. This paper may establish a theoretical foundation for creating and producing miniature gas separation devices applicable in practical engineering contexts.

Pumping speed is an important index to measure the pumping performance of cryopump. The throughput method is generally used to measure the pumping speed of cryopump in China. In addition, the orifice method is also an important method for measuring the cryopump pumping speed. In this paper, detailed introduction of pumping speed test for different gases of ZD-200 caliber cryopump was conducted based on the orifice method specified in the current standards. The results show that the pumping speed of cryopump for N₂ and Ar are 2 410 L/s and 1 884 L/s respectively, which are significantly better than the indicators of similar products at home and abroad. The pumping speed of cryopump for H₂ is 2 577 L/s, which is at the same level as the technical indicators of domestic and foreign products. The test results obtained by the orifice method have high accuracy and credibility.

Taking a vehicle carbon fiber fully-wound hydrogen storage cylinder as the research object, based on the ANSYS workbench platform, the difference of the cylinder structure layer and the uneven distribution of temperature load are fully considered, and the fluid-thermal-solid coupling numerical simulation and analysis are carried out. The specific method is to firstly carry out 3D numerical simulation of the gas flow field inside the cylinder during the fast filling process to study the law of temperature rise, then load the flow field calculation results into the cylinder structural layer for steady-state thermal analysis, and finally load both the flow field and thermal analysis results into the cylinder structural layer for structural static analysis. The results show that the maximum temperature of the cylinder and the maximum stress on the carbon fiber composite layer appear at the connection between the end head and the cylinder when the filling is finished. The thermal stress caused by the temperature load is small compared with the mechanical stress caused by the internal pressure. The difference between the mechanical stress and the coupling stress is not large, and the mechanical stress on the carbon fiber composite layer is slightly smaller than the coupling stress, while the thermal stress caused by the temperature load on the aluminum alloy liner layer is partly offset by the mechanical stress due to the large expansion coefficient, making the coupling stress smaller than the mechanical stress.

The lifespan of rubber sealing structures plays a crucial role in the long-term operation of space stations in orbit. In this study, EPDM sealing was taken as the research object. First and foremost, the stress-strain constitutive relationship of the rubber after thermal oxidation experiment and the compression permanent deformation of the rubber were tested. Secondly, based on the theory of time temperature equivalence, a theoretical model of sealing performance under the influence of thermal oxygen aging was established to analyze the sealing performance of rubber over a long service life. Besides, this model was used to study the impact of aging performance changes on the macroscopic contact performance between EPDM and titanium alloy (TC4), EPDM and polyimide (PI) contact pairs. The results show that the reduction in thermal oxygen aging performance indicators will result in decrease in the macroscopic contact pressure and contact width of rubber seals. Under the same aging performance indicators, the contact width and contact pressure between EPDM and PI contact pair of rubber seals are greater than those between EPDM and TC4 contact pair.

In order to improve the pumping performance of the liquid-gas jet pump, it is proposed to install a multi-stage series nozzle behind the main nozzle of the liquid-gas jet pump. Numerical simulations of the gas-liquid two-phase fluid movement in the conventional liquid-gas jet pump and the multi-stage series nozzle liquid-gas jet pump were conducted using Fluent software. Under the same operating conditions, a comparative analysis was conducted on the pumping power, pressure field distribution, velocity field distribution, and gas phase volume distribution of two liquid-gas jet pumps. The results show that at the inlet pressure (gauge pressure) of the working fluid of 0.3 MPa, 0.35 MPa and 0.4 MPa, the pumping performance of the multi-stage series nozzle liquid-gas jet pump has been improved by 18.1%, 13.4% and 20% compared to the conventional liquid-gas jet pump respectively. The multi-level structure of the nozzle promotes pulse and momentum exchange between the gas-liquid phases. The research results have certain reference significance for the optimization design and improvement of suction performance of liquid-gas jet pumps.

Aiming at the problems that low machining efficiency and poor quality stability of the slotting machine, and high investment of the multi-axis CNC gantry planer in the existing machining technology of the slide valve of the vacuum pump, a special planer for machining slide valve is developed. The mechanical structure design, such as expansion and positioning, the rotation of the slide valve, the movement of the planer, and intelligent reform of the control system are carried out based on the common shaper. Using PLC control and touch screen as a human-computer interface to achieve automatic machining of the slide valve. The production verification shows that the special planer can achieve multi-axis CNC gantry planer machining efficiency, and the production efficiency and product qualification are greatly improved compared with traditional slotting machine machining.

