A series of YSZ coatings were deposited by electron beam evaporation coating. The thermal shock test of the coatings was used to test the peeling of different process coatings under the same thermal shock times. It was found that the thermal shock performance of the coating was best at 350 mA. Discussion on the failure mechanism of the coating shows that the dense coating structure hinders the alleviation of thermal stress, the loose coating structure accelerates the infiltration of oxygen, and accelerates the growth of TGO, which results in the failure of coating.

The vacuum deposition represented by magnetron sputtering has become the mainstream method for preparing thin films. Therefore, it is very important to choose a suitable model to study the distribution of plasma, particles and electrons during gas discharge in magnetron sputtering. According to the basic principle of gas discharge, the fluid model was adopted for cylindrical sputtering device, and the physical model of plasma with electrons, ions, metastable ions and neutral particles as the main particles is established. The finite difference method is applied to the model. The simulation results of plasma particle distribution and electron temperature distribution in DC sputtering system are obtained by computer programming to simulate the process of gas discharge in DC sputtering system.

Single aluminide and Pt modified aluminide coatings were fabricated by chemical vapor deposition(CVD) on single crystal superalloy substrates, and their high-temperature oxidation and hot corrosion behaviors were investigated. The phase composition and microstructure of the two aluminide coatings were analyzed by XRD and SEM. The results indicate that both of the oxidation kinetics curves of the two aluminide coatings are in accordance with parabolic rule after oxidation at 1000℃ for 250 h. The performance of oxidation resistance of Pt-Al coating is improved 55.5 percent compared with single Al coating. The addition of Pt element can reduce the velocity of β→γ′ phase transition, further ensuring to the formation of high quality α-Al₂O₃ scale. The corrosion kinetics curves of the two aluminide coatings are also consistent with parabolic rule after hot corrosion at 900℃ for 100 h. The performance of corrosion resistance of Pt-Al coating is improved 57.9 percent as compared with that of single Al coating. The addition of Pt element can restrict the rapid germination of inner sulfuration and ensure the integrity of α-Al₂O₃ scale.

A series of erbium(Er) films were deposited by DC magnetron sputtering method. The effect of sputtering power on the microstructure of the Er thin films was investigated by X-ray diffraction and scanning electron microscope. The experimental results show that all the Er films deposited with the sputtering power of 20W~60W are mainly composed of hcp phase, and present(110) preferred orientation obviously. The Er films grow with typical columnar crystals that increase accordingly with the increasing of sputtering power. The Er films are dense and flat with the average grain size of 7.7nm~9.6nm and surface roughness of 2.1nm. The Er films deposited by magnetron sputtering exhibit different microstructural characteristics from other Er films grown by electron beam vapor.

Influence of annealing temperature on microstructure and hydrophobicity of the TiO₂ films is studied, which are obtained by anodic oxidation from metallic titanium coatings previously deposited by arc ion plating on glass. Microstructure, surface morphology and wettability of the films are investigated by the X-ray diffraction, scanning electron microscopy and contact angle tester, respectively. The results show that the as-oxidized amorphous TiO₂ films become crystalline after the annealing. The crystalline structure of the TiO₂ films transits from anatase to rutile as the annealing temperature is enhanced. Spiral, nano-wire, and cotton-like surface morphology of the films are observed as the annealing temperature increases. The contact angle is enlarged by annealing and the maximum value of 121.78° is achieved at 500℃.

The surface of single crystal superalloy was pretreated by grit blasting, and the NiCoCrAlYHf coatings were then fabricated on the superalloy substrates by vacuum arc plating technique. The effect of grit blasting on the recrystallization and elemental diffusion behaviors of substrates after isothermal oxidation was investigated in detail. The microstructure and elemental contents of the samples with and without coatings, as well as their interaction mechanisms with recrystallization behavior, were systematically analyzed by SEM and EDS. The results indicate that the recrystallization sizes of the substrate and coating samples gradually increase with the increment of the grit blasting strengths. The coating specimens show no cellular recrystallization when the grit blasting strength is set to be 0.2MPa. However, the function of recrystallization inhabitation of the coatings gradually decreases with the increment of the grit blasting strengths from 0.3MPa to 0.7MPa. The phenomenon of recrystallization was not observed at the interface between the coating and the substrate after thermal exposure at 1100℃ for 250h. Meanwhile, there was no obvious fluctuation of the elemental concentration at the interface, and the contents of the elements on the interface tend to be smooth.

