The properties of electronics, mechanics, magnetics and optics of nanometer materials were changed greatly because of their particular surface effect, volume effect and quantum size effect Nanotechnology was applied successfully to fine ceramics, microelectronics, bioengineering, chemical engineering and pharmacy fields.Its widely applied prospect made nanometer materials and corresponding nanotechnology become one of the hot topics in the scientific research field, which have great improvements on the materials'super-plasticity and high-strength, these characteristics have significant effects on the electronics, thermal dynamics, magnetics and optics of materials, they are regarded as another industrial revolution in the 21th century.

The present status of research and application about the aircraft brake disk and the engine hot components manufactured by carbon/carbon (C/C) composites in the world has been introduced in the paper.The problems in the studying works and the development directions about this field on the future have been discussed.

Main reasons of nano-particles conglomerating is introduced,the progress of physical and chemical surface-modification techniques of the nano-particles is discussed.And finally the latest application of nano-particle in coatings,plastic,rubber and other fields is also reviewed.

High-entropy alloys were newly developed alloys that were composed,by definition,of at least five principal elements with concentration in the range of 5%-35%(molar fraction).Therefore,the alloying behavior of any given principal element was significantly affected by all the other principal elements presented.The definition,distinguished structure and performance characteristics,as well as the potential applications of high-entropy alloys were introduced.In addition,the historical development and the latest research progress in this field are also summarized.

The current high entropy alloys' studies are most in block, powder, coating, film and other areas. There are few studies of high entropy alloys in other areas and they are lack of unified classification. According to the current high entropy alloys' research situation, The paper has focused on the classification on all kinds of high entropy alloys having been researched, introduced the selecting principle of elements, summarized the preparation methods, reviewed the research institutions, research methods and research contents of high entropy alloys, prospected the application prospect of high entropy alloys, put forward a series of scientific problems of high entropy alloys, including less research on mechanism, incomplete performance research, unsystematic thermal stability study, preparation process parameters to be optimized, lightweight high entropy alloys' design, the expansion on the research field, etc, and the solutions have been given. Those have certain guiding significance for the expansion of the application of high entropy alloys subjects in the future research direction.

The history of aluminum-lithium alloys was reviewed.It can be concluded that the alloys could be classified three generations according to time and their properties.Further more,the development of the third generation of Al-Li alloys were investigated in detail.A tendency of the third generation of Al-Li alloys is to develop some new alloys with certain excellent properties.

自美国1994年6月发布关于美军标改革的政策备忘录以来,在军用材料及热工艺方面,截止1999年1月,由美国军用标准转化而来的宇航材料规范(AMS)有151项,转化方式是将原标准代号用AMS代替,即将MS、AND、FED、MIL等改为AMS,原标准代号不变。转化而来的AMS标准清单见表1,供参考。

Fatigue notch factor K_f is usually used to express the reduction in fatigue strength of the component notch.The factor of K_f is very useful in fatigue design.In this paper analysis for many fatigue limit of aluminum alloy,titanium alloy and steel with stress ratio of 0.5,0.06,-1 showed that the relation between most of K_t and K_f is linear except some case.The relation of K_f and K_t not only depends on the kinds of material but also on the stress ratios.

This paper introduces the background materials,process,content and recomended implementation of the new national standards-wrought aluminium and aluminium alloys designation system and temper designation system—for manufacturing,applying,teaching as well as trade and technical exchange of wrought aluminium alloys.

Currently, the utilization efficiency of energy still remains at a low level, although the depletion of fossil fuel is appoaching. Therefore, it is of great significance to develop new materials and technologies for energy-saving and environment protection. Phase-change materials (PCM), which can absorb or release heat through inversible phase change, are very promising in the fields of heat storage and thermal management. In this paper, the characteristics and classification of PCM were introduced briefly in the first section, and then the application and development status of PCM were reviewed and analyzed detailedly. In the third part, the main problems of PCM were pointed out, and the related research work and recent research progress were analyzed and discussed. Finally, it was pointed out that optimizing material properties through new functional composite technology, designing new material system, expanding new application fields are the main development directions of phase change energy storage materials.

