航空材料学报

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2022, 42(4)

[Abstract](27) [PDF 3336KB](17)

Abstract:

Research progress on structural thermal protection integration composite

ZHOU Shihao, NI Nannan, LIU Bin, WANG Zhaodi, DAI Feng, XU Yahong

2022, 42(4): 1-15.

[Abstract](128) [FullText HTML] (38) [PDF 2874KB](53)

Abstract:
More rigorous challenge is put forward by the demand on the structure and thermal protection system of super sonic air-crafts with faster flight speed and longer flight time. The integrated design of structure and thermal protection can give consideration to both load and thermal protection functions, which can give full play to the potential high temperature strength , reduce the thermal stress caused by temperature difference of different parts, and reduce the quality of the thermal protection and structure. It has higher structure efficiency than traditional thermal protection, and can be reused at the same time, reducing the cost. This paper briefly described the research status of integrated thermal protection technology at home and abroad.On this basis, the characteristics and shortcomings of integrated thermal protection were summarized, and the development trend of integrated thermal protection was discussed.China is still in a development stage. Widening the technical cognition of integral technology of structure and thermal protection, actively developing low-cost co-cured technology of structure material and thermal protection material, continuously introducing new thermal protective materials, and sparing no effort to strengthen research and development of the active cooling technology of integrated thermal protection systems is a feasible way of domestic integral technology of structure and thermal protection being quickly applied to models.

Research progress in preparation, property and application of steel foam

LIANG Jichao, ZHANG Guangcheng, SONG Shaowei, ZHOU Yun, ZUO Xiaoqing

2022, 42(4): 16-27.

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Abstract:
As a new type of structural-functional material developed in recent years, steel foam has the advantages of high specific strength and specific stiffness, high specific surface area, light weight, energy absorption and shock absorption, porous filtration, electromagnetic shielding and biocompatibility. It has a broad application prospect in aerospace, automobile, shipbuilding, civil engineering, heat dissipation and heat insulation, catalysis and filtration, electromagnetic shielding, biomedical engineering and other fields. In this paper, the research and development situation and existing problems of new steel foam are reviewed, and the preparation process, structure , performance characteristics and application fields of steel form are introduced, including the advantages and disadvantages of the existing preparation process, cell structure characteristics, mechanical properties （yield strength, elastic modulus, energy absorption value）, physical properties （heat dissipation and insulation, sound absorption and insulation, electromagnetic shielding）, biological properties and application of steel foam. The existing problems of steel foam and the limiting factors of its industrial development and application are analyzed. In general, the existing research has proved the feasibility of steel foam development and application as a light-weight high strength structural material and a special functional material, and pointed out the technical and theoretical research work to be carried out in the future.

Experimental study and molecular dynamics simulation of oxidation mechanisms of direct-sintered silicon carbide

ZHANG Yue, JIANG Rong, ZHANG Leicheng, CHEN Xihui, GAO Xiguang, SUN Zhigang, SONG Yingdong

2022, 42(4): 28-38.

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Abstract:
Oxidation tests of direct-sintered SiC were conducted in tube furnace in static air at 1200 ℃, 1300 ℃ and 1400 ℃ for 1 h, 5 h, 12 h and in Thermogravimetric Analyzer (TGA) at the same temperature for 24 h to obtain continuous mass change curves. Grazing incidence X-ray diffraction (GIXRD), field emission scanning electron microscopy (FE-SEM) and energy dispersive spectroscopy (EDS) were used to characterize the oxidation products and to reveal the underlying mechanisms. And the ReaxFF Reactive Molecular Dynamics (ReaxFF MD) simulation was conducted in open-source LAMMPS code to study the oxidation behaviors of 6H-SiC. The results of Oxidation tests show that the oxidation of direct-sintered SiC obeys parabolic law, indicating the oxidation process is controlled by the diffusion of O₂. Besides, it takes on a 3-stages oxidation kinetics. Morphology of oxide layer initially shows a transition from amorphous SiO₂ to spherulitic features accompanied by a decreasing oxidation rate. After a long-time oxidation, spherulitic features are transformed to fine grain structure along with an increasing oxidation rate. The transition of SiO₂ structure and the variation in oxidation rate are probably associated with the specific diffusion mode of O₂ in the oxide layer. In combination with ReaxFF MD simulation, the oxidation mechanism of 6H-SiC is obtained. It reveals that O₂ diffusion inwards controls the oxidation reaction of 6H-SiC along with the formation of C element, followed by oxidation into CO and CO₂ and escapes in the form of bubbles.

Measurement method of interlaminar shear mechanical parameters of thick section composite materials based on digital image correlation

LIU Liu, HAN Xiuxia, HAO Ziqing, WANG Yana

2022, 42(4): 39-48.

