Abstract:The rapid development of new high-speed aircraft has put forward higher requirements for thermal protection system. The integrated thermal protection materials based on aerogel is of great significance to improve the thermal insulation performance and structural efficiency of thermal protection system.In this paper， based on the difference of thermal protection materials， the research progress，structure and performance of aerogel-based integrated thermal protection materials are summarized， and the problems that need to be solved in the future are briefly described.

Abstract:Research progress of various modified polyacrylonitrile precursors and completely replaceable precursors for carbon fibers are reviewed in this paper， including the preparation process， structure and the performance after carbonization. The potential application fields and the problems facing in the development are also summarized. It is expected to provide useful information and reference for the development of high-performance and low-cost carbon fiber precursors.

Abstract:Continuous fiber-reinforced thermoplastic composites （CFRTP） have been widely used in civil and military fields such as aerospace and avitation， automotive， energy and marine engineering， due to their excellent mechanical properties， fatigue resistance and design flexibility. In order to meet the requirements of large-scale， efficient and low-cost production， simulation can be used in the CFRTP product development stage instead of expensive trial-error tests. In this paper， various methods of CFRTP thermoforming simulation are introduced in detail， and the advantages and limitations for each method are summarized. In addition， the research emphases and development trends of CFRTP molding simulation in the future are prospected.

Abstract:As an important treatment agent，silane coupling agent is widely used in coatings，rubber，plastics and other fields.In this paper， the structural characteristics and action mechanism of silane coupling agents are reviewed.Several typical applications of silane coupling agents in the field of common coatings are introduced， including compatibilization of matrix resin， surface modification of pigments and fillers，and connection between coating and substrate.The factors affecting the effect of silane coupling agent under different conditions are discussed. The development trend of silane coupling agent application in heat-resistant coatings is prospected.

Abstract:This paper reviews the latest domestic and overseas development progresses in the manufacturing process of terahertz feed horns.The main manufacturing methods currently used by the research institutions and enterprises are classified and expounded， including the precision computer numerical control （CNC） machining， precision electroforming， plate stacking method，and additive manufacturing. The typical results of both domestic and overseas process development progresses are introduced， and the corresponding process advantages and limitations in application are discussed. Based on the application development of the terahertz frequency band and the development trend of the product demand of the terahertz feed horn，the analysis is carried out.And the future development direction of the methods in this field is further proposed.It has important guidance and reference value for the subsequent development and research of structural design and manufacturing process of the terahertz feed horn.

Abstract:In this paper，the finite element elastic buckling analysis method was used to study the shear stability of metal webs with different opening diameters. In order to compensate for the loss of stability after opening， the reinforcement effects of common reinforcement rings and flanges under different hole sizes were discussed. The results show that the stability of metal web decreases with the increase of hole diameter. The effect of increasing flange flanging height and thickness to improve web stability is obvious. When the flanging height is 16 mm and the flange thickness is 1.5 mm， the reinforcement effect is the best. This is because the increase of flange flanging height and thickness is equivalent to the increase of stiffness around the opening， and stiffness has a significant impact on web stability.

Abstract:In this paper， the application of a new ablation resistant and heat resistant coating in local heat protection of aircraft wing surface was studied. The influence of local temperature field and thermal stress deformation was studied by finite element analysis method. At the same time， the shear resistance of the new anti-heat coating was tested， and micro morphology was analyzed. The research shows that the application of heat resistant coating can reduce the temperature of local parts of aircraft wing surface， reduce material deformation and effectively improve the service strength of materials. Through the engine ablation test， the application of 0.5 mm heat resistant coating can reduce the back temperature to 147 ℃ when the surface temperature of the sample reaches 1 006 ℃，and the surface morphology is good after ablation. The study provides a reference for the application of the thermal protection coating in local thermal protection of aircraft.

