航空材料学报

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2021, (1): 1-2.

[Abstract](683) [FullText HTML] (345) [PDF 783KB](19)

Abstract:

Research progress on Li- and Mn-rich cathode materials for lithium-ion batteries

Wenzheng NAN, Jixian WANG, Xiang CHEN, Sikan PENG, Shaojiu YAN

2021, 41(1): 1-18.

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Abstract:
As the development of society, the specific energy density of the commercial lithium-ion battery still cannot meet the requirements for practical applications, such as electric vehicles, 3C(computer, communication and consumer electronics) products and energy storage devices. The Li- and Mn-rich cathode materials are expected to be the key electrode materials for high energy density lithium-ion battery due to their high electrochemical capacity (≈250 mAh/g), high operating voltage(≈3.6 V) and low cost. However, several issues and challenges limit their widespread applications for commercial lithium-ion battery, including high irreversible capacity, poor cycle life and fast voltage/capacity fading. In this paper, the latest research progress of Li- and Mn-rich cathode materials is reviewed, with emphasis on material structure, electrochemical reaction mechanism, failure mechanism and modification technology. The results show that ion doping, surface coating, crystal structure regulation and other techniques can significantly improve the electrochemical performance of Li and Mn-rich cathode materials. Finally, the development direction of Li- and Mn-rich cathode materials is prospected.

Research progress in preparation and processing technology of C/SiC composites

Haowen JIAO, Bing CHEN, Bin ZUO

2021, 41(1): 19-34.

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Abstract:
Carbon fiber reinforced silicon carbide ceramic based (C/SiC) composites are widely used in industrial, aerospace and other fields due to their high strength, hardness and wear resistance. However, C/SiC composites are difficult to be removed and processed. In this paper the common preparation methods of C/SiC composites and the performance characteristics of their materials are reviewed. The traditional machining methods, ultrasonic assisted machining, laser processing and other processing methods of C/SiC composites are summarized. The material removal mechanism, processing precision, common defects and problems in the processing are analyzed. Traditional machining needs further optimization cutting tool materials. Ultrasonic assisted machining needs to explore the coupling mechanism of ultrasonic vibration between the tool and the material, and the mechanism of material removal under vibration. The removal mechanism of 2.5-dimensional and 3-dimensional C/SiC composites by laser processing also needs to be studied. On the basis of these studies, the possibility of high efficiency, precision, stability and non-destructive processing of C/SiC composite materials is explored by further adopting the composite machining method.

Investigation of constitutive model of as-extruded spray-forming 7055 aluminum alloy based on BP artificial neural network

Rui LUO, Yun CAO, Yu QIU, Shugang CUI, Haotian ZHOU, Yiming ZHOU, Fei YUAN, Xiaopeipei ZHANG, Xiaonong CHENG

2021, 41(1): 35-44.

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Abstract:
Gleeble physical simulation technique was employed to investigate the high-temperature flow stress characteristics of the studied spray forming 7055 aluminum alloy. Simultaneously, the Arrhenius constitutive model which couples the parameter of true strain and the BP artificial neural network constitutive model were contrastingly utilized to predict the flow stress behavior of the experimental alloy. The result shows that the flow stress of spray forming 7075 aluminum alloy is significantly affected by deformation parameter, which is negative correlated with deformation temperature and positively correlated with strain rate. Through the comparison of the two models, the average relative error of the Arrhenius constitutive model lies over 2%. And the error of the model tends to increase with the rising temperature. Moreover, the average absolute error and the average relative error reach the maximum at hot processing temperature (around 450 ℃). It is difficult to precisely predict the flow stress characteristics of the alloy. However, BP artificial neural network constitutive model has higher prediction accuracy, the average relative error δ value is only 0.813% and has higher temperature stability.

Role of Hf and Re on the lattice misfit between γ/γ′of Co-Ti-V superalloys

Pengjie ZHOU, Dehang SONG, Xinkang GAO, Yinbing LIU

2021, 41(1): 45-52.

