Like water, power, and compressed air, vacuum is a standard utility in chemical process plants. A vacuum pump used in chemical process should be simple in structure, easy operation and handling vapor, corrosive gas, flammable gas. Different various pumps are introduced in this article. Liquid ring pump and screw vacuum pump are best-suited to application for chemical process industries.

Due to the high pumping speed and continuous steady state operation, the diffusion pump is expected to be applied in the divertor pumping system in future fusion reactor to reduce the high tritium inventory in the cryogenic pump, which are widely used in present tokamaks. Because the requirement of compatibility with tritium, the commercial oil diffusion pump can not be directly applied in the fusion reactor. Instead, the mercury will be the ideal working fluid. For the purpose to support the mercury diffusion pump design in the divertor pumping system of future fusion reactor, the optimization study of the mercury diffusion pump design is necessary. In this work, using the direct simulation Monte Carlo (DSMC) method, influence of the nozzle angle on the pumping speed and mercury backstreaming rate are simulated based on a KT-150 diffusion pump structure. The simulation results show that the largest pumping speed of~1.53m³/s is achieved when nozzle angle equals 45 degrees, while the backstreaming rate is not obviously increased.

This paper introduces the design and calculation of the 250mm caliber cryopump, and details the design of components such as pump body, adsorption array, radiation shield and louvers. The strength of the shell and the heat load of the cold screen and the baffles and condensing plates are calculated in detail. By analyzing the temperature field of the cold screen, the barrier plate and the adsorption array, the accuracy of the calculation is checked, and the theoretical basis and temperature reference are provided for the actual test.

Vacuum collection technique for sewage has been wildly used in ships, trains, construction and other fields. The pump station system, whose core component is vacuum crushing pump, is an advanced method for vacuum drainage technology. In this paper, refering to the patents of vacuum crushing pump by Jets company and other relative companies, the design difficulties for pulverized vacuum sewage pump are firstly analyzed, and the design computational formulas about the key parts are derived. Secondly, aiming at the servicing condition in our company, each part of the pulverized vacuum sewage pump is redesigned and optimized, and the model pump is finished. Finally, the experimental test is achieved for the moded pump. According to the test results, performance of the model pump can satisfy the operating requirements. However, some gaps even exist comparing to the calculating values, and further optimization is even necessary.

The device main body structure includes but not limited to high temperature heating control system, rotating ring body, a rotary motor system, block sample conversion system, vacuum system, power control system and support platform. The diameter of the rotating torus is Φ50 mm, the thickness is 2 mm, and the components are bent out of 316L stainless steel. The equipment reserves tungsten ball and sample test mounting interface. The pipe is equipped with a tungsten b-all, and the rotating ring rotates along the axis to simulate the wear of the tungsten ball on the inner wall of the pipe and internal electrical parts at different temperatures and velocities. Circle center pipe diameter is 1000 mm, the limit temperature is 650 ℃ of this equipment, the limiting vacuum is 2 Pa, and the leakage rate of this experimental in each temperature were better than 5×10^-8Pa·m³/s.

In order to study the relationship between composition of composite film and target used in multi-arc ion plating technology, and to compare the tribological properties of (Ti, Cr) N film with different composition, five targets - namely pure Ti target, pure Cr target and titanium-chromium alloy targets with titanium-chromium ratio of 9:1, 4:1 and 1:1 were designed and fabricated. Scanning electron microscopy was used to observe the micro-morphology of the film. X-ray energy spectrum analyzer was used to analyze the composition of the micro-area qualitatively and semi-quantitatively. X-ray diffraction was used to analyze the structure of the film. The wear resistance of the film was tested by friction and wear tests. Finally, the wear volume was calculated with the width, depth and length of the wear marks, and the wear volume was used to characterize the wear resistance of different films. The results show that composition of film prepared by the alloy target is not the same as that of the target, but all of them show TiCrN(200)preferred orientation. The surface of TiCrN film prepared by pure target is the most delicate and the roughness of TiCrN film decreases with the increase of Cr content. The hardness and wear resistance of TiCrN films are obviously better than those of pure target films. Ti_0.3Cr_0.23N films prepared by target(Ti:Cr=4:1)have the highest hardness(HV_0.053274.9)and the best wear resistance. When the film is prepared by alloy target, the composition of the film is greatly affected by the ionization rate of single metal, not the metal ratio of the target. And adding hard elements to the film can improve the quality and wear resistance of the film.

