The transition flow is solved by the joint calculation of NS and DSMC methods. The NS/DSMC coupling method has the advantages of the computational efficiency of NS method and the computational accuracy of DSMC method.In this paper, the principle of key technologies in the development of coupling method is introduced in detail, the application progress of coupling method in spatial plume research is discussed, and the shortcomings of computational domain partition method are explained. Then the application of coupling technology in the flow around neighbor spacecraft is analyzed. It is proposed that the error between the coupling calculation and the experimental results may be caused by DSMC statistical scattering, which can be eliminated by cumulative statistics. In addition, the application of NS/DSMC coupling method using two-phase flow model in MEMS field is also discussed. Finally, the application of coupling method in vacuum field and the research direction of coupling algorithm in the future are prospected.

The cylindrical specimens of a single crystal superalloy with diameter of 15mm and 30mm were prepared using the same melting process and directional solidification process. The stress rupture properties at 980℃/250MPa and high cycle fatigue properties at 800℃ of the alloy with two casting dimensions were tested. Dendrite microstructure, the as-cast γ′ phase, heat treated γ′ phase, micropore, stress rupture and high cycle fatigue fractograph and fracture microstructure of the alloy with different casting dimension were examined by OM, SEM and TEM. The results show that with the increase of casting dimension, the primary dendrite arm spacing, the size of as-cast and heat treated γ′ phase, and the size and volume fraction of micropore increase. The stress rupture properties of the alloy decrease, the fracture mechanism has no obvious change and is dimple model with casting dimension increasing. The quantity and size of micro-crack and the γ′ raft thickness on the stress fracture microstructure increase with the casting dimension increasing, while high cycle fatigue properties of the alloy decrease. At last, the relationship between the property and microstructure of the alloy is discussed.

Through the calibration chamber and vacuum tube installed on the intake pipe of the mass spectrometer, the trace gas with the same content range as the gas in microsphere can be obtained. The precision of quantitative analysis of trace gases by mass spectrometer and the effect of measured deuterium pressure on the calibration factor of D₂ were studied. The results show that the precision of the quadrupole mass spectrometer is high, and the relative standard deviation of the 10 repeated measurements under different pressures is less than 0.004. The mass spectrometer has a high stability within one month after calibration, and it has a high accuracy with the quantitative analysis error is less than 1%. The concentration calibration factors for D₂ and Ar varied no more than 3% within one year, while the pressure calibration factors for D₂ varied more than 8% within one year. The pressure calibration factor η of D₂ is inversely proportional to the pressure P₁ of the measured deuterium gas, and there is a good linear relationship between η and logP₁, which has a high stability in half a year.

Transition layer is a key factor to improve the film/substrate relationship and increase the quality of the film. In this paper, the epitaxially grown process of Cr, which is a common transition layer material, was simulated using molecular dynamics method. Surface topography, roughness, radial distribution function and adhesion strength was analyzed to study the effect of incident energy on the film quality. The results show that at the initial stage of deposition, the film/substrate interfacial interaction was the main factor affecting the growth mode of the film. As the incident energy increased, the growth mode changed from Frank-Vander Merve to Volmer-Weber. As the deposition process progressed, the film surface roughness gradually raised during low-energy deposition(15-50eV). However, the opposite trend exhibited during high-energy deposition(75eV) because of the etching effect, and the surface roughness decreased gradually. Meanwhile, the film/substrate interface was destroyed by the shallow injection in the lower energy range, which weakened the film/substrate adhesive strength. Further improving the deposition could improve the film/substrate adhesive effect by forming a composition gradient layer. The research results in this paper shows important guiding significance for the thin film deposition process: increasing the incident energy during the deposition process does not meaning a positive effect, and it must be controlled in a suitable energy range.

Fluorocarbon(FC) film exhibits characteristics of low dielectric constant and friction coefficient, high thermal stability and chemical inertness, strong ultraviolet absorption, etc. As a surface modification material, it is expected to improve environmental weatherability and insulation stability of dry reactors during operation. Research on FC film preparation by sputtering has the advantages of less contamination by impurity particles, large deposition area, low cost of reactants, and no environmental pollution. The plasma state during sputtering is a key factor affecting the quality of FC film. This paper discusses the synergistic effects of vacuum chamber temperature and substrate temperature on the chemical composition, microstructure, deposition rate and micromorphology of FC film. The results show that the temperature directly influence generation, transportation and deposition of sputtering components. The increment of temperature results in morphology evolution law of particle-cluster-three-dimensional network structure. Deposition rate, roughness, fluorine to carbon ratio and the proportion of sp³ hybrid carbon increase with the sputtering temperature. Therefore, FC film develops in the direction of PTFE-like film, which is expected to exhibit more excellent physio-chemical properties.

The structural characteristics of a three chamber vertical vacuum induction precision casting furnace is introduced first. Then the overview of other major types of precision casting furnaces are described. Finally, through the comparison of technology and market situation, the current market situation and the future development direction of precision casting furnace are analyzed.