The material damping characteristic and its measuring parameters were introduced. The status of research on the testing methods of damping capacity, damping alloys and their damping mechanisms were also reviewed. In addition, the problems existing in the applications of conventional damping alloys were pointed out.

All kinds of ABO₃-type oxides are summarized,including various crystal structure and their electrical,optical,acoustics properties.It is discussed that ABO₃-type crystal and ceramic materials are applied and developed widely in the fields about modern electronics and information,aerospace,defense and military.

Cellulose triacetate(CTA)was prepared in the presence of mixture of acetic anhydride/acetic acid/H₂SO₄.The structure and properties of cellulose triacetate acetylation were determined by IR,¹H-NMR,XRD,DSC and chemical analysis.The results showed that acetyl mass fraction of all CTA samples were at least 60%,the most active reaction position on the anhydroglulose unit was C-6.Compared with that of cellulose,the crystallinity of CTA was much lower,but the processability was improved a lot.

The research status on theoretic models and the coupling relationships of Orowan strengthening, dislocation strengthening, load-bearing effect of the reinforcement strengthening and others strengthening are successfully described in this study for particle-reinforced metal matrix composites(MMCs) with a volume fraction lower than 14%. Some conclusions can be obtained:Orowan strengthening and dislocation strengthening stress can be enhanced by increasing volume fraction, decreasing size of reinforcement and improving homogeneous distribution of reinforcement, load-bearing strengthening stress can also be enhanced by increasing volume fraction; yield strength and ductibility of MMCs can be enhanced much more by increasing load-bearing strengthening stress and plastic deformation region and adopting the material design method of metal matrix surrounded by particles with microstructural inhomogenous distribution; grain boundary strengthening and Peierls-Nabarro stress can also affect the yield strength of MMCs as a part of matrix strengthening, solid solution strengthening can be ignored usually; there are three coupling relationships for the sum strengthening contributions:linear summation, multiplicative combination and the root of the sum of the squares. The linear summation and multiplicative combination can be applied to nanoparticle-reinforced MMCs, the linear summation is generally applicable in the case when there are few factors influencing the strength, the multiplicative combination is the most commonly used method. The root of the sum of the squares is applied to micronparticle-reinforced MMCs.

With the increase of the thrust-weight ratio of the aero-engine, CMC-SiC composites with low density, high strength and toughness, high thermal stability, long lifetime, good ablation resistance and oxidation resistance need to be developed to meet the requirements of the complicated and aggressive environments in the aero-engine. The characteristics, fabrication methods, applications on the hot components of the abroad advanced aero-engines, the domestic research achievements and the open problems of the CMC-SiC composites were introduced. The research tendencies in the high performance fibers, parts design and fabrication, environmental barrier coatings, non-destructive testing technologies, evaluation and verification method and repairing technologies were put forward.

This paper first summarizes simply the mechanism of the electromagnetic wave absorbing as a background knowledge, and the types of absorbing materials according to different standards. Secondly, the current status of ceramic absorbing materials is reviewed in detail, which takes the examples of silicon carbon and ferrite. Finally, the investigation in this field of our lab is introduced.

Two kinds of polyimide films were prepared based on the ODA and ODPA in NMP through two-step thermal or chemical imidization process and characterized by the cone and plate viscosimeter,GPC,FTIR,DSC,TGA and strain properties tests.The results showed that the films prepared from different imidizations had been totally transformed to polyimide films.The glass transition temperature,thermal decomposing temperature of the film from chemical imidization is higher than the one from thermal imidization.The strain tests showed that the film from thermal imidization had larger elongation at break,and the film from chemical imidization had larger tensile strength and elasticity modulus.