By improving the constant pressure method, the differential pressure method was proposed to test the hydrogen absorption performance of non-evaporable getter (NEG). A constant conductance element is installed between the gas room and the induction chamber to provide controllable inlet flow with micrometering valve. The sorption performance parameters of NEG can be calculated by measuring the pressure of induction chamber, gas room and reference chamber. The sorption performance of two NEG absorbers measured by the improved constant pressure method and differential pressure method were compared during sorption test. The results show that the sorption capacity measured by differential pressure method is 0.07268 Pa·L lower than that measured by improved constant pressure method. The suction of clean chamber wall leads to higher test results of the improved constant pressure method than the actual result, while the test results of the differential pressure method are not affected, and the results of the modified improved constant pressure method are close to those of the differential pressure method. The differential pressure method can obtain more accurate and effective performance parameters of getters. In the differential pressure method, the reference part and the experimental part are tested at the same time, which can shorten the test time and reduce the error caused by inlet controlling.

Nano-sized TiO₂ optical films were deposited on PMMA by DC pulsed magnetron sputtering method. The effects of deposition power, substrate temperature on the structure and optical properties of TiO₂ films were studied. The optical properties, elemental composition, crystallization properties and microstructure of the films were analyzed by means of elliptic polarization analyzer, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), spectrophotometer and atomic force microscope (AFM). The results show that with the increase of deposition power, the oxygen content of the film decreases, the particle size of the film decreases, and the refractive index increases, while the transmittance and reflectivity of the visible light band decreases. The increasing substrate temperature reduces the deposition rate of the film and promotes the aggregation of the film particles. The refractive index and visible light transmittance both increase with the substrate temperature. The band gap of TiO₂ film ranges between 3.12-3.16 eV and decreases with the increase of deposition power and substrate temperature.

Three kinds of (Ni,Pt)Al coatings were fabricated on nickel-based single crystal superalloy via chemical vapor deposition (CVD) technique at different deposition temperature and deposition pressure. The influence of critical CVD processing parameters on the high temperature protective performance of (Ni,Pt)Al coatings was systematically investigated. The phase constituent, microstructure and chemical content of the three (Ni,Pt)Al coatings were analyzed by XRD, SEM and EDS. The results show that with the increment of deposition temperature, the diffraction peaks of (Ni,Pt)Al coatings shift to a large 2θ-degree at the same deposition pressure. However, at the same deposition temperature, the coating diffraction peaks shift to a small 2θ-degree at the elevated deposition pressure. The grain size of the coating tends to become larger and the thickness of the coating correspondingly turns into thicker accompanying with the increment both of deposition temperature and deposition pressure. After evaluation of isothermal oxidation (1 100 ℃/250 h) and gas hot corrosion (900 ℃/100 h), the oxidation kinetic weight gain of the coating specimen with deposition temperature of 1 080 ℃ and deposition pressure of 300 mbar is less than that of the other two types of coating samples, and the (Ni,Pt)Al coatings prepared by this process has the best high temperature protective properties. Controlling the premature initiation and growth of microcracks in the oxide film at local position on top of coating surface, and reducing the number of microholes caused by hot corrosion are the trend of CVD processing optimization to improve the high temperature oxidation-resistance and corrosion-resistance of (Ni,Pt)Al coatings.

The secondary surface mirror of colorless transparent polyimide (CPI) film was prepared using magnetron sputtering coating process, with CPI film as substrate and Ag or Al as reflecting layer. The reflectance curve of secondary surface mirror film was analyzed by using Lambda 950 spectrophotometer. The reflectivity differences of secondary surface mirror of CPI film, silver plating on polyfluoroethylene propylene (F46) film and aluminum plating on polyimide thin film (PI) were studied in infrared and visible light bands. The results show that the secondary surface mirror of silver plating on CPI film is similar to that of F46 film in visible light band, up to 95%. Compared with the traditional PI aluminum coating, the reflectivity of CPI aluminum coating is obviously improved. In infrared light band, the reflectivity of CPI thin films is not as good as that of F46 thin films, which is comparable to that of traditional PI thin films. The absorption and emission ratio (α_s/ε) of silver coating on CPI film is 0.19, which is close to that of the silver coating on F46 film, and the temperature resistance is better than that of F46 film.