With the rapid evolution of the MEMS and VLSI technologies, small nano-satellite, being low cost and competent in complicated tasks, has become a crucial orientation of the commercial aerospace in the world. The on-orbit maneuverability ability of the small nano-satellite promotes the serial micro-electric propulsion system′s development and on-orbit verification. In this paper, the demands of the electric propulsion system for the small nano-satellite are firstly demonstrated. Then the characteristics of the micro-electric propulsion system are introduced, including the product engineering and on-orbit verification of the micro-electric propulsion system at domestic and overseas. Finally, the development and on-orbit application of the micro-electric propulsion in China are prospected.

High power proton beam accelerators are widely used in basic physics, nuclear industry, family safety and other fields, in which high-power waveguide RF cavity is very important. Boat shaped RF cavity has the highest no-load Q value and shunt impedance, which is a good choice for GeV proton beam accelerator. For the manufacture of boat shape copper cavity, the biggest difficulty lies in the forming of boat shape cavity and the welding of copper. In this paper, the 6mm thick semi-Y-state oxygen free copper(OFC) electron beam welding joint is studied, and a detailed vacuum electron beam welding process is developed. The results show that after electron beam welding, the welded joint of semi-Y-state OFC plate has no obvious surface defects, and the as-cast microstructure is equiaxed crystal. From weld to base metal, the microhardness of semi-Y-state OFC welded joint changes significantly, and the microhardness of weld is about 65% of the base metal. After stretching at room temperature, the semi-Y-state OFC welded joint has obvious plastic deformation, and the fracture occurs in the weld fusion zone. The tensile strength of semi-Y-state OFC welded joint is equivalent to 95% of the base metal, about 228MPa, and the elongation after fracture is 64%-67%, which can meet the welding and forming requirements of boat shape RF cavity. In this paper, the vacuum electron beam welding process of semi-Y-state OFC plate is introduced in detail, which provides a test basis for the manufacture of boat shape RF cavity.

A high vacuum chamber suitable for MEMS ion source testing was designed. According to the current research on the high vacuum chamber used for mass spectrometry test, in view of the high vacuum acquiring ability, maintaining ability and the convenience of frequent use, and considering the structural strength, inner wall exhaust and other factors, the cylinder structure which can meet the requirements of both strength and low exhaust rate was selected. Based on ANSYS software, the structural stability and dangerous point distribution of the chamber under high vacuum were analyzed comprehensively. The optimized selection range of wall thickness was determined. This study can provide a theoretical basis for the design of high vacuum chamber.

Time of flight second ion mass spectrometry(TOF-SIMS) and pulsed radio frequency glow discharge optical emission spectrometry(Pulsed-RF-GDOES) are two important depth profiling techniques, the former one is widely used in the fields of semiconductor industry and material science, while the latter one is usually applied to the analysis of industrial coating and surface oxynitride. Mo/Si nano-multilayers have been widely used in nanolithography, soft X-ray/EUV microscopy, solar astronomy and other fields because of their excellent reflection characteristics. In this paper, Pulsed-RF-GDOES and TOF-SIMS depth profiling data of Mo(3.5nm)/Si(3.5nm) nano-multilayer are evaluated quantitatively by the convolution and deconvolution methods with the resolution function of the atomic mixing-roughness-information depth(MRI). The layer structure, interface roughness and depth resolution upon depth profiling are obtained. The results show that GDOES depth profiling yields larger sputtering induced roughness, and the depth resolution of SIMS is better than that of GDOES.

Microwave vacuum electronic devices are used in a wide variety of areas such as radar, space technology and electron accelerators. The heater assembly is one of the cores for the vacuum electronic devices. Their performances directly determine the reliability and lifetime of the electronic devices. A strategy to develop a new type of method for heater assembly is proposed in order to overcome the shortcomings of traditional heater assembly preparation process. High temperature vacuum sintering technology is used to melt the heater and the insulating material together, which improves the compactness of the heater assembly, reduces the adsorption of residual gas, enhances the impact resistance of the heater assembly, and overcomes the shortcomings of brittleness of the heater.

In this paper, methods and principles of detection for the small leaks of the missile-borne klystron is described in detail. Firstly, the process of the pressurization detection method is clarified, some key parameters(such as helium storage pressure, storage time, characterizing parameters of the vacuum degree in the device) are theoretically calculated and analyzed, and results with guiding significance are obtained. Secondly, the main device components are described in detail. Finally, the pressed storage experiment of the missile-borne klystron is carried out in the equipment. The experimental results show that the equipment can efficiently eliminate the unqualified components, which meets the expected requirements, and the customer feedback is good.