Polymethacrylimide(PMI)foams were prepared by the casting process using methacrylic acid(MAA)and methacrylonitrile(MAN)as monomers.The structure and properties of the PMI foams were analyzed by infrared adsorption spectrum(FTIR),optical microscope,differential scanning calorimeter(DSC)and thermogravimeter(TG).The results show that the foamable MAA/MAN copolymers were prepared at 40-60℃ by polymerizing the mixture of 50phr MAA,50phr MAN,1-5phr magnesium oxide,2-8phr butanol and tert-butanol,0.2-0.3phr dibenzoyl peroxide and tert-butyl perbenzoate and 0.1-0.2phr DMF.Then the resulting copolymers were expanded at 200-220℃ for 2-3h,subsequently treated at 160℃ for 5-6h,generating PMI foams with excellent mechanical properties and heat-resistance.Molecular rearrangement reaction occurs during the foaming and post-treatment forming hexahydric imide ring.The prepared PMI foams have closed cell structure with the cell size ranging from 0.5mm to 0.7mm and have a good thermostability with the characteristic degradation temperature at about 221.5℃.

After introducing the principle and classification of 3D printing, methods for metal forming using 3D printing were reviewed in details, including electron beam melting(EBM), selective laser melting(SLM), laser direct melting deposition(LDMD). The application fields of metal 3D printing and research status overseas and domestic were also discussed in this paper. At last, based on the current development of metal 3D printing, this paper summarized the key issues that should be solved, which include the quality of powders, the usage of 3D printing equipments, nondestructive testing for 3D printing components, the failure analysis and prediction of lifecycles for 3D printing components. The standards of nondestructive testing for 3D printing components should be established and the database of comprehensive mechanical properties for 3D printing materials should be built.

Graphene is a single atomic layer structure, which is the thinnest 2-D planar sheet composed of sp²-bonded carbon atoms. The special structure of graphene has excellent properties, such as photoelectric property, heat stability and mechanical properties. There has been increasing attention to preparation, property and application of graphene composites in recent years. In the paper, preparation methods of graphene composites is reviewed, such as graphene/polymer composites, graphene/metal (metal oxide) composites, and ternary composites of graphene. The advances in application of graphene composites are also reviewed, such as in lithium battery, supercapacitors, photovoltaic devices, sensor applications. Furthermore, the important research direction of graphene composites is pointed out.

The nature physics-chemical property and the present experimental investigation of nano-titanium dioxide(TiO₂)was briefly introduced.The investigation progress of calculation simulation about the microstructure,photocatalysis and modification of TiO₂-based nanomaterials using first-principles calculations based on density functional theory(DFT)had importantly discussed in detail.The problem existed nowadays and the development trends in this field were pointed out.

The stress corrosion testing methods of high strength aluminum alloys are reviewed.The principles and applications of these methods are presented.The advantages and shortcomings of those methods are analyzed.Because only one method can not evaluate the stress corrosion properties of aluminum alloys comprehensively,it would be better to measure aluminum alloys with different testing methods mentioned.

The fundamental principle,development state,solidification microstructure and forming characters of laser solid forming(LSF) were investigated throughly.It was found that to acquire idea forming result,the height,width and the overlap rate of the single cladding layer must be accurately controlled.The forming principle of the microstructure was also studied during laser solid forming in this paper.The microstructure of the sample was made up of thin and long epitaxial growth dendrites,the primary spacing of which is about 10~30μm. The directional solidification microstructure or even single crystal was obtained based on the rigid processing characters control.Combining the research results of the forming character,the samples with different metal were obtained by using optimized processing characters.The inner part of the sample wa dense,the surface quality was fine and was free of defect.

The preparation methods of electroconductive polymer composites for shielding electromagnetic interference(EMI) were introduced, and the main factors affecting shielding effectiveness of the composites, such as species, shape, filler content of electroconductive filler and different composite technological, were discussed in this paper.

