航空材料学报

2019-02目录

2019, 39(2): .

[Abstract](1946) [FullText HTML] (1328) [PDF 1004KB](25)

Abstract:

Recent progress of 4D printing technology

Haizhou LU, Xuan LUO, Tao CHEN, Zhao LIU, Chao YANG

2019, 39(2): 1-9.

[Abstract](6041) [FullText HTML] (3157) [PDF 1100KB](165)

Abstract:
4D Printing technology can achieve additive manufacturing of smart materials. Recent progresses of 4D printing composite materials, shape memory polymers, shape memory alloys and other smart materials were reviewed. 4D printing technology is developing towards multi-material precise compounding, fast response and functional forming materials recently. 4D printing technology of shape memory polymers is developing towards shape controllable and accurate movement. 4D printing technology of shape memory alloys is developing towards precise control of phase transition behavior and deformation controllable. Several considerations about 4D printing shape memory alloys were proposed based on unsolved problems, such as: the factors should be considered for obtaining near-full dense 4D printed shape memory alloys, effect of voids on its comprehensive properties, regulation of structure and properties, and deformation control, etc. Overall, with the development of new materials, forming methods, control software and machine accuracy, 4D printing technology is developed rapidly, and is gradually moving towards intellectualization, accuracy and efficiency.

Effect of sintering temperature on microstructure and mechanical behavior of alumina-based ceramic shell by SLS

Qian WEI, Zilin XU, Qingyan XU, Baicheng LIU

2019, 39(2): 10-15.

[Abstract](7016) [FullText HTML] (3001) [PDF 3555KB](81)

Abstract:
Selective laser sintering (SLS) was adopted to rapidly prepare silica-based ceramic shell for superalloy turbine blade, and combined with high-temperature sintering process to further improve the mechanical properties of ceramic shell. The effects of different sintering temperatures (1450~1600 ℃) on the flexural strength of alumina-based ceramic shells were investigated. The phase constitution and fracture morphology of alumina-based ceramic shell molds were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that ceramic shell with excellent mechanical properties can be obtained by SLS+high-temperature sintering quickly and effectively. As sintering temperature increases from 1450 ℃ to 1600 ℃, flexural strength of ceramic shell at room temperature increases, and reaches 38.03 MPa at 1600 ℃. Columnar mullite phase is the main strengthening phase, with the increase of sintering temperature, the content of mullite phase in the shell increases, the content of quartz phase decreases, and the content of cristobalite phase increases first and then decreases. The crack propagation form changes from slow expansion to rapid expansion and causes transient fracture. The fracture changes from a tearing shape to a flush small section, and appear the intergranular and transgranular fracture mode, the crack is tended to expand to the mullite particles.

Characterization and mechanism of porous silicon carbide ceramics processed by high temperature chemical corrosion

Shanyong LIU, Yuling WANG, Shufeng SUN, Jing SHAO, Qingyu LIU, Jin WANG

2019, 39(2): 16-24.

[Abstract](2660) [FullText HTML] (1365) [PDF 945KB](27)

Abstract:
The influence of the process parameters of SiC ceramics on the processing quality was discussed. The corrosion mechanism of SiC ceramics was analyzed. The corrosion rate and porosity of samples were measured by the method of weight-loss and Archimedes respectively. The surface morphology and structure of the specimen were characterized by XRD, SEM and roughness tester. The results show that the corrosion rate increases with the increase of temperature and KOH concentration, and the corrosion effect is significantly improved when the temperature is higher than the boiling point of the alkali solution. The high concentration of alkali solution causes the porosity to decrease, and the increase of temperature can slow down the decrease of porosity. Under the optimized process parameters, the high temperature chemical corrosion can reduce the roughness of the sample, and the minimum roughness(R_a) of the surface is 1.6 μm. The surface quality is improved, the length of contour support is increased, and R_{mr (50%)} reaches 89.70%. The excessive corrosion temperature or too long time causes the grains to fall off, resulting in a sharp drop of surface quality. In addition, compared with the machining samples, no cracks are found on the sample of high temperature chemical processing. After simple cleaning, the surface has no reactant residue.

Properties of graphene oxide modified epoxy resin and its composites

Zhidong REN, Sijia HAO, Yue XING, Cheng YANG, Shenglong DAI

2019, 39(2): 25-32.

