航空材料学报

2019, 39(4)

[Abstract](1466) [PDF 1001KB](34)

Abstract:

Research progress on the preparation of porous polymer derived ceramics

Jianyong TU, Yangyang MU, Hailong XU, Xiaowei YIN, Laifei CHENG

2019, 39(4): 1-11.

[Abstract](5329) [FullText HTML] (2784) [PDF 2014KB](102)

Abstract:
Polymer derived ceramics (PDCs) has been greatly developed over the past 40 years, due to its advantages of simple operation, low sintering temperature and strong design ability. The research progress of porous PDCs, including template method, foaming method, freeze casting technology, additive manufacturing technology and other preparation methods is reviewed in this paper. In addition, the molecular side chain design and synthesis of ceramic precursors such as polycarbosilane, polysiloxane and polysiloxane for adjusting the composition, microstructures and mechanical properties of porous PDCs are summarized. It is proposed that the design of ceramic precursors and the additive manufacturing method may be the future development direction in porous PDCs.

Effect of hot isostatic press and hot extrusion on microstructure of spray formed GH738 alloy

Yue WANG, Wenyong XU, Na LIU, Hua YUAN, Liang ZHENG, Zhou LI, Guoqing ZHANG

2019, 39(4): 12-18.

[Abstract](2361) [FullText HTML] (1318) [PDF 1286KB](39)

Abstract:
The large-sized (ϕ300 mm) nickel based superalloy GH738 billet was fabricated by spray forming followed by hot isostatic press (HIP) and hot extrusion (HEX) within varied deformation temperatures. The micro-defect, carbonitride distribution, γ/γ′ evolution during the hot processes were investigated by the relevant approaches including XRD, SEM, TEM, EBSD and phase analysis technique respectively. The results show that the porosities in γ matrix of spray deposited billet are welded up to closure after HIP process. The difference of characteristic microstructure after dynamic recrystallization obtained after the hot extrusion is mainly based on the varied deformation conditions including temperature and strain-stress state. The grain-boundary-distributed carbonitrides in HIPed billiet are transformed into extrusion-direction-along distribution after hot extrusion. The effects of temperature field delivered and cooling condition on elements constitution, mass fraction, morphology, size and distribution of γ′ in GH738 are validated during different hot processes as well.

Effect of deformation parameter on solution heat-treated microstructure of extruded Ni-based powder metallurgy superalloy

Yang CHEN, Gaofeng TIAN, Jie YANG, Yingchun CHEN, Guojun MA, Jinwen ZOU

2019, 39(4): 19-25.

[Abstract](2306) [FullText HTML] (1400) [PDF 1288KB](33)

Abstract:
The effect of forging temperature, strain rate and strain state on grain microstructure during solid solution heat treatment of extruded Ni-based Powder Metallurgy Superalloy was studied based on the heat-compression experiment of double cone (DC) specimens. The corresponding relationship between forging temperature, strain rate and grain microstructure in the range of forging temperature from 1060~1120 ℃ and strain rate from 0.003 s^–1 to 0.3 s^–1 was obtained. The results show that in the Double Cone compression experiment, at the same strain and temperature, the flow stress increases with the strain rate. And at the same strain rate, the higher the temperature, the lower the flow stress is. After supersolvus heat-treatment, at the same strain rate, the grain microstructure is inhomogeneous. And at the same forging temperature, the average grain size of the specimens under the three strain rates of three strain rate is 18~20 μm, but the specimens with higher strain rate clearly show inhomogeneous grain microstructures. In order to obtain the homogeneous grain structure, the more appropriate forging parameter is: the temperature of 1120 ℃, and the strain rate of 0.003 s^–1. At the same forging temperature and strain rate, with the decrease of local strain, the average grain size is increased gradually.

Structure evolution and thermal conductivity of lanthanum zirconate coating after high temperature exposure

Yanfei WANG, Di JIANG, Siqing WANG, Rongjun LIU, Jing HAN

2019, 39(4): 26-31.

[Abstract](3191) [FullText HTML] (1368) [PDF 751KB](37)

Abstract:
La₂Zr₂O₇ powders were synthesized by solid-state reaction method. After spray granulation, the La₂Zr₂O₇ coatings were fabricated by air plasma spray technique. The effect of heat treatment time on the properties of La₂Zr₂O₇ coatings was investigated, focusing on phase composition, microstructure evolution and thermal conductivity. The results show that a single pyrochlore phase of La₂Zr₂O₇ coating has been successfully fabricated. And the average porosity is 11.3%. The phase composition and porosity do not change with the prolongation of heat treatment time. The thermal conductivity of the as-sprayed coating can be as low as 0.392 W•m^–1•K^–1. A number of amorphous structures exist in the as-sprayed coating, which can effectively block the transmission of phonons. With an increase of thermal exposure time at 1300 ℃ in air, the amorphous structure is gradually transformed into crystalline structure, and the phonon transfer efficiency is obviously improved, resulting in a significant increase in the thermal conductivity of the coating. Interestingly, after heat treatment, the rebound effect of thermal conductivity at high temperature didn’t appear in this research.