With the wide application of thin film materials in modern industry,arc ion plating technology has become an important method for preparing functional films, such as functional surface modification and surface metallization of composite materials in the field of aerospace. In order to verify the state of cathode spot movement under different magnetic fields, the cathode spot on Ti target was controlled by magnetic field. TiN films were prepared under five magnetic fields, and the surface morphology, microstructure, chemical composition and thickness of TiN film were detected and analyzed through scanning electron microscope, energy disperse spectroscopy, step profiler and X-ray diffractometer. The results show that the film has the least number of large particles, the film is the thickest, and the crystal preferential growth direction is (111) crystal plane, when the cathode spot controlled by the magnetic field is uniformly distributed on the entire Ti target surface and the cathode spot movement speed increased.

Air has become one of the key constraints for the further acceleration of high-speed trains.In order to develop the next generation of higher-speed transportation systems, an innovative transportation system concept combining low-vacuum pipes and ultra-high-speed trains has been proposed and developed. In this paper, a two-dimensional calculation model of the tube train is established, and the shock wave characteristics of the supersonic train running in tube are analyzed based on the verified grid and turbulence model. It is concluded that when the supersonic train is running, the shock wave in front of the train forms a congested section forward in the form of a normal shock wave. The position of the normal shock wave moves forward with the running time, and the position of the pressure surge moves forward synchronously, but the pressure rise ratio before and after the shock wave is basically unchanged. The running time and the running Mach number affect the length of the congested section. The shock wave will undergo multiple Mach reflections between the tube and the train body and in the wake area to form a shock wave train. As the running time increases, the shock wave between the tube and train body weakens, and the intensity of the shock wave and reflected shock wave at the rear of the train is strengthened.

The cross-sectional profile of the existing screw rotor has sharp points and the contact line is discontinuous. To solve this problem and simplify the composition of the section profile, this paper uses a sinusoidal helix to smoothly connect the tooth tip arc and the tooth root arc, and then proposes a new type of fully meshed sinusoidal helical screw rotor. The meshing model of the sinusoidal helix and its conjugate curve are proposed, and the equation of the section profile is deduced. The influence of the radius ratios and helical central angle of the new section profile on the performance of the twin-screw vacuum pump is analyzed, and their reasonable value range is given. The results show that the section profile of the as-proposed new full meshing screw rotor is completely smooth, and the spatial contact line is continuous, which is beneficial to improve the performance of the twin-screw vacuum pump.

In order to solve the problem of poor reliability of brazing seal in space environment simulation equipment due to the large installation gap between heat sink and vacuum container, the following methods were adopted. Remove the oxide layer of base metal and solder surface before welding. BAg45CuZn eutectic solder with 45% silver content is selected. The welding heat source with external flame temperature of about 900℃ is used. Heat sink copper pipe and stainless steel pipe with larger wall thickness are selected. The welding gap is controlled in 0.1mm to 0.2mm by welding auxiliary parts. The welding heating time is controlled in 30s. After brazing and sealing of stainless steel pipe and copper pipe with the above processes, the welding test results are good and the welding seam is reliable. Leak detection is carried out by helium mass spectrometer after cyclic impact at low temperature of -186℃ and high temperature of 120℃ on the weld. The leak detection data prove that the sealing performance of the weld meets the use requirements of the equipment.

The beam power of the CSNS II accelerator will be upgraded from 100kW to 500kW, which requires the average beam power of the linear accelerator to be increased from the current 5kW to 25kW, and the pulse beam intensity to be increased from 12.5mA to more than 40mA. For this reason, the Penning type surface negative hydrogen ion source currently in use will be replaced by a radio frequency（RF） negative hydrogen ion source. Considering that the beam cutting ratio of the beam chopper ranges from 35% to 50%, and the LEBT transmission rate can reach 75% to 95%, the RF negative hydrogen ion source needs to produce a negative hydrogen ion beam of at least 50mA. Therefore, the hydrogen gas consumption of the ion source needs to be increased from the current 10sccm to more than 20sccm,and the pressure of LEBT second chamber is required to be ≤5.0×10^-3Pa. Based on this, the ion source and the LEBT vacuum system are modified in this paper,and the beam transmission rate of LEBT is improved. In addition, the pumping speed of hydrogen with two domestic and imported magnetic levitation molecular pumps is compared,which provides a certain reference for the selection of molecular pumps and localized substitution.

To address the problems of low deposition rate and uneven film thickness in the preparation of SiC films by pulsed laser method and sublimation method, this paper adopts the vacuum DC magnetron sputtering technique to deposit SiC films on the surface of flat glass substrate using a SiC target with high carbon content. The effects of different parameters on the deposition rate and film thickness uniformity were investigated by varying the DC power and sputtering pressure. The thickness, cross-sectional morphology and Si, C content of the films were characterized by step meter, scanning electron microscope（SEM）and energy spectrometer（EDS） respectively to obtain the optimal process parameters. The experimental results show that the film deposition rate reached 15.39nm·min^-1 when the sputtering power was 2000W under the same sputtering air pressure condition.The variation coefficient of thickness uniformity of the deposited films was within 3% while the film deposition rate reached 10.67nm·min^-1 when the sputtering air pressure was 0.8Pa under the same DC power condition. In addition, the films prepared by DC magnetron sputtering were dense and porosity-free inside,and the Si, C content was above 99%.