Perovskite solar cells(PSCs) have been developed rapidly as one of the most remarkably growing photovoltaic technologies in the last five years. The power conversion efficiency(PCE) of the solar cells has been unprecedentedly increased over the relatively short period. It is of great significance to study the perovskite materials in this kind of solar cells for improving the efficiency. The most focused issues as well as the main progress in varied fabrication techniques and synthesis of new materials in recent years were reviewed in this paper. The characteristics and improvements of varied fabrication techniques are introduced in detail, the necessity and the problems facing for new materials synthesis were analyzed. Finally, a perspective view on reducing the toxicity of perovskite, preparing large-scale perovskite solar cells, and the cost reduction was given to provide the direction for the future research of high-efficiency and stable perovskite solar cells.

The development trends of advanced composite in near term are introduced,including some aspects of become-manyfaceted,low-cost,internationalization and standardization.

Graphene-reinforced aluminum matrix nanocomposites were successfully synthesized through ball milling and powder metallurgy. The tensile strength and yield strength of graphene-reinforced aluminum matrix nanocomposites are remarkably enhanced by adding graphene nanoflakes(GNFs). Importantly, the ductility properties are remained excellently, which is firstly found in the second phase reinforced metal matrix nanocomposites. The microstructures were observed by OM, SEM and TEM method. And the tensile properties were tested.The results show that graphene nanoflakes are effectively dispersed and well consolidate with aluminum matrix, however, chemical reactions are not observed. The original structured characteristics of graphene nanoflakes are preserved very well. The average tensile strength and yield strength of nanocomposite are 454MPa and 322MPa, respectively,which are 25% and 58% higher than the pristine aluminum alloy at a nanofiller mass fraction of 0.3%, while the ductility increases slightly. The relevant mechanisms of strengthening and toughening enhancement are discussed on the base of 2D and wrinkled structured properties of graphene nanoflakes.

Mechanical properties and their present research levels of some Laves phase alloys are introduced,including hardness,strength,ductility,mechanical behavior and fracture toughness.The further research directions for Laves phase alloys are suggested.

Sintering mechanism of the single-component/multi-component metal powders and the pre-alloyed powders during Direct Metal Laser Sintering (DMLS) process were analyzed. The material properties such as surface tension, viscosity, particle size and its distribution, and absorbance/ reflectivity together with the processing variables such as laser parameters, layering thickness of powders, atmospheric control, bed pre-heating temperature, and sintering assisted material, which affect sintering and densification of DMLS-processed parts, were discussed. The further directions of the research method in DMLS were addressed.

In this paper, a series of significant aerospace applications of silicon carbide particulate reinforced aluminium matrix composites achieved in recent years are summarized, these successful applications and their positive effect on the corresponding products and equipment are presented in detail also. In addition, several potential applications of the composites in the inertial guidance systems, optomechanical structures, electronic components of homemade aircraft and spacecraft are described and analyzed.

The energy crisis and environmental pollution problem is increasingly serious on a global scale, however the rapid development of photocatalytic technology brings the dawn to solve the problem, and the photocatalytic materials system as a basic element has become the focus. The photocatalytic degradation of organic pollutants in water was focused in this article, and the development status of photocatalytic technology, nine types of photocatalytic materials and their properties, mechanism of action and the application of research, as well as modification methods of the materials were summarized. Finally, it was proposed that the materials still has the problems of low solar energy utilization, low quantum yield, and insufficient photochemical stability at the current stage, nevertheless the new material system of metal-organic framework (MOF) and the modification methods of micro/nano mesoporous, multi-hole composite, Z-scheme semiconductors provide a broader space for the exploration of photocatalytic materials.

The background of application and search of thermal conducting polymers was reviewed.The progress in the study of thermal conductive plastics、rubbers and adhesions in recent years were described, thermal conducting mechanism of polymer composites was commented and several pieces of advice were given to obtain effective thermal conductive polymer composites.