Prediction of acid salt spray corrosion experiment of 2024 aluminum alloy based on RBF neural network

Baohui JIA, Yibin FANG, Yiqiang WANG

2019, 39(4): 32-39.

[Abstract](2629) [FullText HTML] (1360) [PDF 992KB](30)

Abstract:
With the increasingly serious industrial pollution, aircraft structural materials are inevitably exposed to acidic environment during the service. 2024 aluminum alloy was used for acid salt spray experiment under different conditions. The pH values of salt spray experiment were set as 2, 3, 5, the salt spray concentration was 25 g/L, 50 g/L, 75 g/L, and the corrosion time was 24 h, 48 h and 72 h respectively. Combine radial basis function (RBF) neural network with orthogonal experiment design, different experimental conditions were selected as the learning sample set of the neural network, and the results of orthogonal test are analyzed by range analysis. The results show that RBF combined with orthogonal experimental design can accurately predict the corrosion rates under arbitrary experimental conditions, reduce the number of experiment, and improve the prediction accuracy. The prediction result of using both the orthogonal group and supplementary peak group as the sample set is better than that of using only orthogonal group as the sample set. The results of range analysis show that the most important factor affecting the mass loss per unit area of 2024 aluminum alloy is the pH value of the solution, followed by the concentration of salt spray and the corrosion time is the least.

Effect of cyclic hygrothermal aging on interlaminar fracture toughness of T700/TDE86 carbon composite

Kailong XU, Lulu LIU, Zhenhua ZHAO, Chao SHUANG, Wei CHEN

2019, 39(4): 40-48.

[Abstract](2572) [FullText HTML] (1437) [PDF 1831KB](37)

Abstract:
The artificial accelerated cyclic hygrothermal aging test was conducted on T700/TDE86 carbon fiber reinforced resin matrix composites, and the effects of different cyclic hygrothermal aging days on interlaminar fracture toughness of composites with open type (mode Ⅰ) and slip type (mode Ⅱ) were investigated. The results show that the model Ⅰ interlaminar fracture toughness of composite after cyclic hygrothermal aging exists an obvious R curve, the initial extend energy release rate (G_IC,init) and the propagational extend energy release rate (G_IC,prop) of composite are improved remarkably with the increase of cyclic hygrothermal aging days. The model Ⅱ interlaminar fracture toughness of composite appears a trapezoidal descent with the increase of cyclic hygrothermal aging days, and the decline is the largest at the early stage of cyclic hygrothermal aging and the largest descent is 21.68%.

Electrothermal coupling model for lightning strike protection of composite materials

Xiang LU, Miao ZHAO, Zezhong SHAN, Mingjun LUO

2019, 39(4): 49-58.

[Abstract](2573) [FullText HTML] (1247) [PDF 1475KB](50)

Abstract:
In order to study the damage law of the composites lightning strike protection caused by lightning current, the electrothermal coupled mathematical model of the ablation damage of composite laminates protected was constructed based on the principle of energy balance. According to the model, a thermal-electrical coupling analysis finite element model of carbon fiber reinforcement plastic（CFRP）with protection subjected to lightning current was established based on ABAQUS, the lightning strike ablation damage was analyzed, and compared with the experimental results to verify the validity of the simulation. Thus, the ablation damage mechanism of composite laminates under different peak currents, different combination waveforms and different aluminum coating thicknesses is obtained. The results show that when the peak current increased from 50 kA to 100 kA with the same thickness of aluminum coating, the damage area of composite laminates increased by about 1.5 times. Under the action of lightning current waveform of 10/350 with peak value of 50 kA, the damage area of the composite reference is about 4 times of that the composite materials under the protection system of aluminum coating with thickness of 0.05 mm.

A novel high specific capacity hybrid cathode for lithium fluorocarbon battery

Sikan PENG, Chen WANG, Nan WANG, Shaojiu YAN

2019, 39(4): 59-64.

[Abstract](3167) [FullText HTML] (1673) [PDF 754KB](39)

Abstract:
A novel high specific capacity hybrid cathode material was designed by increasing the specific capacity of cathode material to improve the discharge performance under large current. The carbon fluoride-sulfur hybrid material was prepared through grinding, dispersing and melt-diffusion treatment. Electrochemical tests and analysis showed that the new material could achieve synchronous improvement of capacity and high current discharge performance. At the same time, it has the capacity of secondary reversible cycle charge and discharge. The research results show that the energy density and power density of carbon fluoride-sulfur cathode have outstanding advantages, it can be significantly improved at different current densities. The energy density and power density are increased by 433% and 10.7% respectively than that of the pristine carbon fluoride cathode.