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Abstract:
The relationship between γ′ phase morphology and γ/γ′ lattice misfit degree in Co-Ti-V superalloy with different Hf and Re contents was studied by observation of microstructure and X-ray diffraction analysis. The EDS is used to analyze the relationship between the distribution behavior of each element and lattice misfit between γ/γ′ of Co-based superalloys. The effect of Hf and Re content on the high temperature compression properties of Co-based superalloys was studied by 1000 ℃ high temperature compression test. The results show that the morphology of γ′ phase shifts from square to spherical, and the lattice misfit between γ/γ′ phase decreases with the increment of Hf content.The morphology of γ′ phase changes from square to long strip, the γ′ phase turns coarse, and the lattice misfit between γ/γ′ phase decreases with the increment of Re content. According to the EDS analysis, Co, Hf and Re are enriched in the γ phase, while the Ti and V are enriched in the γ′ phase. With the increase of Re content, the yield strength and ultimate strength of the alloy are increased. The yield strength and ultimate strength of the alloy are decreased firstly and then increased with the increase of Hf content.

Effect of re-solution treatment on microstructure and mechanical property of nickel-base alloy Inconel 718

Kang WEI, Tao WANG, Mingjun ZHANG, Yong ZHANG, Zhao LI, Zhipeng WAN

2021, 41(1): 53-59.

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Abstract:
The microstructures and mechanical properties of Inconel 718 alloy were analyzed by using 982 ℃ water cooled solid solution bar after repeated solution and re-aging treatment, and compared with direct aging treatment.The effects of repeated solution treatment temperatures ranging from 941 to 1010 ℃ on microstructures and mechanical properties of the alloy were systematically studied. The results show that with the increase of repeated solution temperature, the content of γ′′ phase / δ phase gradually increases / decreases with no obvious change in grain size, leading to an evident improvement on room-temperature hardness, high-temperature tensile strength and stress-rupture life of the alloy. The maximum values of the tensile elongation and the stress rupture ductility are reached at the repeated solution temperature of 982 ℃. As compared to the direct aging treatment condition, there is no apparent change in microstructure and mechanical properties of the alloy aged after the repeated solution treatment at 982℃. On the contrary to the higher repeated solution temperature, the lower repeated temperature produces unfavorable effect on the mechanical properties.

Preparation of organosilicone modified polyurethane and its effect on the physical properties of organic-inorganic glass laminates

Yingde LI, Jinshan LU, Fan ZHONG

2021, 41(1): 60-66.

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Abstract:
In this paper, organosilicone-modified polyurethane was synthesized by the prepolymerization method by using polypropylene glycol and isophorone diisocyanate as the synthetic monomers, and γ-aminopropyltriethoxysilane (KH550) as the silicone source. The modified polyurethane was used as the interlayer to prepare the organic-inorganic glass laminates. The effects of silicone contents on the optical properties, thermomechanical properties, and interfacial adhesion property of the glass laminates were investigated. With the KH550 content increasing, the polymerization degree of polyurethane is decreased, resulting in lower transparency, higher haze and lower surface hardness. The storage modulus of the modified polyurethane is increased at first and then decreased, and the glass transition temperature of hard segments is firstly increased and then decreased. Both reached the maximum value when the additive amount of KH550 is 1%. Using polyurethane adhesive layer as the interlayer of glass laminates, the interfacial shear strength of the unmodified glass laminates is 6.7 MPa, while the interfacial shear strength of glass laminates containing 0.5% KH550 is 7.7 MPa.

Factors affecting the density of C/C-SiC composite

Zhiyong CHEN, Yingqiang XU, Li XIAO, Miaoling LI, Bin LI, Mingyuan GAO

2021, 41(1): 67-73.

[Abstract](732) [FullText HTML] (271) [PDF 880KB](30)

Abstract:
C/C-SiC composites were prepared by precursor transformation method. The microstructure and properties of the samples were analyzed. The effects of silicon infiltration temperature, holding time, vacuum degree and cracking cycle on the density of C/C-SiC composite were studied. The results show that with the increase of siliconizing temperature, the density of the material increases at first, and then decreases rapidly. With the increase of heat preservation time, the density of the material increases rapidly at first, keeps stable for a period of time and then decreases slowly. With the increase of sintering vacuum, degree, the density of the material increases rapidly. With the increase of cracking cycle, the density of the material increases continuously, but the growth rate decreases gradually. After 11 cycles of “impregnation curing cracking” process, the C/C-SiC composite prepared obtained a maximum density of 2.09 g/cm³ and a minimum porosity of 7.6%. At this time, it also has the most excellent comprehensive mechanical properties: bending strength of 468 MPa, tensile strength of 242 MPa, fracture toughness of 19.6 MPa·m^1/2 and Vickers hardness of 17.2 GPa.