[Abstract](2776) [FullText HTML] (1509) [PDF 848KB](57)

Abstract:
Graphene oxide (GO) modified epoxy resin (GH81) was prepared by mechanical grinding, and the dispersion of GO in the epoxy resin (H81) was analyzed by optical microscope, while the melting performances and curing behaviors of H81 and GH81 were researched through rheometer and differential scanning calorimeter respectively. The results show that GO is uniformly dispersed into the matrix resin, and the addition of GO hardly affects the melt viscosity and curing condition of the matrix resin at all. In addition, the 0° tensile strength, bending strength and compression strength of GH81 based carbon fiber reinforced composite (GH81-300) are 2270 MPa, 2239 MPa and 1529 MPa respectively, which is increased by 6.4%, 7.2% and 7.1% respectively, as compared with that of composite without GO.

Effect of welding parameters on microstructure and high temperature tensile properties of FGH96 superalloy inertial friction welded joints

Jun YANG, Jinglong LI, Dengke DONG, Jianghai LIAO

2019, 39(2): 33-41.

[Abstract](2530) [FullText HTML] (1385) [PDF 1517KB](48)

Abstract:
This study aims to evaluate the FGH96 superalloy joints fabricated by inertia friction welding (IFW) in different welding parameters, such as initial rotational speed and axial friction pressure, where the moment of inertia remained constant. The microstructure and the width of the weld nugget zone (WNZ) were analyzed, and tensile property of joints was examined. The effect of welding parameters on high temperature tensile property of FGH96 joints was investigated. The results show that the joint presents a significant microstructure change across the faying interface, characterized by the very small uniform equiaxed grains of WNZ, coarse and fine grain coexistence of the thermo-mechanically affected zone (TMAZ). As the rotation speed increases, the tensile property remains constant. However, with increasing friction pressure, they show a substantial increase.The change tendency of the width of WNZ with welding parameters is in agreement with that of tensile property, which is related to the weld heat input and the plastic flow of the material. The high temperature tensile specimens are fractured in the WNZ. This is related to the complete γ′-phase dissolution which softens the joint and decreases the joint tensile property. Therefore, the post-weld heat treatments are necessary for IFW FGH96 superalloy in order to further improve the joint properties.

Effect of size of lubrication phase on properties of Ni-graphite abradable seal coating

Jianjiang TANG, Fangli YU, Haihong ZHANG, Tianqi LI, Yu BAI

2019, 39(2): 42-48.

[Abstract](2459) [FullText HTML] (1446) [PDF 895KB](39)

Abstract:
Ni-graphite abradable seal coatings were deposited by conventional atmospheric plasma spraying system (APS) and high efficiency supersonic atmospheric plasma spraying system (SAPS) respectively. The influence of the size of lubrication phase on mechanical properties, corrosion resistance and erosion resistance of the Ni-graphite coatings was investigated. The results indicate that the graphite phase in the SAPS coating has a smaller size than the APS coating. The bonding strength (21.0 ± 1.4) MPa and surface hardness (92 ± 1) HR15Y of SAPS coating are 29.6 % and 23.5 % higher than those of APS coating respectively. The relative erosion rates of APS coating at 30° and 90° angle of attack are 7 % and 13% higher than those of SAPS coating respectively, indicating that SAPS coating has a better erosion resistance than APS coating. Both APS coating and SAPS coating exhibit an obvious electrochemical corrosion in acetic acid environment at 250 ℃．However, the corrosion resistance of SAPS coating is better than that of APS coating.

Influence of ternary co-doping on thermo-physical properties of YSZ thermal barrier coatings

Xu WU, Rende MU, Kaijun WANG

2019, 39(2): 49-54.

[Abstract](3617) [FullText HTML] (1526) [PDF 921KB](38)

Abstract:
NiO, Er₂O₃, Yb₂O₃, Y₂O₃ and ZrO₂ powders were used as raw materials to prepare composite ceramic materials by the method of high temperature solid phase synthesis. The specific heat, thermal diffusion coefficient, thermal conductivity and other thermal physical properties of the composite ceramic materials were studied and compared with the traditional 8YSZ thermal barrier coating materials. The crystal structure and phase composition were tested by XRD. The results show that after NiO, Er₂O₃, Yb₂O₃, Y₂O₃ and ZrO₂ co-doping, the thermal diffusion coefficient is 0.36-0.56 mm²/s, which is 20% lower than that of YSZ from room temperature to 1500 ℃, the thermal conductivities is 1.45-1.55 W/(m•K), which is 18% lower than that of YSZ from room temperature to 1500 ℃, 2EYNYSZ material has single phase structure, and 1500 ℃ heat-treatment does not occur phase transition within 100 h.