CrCN films prepared by magnetic filtration cathodic arc deposition（FCVAD）technology have excellent mechanical properties and can be used as surface modified films in textile equipment, pcb drill bits and piston rings. In this paper, the thermal stability of CrCN films was investigated for the situation that the structure and properties of films will change due to high temperature caused by friction or high temperature of application environment. Structure of the films from room temperature to 800℃ was characterized by X-ray diffraction（XRD）, field emission scanning electron microscopy（FESEM）, Raman spectroscopy（Raman）, and X-ray photoelectron spectroscopy（XPS）. The results show that the upper limit of thermal stability of CrCN films prepared by FCVAD technique is about 400℃. When the temperature is below 400℃, the structure of CrCN films is stable and remains disordered. When the temperature reaches 500℃, fine grains appear on the surface of the films, and the CrN phase in the films is transformed into Cr₂N phase. As the temperature continues to increase, the CrCN solid solution phase starts to graphitize, and the grain size within the films becomes larger. When the temperature is greater than 700℃, carbon in the films leaves in the form of CO or CO₂, and Cr element exists in the form of Cr₂O₃ phase and grows into grains with a size of about 400nm at 800℃.

The intravehicular activity space suit is an important guarantee for astronauts to sustain life in the case of pressure loss in the cabin. The thermal comfort of astronauts is one of the important factors to be considered in the long time pressure loss condition. Based on the lumped parameter method, the thermal model of the spacesuit in the cabin is established, and the human-spacesuit thermal model is established with the Fiala model. The correctness of the simulation is verified by the domestic experimental data. Based on the simulation, the change rules of thermal comfort and humidity of ventilation gas under different pressure loss conditions were obtained, and the system optimization scheme was put forward, which provided reference for the design of emergency cabin pressure protection system and the formulation of life protection scheme in China.

Amorphous alloy films have been widely investigated because of their excellent properties such as non-stick and corrosion resistance, which are especially prominent for bulk-metallic-glass-forming Zr₅₅Cu₃₀Al₁₀Ni₅ composition. In this work, amorphous alloy films are prepared by magnetron sputtering using Zr₅₅Cu₃₀Al₁₀Ni₅ bulk metallic glass as the target. The effects of different sputtering power on the mechanical properties, non-stick, corrosion resistance and surface roughness of the films were studied. The results show that high-quality amorphous films, as evaluated by mechanical properties, non-stick, and corrosion resistance, can be obtained at a magnetron sputtering power range from 75W to 165W, with hardness of ~9.2GPa, modulus of elasticity of ~164GPa, hardness-to-elasticity ratio of ~0.055, self-corrosion current density of ~1.16μA·cm^-2, self-corrosion potential of -241.27mV, and the maximum wetting angle of 104°. Such data are generally comparable with the reported ones（the hardness is even higher）, confirming a good potential for non-stick and corrosion resisting purposes.

An ultrasensitive leak detection technology applied to high pumping speed automatic exhaust system is designed to solve the problem of small leak detection with leakage rate less than 5×10^-12Pa·m³/s in the process of exhaust and sealing off for traveling wave tube. The device is mainly composed of main vacuum system, external vacuum and baking system, cumulative comparison leak detection system, standard gas flow system and electrical control system. The exhaust table has eight stations, whose limit vacuum reaches ultra-high vacuum without load, and the vacuum furnace can be heated to high temperature. The whole process automation of exhaust process is achieved using program control and possessing functions of automatic collection, storage, analysis and transmission. The standard gas flow system can provide a micro flow from 5×10^-7Pa·m³/s to 5×10^-16Pa·m³/s, and the lower limit of cumulative comparison leak detection system reaches 5×10^-16Pa·m³/s, with a combined standard uncertainty of leak detection results less than 15%.

Nowadays, more and more vacuum test need to detect pressure inside the test specimens. Although direct installation of sensors is the most effective and accurate way to measure the pressure of the test specimens. However sometimes sensors cannot be installed in the test specimens, which makes direct measurement difficult to be realized. In this paper, internal pressure of test specimens under molecular flow was simulated by the method of Monte Carlo. Geometric model of test specimens were established. Material degassing quantity was considered. The variation of vacuum degree with time was calculated under molecule flow. This paper provides a theoretical basis for the pressure prediction of specific location during vacuum test.

Ni films with different thickness were prepared on the surface of Zr/ZrVFe porous getter by magnetron sputtering technology. The influence of Ni films on the gettering performance of the getter was studied. The surface morphology and elemental composition of getter were analyzed by SEM and EDS technology,and the gettering performance at room temperature was studied by constant volume method. The results show that during the getter activation process, H₂O, CO₂ and CO/N₂ have been desorbed below 350℃. When the activation temperature reaches 350-450℃, only H₂ and CH₄ remain in the desorption gas,and CH₄ is obtained by the reaction between the H₂ and the filament of the four-stage mass spectrometer. The as-prepared Ni film uniformly covers the getter surface without changing the getter surface morphology. The surface modification of getter by Ni film obviously increases the getter capacity. The equilibrium pressure of getter obtained by coating for 2h is the smallest and the adsorption performance is the best.