Electrical conductivity modification and lightning resistance of carbon fiber composites

Yao XIAO, Bin LI, Xiaoshan LIU, Xianfeng ZHANG, Jun DONG, Xiaolong WEI

2021, 41(1): 74-82.

[Abstract](1055) [FullText HTML] (373) [PDF 1110KB](47)

Abstract:
The resin matrix of traditional carbon fiber composite (CFRP) has a high resistivity, which produces a lot of resistance heat and causes damage under the strong current. Strengthening its conductivity can effectively improve the lightning protection performance of CFRP. The particles of the silver powder were added to the resin matrix for conductivity modification, and the influence of silver powder content on lightning protection performance was analyzed by finite element simulation. The optimum content of silver powder in CFRP matrix was determined to be 38%. The conductivity modification effect along the thickness direction was the best, which was improved by 217.3 times. Simulated lightning strikes test was carried out on the modified CFRP laminates with different peak lightning currents of D waveform, and unmodified laminates and the laminates with copper wire mesh on the surface were compared at the same energy level. The damage characteristics and damage area were compared by visual damage observation and perspective ultrasonic scanning to evaluate the lightning resistance of the matrix modified CFRP. The results show that the matrix modification can prevent the surface layer from breakdown and reduce the fiber fracture warping and lamination damage. Under the peak current of 20 kA, 40 kA and 60 kA, the copper wire mesh protection can reduce the lightning damage area by 100%, 86.61% and 37.46%, and the matrix modified overall protection can reduce the lightning damage area by 84.02%, 81.03% and 40.91% respectively.

Analysis of lightning ablation damage of fastener-containing laminates under different factors

Zezhong SHAN, Mingjun LUO, Xiang LU, Minghui TIAN

2021, 41(1): 83-90.

[Abstract](811) [FullText HTML] (315) [PDF 857KB](49)

Abstract:
In order to study the ablation damage law of composite laminates with fasteners under the action of lightning current, the lightning finite element analysis model of fastener-containing laminates was established based on thermoelectric coupling, and the results of lightning ablation damage were analyzed and tested. The results were compared with the validity of the model. The ablation damages of fastener-containing laminates under different peak currents, fastener sizes and laminate width ratios were analyzed, and the variations of ablation damage area under different factors were summarized. The results show that the peak current of the lightning strike, the size of the fastener, and the width of the laminate have great influences on the ablation damage areas of the fastener-containing laminates. The same lightning strike current waveform, the ablation damage area caused by lightning current with a peak value of 150 kA is 15.39 times that of 50 kA The smaller the fastener is, the larger the area of ablation damage is, and the larger the area of delamination damage is. Among them, when the diameter of the fastener is reduced by 2 times, the ablation damage area can be increased by 4.97 times, and the delamination damage area can be increased by 1.91 times. The damage area increases first and then decreases with the increase of the width, and finally tends to be stable. The ratio of the largest damage area to the minimum damage area can reach 1.81 times, and the ratio increases with the increase of the fastener diameter.

Effect of low temperature on fatigue and crack propagation behavior of aeronautic aluminium alloy

Mudong LIU

2021, 41(1): 91-100.

[Abstract](841) [FullText HTML] (325) [PDF 1994KB](63)

Abstract:
Fatigue and crack growth tests were performed on two categories of the common aeronautic aluminum- alloys 2524-T3 and 7050-T7451 at ambient temperature of 25 ℃ and cryogenic temperature of –70 ℃, in order to investigate the fatigue and crack propagation properties and micro mechanism. The test results show that the cryogenic fatigue life under the same amplitude loading rises and cryogenic crack growth rate decreases, which demonstrates the beneficial effect of cryogenic temperature on fatigue and crack growth properties. Furthermore, the fractographic micro mechanism reveals significant cleavage facets appeared during fatigue crack initiation at the cryogenic temperature of –70 ℃, leading to a concavo-convex morphology on fracture surfaces, and the fatigue crack initiation becomes difficult. On crack growth zones, the fatigue striations and dimples become unobvious, while evident intergranulars are occurred. As a result, the local fatigue crack tends to propagate zigzag and intergranularly, and fatigue and crack growth lives are increased. With the increasing loading stress level, the concavo-convex morphology and ductile transgranulars are reduced, while the fatigue striations and dimples are increased on fatigue surfaces, which demonstrates the cryogenic effect on fatigue crack initiation and propagation becomes weaker. This results have important theoretical and practical value.

2021 Vol. 41, No. 1