This paper introduces the process principle and technical characteristics of CVD reaction furnace for graphene preparation. Taking one of the as-developed CVD reaction furnace as an example, the design ideas and characteristics of the equipment are elaborated in detail. The equipment adopts advanced temperature control technology to control the heater′s rapid heating, and realizes the automatic control of chamber pressure in the process by closed-loop control. It has the advantages of high control accuracy, fast response and good consistency.

Using high purity graphite as target, Ar and N₂ as sputtering and reacting gases, a series of CN thin films with different N content were prepared by DC magnetron sputtering. The composition, morphology, transmittance and electrical resistivity of the films were detected by means of XRD, SEM, spectrophotometer and high impedance meter. The results show that the CN film has the first crystal shape, and with the increase of N₂ content in the sputtering chamber, the content of N in the film increases first and then decreases finally to the stable state. The resistivity of the film is maintained within the range of 10^-5Ω·cm to 10¹⁵Ω.cm and the transmittance is basically maintained between 85% and 91%. The incorporation of N played a stabilizing role in the sp3 hybrid C in the films.

Aiming at the DLC treatment of inner surface of 20mm guide sleeve of high-end valve, the effects of pulse voltage, pulse width, frequency and working pressure on the volt-ampere characteristics of hollow cathode discharge in tube under argon and mixed atmosphere were studied by using high frequency and high voltage pulse power supply. The results show that the hollow cathode discharge is realized in the five axially aligned tubes. The discharge current under argon condition shows obvious characteristics of hollow cathode discharge, while the current amplitude under mixed gas condition is relatively flat. The increase of pulse voltage or pressure is beneficial to the increase of discharge current, while the increase of pulse frequency decreases the peak current slightly, and the increase of pulse width increases the peak current gradually under the pure argon condition, but has little effect on the peak current under other mixed conditions, only increases the average current. Under fixed pressure of 10 Pa, the change of acetylene flow rate has little effect on discharge current, which is beneficial to enlarge the process window range of DLC film deposition. The above results may provide a technological basis for the preparation of DLC film on inner wall of small diameter guide sleeve of high-end valves.

The material of photocathode determines the important properties of photoemission, such as quantum efficiency, dark emission current and energy distribution of emitted electrons. Various types of photocathode emission materials, including alkali metal and semiconductor materials, are introduced in this paper. Among them, the multi-alkali photocathode and negative electron affinity (NEA) photocathode in semiconductor materials are mainly introduced, and the preparation process and performance test of the multi-alkali photocathode and the factors affecting the quantum efficiency of NEA photocathode are analyzed in detail.

With the development of military vacuum electronic tubes toward miniaturization and high frequency bands, traditional vacuum diffusion welding is unable to meet the high quality of parts welding needs. After comparing several pressure loading methods, the electric-servo control system is chosen. This paper introduces the design points of the electric-servo control system, and analyzes and evaluates the test data. Compared with the traditional equipment, the electric-servo system has the advantages of high precision, high flexibility, and high precision welding.

This paper presents a simplified model describing the distribution of leakage among working chambers in the screw vacuum pump. Based on the model, the gas thermodynamic processes in the screw vacuum pump is analyzed in depth. The thermodynamic parameters of each processes, including sucking process, compressing process, transferring process, backlashing process and exhausting process, which vary with the time are derived. At the same time, a special experimental test bench is set up, and multi-stage gradational screw rotors are adopted, and five pressure test holes on the side of the pump cavity are produced. The actual tests are carried out under the ultimate vacuum condition of the screw vacuum pump. They indirectly verify the correctness of the leakage model and thermodynamic calculations.