To study the application of ITO films in the 1064nm laser window of wide magnetic shielding, ITO thin films were prepared by using dual ion beam sputtering technology under different technological conditions. According to the test results of photoelectric properties of the films,the effects of oxygen flow rate, auxiliary ion source and substrate baking temperature on the transmittance and conductivity of ITO films were analyzed. Using Ti₂O₃ and SiO₂ as high and low refractive index materials and ITO film as electromagnetic shielding film on K9 glass substrate, a 1064nm laser window film with 0°-45° incidence was designed and fabricated for 2-18GHz efficient shielding. The test results show that the thin film prepared under suitable technological conditions has good transmittance and electromagnetic shielding performance, and is suitable as a high-efficient electromagnetic shielding,0°-45° incident of 1064nm laser window film.

Carbon nanotube is a one-dimensional quantum material with special structure. It has excellent mechanical, electrical and chemical properties. It is an ideal candidate material for electronic components in the future. When carbon nanotubes are used in spacecraft, the influence of space charged particle radiation environment on their properties should be fully considered. According to the space application requirements of carbon nanotubes and based on the radiation environment of charged particles in geosynchronous orbit, this paper studies the effects of electrons and protons on the microstructure and conductivity of carbon nanotube paper. The electron energy is 200.0kev, 500.0keV and 1000keV, and the proton energy is 500.0keV and 1.0MeV. The results show that the degradation of the electrical properties of carbon nanotube paper materials is due to the change of surface structure of the material, and the number of defects in the material increases under irradiation, which affects the migration path of carriers in the material and leads to the decline of its electrical properties.

Space TWTs are widely used in communication satellite, radar satellite, positioning and navigation and other fields. The acquisition and maintenance of extra high vacuum is the key to the high reliability and long life of space TWTs. The extra high vacuum(XHV) of TWTs needs to be obtained on special vacuum exhaust equipment. Vacuum exhaust system is the most important process in the manufacturing process of micro-wave vacuum electronic devices. The acquisition and maintenance of XHV involves a variety of vacuum related technologies, including the choice of materials, the optimized design of vacuum chamber, vacuum pump selection, acquisition and measurement of extra high vacuum, vacuum degassing technology, high sensitive vacuum leak detection and residual gas analysis technology. This paper introduces the development process of space TWTs extra high vacuum system equipment and its application in scientific research and production. The vacuum system realizes that the no-load vacuum degree is better than 1×10^-9Pa, and the multi-channel load vacuum degree is better than 5×10^-9Pa, which has a certain reference value for the acquisition of ultrahigh vacuum and extra high vacuum, and the manufacturing process and application of vacuum exhaust equipment.

The ITO films were deposited at room temperature by DC magnetron sputtering of a lab-made ITO target on organic glass substrates. The photoelectric property of the ITO film was evaluated by changing the process parameters of sputtering power, sputtering pressure, target distance and oxygen-argon flow ratio. The ITO films were characterized with ultraviolet visible near infrared spectroscopy. The results show that the transmittance of ITO films decreases with the increase of sputtering power and target-substrate distance. When the sputtering power is 110W and the target-substrate distance is 70mm, the transmittance and conductivity of ITO films are better. In the near-ultraviolet light band and the near infrared light band, the transmittance of the ITO film decreases as the sputtering pressure increases. When the oxygen-argon flow ratio is 4:30, the ITO film shows the best transmittance and comprehensive performance in the visible light range from 500nm to 600nm.

Compared with the vapor jet vacuum pump system served at present,the high differential pressure Roots pump combination pumping system is being widely used for large vacuum distillation unit because it has the characteristics of quick start and obvious energy saving effect.In this paper,one kind of combination pumping system consisted of high differential pressure roots pump used in a large vacuum distillation deep cut unit is introduced,and the structure,control principle,performance parameters and solutions to some key technical problems of the system are described in detail.

