Abstract:This paper reviews the research status of laser processing of fiber-reinforced composites （FRP） at home and abroad. The mechanism of FRP laser processing is summarized from the aspects of the material removal process， removal mechanism， and thermal absorption characteristics in laser processing. The research status of FRP heat-affected zone （HAZ） in laser processing was summarized from the aspects of the influence of HAZ on material properties， influencing factors of HAZ， and prediction of HAZ. The research progress of FRP laser-assisted machining technology is summarized. A large number of studies have shown that due to the anisotropy of FRP， there are significant differences between FRP laser processing and homogeneous material laser processing. At present， the heat-affected zone of FRP laser processing can be effectively reduced to several microns， which significantly reduces the impact of heat affected zone on the component performance. To maximize the advantages of laser processing， the application of FRP laser composite processing technology in the field of FRP processing has gradually attracted attention， and become an important development direction of FRP processing technology improvement.

Abstract:W-Ti alloy targets can be used as raw materials to prepare W-Ti， W-Ti-N， W-Ti-O and other functional films by magnetron sputtering technology， which can be used in integrated circuits， thin film solar cells and other fields. In this paper， the performance indexes， preparation techniques and application areas of W-Ti alloy targets were introduced. Finally， the authors suggest that high purity， full density， less Ti-rich phase， small particle size， large size and low cost are important directions of W-Ti alloy targets.

Abstract:Liquid metal is an attracting phase change material which has the advantages of high thermal conductivity，large volume latent heat and low volume expansion rate. It has potential application prospects in the field of aerospace thermal control. In order to explore the applicable scope of liquid metal phase change materials， the heat transfer performance and temperature control time between low melting point metal represented by gallium and paraffin phase change material represented by n-octadecane were compared and analyzed by numerical simulation. The results show that gallium module is more suitable to deal with transient high heat flux and short time operation of electronic electronic devices，while n-octadecane module is suitable for low heat flux and long-time operation of electronic devices.In addition，the thermal control time per unit volume of gallium module is longer than that of n-octadecane module； for unit mass of phase change material，the gallium module is dominant in a short time and n-octadecane module is dominant in a long time.The analysis of two space application scenarios shows that low melting point metal phase change materials can be used for antenna TR module and high power laser chip temperature control.

Abstract:Milling force is large during disc milling grooving of titanium alloy because of big diameter of the cutter and large cutting output， which leads to obvious vibration of cutter and shorter tool life. In the study， in order to optimize and control the process of disc milling grooving in titanium alloy， single factor experiment and orthogonal experiment are designed， and milling force is measured by three-way piezoelectric dynamometer. The prediction model of milling force is built by linear regression method， and the significance of model is checked by “F” test method. The effect of technological parameters on milling force is analyzed by the extremum difference analysis. The interaction effect of technological parameters on milling force is studied by response surface method. Experiment results show that the sensitivity to changes in cutting depth is in the order of milling force F_x >feed speed>spindle speed. The sensitivity to feed rate changes is in the order of milling force F_y >cutting depth>spindle speed. The sensitivity to milling force F_z changes in the order of spindle speed>cutting depth. Milling force decreases with the increase of spindle speed and increases with the increase of cutting depth and feed speed. In addition， milling force F_x is greater than F_y and F_z， which plays a leading role in machining performance and tool wear.

Abstract:Effect of stress states （tension/ /compression） on creep aging behavior in the process of creep aging forming of 2219 aluminum alloy was studied. The mechanical properties of 2219 aluminum alloy under uniaxial tension/compression were investigated when ageing at 165 to 185℃ by room temperature tensile test. The results show that the optimal creep aging time is 11h. Under the same aging regime， the creep deformation of tensile stress and compressive stress increases with the increase of temperature， and the creep deformation of tensile stress is always greater than that of compressive stress. Regardless of the creep aging under tensile/compressive stress or the conventional aging without stress， the aging properties decrease with the increase of temperature. However， the decrease of properties is most obvious after tensile stress aging. Finally， when the aging temperature is 165℃， all the performance indexes are the best under different stress states.

Abstract:The as-cast Mg-6Y-3Zn-xLi （x=0，5，8 and 11wt%） alloys were prepared by vacuum induction melting under controlled argon atmosphere.The alloys were then processed by homogenized treatment and hot extrusion. The effects of Li content on the microstructure and mechanical properties of the alloys were investigated by using OM， SEM and tensile test. The results showed that， with increasing Li content， the as-cast Mg-6Y-3Zn-xLi alloys were transformed gradually from single α phase structure to （α+β） dual-phase structure. Meanwhile， the grain size of Mg matrix， morphology and distribution of eutectic compounds were changed remarkably. After homogenized treatment， block-like long-period stack ordered （LPSO） phases formed in the Mg-6Y-3Zn-xLi alloys. As Li content increased， the volume fraction of LPSO phases decreased， while the amount of （Mg，Zn）₂₄Y₅ phases increased. Tensile test results indicated that as-extruded Mg-6Y-3Zn-8Li alloy exhibitsed the best comprehensive mechanical properties，i.e.，the ultimate tensile strength and elongation reached to 278 MPa and 11.6%， respectively.The improvement of mechanical properties was mainly attributed to the complex strengthening mechanism by the distributed fragmented and refined LPSO phases and the great amount of fine dynamic recrystallized grains.

