Abstract:This review summarizes the recent reports on filled compound polymer-based electromagnetic shielding （EMI） materials.According to the fillers morphology （nanoparticle fillers，fillers with high aspect ratio structure， fillers with sheet structure， fillers with 3D network framework structure），the electromagnetic shielding performance data of related composites is compared and counted.Moreover，the fillers selection and treatment and the matrix structure design and preparation method are summarized and analyzed in detail based on the goal of building efficient conductive network.The key problems and research status are proposed， and the future development direction of filled compound polymer-based EMI materials is presented.

Abstract:This paper reviews the research progress of neutral polymeric bonding agents in recent years， summarizes the research achievements in synthesis and application of neutral polymeric bonding agents， extracts the development trend of neutral polymeric bonding agents， and puts forward some suggestions for its future development.

Abstract:The uncertainty of internal damage of carbon fiber reinforced polymer（CFRP） and the complex characteristics of multi-mode damage coupling of heterogeneous materials seriously restrict the low-redundancy design of components and the long-life and reliable application in harsh environment. With the continuous progress of test and numerical simulation， the research on the degradation and failure process of mechanical properties of carbon fiber reinforced polymer is strongly promoted on the basis of summarizing the damage behaviors of polymer， this paper reviews the effects of static， impact， fatigue loadings and humid-hot environments on the damage evolution and failure behavior of CFRP， various damage models， test methods and results obtained for CFRP are summarized. Furthermore， the development of high-precision models for mechanical behavior prediction and damage mechanism of anisotropic materials in different modes is prospected.

Abstract:The aviation industry has now become one of the standards that can measure the hard strength of a country''s national defense. The performance index of aviation parts marks the development level of aviation industry， and the aviation metal parts，which occupy a majority of aviation parts， determine the performance index of the aviation parts. Therefore， the forming process of aviation metal parts is particularly important. In this work， the main forming processes and related research in the production of aviation parts at domestic and abroad are reviewed. The forming processes in aviation application and research status include liquid forming， plastic forming and powder metallurgy. The current forming processes of aviation metal parts have some shortcomings， such as single forming process and high energy consumption. At the same time， the development of the forming process of aviation metal parts is prospected， and the combination， intelligence and greening of the forming process of aviation industry will be the development trend of aviation industry in the future.

Abstract:In order to study the grain growth behavior of a new-type nickel-base superalloy at elevated temperature， grain growth tests are carried out of Haynes 282 alloy within the holding temperature range from 973 to 1 373 K and holding time range from 0 to 10 800 s.The influence of the insulation time and insulation temperature on the grain size is analyzed， and the evolution law of the grain size under the experimental conditions is studied.The mathematical model of grain growth of Haynes 282 alloy is constructed， which can effectively characterize the grain growth behavior of Haynes 282 alloy at high temperature.

Abstract:Type X carbonyl iron powder mixed with different proportions of paraffin were used for testing permeabilities and permittivities of these materials to study interference phenomenon of electromagnetic wave in radar absorbing coatings （RACs）. The formula of reflection coefficient of type X RACs to plane electromagnetic wave with the thickness of quarter-wavelength was solved by the method of multiple reflections. And the formula of reflection coefficient of type X RAC to plane electromagnetic wave of frequency at 9.5 GHz with different thickness was also solved in which the first six terms were chosen for calculating reflection coefficient Γ_a and reflectivity R_a. The results show that interference phenomenon is caused by the multiple reflections of wave. The value of Γ_a and the value of reflection coefficient Γ calculated by method of transmission line are close to each other which shows Γ_a and R_a can approximately represent Γ and reflectivity R of type X RAC separately. If the thickness of type X RAC is smaller than 1.9 mm or in the range from 3.2 to 6.6 mm， the second reflected wave will enhance the first reflected wave and increase the reflectivity which indicates the optimum thickness of type X RAC is in the area from 1.9 to 3.2 mm.

Abstract:In order to study the effect of fiber wrinkle on the compression properties of carbon fiber composite laminates， the compression properties of carbon fiber laminates containing fiber wrinkle were tested according to ASTM D6641-2014 standard. Meanwhile， the progressive damage method based on Hashin failure criterion and property gradual degradation was analyzed by finite element method. The results show that the ultimate compression load of the sunken test piece with 30% wrinkle is 58.48% lower than that of the intact test piece. The compressive strength of sunken test pieces is lower than that of raised test pieces under the same degree of wrinkle. The stiffness of the sunken test piece with 30% wrinkle is 35.80% lower than that of the intact test piece. The finite element analysis results are in good agreement with the test results， the initial damage is matrix damage， and the test piece finally fractures at the wrinkle after expansion.