Three kinds of aluminide coatings were fabricated by chemical vapor deposition（CVD）on the surface of the nickel-based superalloy substrates at the deposition pressure of 150, 200 and 250 mbar, respectively. The effect of deposition pressure on phase structure and high temperature oxidation behavior of the specimens with aluminide coating was systematically investigated. The phase structure, surface morphology and elemental composition of the three kinds of aluminide coatings were analyzed by XRD, SEM and EDS. The results indicate that the phase constituents of three kinds of aluminide coatings are detected to be β-NiAl. Two phases including of Ni_1.04Al_0.96 and Ni_1.1Al_0.9 are gained in the coating specimens prepared at the deposition pressure of 200 mbar. After the isothermal oxidation at 1100℃ for different dwelling times, the main phase β-NiAl transforms into γ′-Ni₃Al with formation of Al₂O₃. Differently, the peak intensity of γ′-Ni₃Al phase is the weakest for the specimens deposited at the pressure of 250 mbar. The oxidative weight gain rate of the three aluminide coatings is 0.037, 0.022 and 0.018g/（m²·h）, respectively. The oxidation weight gain of the coating specimens at the deposition pressure of 150 mbar is correspondingly larger than that of the other two coating specimens. The lower deposition pressure is, the more micropores on the surface of the coating exist,and the more easily microcracks appear on the thin film of the coating surface and further form into the spllation of oxide scale after high temperature oxidation. Based on the experimental results, the coating specimens prepared at deposition pressure of 250 mbar show the best surface microstructure,elemental content and high temperature oxidation resistance.

When using tungsten crucible and electron beam evaporation equipment to evaporate silver thin film, silver is infiltrated with tungsten crucible in the molten state,and the liquid level of molten metal in the crucible is concave. Such concave evaporation sources often lead to poor uniformity of the as-deposited films. According to the principle that the microstructure of the object surface will change the contact angle between liquid and solid, a groove array is fabricated on the smooth inner wall of tungsten crucible by chemical corrosion. By changing the contact angle between the molten metal material and the inner wall of the tungsten crucible, the wettability of liquid silver and the wall of tungsten crucible can be adjusted. The results show that when the groove width is about 1mm,the depth is about 0.5mm and the period is about 2mm, the inner wall of the molten silver and tungsten crucible becomes no longer infiltrated. 100nm-thick silver film is evaporated with unmodified and modified tungsten crucible, respectively, and it is found that the uniformity of the evaporated film can be improved effectively by using the modified tungsten crucible.

This paper introduces a set of virtual instrument experiment system for school teaching and enterprise training based on the unity3D platform. With various virtual instruments, the system provides high reality experimental environment with intelligible human-computer interaction and can well simulate the manipulation of the experiment. The as-developed system has two forms, in which one is the realization of VR scenes and the other one is the client APP form. It is suitable for different cenes and meets different teaching and training needs. This paper also provides a reference for the development of such VR platforms.

The performance of agricultural machinery farming parts is seriously affected due to wear failure, and the development of agricultural mechanization is restricted. Surface modification technology has become an important technical means to improve the wear resistance of farming machine parts owing to its advantages of flexible technology, strong applicability, convenient operation and low cost. The surface modification technology has been widely used in agricultural machinery,such as thermal spraying, spray welding, surfacing welding, cladding and biomimetic technology. The advantages and disadvantages of different technologies and their applicable conditions are different. This paper introduces the research situation of surface modification technology in improving the wear resistance and surface performance of farming machine parts, and puts forward its application prospect and development trend.

In order to study the effect of matrix surface microstructure on the adhesion between coating and matrix, the adhesion between coating and matrix was tested. The hardness of the coating was measured. The interfacial microstructure between coating and matrix,and the matrix surface microstructure were observed. The relationship between adhesion and surface morphology was analyzed. The results show that after water blasting and dry blasting, V-grooves are formed on the matrix surface, which are expressed as type θ₁ and type θ₂ respectively（θ₁<θ₂, θ is the ratio of groove opening width to groove depth）. The matrix surface microstructure can significantly affect the adhesion between coating and matrix. But the phase, density and residual stress of coating are not influenced. According to the nucleation mechanism, the atoms will nucleate and grow at the upper edge of θ₁ “V” groove. A large number of atoms are blocked, resulting in hollow bottom of “V” groove. In θ₂ “V” groove, a large number of atoms enter the groove. With the diffusion of atoms, the almost completely filled“V” groove is formed. As a result,the bonding area of coating and matrix increases, and the adhesion of coating and matrix improves.

Manned spacecraft hatch is the aisle for astronauts and cargo to enter and leave the sealed capsule of spacecraft. Once leakage occurs, it will affect the normal operation of manned spacecraft, and even threaten the life safety of astronauts. In order to ensure the sealing performance of manned spacecraft hatch, strict leak detection tests must be carried out before launching. In view of the special structure of manned spacecraft hatch, this paper mainly introduces the leak detection methods for hatch body and frame sealing ring, the whole hatch and the part of hatch. It forms a set of leak detection technology suitable for the whole development process of manned spacecraft hatch, which can meet the leak detection requirements of manned spacecraft hatch, such as Shenzhou spacecraft, space station, lunar module and so on.