Abstract:SiC matrix was obtained by sintering polycarbonsilane at 800， 1 000， 1 200 ℃， and the effect of temperature on the density and crystallization degree of SiC was studied. With the increase of temperature， the crystallization degree， the density of the matrix and the proportion of Si increases. At 800 ℃， the density of the matrix is 2.30 g/cm³， and the matrix structure is close to the amorphous state . At 1 000 ℃ and 1 200 ℃， the densities of the matrix are 2.50 and 2.56 g/cm³ ， and the grain sizes are 2.6 and 4.1 nm， respectively. C/SiC composites are prepared by PIP process with polycarbosilane as precursor and carbon fiber fabric as reinforcement， the maximum pyrolysis temperatures in the whole pyrolysis process are also 800 ， 1 000 and 1 200 ℃. The effect of matrix structure on the mechanical behavior of the composites is studied by mechanical properties test and microstructures observation. The results show that increasing the pyrolysis temperature in a certain range is beneficial to improve the properties of the matrix and the matrix’s densification efficiency ，which make the mechanical performance of the material improved， and especially has obvious effect on improving the bending strength ， interlaminar shear strength and compression strength of C/SiC composites.

Abstract:Due to the traditional hermetic packaging methods would have adverse effects on electronic devices during the packaging process， a new hermetic packaging method based on current assisted sintering of silver paste was proposed， which can be used for the hermetic sealing of the aerospace power discrete device. In this paper， the changes of temperature， microstructure and shear strength of the sintered joint during the process of current assisted sintering of silver paste have been studied. During the process of current assisted sintering of silver paste， the heating rate drops dramatically after the removal of organics. It facilitates the initially separated silver particles to contact with each other. With the prolongation of current-on time， the sintered silver joint becomes denser， which leads to the improvement of shear strength of sintered silver joint. Finally， the sealing performance of sintered joint can meet the requirements of hermeticity.

Abstract:With 20 % short carbon fiber reinforced PEEK as the main raw materials， the air inlet and samples were prepared by the iniection-moulding method. The mechanical properties and microscopic morphology of samples， X-CT nondestructive testing and three coordinates testing of the air inlet were analyzed. Experimental results show that the tensile strength of PEEK composites reaches 208 MPa， tensile modulus reaches 16.7 GPa， punch-type shear strength reaches 100 MPa， the distribution of irregular fiber is even， the inner defects of inlet are low， both inner and outer contour of inlet are smooth， size precision is higher。

Abstract:An autoclave molding strategy in the preparation of a large-size， thick-wall， special-shaped composite tubular support was described， in which the mold design， lay-up process and molding pressure were optimized. Based on the dimensions and quality requirements of the product， a set of split molds with designed dimensions was used. In the lay-up process， the disconnect way of the carbon fiber was designed. Last， in the curing process， a cycling gradient pressure was applied， the pressure at different temperature and the maximum pressure were controlled. The results show that these methods effectively guaranteed the molding pressure of the support. The surface of the prepared support is smooth， and there are no defects such as delamination， porosity and so on. In addition， the dimensional accuracy， content of resin meet the user’s requirements.

Abstract:SiC_f/SiC composites was processed by ultrasound-assisted grinding， and the effect of feed rate on the machining damage of the composites by MI process was studied. The results show that when the surface of SiC_f/SiC composite is processed by ultrasound-assisted grinding， many machining defects will come into being， such as the fiber debonding， fracture， breakage， matrix crack and shedding. And the interface between the fiber and matrix also has cracks. With the increase of feed speed， the surface damage of the composite material is aggravated， which leads to the decrease of proportional ultimate strength and maximum load. When the feed rate increases from 400 mm/min to 1 000 mm/min， the tensile strength and bending strength of SiC_f/SiC composites reduce by 4.7% and 20.6%， respectively.

Abstract:In order to solve the problem of poor surface quality in the non-circular isometric profile grinding， a theoretical model of X-C linkage grinding was established based on the constant removal rate. The ceramic CBN grinding wheel was used in the orthogonal experiments for high speed grinding of the three-arc non-circular isometric profile. The influences of the grinding wheel velocity， workpiece speed and grinding depth on the grinding specific energy， tangential grinding force， grinding temperature and surface roughness were investigated. The analysis shows that the grinding wheel velocity has the greatest influence on the tangential grinding force and surface topography， and the grinding depth has the greatest influence on the grinding specific energy， grinding temperature and surface roughness. No obvious grinding burn is detected by surface topography observation， which is proved that the method of X-C linkage grinding with the constant removal rate can be used for the non-circular isometric profile grinding.

