Abstract:With the rapid development of science and technology， new aerospace equipments put forward new requirements for high temperature thermal protection， thermal structure and multi-function materials， which also bring new opportunities for the research and application of carbon/carbon （C/C） composites. In this paper， the recent progress of unltra-high thermal protection C/C， thermal structural C/C， high thermal conductivity C/C， non-ablation low density C/C composites are respectively reviewed. Finally， the existing problems of several C/C composites are discussed， and the development trend in the future is also put forward.

Abstract:The advancement of microwave technology has spurred the development of electromagnetic （EM） protection technology. Being capable of dissipating excess electromagnetic radiation in the form of heat， EM wave absorbing materials have gathered widespread attentions. Confronted with complex EM environment， it is of great significance to explore EM wave absorbing materials with both strong and broadband absorbing capacity within the frequency band of 1 to 18 GHz. At present， the design methods for EM wave absorbing materials mainly include nano-composite construction and doping modification. Through combining dielectric loss-type and magnetic loss-type nanomaterials， the dielectric and magnetic loss coupling can be achieved. However， complex preparation process， difficulty in accurately controlling the dispersion of nanofillers and poor high-temperature stability and resistance to oxidation are the main drawbacks for these types of materials. Ultra-high temperature ceramics （UHTCs） possess good thermal stability and resistance to oxidation， however， the poor impedance match makes it unsuitable for EM wave absorption. Through designing and preparing high-entropy ceramics containing magnetic components， strong and broadband absorbing capability can be achieved in UHTCs. The high-entropy design paradigm can simultaneously adjust the conductivity and enhance the magnetic loss capability， which opens a new window to tune the impedance match for dielectric materials with high conductivity.

Abstract:The continuous development of China''s aerospace industry has put forward higher requirements for spacecraft thermal protection materials. Aerogel， as a nano-network porous material， has super thermal insulation performance due to its nano-scale effect， and is a hot spot and frontier of research on super thermal insulation materials in recent years. This paper reviews the research progress of aerogel thermal insulation materials in the past ten years， including inorganic oxide aerogel， organic aerogel， carbon aerogel and carbide aerogel thermal insulation materials， as well as their preparation methods， thermal insulation performance and current status of thermal protection applications， and proposes the future development of aerogel thermal insulation materials in the light of the current demands in the aerospace field and the difficult problems of aerogel thermal insulation materials research. The paper presents the future development of aerogel thermal insulation materials， taking into account the current needs of the aerospace industry and the difficulties of aerogel thermal insulation materials.

Abstract:The development of aerospace technology has put forward higher requirements for advanced composite materials， and the three-dimensional fabric has been comprehensively developed.This paper reviews the research status of three-dimensional fabric structure， molding process， manufacturing equipment and application of composite materials at home and abroad， and points out the future development direction based on the characteristics of three-dimensional fabric and the development status in China in recent years.

Abstract:Thermal environment for aerospace equipment is becoming more and more severe， which comes up with a strict requirement for thermal protection system. Three-dimensional （3D） braided carbon/phenolic composite is a kind of ablation material with excellent designability due to the special structure of 3D braided preform， which helps to realize the integration of heat-proof requirement and mechanical requirement. With the development of braiding and molding technology， 3D braided carbon/phenolic composite has gradually become an ideal candidate material for thermal protection system in aerospace field. This article summarizes the research progress of 3D braided carbon/phenolic composites from four aspects： 3D braided carbon fiber preform， phenolic resin matrix， molding process， and composite material ablation performance.

Abstract:Additive manufacturing technology is a kind of net forming technology that produces complex 3D parts by adding materials from point to point， line to line and surface to surface. 3D printing is a kind of mature technology that can manufacture all kinds of products with dense microstructure and stable performance. Recent years， researchers adapt additive manufacturing technology to smart materials， which enables the expansion of the technology from spatial dimension to time-space dimension. In this paper， the research status and development prospect of 3D printing and 4D printing is introduced in detail in order to provide reference for staffs engaged in this field.

Abstract:Aluminum alloy additive manufacturing has attracted extensive attention in the manufacturing of aerospace structural components due to the advantages of lightweight materials and the characteristics of additive manufacturing technology in material utilization and complex structure manufacturing. Aiming at the application of aluminum alloy additive manufacturing in aerospace field， this paper analyzes the research status and existing problems of aluminum alloy additive manufacturing technology through three representative processes of wire arc additive manufacturing， selective laser melting and laser melted deposition. And the application status and future development of aluminum alloy additive manufacturing technology in aerospace field are briefly described.

Abstract:A series of development plans implemented by the US and Europe in recent years to promote the application of composite in aircraft are summarized.The importance and value of developing the liquid composite molding technique for the development of the aviation composite field are illustrated.The current status of the technology and application of liquid composite molding for military and civil aircraft in advanced technology countries is analyzed and summarized. Additionally， the representative progress and application status of domestic liquid forming technology for aviation composites is compared and analyzed. Finally， the gap between China advanced technology countries is summarized. On this basis， the development trend of aviation composite and liquid forming technology is outlined.