The thermal expansion and oxidation resistance of bond coating alloy are closely related to its phase structure, which directly decide the reliability of thermal barrier coating and the service life of turbine blade.In this work, the equilibrium phase structure, the microstructure and element distribution under non-equilibrium condition, the coefficient of thermal expansion(CTE)variation versus temperature, and the isothermal oxidation behavior at 1100℃ of the NiCrAlYSi bond coating alloy were comprehensively investigated by using thermal dynamic calculation and experimental analysis. The results show that the main equilibrium phase constituent is FCC_L12 γ′-Ni₃Al phase, combined with some BCC_B2 α-Cr and β-NiAl at room temperature.When the temperature reaches 870℃, the equilibrium phase changes to β-NiAl and γ-Ni. The non-equilibrium microstructure consists of γ-Ni+β-NiAl. Moreover, the α-Cr and γ′-Ni₃Al precipitate in the β-NiAl matrix and the γ-Ni phase is surrounded by the γ′-Ni₃Al. The element Si primarily solid solutes in γ′-Ni₃Al phase and Y mainly exists in the form of Ni₅Y, both of which are distributed at grain boundaries. The CTE(×10^-6K^-1) is increased from 11.9±0.17 to 20.5±0.13 as the temperature increases from 100℃ to 1200℃, and the increasing rate is obviously larger at the temperature higher than 900℃. The oxidation layer with the poor continuity and density is obtained, which is separated from Al depletion zone. When the oxidation time prolongs from 20h to 100h, the thickness of the oxidation layer increases from (1.70±0.072)μm to (3.28±0.275)μm, and the Al depletion zone thickness increases from （7.48±0.606）μm to（10.67±2.654）μm, respectively. The average weight gain gradually increases from 0.608g·m^-2 to 3.623g·m^-2. The average oxidation rate first decreases from 0.030g·m^-2·h^-1 to 0.020g·m^-2·h^-1, and then increases to 0.036g·m^-2·h^-1, of which the minimum value is obtained at 60h.

In recent years, palladium thin films have attracted wide attention due to their excellent properties such as low resistivity and high catalytic activity. Palladium and its alloy thin films have gained more and more interest from researchers in the applications of integrated circuit interconnection, hydrogen sensing, hydrogen storage and catalysis. There are many researches of the preparation of palladium metal film, this article focuses on the research development of preparation of palladium membrane using physical vapor deposition, chemical vapor deposition, atomic layer deposition and plasma auxiliary atomic layer deposition technology, and discusses the pros and cons of various preparation methods, sums up the precursor used to do, and prospects the development trend of preparation technology of palladium film.

The vacuum tester can measure internal vacuum of the vacuum interrupter using the proportional relationship between ion current and pressure without disassembling it. The vacuum tester needs to be calibrated for different tube types before use. In this paper, the design of calibration system including installation of magnetic coil, shielding of strong magnetic fields, special lifting device for baking and carriage, and calibration theory are discussed. The calibration system consists of calibration chamber, ultra-high vacuum system, magnetic field coil, heating device, lifting system and vacuum tester. The basic principle of the calibration system is dynamic contrast method, with standard vacuum gauge, under the dynamic balance of pumping and charging, the data of standard vacuum gauge and ion current of the vacuum interrupter are obtained, then the calibration contrast curve is formed, which realizes the rapid, high-precision and wide-range calibration test.

This paper discusses the common structure and future development direction of vacuum induction furnaces.First of all, the characteristics of different structural furnace types are introduced. Then the overview of various furnaces in the current mainstream market environment is analyzed. Finally, the future development direction of vacuum induction furnaces is predicted through the comparison and analysis of technology and market conditions.

With the rapid development of aerospace technology, the situation of vacuum container attached to the outer board of the aircraft often happens. Lifting rings are often used to fix airborne external mounting devices, and often need to bear extremely high acceleration load, so the structural design and stress and deformation analysis of lifting rings are particularly important. In this paper, structural design of the lifting ring applied to airborne external vacuum chamber is carried out, and statics analysis using ANSYS Workbench and topology optimization is carried out on this basis. The results of simulation show the impact of circular ring thickness and lifting ear thickness on the stress and deformation of the lifting ring. The best design parameters are obtained, and the lightweight design of the lifting ring is realized, which may provide a certain reference for the design of airborne lifting ring.

Screw vacuum pump is widely used in semiconductor, coating, chemical and other industries owing to its ideal performance. The inner compression screw vacuum pump begins to compress the working gas during the gas delivery stage and has a series of outstanding advantages. This paper divides the internal compression screw rotor into two types of variable pitch and variable section,and the relevant research progress of their mathematic model design, performance analysis method and dynamic balance calculation is introduced respectively, which can provide a reference for the theoretical research of internal compression screw rotor.