The electric and absorbing wave properties of fibers in structural radar absorbing material are reviewed. Glass fibers and Kevlar fibers are transparent to radar wave. Carbon fiber graphited at high temperatures strongly reflects the radar wave. Ungraphited carbon fiber reflects radar wave when it is parallel to the electric filed and absorbs radar wave when it is perpendicular or oblique to the electric filed. The radar wave absorption of SiC fiber is related to the fiber′s composition and processing temperatures. During fabrication of SiC_f/glass ceramic composites, reaction takes place between fiber and matrix. As a result, a carbon rich layer interface is formed. It facilitates the radar wave absorption of the composites.

Titanium silicon carbide has excellent electrical and thermal conductivity,high strength of up to 1300℃,good oxidation and thermal shock resistance and thus has been considered as candidate material for high temperature applications.The present paper described the structure,processing,and properties of titanium silicon carbide.The potential of further applications was also discussed.

This paper summarized the processing principles and characteristics of the cold gas dynamic spray(cold spray)technology.It emphasized to discuss the coating deposition mechanism and the parameters which influenced the critical velocity of the particles and the coating quality.It is believed that using the proper parameters in the coating process is vital for getting high quality coating,improving the structure of the spray gun,fabricating functional and composite coatings are considered as the main directions of the cold spray in future.

据美国AIAA81-0508文件,波音747是目前起飞重量最大的客机,空重为164吨。制造一架这种飞机所需各种金属材料如下:铝180吨、铁72吨、钛15吨、铜9.9吨、锌3.2吨、镍2.7吨、锰1.5吨、铬1.2吨,共计285.5吨。

The corrosion types and feature is presented for aircraft structure materials,and the service corrosive environment and the major corrosion reasons is analysed.The repair methods and corrosion control of the corrosive damage areas in structure are proposed with practical engineering maintenance.

The research progress and application status of ceramic 3D printing technology, and its materials characteristics were reviewed. The characteristics and research progress of inkjet printing technology, melt deposition molding technology, photocuring molding technology, layered entity manufacturing technology, laser selection melting technology/laser selective sintering technology, three-dimensional printing technology, and slurry write-through molding technology were discussed. The characteristics and application status of tricalcium phosphate ceramics, alumina ceramics, ceramic precursor, SiC ceramics, Si₃N₄ ceramics, and titanium silicon carbide ceramics were analyzed. It was pointed out that the development direction of ceramic 3D printing technology is combined with traditional ceramic technology to realize the rapid production of ceramic products and the manufacture of bio-ceramic products and high-performance ceramic functional parts.

Graphene is a kind of two-dimensional atomic crystal with one atomic layer, which is the basic structure unit of other dimensions of graphite materials, such as zero dimensional fullerenes, one-dimensional carbon nanotubes and three-dimensional graphite. Graphene has a lot of unique electronic and mechanical properties, which have attracted high attention of many scientists in the field of chemistry, materials and other fields. Raman spectroscopy as a sensitive and convenient characterization method, has played a very important role in the study of graphene. Raman spectroscopy is an integral part of graphene research. The application of Raman spectroscopy in graphene characterization in recent years is reviewed in this paper. The characteristic peak of monolayer graphene was first intnduced. Then, through the analysis of the changes of D peak, G peak and 2D peak intensity, position and half peak width of Raman spectra, the number of graphene layers can be quickly and accurately characterized, as well as, the stacking orders, edge chirality and doping degree of graphene were defined. At the same time, the effects of substrate, doping, temperature and laser power on the intensity, position and half width of D peak, G peak and 2D peak of Raman spectra in the process of preparing graphene were also systematically analyzed.

The microstructure and mechanical properties of as-extruded Mg-6Zn-Mn magnesium alloy with different Nd content were investigated by OM, XRD and tensile testing, respectively. It was found that the dendrite arm spacing of as-cast Mg-6Zn-Mn magnesium alloys was effectively decreased with Nd addition. Furthermore, the microstructure of Mg-6Zn-Mn magnesium alloys changed significantly after hot extrusion at 360℃ with Nd doped under extrusion ratios of 25. The Mg-6Zn-Mn magnesium alloy with 0.2% Nd shows the highest yield strength (about 250 MPa) and ultimate strength (above 300MPa) by tensile tests at room temperature.