Abstract:Due to the complicated structure and high precision requirement， the subordinate frame structure of aviation is still mostly made of aluminum alloy by CNC machines. In order to explore the feasibility of integrated forming solution for composite frame structure， this paper studies the resin transfer molding （RTM） method of a thin-wall composite frame with longitudinal and transverse stiffeners and partial flanging structure characteristics. Simulation results show that the full （0/90）₈ layer combination can reduce the warping deformation of the structure to the greatest extent， which was also verified by the actual manufacturing results. The flow simulation results show that surface-injection method can significantly reduce the filling time and pressure compared with point-injection and line-injection plans. By combining the optimized scheme with automatic laying-up blanking， pultruded filling material and other automatic processes， the integral insulation frame of composite material with qualified internal quality and similar sampling mechanical properties to the traditional autoclave forming process was successfully fabricated.

Abstract:In order to obtain the suitable forming process control method for composite laminates with high surface accuracy， this paper aim at typical diameter of Φ500 mm curved composite laminates， six groups of molding comparative experiments with different process parameters were designed， and the effects of edge effect， laying method， curing temperature and other parameters on the curing deformation of laminates were analyzed. The results show that increasing carbon fiber modulus and reducing lamina thicknesses of prepreg can improve the surface accuracy of composite laminates. The size of placed prepreg over 5% of diameter can reduce the influence of the edge effect. Automatic fiber placement has high consistency of laying quality， while composite laminates of high surface accuracy can be manufactured by manual layup， but the probability is smaller. Reducing curing temperature and cooling rate of composites can raise the surface precision of composite laminates. The experimental results have a certain guiding significance for high-precision molding of composite materials.

Abstract:To determine the heat insulation performance of the thermal protection materials cladding the gas cylinders， a thermal vacuum test is implemented on two species thermal protection sets， with a radiant heat source simulated by a quartz lamp heater， and the atmospheric environment simulated by a vacuum tank. Results indicate that two species thermal protection schemes are both satisfied within the upper limit of the temperature， and the heat insulation property of the combination thermal protection structure “flexible insulation+ middling temperature MLI ” has better insulation performance. The indeterminacy of the thermal analysis method is evaluated by comparison with the result of the thermal test. The test data may server as a reference for future thermal protection design of spacecrafts.

Abstract:Based on ablative mechanism and light weighting principle， heat-shielding & insulating and radar-absorbing composites （HRC）， which efficiently integrated the functions of thermal protection， insulation and radar absorption in wide frequency， were prepared by sol-gel technology and resin transfer molding. SEM images showed that wave-absorbers of multi-walled nanotube （MWNT） well dispersed in the skeletons of hybrid phenolic aerogel. With increasing MWNT loading， the average pore diameter of HRC decreased and the mechanical properties were largely improved. When the MWNT loading was 5.0 wt%， compressive modulus of HRC was 1.8 times higher than that of HRC without MWNT addition. The introduction of MWNT wave-absorbers greatly improved radar-absorbing performance of HRC. The reflection loss of HRC lowered －8 dB after introducing MWNT wave-absorbers between 4 GHz and 18 GHz. In addition， HRC displayed outstanding ablative and heat-insulating properties during test of arc-jet wind tunnel. As the surface temperature of HRC reached 1700℃， temperature rise of backface with 20 mm thickness was only 153℃ and had near zero ablative recession after 400s ablating. In particularly， HRC still possessed good radar-absorbing performance in wide range of frequency after ablation in arc-jet wind tunnel.

Abstract:In order to find a convenient method for preparing nano-SiC reinforced carbon fiber laminates， the nano-SiC particles were uniformly dispersed in anhydrous ethanol to prepare nano-SiC reagent with different mass fractions， and then the nano-SiC reagent was uniformly sprayed on the surface of carbon fiber prepregs and solidified. The friction and wear tests of different specimens were carried out to obtain the effects of different content on the friction coefficient and wear amount of carbon fiber laminates， and the wear morphology and hardness of composites were analyzed. The experimental results show that spraying nano-SiC particles on the surface of carbon fiber prepreg can effectively improve the friction and wear performance of carbon fiber laminates. When the concentration of nano-SiC is 1%， the friction coefficient， wear， width and depth of the laminates decrease by 52%， 63%， 32.3% and 54.8%， respectively， compared with that of the specimens without nano-SiC.