For space applications, the power-on process of a vacuum electronic device is influenced by the interactions of its electrical, thermal and pressure properties. In some cases, such devices fail to switch on normally at the first time of power-on. This paper analyzed the pumping mechanism of the heating cylinder for a vacuum electronic device and established the pressure change model within the cylinder. It is determined that the primary influences are the diameter of the outlet channel of the heating cable and the inner material outgassing of the heating cavity. On this basis, simulation tests for assessing the amount of material outgassing and iterative calculation of the pressure variation in the cavity for typical vacuum electronic product were conducted. The results show that the significant increase of the outgassing rate from the interior of the cavity and the uncertainty of the diameter of the outlet channel of the heating cable are the main reasons for the occasionally failure of this type of device to power on at the beginning.

Frost phenomenon widely exists in the fields of refrigeration and air conditioning, aerospace and astrophysics. A lot of research on frosting have been carried out under different conditions, which can be divided into atmospheric and vacuum frosting phenomena according to frosting pressure conditions, and can be divided into frosting mechanism theory and experimental research and mathematical and physical model of frosting process research according to contents. This paper mainly summarizes the experimental study and theoretical model of frosting phenomenon under vacuum condition, and compares it with frosting phenomenon under atmospheric pressure.

Based on the finite element analysis method, and combined with the Inconel 625 nickel-based alloy's material properties and process characteristics, everal stress control methods of laser melting additive manufacturing are analyzed. The simulation results show that the internal stress can be removed by the four control methods, which are the single point of preheating stress control method, surface sweeping by laser stress control method, based on the internal stress of environment temperature stress control method, and the partition formed first, then the whole connection stress control method. The control methods are simple and have strong significance in the field of engineering.

There are deformation and even cracking caused by excessive internal stress in the process of additive manufacturing of laser rapid prototyping technology. In order to solve the shortcomings, a partition adaptive process adjustment algorithm is proposed from the perspective of controlling the processing path, and the whole model is processed into groups. The processing path of each group needs to be generated in real time. The generation is based on the average height value of the sub-region of the previous set of formed surfaces, and the adaptive relationship between the average height value of the sub-area and the filling interval of its corresponding area is established. Finally, the C++ language is used. The algorithm is implemented by programming, and the simulation is carried out. According to the average height value of each sub-area, the corresponding filling pitch is obtained, and the correctness of the algorithm is verified.

An efficient additive manufacturing slicing algorithm base on face-vertex triangle mesh model and corner table data structure is proposed. The as-proposed algorithm introduces the use of connectivity representation of face-vertex triangle mesh, including incidence, adjacency and ordering. Secondly, based on the interval tree data structure, effective intersection query method of triangle mesh and plane is established, which can find all the triangles in the triangle mesh that intersect with the given plane. Finally, efficient additive manufacturing slicing algorithm based on face-vertex triangle mesh is proposed, which is based on the connectivity representation of face-vertex triangle mesh and triangle mesh-plane intersection query method. Owing to the use of triangle mesh connectivity representation, the triangle mesh slicing algorithm studied in this article proves particularly simple and efficient, and several calculation examples are shown to verify the as-proposed algorithm.

This paper studies the filling algorithm of planar contour based on direction-parallel filling path, and solves the problem that the traditional filling algorithm of direction-parallel contour is only suitable for filling polygon contour with relatively simple shape, but it is easy to fail in dealing with polygon contour composed of a large number of short lines. The algorithm first generates the scan lines of the plane contour, then generates all monotone chains of the plane contour polygon, and then establishes the undirected graph of the parallel filling trajectory based on the generated scan lines and monotone chain set. In the undirected graph, the edge types of undirected graph are divided into three types of segment edge, horizontal edge and vertical edge. Finally, the direction-parallel filling trajectory joining algorithm based on undirected graph is studied, and the effectiveness of the algorithm is verified by computing examples.