Abstract:Fiber reinforced SiC matrix composites （FRCMC-SiC） have significant potential in aerospace application and other high temperature conditions due to their special properties such as low density， high strength， thermostability， anti-oxidation and anti-ablation. However， the application of these composites has been hindered seriously because of their poor machining characteristics. The high-quality and low-damage machining technology must be solved in the use of this kind of high hardness， high brittleness and anisotropy materials. In this paper， the recent progress on the different machining technologies of FRCMC-SiC is reviewed. The material removal mechanism， theoretical model construction， parameters optimization， defect form and surface quality control are summarized and discussed. Finally， the existing problems are discussed， and the development trend of machining technology of FRCMC-SiC in the future is also put forward.

Abstract:The level of intelligent health monitoring for aerospace composite materials is one of the key features to evaluate the reliability and advancement of aerospace vehicles. Intelligent health monitoring technology is fundamental to support the development of repeated and long-term reliablity of various aerospace vehicles. In this paper， the main research progress and development status of intelligent health monitoring for composite materials in recent years are summarized in sensor fabrication， the integration of sensor and composite material， composite material status monitoring， composite material damage and failure characterization technology， artificial neural network data processing and analysis technology，and put forward the existing problems of monitoring technology and future directions of intelligent health monitoring for aerospace composite materials.

Abstract:In this paper， the true stress-strain data of Haynes 282 alloy were obtained by conducting isothermal compression tests on a thermal-mechanical simulator.Haynes 282 alloy shows typical dynamic recrystallization characteristic during the deformation process at elevated temperature.Moreover， the flow stress was quite sensitive to the thermodynamic parameters and represents complicated highly-nonlinear relationship with the thermodynamic parameters. In order to accurately describe and predict the true stress-strain relationship of Haynes 282 alloy， a back-propagation neural network was constructed by employing hot deformation parameters as the inputs， and employing flow stress as the output. The evaluation results of the constructed neural network show that the constructed neural network in this research can accurately characterize the hot flow behavior of Haynes 282 alloy. Accurate simulation of the hot flow behavior of Haynes 282 alloy is achieved by implanting the neural network into a finite element software in the form of material subroutine and constructing the finite element model of isothermal compression test.

Abstract:The isothermal stamping process of hemisphere shell for the large-size TA7ELI helium cylinder used for future launch vehicles had been researched in this work. The isothermal stamping process of hemisphere shell was simulated by finite element analysis software before a forming process， the influence of the process on the material properties was investigated by comparing the changes of the material microstructure and mechanical properties before and after the forming. Experimental result indicates that during isothermal stamping， the stress and strain of the material gradually extends from the core to the edge， the applied load reaches the maximum value when the forming process operates later period. Furthermore， the thinnest position of the hemisphere shell is around the center of the ball bottom. The grain morphology and size of TA7ELI material changes little after stamping， and the strength of the shell at room temperature and 20 K is almost the same as that before forming. The elongation of the shell at room temperature increases after forming， and the elongation of the bottom of the shell at 20 K decreases but still meets the requirements.

Abstract:Micro porosity is the main issue in wire arc additive manufacturing （WAAM） of 2219 aluminum alloy. In this study， the effect of process parameters on the porosity characteristic of WAAM 2219 aluminum alloy was quantitatively investigated. It is found that the porosity was influenced by the heat input. When the heat input is low， the porosity increases with the increasing of heat input due to the nucleating and growing of pores. When the heat input is high， the porosity decreases with the increasing of heat input due to the escaping of pores. The porosity is below 0.2% when the heat input is as low as 230.5 J/mm or as high as 439.5 J/mm.

Abstract:Characterizing the axial compressive properties is always the difficulty in the fields of investigating the mechanical performance of the composite materials. In this paper， the pros and cons of four test methods for determining the compressive properties of the composite materials are comparatively summarized， by experimental investigations， mechanism analysis and computational simulations， based on domestic T800-grade composites and M40J-grade composite. Additionally， the optimized test conditions are proposed. The results of experiments and simulations indicate that the compressive strength determined by the test method of GB/T 3856—2005 is decreased by 9% than that of the test method of ASTM D3410—2016， due to premature failure， although the compressive force is both introduced through shear for the two methods. Whereas， the compressive strength measured by the end-loaded method of SACMA SRM 1R-94 is 3% to 6% higher than that of the method of ASTM D3410—2016 and D6641—2014. Moreover， the experiments for optimizing the test conditions demonstrate that the strengthening tabs have a noticeable effect on the measured compressive properties for the high-performance carbon fiber composites. Accordingly， tabs made of metal are suitable for composite materials with strong interfacial bonding and high fracture strength； while tabs made of glass fiber reinforced polymer are suitable for those with weak interfacial bonding and low fracture strength. From the images of the fracture appearance of the specimens， it is observed that there are typical failure modes of ‘kinking band’ of the fibers for both the shear-loaded method and the end-loaded method. Therefore， the end-loaded compression method is a preferable method for determining the compressive strength of the composite materials， considering the measured results and failure modes.