Abstract:In order to explore the application reliability of nano-silver pastes in high-power electronic devices， it is necessary to obtain the sintering characteristics and thermo-mechanical properties of sintered nano-silver.By varying sintering temperature， sintering time， heating rate and sintering method， the mechanical strength of sintered nano-silver is investigated with systematical observations of material morphology. Furthermore， the thermal conductivity of sintered nano-silver is compared with the conventional die-attach materials in aerospace electronic products such as Au80Sn20 solder， Sn96.5Ag3.0Cu0.5 solder， and H20E adhesive. The results indicate that the shear strength up to 40 MPa can be achieved from those nano-silver samples prepared at the temperature of 200 ℃ for 90 min in air atmosphere with a controllable heating rate. It is also found that the sintered nano-silver has a similar thermal conductivity with the Au80Sn20 solder， which is significantly greater than H20E adhesive and Sn96.5Ag3.0Cu0.5 solder. After harsh thermal and mechanical experiments， the shear strength of sintered nano-silver remains stable， which confirms that nano-silver pastes with high thermal conductivities can serve as bonding materials for potential aerospace applications in the assembly of high-power devices.

Abstract:The butt weld is common in the friction stir welding. The assembly quality of the weld， which could have a great influence on the joint performance， is generally described by gaps， misalignment and non-centering of probe （NCOP for abbreviation）. Linear structured light is a common method for extracting the characteristics of welds. Nowadays， the contour information of the weld is mostly represented by discrete points based on linear structured light. How to efficiently extract the contour information of the weld from the contour points becomes a new challenge. This paper proposes a method for evaluating weld assembly quality based on machine vision， which converts discrete contour points into bitmaps， improves the recognition reliability of line features by using anti-aliasing algorithms， Then， the assembly quality information is acquired for weld assembly quality evaluation. Compared with the traditional discrete point fitting method， this algorithm has obvious efficiency advantages.

Abstract:When the laser selective melting forming （SLM） steel products with large thickness variation in airspace engine such as centrifugal wheel and turbine stator are detected by conventional X-ray film photographic inspection （RT），quality problem of missed detection may exist since low tolerance of industrial X-ray films give rise to low testing coverage rate. In order to solve the problem，computed radiography testing （CR） was used to detect steel products defects，of which the thickness difference ranges from 5 mm to 20 mm. By comparing the CR image and the RT image，test results show that the tolerance of CR image is 3 times that of RT image. Taking linear defects of CR testing in centrifugal wheel as an example，through CT testing and physico-chemical testing，it is proved that defect detection sensitivity of CR is essentially the same as that of RT.

Abstract:Cracks in the blades’ root of turbo rotor made from high temperature alloy were detected by fluorescence examination after several engine trial runs. The results indicate that the cracks are located in the thin-walled area in the blade， and the cracking mode is high temperature fatigue cracking， which can be classified into low-cycle fatigue and life-relevant failure. In the trail run process， the stress concentration location is exposed to the effect of high temperature and alternating stress. Therefore， selective oxidation in the grain boundaries happen and oxide products grow in a wedge-like shape along the grain boundaries.By the mutual influence of both high temperature oxidation and alternating stress， the stress concentration location in the blades’ root also experiences creep and slippage.With the effect of creeping damage and intergranular oxidation， the weakened grain boundaries start to crack and cracks expand along the grain boundaries， forming the fatigueorigin. At last， high temperature fatigue cracks further expand in the subsequent process.

Abstract:The heat source distribution of engine in altitude simulated test is relatively similar to real flight case compared to the normal pressure test case. In this article， the correctness of high temperature heat shield design is validated through altitude simulated test. The heat transfer model is modified by considering the gas conduction and contact conduction between each layer in high temperature heat shield. This thermal model has a relative high precision to the data getting from the altitude simulated test. Thermal model of the main engine and high temperature heat shield in altitude simulated test is made. Then， it is modified by considering the infrared radiation and the heat conduction with the gas in vacuum chamber.

Abstract:In order to study the environmental adaptability of nylon in long-life in-orbit spacecraft， space environmental adaptability evaluation indexes of nylon in space environment were proposed， and space environmental adaptability evaluation tests were designed and implemented.The test results show that the nylon shows friendly environmental adaptability in combustion heat， escaping harmful gases， vacuum mass loss and condensable volatiles， antibacterial and mildew resistance， tolerance to alternating temperature， and ionizing radiation. The fracture strength of nylon decreases significantly when subjected to atomic oxygen and ultraviolet radiation in space environment， and the synergistic effect of atomic oxygen and ultraviolet irradiation has a strengthening effect on the mechanical property damage of nylon. The nylon could be used as a material for long-term use in the space cabin environment， When used in the extravestrated environment， special consideration should be given to its mechanical properties under the influence of atomic oxygen and ultraviolet radiation.