Resistance abilities of （100）/（111）-faceted diamond films against oxygen plasma etching

Qi SUN, Jianhua WANG, Chong CHENG, Xianglei CHEN, Rongjun WU, Dan LIU, Jiao ZHU

2019, 39(2): 55-60.

[Abstract](2678) [FullText HTML] (1434) [PDF 1036KB](26)

Abstract:
The resistance abilities of (100) and (111)-faceted diamond films against oxygen plasma, 100 μm as film thickness, were investigated by the microwave power chemical vapor deposition (MPCVD) technique. The results indicate that the preferred etching points of the (100)-faceted diamond films are located at the grain boundaries and the preferred etching points of the (111)-faceted diamond films are located at the crystal surfaces. After 30 minutes etching, the (100)-faceted crystal can still be obviously shown while the (111)-faceted crystal is unobvious. After 60 minutes etching, the preferential orientations of (100)-faceted and(111)-faceted diamond films both are disappeared. The FWHM value of the (100)-faceted diamond films is increased from 8.51 cm^–1 to 12.48 cm^–1 and the FWHM value of the(111)-faceted diamond films is increased from 8.74 cm^–1to 148.49 cm^–1 when the etching time is 60 minutes. The etching rate of the (100)-faceted diamond film is 0.35 μm/min when the etching time is 40 minutes and it is increased to 1.34 μm/min when the etching time is 60 minutes. At early stage, the (100)-faceted diamond film presented better resistance ability than the (111)-faceted diamond film against the oxygen plasma etching. But the resistance abilities to the plasma etching of the (100) and the (111)-faceted diamond films are similar when the etching time is 60 minutes.

DFR method based on Gerber model under corrosion conditions

Yueliang CHEN, Xingjun WU, Xu LIU, Guixue BIAN, Yong ZHANG, Andong WANG, Hailiang HUANG, Zhuzhu ZHANG

2019, 39(2): 61-67.

[Abstract](2627) [FullText HTML] (1405) [PDF 875KB](27)

Abstract:
In order to study the influence of the equal-life curve models on DFR, the fitting accuracies of Gerber model and Goodman model for high-cycle fatigue data were compared with six typical aviation materials．The formula of DFR based on Gerber model and the expression of corrosion conversion coefficient C_C were derived, pre-corrosion fatigue tests for 0 h, 6 h, 12 h, 24 h, 36 h, and 72 h of 2024-T3 aluminum alloy (surface anodizing) were carried out, and the fatigue fracture of pre-corrosion for 72 hours was analyzed. The results show that Goodman model is suitable for brittle materials while Gerber model is suitable for ductile materials. As the pre-corrosion time increases, the DFR of 2024-T3 aluminum alloy decreases．The DFR based on Gerber model are 84.251 MPa, 84.721 MPa, 79.683 MPa, 80.745 MPa, 77.026 MPa and 74.996 MPa respectively, and the C_C is 1.006, 0.946, 0.958, 0.914 and 0.890, the fitting curve of the DFR with the pre-corrosion time is $ DFR=84.251{\left[ {\lg \left( {t + 10} \right)} \right]^{ - 0.15578}}$. It is found that when N_95/95 > 10⁵, the DFR method based on Gerber model can give full play to the fatigue performance of ductile materials．Corrosion pits produced by pre-corrosion and inclusions in materials can accelerate the formation and expansion of fatigue cracks, but DFR of the anodized specimens is decreased in a corrosive environment compared with the bare materials.

Simulation on low velocity impact to GLARE laminate based on ABAQUS

Xu CUI, Bin LI, Shuo WANG, Hongqian XUE, Zhenyu ZHANG

2019, 39(2): 68-74.