Abstract:Due to the differences in physical property， low density niobium alloy and niobium-hafnium alloy were easy to produce welding defects when they were welded by conventional electron beam method. To further explore the feasibility of welding between low density niobium alloy and niobium-hafnium alloy， properties of the welded joint were numerical simulated and experimental studied. Firstly， the finite element model of dissimilar materials was established， and the temperature field of the joint was analyzed. Then， the experimental study was carried out by electron beam welding， and the macroscopic morphology， mechanical properties， microstructure and element distribution of the joint were analyzed. The results show that the joint of low density niobium-hafnium alloy and niobium-hafnium alloy without cracks， pores and has good tensile strength can be obtained by electron beam welding with niobium-hafnium alloy side offset.

Abstract:The new satellite platform put forward application requirements for polyimide foam with lower thermal conductivity and higher dimensional stability. In order to ensure the reliability of the bonding quality and process feasibility of the polyimide foam sandwich structure， it was necessary to evaluate the agent selection and performance evaluation. In this paper， the silicone rubber （RTV-X， GD414） was tested and discussed. Through the comparison of the mechanical properties， temperature resistance， rheological properties， and 90° peel properties of the adhesive， it was confirmed that the RTV-X adhesive is suitable for bonding process of polyimide foam sandwich structure. Through analysis and verification， the bonding pressure method and bonding pressure were determined， and the high and low temperature mechanical properties and mechanical properties of the specimen after temperature impact were evaluated. It is concluded that with the selection of RTV-X adhesive and positive pressure ≥1kPa， the bonding process of polyimide foam sandwich structure is reliable， and the bonding performance of products is good. The obtained results can provide technological reference for more task requirements of spacecraft products such as deep space exploration.

Abstract:The pyrolysis and combustion characteristics of Airbus 320 cargo hold liner （fiberglass/phenolic resin） and 3240 fiberglass board-FR4 （fiberglass/epoxy resin） were analyzed and compared by thermal gravimetric analyzer and cone calorimeter under the same conditions. The results show that the pyrolysis of Airbus 320 cargo hold liner and 3240 fiberglass board-FR4 can be divided into four and three stages， and the initial thermal decomposition temperature， ignition time and combustion duration of the cargo hold liner are all less than that of 3240 fiberglass board-FR4. The smoke time， release smoke rate （RSR） and total smoke release （TSR） of 3240 fiberglass board-FR4 are higher than the cargo hold liner， and the release smoke rate （RSR） and total smoke release （TSR） are 2 and 3.45 times higher than the cargo hold liner. The heat release rate （HRR） and total heat release （THR） of 3240 fiberglass board-FR4 are greater than that of cargo hold liner， and the peak heat release rate （pk-HRR） and total heat release （THR） of 3240 fiberglass board-FR4 are 1.47 and 1.94 times of cargo hold liner. Therefore， the Airbus 320 cargo hold liner is less dangerous to human life and aircraft operation safety after a fire.

Abstract:A composite cylinder leaked during autofrettage. The fracture reason of leakage was found out by fracture， metallographic and stress analysis. The results show that the main reason of fracture and leaage in low pressure is the anisotropic coarse grain structure around the neck of the liner which reduced the toughness， plasticity and strength of the structure. The necking-in heating process and spinning technology is refined， and microstructure around the neck of the liner is improved. Finally， the leakage problem is solved and the quality of composite cylinder is stabilized.

Abstract:Aiming at the domestic components for aerospace high reliability and long life electronic products， through the application practice of component localization in recent years， the common problems affecting the assembly reliability in the process of components localization are analyzed and summarized，and the enlightenment of these problems in the process of component localization for us are discussed，as well as the relevant suggestions should be paid attention to.