Duplex-treated CrN and CrVN composite coatings were prepared on DC 53 cold work die steel substrates by plasma nitriding and arc ion plating. The microstructure, mechanical and wear properties of coatings were investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), microhardness tester and tribometer, respectively. The results showed that the as-deposited coatings were fcc structures with a (111) preferred orientation. The CrVN solid solution structure based on the fcc-CrN phase was obtained in CrVN coating. Compared to the CrN coating, the columnar grain growth was suppressed with the addition of V and the CrVN coating became denser. The microhardness and adhesive strength of V-doped CrN coating were obviously improved, while the friction coefficient and wear rate of the coating were reduced. The sticking resistance of aluminium was enhanced for CrVN coating due to the low surface roughness and the formation of self-lubricating VO₂ during the wear process.

In order to improve the erosion resistance of titanium alloy material, CrAlN coating was deposited onto TC11 titanium alloy by vacuum cathodic arc deposition technique. The effects of target current, bias voltage and furnace pressure on the structure and properties of the coating were investigated. Scanning electron microscopy was used to observe the surface and cross-section of the film layer. Metallographic microscope was used to quantitatively analyze the large particles on the surface. Microhardness tester was used to measure the Vickers microhardness. The sandblasting tester was used to resist the erosion of the coating. The properties were tested by measuring the thickness of the coating and the depth of the etch pit by a three-dimensional surface profilometer. The X-ray diffractometer characterizes the crystal structure in the coating. Increasing the target current from 70A to 110A, although increasing the deposition rate of the coating, it will increase in the number of large particles on the surface of the coating to decrease the erosion resistance of the coating. The furnace pressure is increased from 1 Pa to 4 Pa, which is effective to reduce the size and quantity of particles on the surface of the coating, but also reduce the deposition rate and hardness to a certain extent. The bias has the greatest influence on the structure and properties of the CrAlN coating. When the bias voltage is-50V, the coating has a preferred orientation of(200). The 100V coating has a(111)preferred orientation. At-200V, the preferred orientation of the coating is not obvious; and as the bias voltage increases, the hardness and erosion resistance of the coating increase, and at high erosion angles, the failure mechanism of erosion is brittle failure. The target current has the greatest influence on the surface quality in the process parameters; the growth orientation of the coating is closely related to the bias voltage; the surface quality and hardness of the CrAlN coating directly affect the erosion resistance of the sand, and the influence of the bias voltage on the erosion resistance of the coating maximum. The final optimized process parameters are of target current 90A, bias-100V and furnace pressure 4Pa.

The WO₃ thin film was prepared at room temperature by using a DC reactive magnetron sputtering method. The effects of sputtering power on the structure and electrochromic properties of the WO₃ thin films were investigated. The structural evolution and electrochromic properties of WO₃ films after annealing were investigated. The results show that the WO₃ film exhibits better electrochromic performance at a sputtering power of 270 W, with a modulation amplitude of 78.5%, coloring time of 9s and fading time of 3.2s. The WO₃ film prepared at this power is annealed, and its structure changes from amorphous to crystalline, but the modulation amplitude and response time characteristics are degraded to some extent. It is known that the amorphous WO₃ film has faster response time and wider modulation amplitude than the crystalline structure, but the crystalline film has better cycle stability.

The influence of working pressure, pulse voltage and frequency on the volt-current characteristics of hollow cathode discharge in argon atmosphere was studied by using high frequency and high voltage pulse power supply for the inner surface treatment of 20mm guide sleeve of high-end valve. Discharge structures such as tube spacing and anode distance were also studied. The results show that the discharge of hollow cathode in tube needs a stable process, and the pulse current decreases gradually with the increase of time, and then reaches a stable discharge stage. The peak current of hollow cathode pulse increases with the increase of pulse voltage or working pressure. With the increase of pulse width or frequency, the peak current of the pulse does not change, but the average current increases, and the excitation time decreases with the increase of frequency. The analysis of discharge structure shows that the peak discharge current increases slightly with the decrease of tube spacing and the decrease of the distance between tube orifice and anode. The above results may provide effective guidance for the preparation of inner wall film such as small diameter guide sleeve of high-end valves.