[Abstract](42) [FullText HTML] (11) [PDF 2695KB](36)

Abstract:
Short beam shear (SBS) test combined with digital image correlation (DIC) can quickly identify the multiple mechanical properties of unidirectional fiber reinforced resin matrix composites. In addition, the complete interlaminar shear stress-strain behavior and interlaminar shear strength of composite materials under uniaxial stress state can be obtained, which is very important to establish the strength criterion of three-dimensional stress state of composite materials with thick section. In order to study the influence of experimental design on the identification accuracy of interlaminar shear mechanical parameters of materials, two stereo digital image correlation systems composed of four CCD cameras were developed for the first time in this paper, and the strain distribution in the front and back surface gage regions of the sample during loading in SBS test was measured. The experimental results show that the shear strain distribution on the front and back surfaces of the sample is asymmetrical, and the relative deviation is up to 44%, because of the thread clearance of fixture and insufficient fixture stiffness. On the one hand, a new method is proposed to identify the shear mechanical properties of materials according to the asymmetrical distribution of shear strain on the front and back surfaces of the sample. By using DIC technology and finite element model updating (FEMU), the measured average shear strain in the distance region of the front and back surfaces of the specimen and the variance of the calculated strain data at the corresponding position of the finite element model are used as the objective function to identify the constitutive parameters and off-axis angles. The complete nonlinear shear constitutive parameters can be obtained, and the identification process is not sensitive to the initial parameters. On the other hand, by improving the test fixture to improve the tool stiffness, the phenomenon of asymmetric shear strain distribution is eliminated, and the complete interlaminar shear stress-strain constitutive relationship parameters of unidirectional laminates are accurately identified.

Hot deformation behavior and processing map of ultra-high strength stainless steel

LIU Mutong, ZHONG Ping, LIU Dabo, WANG Kelu, ZHANG Kaiming, LU Shiqiang

2022, 42(4): 49-56.

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Abstract:
The 10Cr13Co13Mo5Ni3W1VE(S280) ultra-high strength stainless steel was subjected to isothermal and constant strain rate compression experiments at deformation temperature of 800-1150 °C, the strain rate of 0.001-10 s^–1, and the deformation amount of 70% by using Thermecmaster-Z thermal simulation testing machine. The hot deformation behavior of the steel was analyzed, and the processing maps based on Murty instability criterion were established. The results show that the flow stress of S280 ultra-high strength stainless steel during hot deformation is sensitive to deformation temperature and strain rate. With the increase of strain rate and the decrease of deformation temperature, the flow stress increases significantly. It is determined that the region of instability occurs in the temperature range of 800-1040 °C and strain rate range of 0.06-10 s^–1, and the corresponding instability deformation mechanism is mainly flow localization. The desired parameters are 1095-1150 ℃ and 0.001-0.04 s^–1 with the plastic deformation mechanism of dynamic recrystallization, and the optimum parameters are around 1125 ℃ and 0.001 s^–1.

Carbide precipitation behavior during vacuum arc remelting of GH4742 alloy

ZHOU Yang, YU Ping, YANG Shufeng, WANG Anren, QU Jinglong, LI Jingshe, QIN Heyong

2022, 42(4): 57-64.

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Abstract:
The different heat transfer conditions in each region of the vacuum arc remelting superalloy ingot lead to significant difference in the morphology and size distribution of carbide in the ingot. Based on industrial vacuum arc remelting GH4742 alloy as a raw material, using metallographic and scanning electron microscopic analysis quantitative analysis method to study the ingot different position distribution of the carbide precipitation behavior and microstructure, supplemented by MeltFlow-VAR simulation software, the solidification process of remelting different cooling rate and local solidification time on the influence of carbide were analyzed. The results show that Nb and Ti elements are enriched in the carbide precipitates of GH4742 alloy, and the segregation degree of Nb element is the largest. The area of the precipitated phase is decreased from the center to the edge, and the morphology is changed from skeleton-like and cursive to interconnected fine strips. As the cooling rate increases, the dendrites become more slender and compact, and the dendrite spacing decreases. The area of precipitated phase is linearly related to the secondary dendrite spacing. Increasing the cooling rate can reduce the dendrite spacing, thus the area of precipitated phase is reduced effectively.

Influence of core spacing on bending properties of AlSi10Mg lattice sandwich panel formed by selective laser melting

ZHANG Bo, WANG Guowei, YANG Jialin, WU Hongfei, SHEN Xianfeng, TIAN Daqing

2022, 42(4): 65-74.

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Abstract:
The light-weight and high-stiffness metal lattice sandwich structure formed by selective laser melting has an important application prospect in aerospace, military and other fields. In this study, the response of square lattice sandwich panels with different core spacings under three-point bending was analyzed by finite element analysis, and the results were verified by experimental samples formed by selective laser melting. The results show that there is a linear relationship between the core spacing and cylindrical bending stiffness when the core spacing is within a certain range, the influence of core spacing on cylindrical bending stiffness is very significant and the influence of core spacing on the cylindrical bending stiffness of the square lattice sandwich panel of 45° is greater than that of the square lattice sandwich panel of 0°. The cylindrical bending stiffness of square lattice sandwich panel of 0° and 45° is basically the same under the same relative density when the relative density is within a certain range, which means that they have similar cylindrical bending stiffness under the same weight. When the relative density is less than 5%, the relative density has a significant influence on the cylindrical bending stiffness, and the influence decreases when the relative density exceeds 5%. With the increase of the core spacing, the stress concentration area is transferred from the part of panel under the loading pad to the ends of cores between the support pads due to the reduction of the cylindrical bending resistance of the lattice structure. According to the mechanical analysis, the initial load prediction formula for the yield and plastic stages can be proposed, The comparison between the theoretical results and the FEA results shows that the relative error is less than 13.6%, indicating that the formula is relatively accurate. The experimental results are in good agreement with the FEA results, especially for the cylindrical bending stiffness, the relative error between the FEA value and the experimental value is only less than 6.5%, indicating that the three-point bending deformation and mechanical properties of the lattice sandwich panel can be effectively predicted by FEA.