Aluminide coating was deposited on the nickel-based single crystal superalloy DD5 by chemical vapor deposition(CVD), then NiCoCrAlYHf(HY5) metal bond coat was deposited in situ by vacuum arc ion plating(ARC), and yttria-stabilized zirconia(6~8YSZ) was deposited by electron beam physical vapor deposition(EB-PVD). The isothermal oxidation protection performance of DD5+(HY5+YSZ) and DD5+(Al+HY5+YSZ) samples at 1100℃ was compared. X-ray diffraction, scanning electron microscope and electron probe methods were used to analyze the evolution of microstructure and composition of the two coatings during high temperature oxidation. The results show that DD5+(Al+HY5+YSZ) coating has a dense multi-layer structure and combines well with the substrate. After isothermal oxidation for 250h, the appearance of the two coatings both keep intact. During the isothermal oxidation process at 1100℃ for 250h, the oxidation rate constants of DD5 alloy, DD5+(HY5+YSZ) coating, and DD5+(Al+HY5+YSZ) coating are 0.415, 0.410, 0.354g²·m⁴·h^-1, respectively. After isothermal oxidation for 250h, the highest Al contents in DD5+(HY5+YSZ) and DD5+(Al+HY5+YSZ) coatings are 5.8wt% and 16.7wt% respectively, which is in good accordance with Al content on the bond coat upper surface of 3.7wt% and 6.0wt%, and the thicknesses of thermal grown oxide(TGO) are 6.6μm and 9.4μm respectively. Element interdiffusion occurs between two coatings and the substrate,leading to the appearance of secondary reaction zone(SRZ). The SRZ in the DD5+(Al+HY5+YSZ) coating is more obvious and continuous than that in DD5+(HY5+YSZ).

The porous metal materials are a new type of metal materials with excellent properties. This review briefly describes the preparation methods and applicability of several commonly used porous metal materials.Then the application of porous tungsten materials in the fields of microwave vacuum devices and space electric propulsion technology is introduced, and the existing problems in the preparation of porous tungsten materials are pointed out. In response to these problems, the preparation process of porous tungsten materials and parts is studied in depth. The tungsten powder is classified by the classification technology. The results of the laser particle size tester show that the size of classified tungsten powder particles is more concentrated. The gas purification and detection system can remove residual oxygen and water in the hydrogen gas, and reduce the dew point of hydrogen from -50℃ to below -90℃, which provides a good sintering atmosphere for preparing the non-oxidized tungsten sponge matrix. Porous tungsten materials are prepared by cold isostatic pressing technology and high temperature sintering, and the porosity of porous tungsten materials is studied by mercury porosimeter. The pore size distribution becomes narrower and the pore size becomes more uniform. The porous tungsten-copper alloy materials are prepared by vacuum impregnation. The impregnation rate is much higher than that of copper impregnation under the hydrogen condition, and the impregnation rate is increased by more than 4%. The tungsten copper alloy substrate is heated by a high frequency heating coil crucible localized firing. The results show that this technology has the advantages of no residual on substrate surface, short time, no pollution to furnaces and environmental. The porous tungsten have been successfully used in the microwave vacuum electron devices.

Oxide thin film transistors(TFT) are the core driving components of active matrix organic light-emitting diodes, and are the key technology for developing new displays today. They have broad application prospects in flat panel displays. However, there are a large number of defect states in oxide semiconductors caused by oxygen vacancies, which destroy the performance and stability of TFT device, and become a bottleneck technical problem for its commercialization. Therefore, IZO TFT was prepared by RF-sputtering and treated with O₂ plasma to study the effects of O₂ plasma treatmert on IZO film and device performance and stability. The results show that after plasma treatment, the mobility of IZO TFT increases from 8.2cm²/（V·s） to 9.5cm²/（V·s）, the threshold voltage changes from -3.2V to -5.1V, the sub-threshold swing decreases from 0.45V/decade to 0.38V/decade, and the switch ratio changes from 2.3×10⁷ to 4.4×10⁷. Under negative light bias, the threshold voltage drift of the device reduces from 7.1V to 3.2V. The threshold voltage drift of the device decreases from 12.5V to 6.4V when aging at 100℃. O₂ plasma treatment can effectively improve the electrical performance and stability of IZO TFT.

A special equipment is developed to meet the emission requirements of hydrogen, methane and carbon dioxide wastes and the injection requirements of carbon dioxide into the sealed chamber during the thermal vacuum tests of the environmental control and life support system (ECLSS) of a spacecraft. The equipment adopts a scheme which combines the electric heating belt and the multi-layer insulation materials to keep the pipeline temperature above 12℃. The scheme solves the problem of hydrogen and methane condensation in extreme low temperature conditions and avoids risks of pipe blocking due to carbon dioxide freezing. The scheme also improves the safety level during methane emission via mixing the highly pure nitrogen into methane, solving the safety issue for the emitting methane into vacuum space, since the concentration of methane decreases to within 3.6%, lower than its blasting threshold of 4.4%. Eventually, the stability and the fulfillment of the requirements of the equipment are verified by the practical thermal vacuum tests.

In order to predict the time of gas pressure drop in the rapid decompression environment simulation system, an approximate theoretical calculation model for rapid decompression was established based on the orifice outflow principle of hydrodynamics, and the numerical iterative calculation method was given. At the same time, the finite element simulation method was used to analyze the pressure balance process, and a set of test system was built. By comparing the results of the two methods with the experimental data, the correctness and feasibility of the calculation method are verified.