This paper introduces the topology and working principle of matrix converter in detail, and discusses the switching function modulation method and space vector modulation method of matrix converter. Finally, the matrix converter with two modulation strategies is simulated. The results show that: when space vector modulation is used, the motor starts up faster, and its performance is better than switching function modulation at low frequency and high frequency. However, when switching function modulation is used, the harmonic characteristics of stator current of the motor are better than the results obtained by space vector modulation.

In order to meet the thermal vacuum test requirements of a certain aerospace product, a special temperature-controlled heat sink is designed, which consists of a heat sink, a heater and a supporting temperature control system. This paper briefly describes the design of a special temperature control heat sink for a certain product, and carries out simulation analysis and verification of the structure. The analysis results show that, when the product heat is 200W, the space temperature can be higher than +120℃, the heat sink body temperature can be lower than-180℃, with temperature control conditions. The temperature control system adopts PID adaptive adjustment. The results show that the space temperature can be controlled from -180℃ to +120℃, and the temperature control accuracy can reach ±0.5℃, which meets the test requirements.

Vacuum cooling technology has the advantages of fast cooling speed and low energy consumption, which has been used and developed rapidly in the food cold chain. In this paper, by changing the temperature of the cold trap and conducting the vacuum cooling experiment of cooked meat products, the effects of different cold trap temperatures on the cooling rate, mass change and vacuum chamber pressure were analyzed. The results show that different cold trap temperatures have different effects on the cooling rate, the quality changes before and after cooling, and the pressure in the vacuum chamber during the cooling process. In addition, it is not the lower the temperature of the cold trap, the better the cooling effect. The vacuum cooling process with the temperature of the cold trap at -15℃, -25℃, and -35℃ was compared. The optimum temperature value was -25℃, and minimum cooling time was 320s.

Aiming at the problem of color contour generation in color 3D printing, this paper proposes a color contour generation algorithm based on the texture mapping model. According to the plane projection method, the mapping relationship between the texture and the 3D model is established, and then the model is sliced to obtain the geometric information and texture information of the contour vertex. According to the mapping relationship between the contour vertex and the texture image, the color information between the vertex is interpolated. At the same time, it gives a fast recognition algorithm for inner and outer contours, and a color contour biasing method based on the offset algorithm is proposed to form the color thickness and eliminate the staircase effect.

In this paper, the electrolytic polishing process of TC4 titanium alloy fabricated by selective laser melting was studied by using perchloric acid solution as the electrolyte. The effects of current density, electropolishing time, temperature, cathode material and other related parameters on the weight loss, surface roughness and thickness loss rate of the samples were investigated. The surface morphology of the polished samples was also analyzed. The results show that the effect of electropolishing using an electrolyte consisted of 10ml of perchloric acid, 100ml of glacial acetic acid and 12ml of water works well. The optimum parameters are as follows: current density of (0.27-0.37)A·cm^-2, temperature of (30-35)℃, and time of (15-20)min. After electropolishing, the surface roughness Ra of the sample decreased from 13.66μm to 1.52μm, and the thickness loss rate was about (6-7)%. The surface uniformity of the polished samples achieved ideal results.

Laser peening technology is adopted to improve the residual stress caused by metal laser deposition on the surface of additive manufacturing parts. Laser peening effectively improves the microstructure of materials, improves mechanical properties and also reduces or delays the formation and propagation of cracks, the fatigue life, wear resistance and corrosion resistance of metal materials are effectively improved. A laser peening automation system constituted by robot, laser, optical path system etc, uses off-line programming, machining environment simulation, system integration control and other methods to solve technological process on the surface of various parts, and the light path system is put in vacuum environment.

In order to make sure the warp distortion behaviors for laser melting additive manufacturing, the relevant laws of the warp distortion behaviors are obtained. The process of the warp distortion of Inconel 625 nickel-based alloys material is studied. The experimental results show that the size of warp distortion depends on the length of scanning path and the influences on the warp distortion are different with the different process parameters. Generally, the two directions' warp distortion will be caused during the process of laser melting additive manufacturing. Simultaneously, the size of warp distortion increases with the increase of the laser power and the scan speed. But the distortion decreases with the increase of the powder feeding.