The background and main contents of the new four parts of GB/T 26332 optics and photonics-optical coatings in 2022 were introduced. The differences between Chinese national standard GB/T 26332 and the adopted international standard ISO 9211 were discussed. The changes in the contents of different editions of the international standard ISO 9211-7 were analyzed. Finally, suggestions and prospects for the subsequent formulation and revision of GB/T 26332 were given.

The external mechanized chamber heat treatment furnace is an important equipment for heat treatment of steel pipes and bars. The scientific and rational design is conducive to improving the operating efficiency of the external mechanized chamber heat treatment furnace and the steel pipe quality. This article analyzes the overall equipment design requirements of the external mechanized chamber heat treatment furnace from the perspective of process and structure design. Taking the design of a certain treatment furnace as an example, combined with its process requirements, installation process, safety and quality inspection requirements, the difficulties in heat treatment furnace design were explored from different aspects, in order to provide a reference for relevant personnel.

A crucible cooling device used to safely cool the crucible in the vacuum electron beam melting furnace was independently developed by the institute of physical and chemical engineering of nuclear industry. In this paper, the seismic identification test of the crucible cooling device was carried out. The resonance frequency of the crucible cooling device before and after the seismic test was measured, and five operation benchmark seismic tests and one safe shutdown seismic test were carried out by seismic station. The test results show that the crucible cooling device has sufficient seismic strength, and can operate normally under the specified seismic conditions to meet the seismic performance requirements.

The temperature gradient and liquid steel flow in the tundish of continuous casting in the vacuum induction melting process play an important role in the removal of solid inclusions, which directly affect the purity of liquid steel. Based on the analysis of the current situation of numerical simulation of temperature field, flow field and stress field coupling in continuous casting tundish, the numerical simulation of inclusion removal under multi-field coupling is summarized. The heat flow coupling, fluid solid coupling and fluid solid thermal coupling simulation methods are introduced. The numerical simulation of inclusion removal under fluid-thermostructure coupling is proposed. A reasonable combination of flow control devices and a selection of resistant materials can improve the quality of liquid steel.

The constraint frame of hot isostatic pressure furnace plays the role of restricting the two ends of the container when the container is pressurized and carrying the axial force inside the container. In order to optimize the structure quality and force distribntion of the frame, simulation calculation was conducted on components of different sizes using the static analysis function of CAD software, and the optimal size parameters were obtained. The results show that when the frame thickness is 220 mm, the width is 740 mm, the end width is 390 mm, and the four corners are chamfered 140 mm, the frame quality and stress distribution are optimal, which can meet the design requirements.

In order to meet the requirements for the development of long-pulse high-power cyclotron oscillator, the preparation process and quality reliability of large-size (100 mm diameter slices) diamond window assemblies were studied. The sealing stress distribution is calculated by thermodynamic simulation software, and it is concluded that the window slices are subjected to the lowest stress when the sealing width is 3 mm with double-sided flat sealing structure. The diamond window assembly with airtight sealing is developed by combining Ti-Ag-Cu active brazing and electron beam high-energy welding. The large-size diamond window assembly has good dielectric properties, can withstand 550 ℃/48 h hot baking test, and the average tensile strength of the diamond-oxygen free copper sealing part reaches 118.2 MPa, which meets the requirements for the use of cyclotron tubes.

In a high-temperature superconducting （HTS） electrodynamic suspension （EDS） transportation system, the application of vacuum technology provides a perfect vacuum environment which can obtain and maintain the superconductive performance of the coils for HTS magnets, so that it can satisfy the requirements of the train propulsion, levitation, and guidance. In this paper, the EDS transportation system principle and the structure composition of onboard HTS magnets are introduced. Through vacuum system design and vacuum acquisition equipment selection, combined with vacuum measurement and leak detection technology, the high vacuum holding system with a vacuum degree of 1×10^-5 Pa and a maximum leakage rate of 1.33×10^-10 Pa·m³/s for superconducting magnet was developed. And it has been stably put into service in the full elements test system of HTS EDS which is the first self-developed in China.