Abstract:A series of polyaluminosilazanes （PASZ） precursors were prepared by thermal polymerization with different proportion of polysilazanes liquid oligomers and aluminum acetylacetone ［0.1%~1%（w）］ as raw materials. The continuous SiAlCN（O） fibers were obtained via the melt spinning， air pre-oxidation treatment and high temperature cracking of PASZ. The PASZ and SiAlCN（O） fibers were characterized by FT-IR， GPC， SEM， XRD and metallographic microscopy. The results show that the mass average molecular weight of PASZ is from 7 191 to 11 275 g/mol， and prepared PASZ with 0.2% aluminum acetylacetone mass fraction shows shear thinning and excellent spinning property in molten state which could be continuously prepared up to 3 km. The SiAlCN（O） fiber is amorphous aluminum-containing silicon nitride fiber and the diameter of the fiber is about 20 to 70 μm， and the fiber surface is smooth， without obvious defects such as cracks and grooves.

Abstract:Al₂O₃/Al₂O₃ composite was prepared by slurry infiltration method in one processing cycle using Nextel 720 alumina fiber as reinforcement in order to facilitate the preparation of large components. Physical and mechanical properties of the composite were evaluated and the cross section and microstructure were studied by optical microscope and SEM. The results show that the bulk density of Al₂O₃/Al₂O₃ composite is 2.64 g/cm³ and the apparent porosity is 26%， porous nature of the matrix is evident. The transverse thermal conductivity from room temperature to 1 200 ℃ is 3.49 to 2.04 W/（m·K） for the prepared composite. The CTE in thickness direction from 200 ℃ to 1 200 ℃ is 4.7×10^-6 to 7.1×10^-6/K. The in-plane tensile strength at room temperature， 1 100 ℃ and 1 200 ℃ are 202.4 MPa， 222.4 MPa and 228.4 MPa，respectively. It is clearly observed that many fibers are pulled out of the ceramic matrix from the optical micrographs and SEM image of fracture surface of tensile specimen. Flexure strength of Al₂O₃/Al₂O₃ composite at room temperature is 200.5 MPa， and the sample shows ductile fracture. Interlaminar shear strength of Al₂O₃/Al₂O₃ composite is 21.0 MPa. The main properties of the prepared materials are equivalent to the same type of material from ATK-COI Ceramic， USA， and some mechanical properties are better.

Abstract:In this paper， high transmittance modulated NiO_x thin films were prepared by DC reactive magnetron sputtering method at room temperature by using indium tin oxide （ITO） glass as the substrate. The film was analyzed and characterized by X-ray diffractometer （XRD）， scanning electron microscope （SEM），UV-Vis spectrophotometer （UV 3600）， the effects of argon-to-oxygen ratio， air pressure and power on the electrochromic properties of the film during sputtering was studied. The results show that the prepared NiO_x film has obvious crystal grains and pores on the surface， and preferentially grows on the（200）crystal plane.With the increase of air pressure， power and oxygen partial pressure， the transmittance modulation first increases and then declines.When the time is 45 min， the sputtering pressure is 4.9 Pa， the argon-oxygen ratio is 113∶7，and the power is 215 W， the maximum can reach 58.3%. The coloring and fading response times are 9 s and 19 s，respectively， and the corresponding coloring and fading efficiency are 77.56 cm²/C and 40.39 cm²/C； the electrochromic devices with the structure of Glass/ITO/NiO_x/Li-electrolyte/WO₃/ITO/Glass are prepared with the optimal NiO_x film， and the light modulation amplitude of the device at 550 nm is 46.5%， the dyeing and fading times are 27 s and 45 s， the corresponding dyeing and fading rates are 1.5 %/s and 0.9 %/s， and the transmittance modulation remained above 40% after 500 cycles.