Effect of high temperature oxidation and particle erosion on the performance of C/C-SiC composites materials

WANG Lingling, WANG Kunjie, ZHANG Xiaolong, YAN Liansheng, YAO Xi

2022, 42(4): 75-82.

[Abstract](207) [FullText HTML] (73) [PDF 2596KB](59)

Abstract:
C/C-SiC composites was prepared by “chemical vapor infiltration + precursor impregnation pyrolysis” (CVI+PIP) combined process by needle preform laying separately with 3K twilled carbon cloth and 12K non-latitude cloth. The long-term oxidation resistance and erosion resistance test of composites were realized by using long-term oxyacetylene ablation test and high- temperature particle erosion test, and the main factors affecting their anti-ablation benavior were studied. The results show that the C/C-SiC composites have certain degree of ablation occurred after 600 s acetylene ablation, the linear ablation rates, mass ablation rates and ablation depth of the material formed by the preform of the non-latitude cloth are lower than that of the material prefabricated with the twilled carbon cloth. Using particles erosion test, the results of the two materials are consistent and the specimen flushing surface presents obvious characteristics of mechanical flushing the the depth of the flushing pit can be reached 7.21-7.25 mm after just 10 seconds. While without the particle airflow flushing test, the degree of material erosion decreased significantly. C/C-SiC composites in the actual use of the process is generally subject to air flow pressure, particle impact and high temperature oxidation of the combined effect, among them the mechanical ablation caused by particle impact has a greater impact on the failure of C/C-SiC composites than thermo-chemical ablation caused by long-term high temperature oxidation, which directly affects the performance of the material.

Melting behavior and tribological properties of titanium-based laser cladding layer WC on the surface of TC4

ZHANG Tiangang, LI Baoxuan, ZHANG Zhiqiang, HAI RE GU LI · Ai He Mai Ti

2022, 42(4): 83-94.

[Abstract](27) [FullText HTML] (10) [PDF 6489KB](26)

Abstract:
WC is one of the cladding synthetic materials that effectively improve the surface tribological properties of TC4 alloy, but it is easy to produce residues in the coating, which always plagues the quality and performance of the coating. In this study, TC4+WC titanium wear-resistant coatings with different WC addition ratios (5%, 10% and 15% (mass fraction /%)) were prepared on the surface of TC4 by coaxial powder feeding laser cladding technology, and the macrostructure, microhardness and tribological properties of the coating were analyzed and studied, focusing on the melting and residue mechanism of WC in the molten pool. The results show that the addition of WC does not affect the types of phases formed in the coatings. The precipitated phases mainly include in-situ TiC and matrix phases α-Ti and β-Ti. Among them, TiC and the remaining WC particles in the coating form a coherent package mosaic structure phase. The decomposition of WC in the molten pool is prevented, leading to the remaining WC is prone to residue and agglomeration. The amount of WC added is positively correlated with the microhardness of the coating. As the WC content in the material system gradually increases, the wear resistance of the coating gradually increases, and compared with the TC4 substrate, the wear rate of the coating decreases by about 21.1%, 38.2%, and 56.1%, respectively, but the residual WC leads to local stress concentration in the friction and wear process of the coating, the tribological performance fluctuates significantly.

Effect of pressure in pore on pore morphology of porous Cu-1.3Cr alloy with directional pores

SONG Qunling, LI Yingjuan, TENG Yu, JIN Qinglin, LI Fenrui

2022, 42(4): 95-103.

[Abstract](73) [FullText HTML] (25) [PDF 1912KB](27)

Abstract:
Cu-1.3Cr alloys with directional pore structure were fabricated under hydrogen atmosphere. The pore morphology during the solidification is investigated. It is found that the porosity is increased from 18% to 44% and the average pore diameter was decreased from 3.24 mm to 0.44 mm when the hydrogen pressure varies from 0.1 MPa to 0.6 MPa. Theoretical analysis shows the gas pore pressure drops significantly during the growth of pore. For a coarse pore, the drops of pore pressure will result in a backflow of the melt from solidification interface into gas pore, and this will result in a “bamboo” like structure. For small gas pores, the pressure difference between two neighboring gas pores drives the hydrogen gas from the short one to the long one. This is the reason that a short pore more easily coalesce with a long pore.

2022 Vol. 42, No. 4