[Abstract](2816) [FullText HTML] (1473) [PDF 753KB](79)

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The material behavior of glass fiber reinforced aluminum laminates (GLARE) under low-speed impact of a falling hammer was studied, and a finite element model of ABAQUS for simulation and experimental verification was built. According to the characteristics of fiber metal matrix materials, the continuous damage mechanics (CDM) model was adopted, and the impact energy values of the falling hammer were set as 6.22 J, 12.38 J and 14.46 J respectively. The corresponding boundary conditions and loads of the model in ABAQUS were confirmed to obtain the velocity-time curve and energy loss curve of the falling direction of the falling hammer. The cohesive layer between metal layer and composite layer was taken into consideration, and the ‘Cohesive Layer’ in ABAQUS was adopted to bond metal layer and composite material layer. The tensile and compressive damage states of fibers and matrix in simulation were observed and compared with the experimental results. The results show that the finite element simulation can accurately simulate the crack and bulge effect on the back of GLARE laminates after the impact, as well as the damage situation of the matrix and fiber, so as to well predict the internal damage of the composite material.

Numerical calculation of high temperature thermal response of 3D braided carbon/phenolic composite

Bai ZHANG, Xudong LI

2019, 39(2): 75-83.

[Abstract](1662) [FullText HTML] (1126) [PDF 1062KB](6)

Abstract:
In order to accurately calculate the thermal response of 3D braided carbon/phenolic composite under high temperature, the matrix and fiber bundle of composite were established separately and a mathematical model was adopted based on the conservation of energy and mass, changes in phenolic matrix density as well as material thermal properties in pyrolysis process. The distributions of temperature field and pyrolysis degree were predicted, and the mass loss rate, the formation position and the thickness of char layer were shown. The results show that the temperature distribution of the 3D braided carbon/phenolic composite is extremely uneven, and the matrix temperature on the heating surface is significantly higher than the fiber bundle temperature, while the vertical fiber bundle temperature inside the material is higher than the matrix temperature. At the beginning of heating, the char layer is not generated immediately, but requires a transition period, during which the average thickness of the char layer is zero. The calculation of thermal response can better understand the behavioral characteristics of the composite, and provide reference and basis for the design and optimization of the thermal protection materials.

Nonlinear mechanical behavior of non-conservative of hinged-fixed FGM beams in thermal environment

Qinglu LI, Fanzhuan YANG, Jinghua ZHANG

2019, 39(2): 84-89.

[Abstract](2490) [FullText HTML] (1449) [PDF 875KB](29)

Abstract:
Nonlinear mechanical behaviors of functionally graded material (FGM) beams subjected to tangentially distributed loads in uniform and inhomogeneous heating fields were investigated. Based on the geometric nonlinear theory of extensible beams, the governing differential equations of functionally graded material beams under tangentially distributed loads in thermal environment were established. The nonlinear mechanical behavior of FGM beams composed of ceramic zirconia and titanium alloy was analyzed by using shooting method. The equilibrium paths and configurations of FGM beams subjected to tangentially distributed loads under different uniform and non-uniform heating conditions were given. The effects of uniform and inhomogeneous temperature rise and material gradient parameters on bending and post-buckling behavior of beams were discussed in detail. The results show that FGM beams have the bending behavior, whereas the beams with homogeneous materials exhibit post-buckling behavior in thermal environment, and the non-uniform heating has a great influence on the mechanical behavior of non-conservative beams.

Airworthiness verification of additive manufacturing technology for large integral metallic structure

Wu JIANG, Mujun LIU, Xiaoning HAO, Linyin LUO

2019, 39(2): 90-98.

[Abstract](2837) [FullText HTML] (1511) [PDF 636KB](77)

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In order to solve the problems existing in airworthiness verification of the large integral metallic structure for civil aircraft main bearing part, the airworthiness verification of the metallic structure additive manufacturing technology was carried out. Through the analysis of applicable airworthiness clauses of additive manufacturing technology, the general idea of airworthiness verification of the metallic structure additive manufacturing technology of civil aircraft is given, including the establishment of material specification, the determination of material strength properties, the selection of structural special factor, and the verification of structural performance. Each verification method gives a specific implementation approach. Taking outer cylinder of the nose landing gear pillar which is made by additive manufacturing technology with A-100 ultrahigh strength steel as an example, a specific implementation plan for airworthiness verification of additive manufacturing technology for large integral metallic structure is given.

2019 Vol. 39, No. 2