Abstract:The effects of peroxide vulcanization system and sulphur vulcanization system commonly used in ethylene propylene diene monomer （EPDM） insulation on the types and content of volatiles are studied by headspace gas chromatography-mass spectrometry and thermogravimetric method.The results show that the main volatiles of dicumyl peroxide （DCP） are phenylpropene，acetophenone and 2-phenyl-2-propanol；the main volatiles of 1，3-bis （tert-butyl peroxide isopropyl） benzene （BIPB） are acetone、tert-butanol and 1，3-diacetylbenzene；the main volatiles of 2，5-dimethyl-2，5-tert-butyl peroxyhexane （DBPH） are acetone，tert-butanol，2-methyl-2-methoxypropane and 2，5-dimethyl-2，5-hexanediol.The analysis of vulcanization characteristics of different peroxide systems shows that the dosage of BIPB is the least when the degree of vulcanization is equal to DCP. Compared with DCP and DBPH systems，the content of volatiles of BIPB simple vulcanization system is the lowest when pre-baked at 80 ℃.The analysis of the content of volatiles of peroxide vulcanization systems and sulfur vulcanization system shows that the volatiles content of sulfur/tetramethylthiuram disulfide/2-mercaptobenzothiazole （S/TMTD/M） full formula system is significantly lower than that of other three peroxide systems when pre-baked at 80 ℃，and the weight loss rate of pre-baked for 100 h is 31.50% lower than that of DCP system.The difference of vulcanization mechanism between peroxide and sulfur systems and the difference of vulcanization agent dosage are the main factors affecting the content and types of volatiles emission in EPDM insulation.

Abstract:High-cycle fatigue tests were carried out to investigate the effects of stress ratio on the fatigue ultimate strength and S-N fatigue life for 0Cr18Ni9 stainless steel welded joints. The results show that the fatigue life increases with stress ratio under the given maximum stress. Based on the tests results， the Goodman and Walker high-cycle fatigue life prediction models are obtained to reflect the effects of stress ratio. And the comparison also reveals that the Walker model predicted life coincides with the tests data better than Goodman model with the fact that the former models'' data distributes on the more narrow band.

Abstract:In order to give full play to the different performance advantages of dissimilar aluminum alloys and ehance the performace of aviation material， 6061-T6 aluminum alloy and 7075 aluminum alloy were selected for FSW test. Under the welding parameters of preheating time of 20 s， pressing volume of 0.1 mm， inclination of 2.5° and welding speed of 100 mm/min， the rotational speeds of 800，1 000， 1 200 and 1 500 r/min were tested respectively. Through the observation of the weld formation， mechanical properties and microstructure， the results show that when the rotating speed is 1 200 r/min， the surface of the weld is the best， and the tensile property is 255 MPa， which is 89.5% of 6061-T6 aluminum alloy. In the meanwhile， the heat generated by the forward side is higher than that generated by the backward side， so it is more suitable to place the metal with higher specific heat capacity and melting point in the forward side. Better appearance and performance of welded joint can be obtained through the test parameters in this paper.

Abstract:In order to study the wear and selection of different materials cutting tools in high speed milling of 7075 aluminum alloy， micro （MCD）/nano （NCD） diamond coated tools were prepared by chemical vapor deposition.The surface morphology of the film was observed by field emission scanning electron microscopy.Analysis of the structure and composition of CVD diamond coated tool films were analyzed by Raman spectroscopy.The same size cemented carbide cutting tool and MCD coated cutting tool were used to carry out rough machining high-speed milling experiment under the condition of dry cutting without lubrication.The wear condition of the two kinds of cutting tools after machining a certain distance was observed.In order to observe and analyze the surface roughness of the workpiece after finish milling，the same size cemented carbide tools，MCD coated tools and NCD coated tools were used to finish high-speed milling experiments under the condition of dry cutting without lubrication.The results show that the life of MCD coated tool is three times longer than that of cemented carbide tool when milling 7075 aluminum alloy with large depth and high speed.In the high-speed finish machining of 7075 aluminum alloy with small cutting depth and large feed，the average surface roughness of the workpiece milled by three kinds of cutting tools is 0.981 μm，1.122 μm and 0.960 μm.The machining effect of NCD coated tool is better than that of MCD coated tool.At the same time，through the comparison of rough and finish machining experiments of the same material tool，it is found that the life of the same specification tool in small cutting depth and large feed high-speed finish machining is ten times of that in large cutting depth and large feed high-speed rough machining.The results show that MCD coated tool is the best for rough milling and ncd coated tool is the best for finish milling of 7075 aluminum alloy.