Application of solid polymer electrolyte in lithium sulfur batteries

Chen WANG, Sikan PENG, Nan WANG, Shaojiu YAN

2019, 39(4): 65-70.

[Abstract](2880) [FullText HTML] (1552) [PDF 1276KB](44)

Abstract:
Polymer electrolyte coated sulfur@carbon fiber composite solid electrode was prepared by the two methods of microscopic and macroscopic coating with polymer electrolyte in the cathode sheet of lithium sulfur battery. The microscopic morphology of the electrode was characterized by scanning electron microscopy, and the corresponding performances of the battery with different cathode structures were also analyzed. Results show that the electrode structure of microscopic polymer solid electrolyte coated active material is favorable for ion transfer. Macroscopically constructing a polymer solid electrolyte film on the electrode surface can improve the cyclic stability of the electrode and inhibit the shuttle effect. The all-solid lithium-sulfur battery assembled with the membrane electrode structure has good cycle performance. After 270 cycles, the Coulomb efficiency still keeps over 98 %.

Composite of CNT foam and phase change material: nano pore structure and the packing of phase change material

Wei SUN, Guoxiang ZHOU

2019, 39(4): 71-77.

[Abstract](2734) [FullText HTML] (1446) [PDF 1053KB](30)

Abstract:
Thermal energy is a very promising and widely existing energy source. However, the current heat storage method of phase change material not only has a long energy conversion time but also has low heat storage efficiency. Carbon nanotubes (CNTs) based phase change composite materials were prepared by using the carbon nanotubes foam as the highly 3D thermal conductive network and impregnated with phase change material by capillary forces. The morphology of the sample was studied by FIB/SEM focused ion/electron double beam microscopy, showing excellent dispersion quality of CNTs throughout the matrix. The latent heat and crystal structure of the sample were analyzed by DSC and XRD respectively, based on which the mechanisms for the improvement of energy storage capability were investigated. Further, the mechanical properties of the sample were tested by tensile testing machine, and revealed high structural robustness which was very important for their practical applications. This study shows that the CNT foamed based on nanocomposite not only possess very high thermal energy storage efficiency, also reduces the phase change material loss in the circulation phase.

Tensile anisotropy of the fourth generation single crystal superalloy at different temperatures

Zhenxue SHI, Shizhong LIU, Jiarong LI

2019, 39(4): 78-85.

[Abstract](2682) [FullText HTML] (1199) [PDF 1909KB](53)

Abstract:
The fourth generation single crystal superalloy with [001], [011] and [111] orientations was cast using seed method in the directionally solidified furnace. The tensile properties of the alloy with different orientations were investigated at 23 ℃, 800 ℃ and 980 ℃.The alloy microstructure, fracture surface and fracture microstructure with different orientations at different temperatures were investigated by OM and SEM. The results show that the alloy with different orientations has obviously various as-cast dendritic structure and heat treated microstructure on the section perpendicular to the crystal growth direction. The yield strength and ultimate tensile strength of the alloy at different temperatures are decreased with the sequence of [111], [001] and [011] orientation. The elongation and contraction of area of the alloy with [011] orientation are the largest at 23 ℃ and 980 ℃, and those alloys with [111] orientation are the largest at 800 ℃. The tensile fractures of the alloy with different orientations at 23 ℃ and 800 ℃ are quasi-cleavage, while that the alloys with [111] and [001] orientations are dimple fractured, and that the alloy with [011] orientation shows quasi-cleavage and dimple mixture mode. After tensile fracture, the γ′ phase of alloy with different orientations at 23 ℃ and 800 ℃ still remains in cube shape. The γ′ phase of alloy with [001] orientation at 980 ℃ becomes longer along the stress direction, while that the alloy with [111] orientation turns parallelogram and that with [011] orientation is cut through by single slip band.

Ultra-high frequency fatigue testing approach and verification of TA11 Ti-alloy based on electrodynamic shaker

Wei XU, Yanguang ZHAO, Bin ZHONG, Xianfeng YANG, Chunhu TAO

2019, 39(4): 86-92.

[Abstract](2523) [FullText HTML] (1186) [PDF 810KB](56)

Abstract:
This paper proposes an ultra high frequency fatigue experimental approach based on electrodynamic shaker. The ultra high frequency fatigue specimen of TA11 titanium alloy sheet was designed after FEM calculation. The actual testing frequency of the designed specimen could be reached as high as 1756 Hz. The fatigue tests of both the ultra high frequency specimen and standard vibration fatigue specimen were carried out under the same stress level, and the consistency of test results was statistically verified. The results show that under the same stress condition,the testing results of the high frequency fatigue specimen proposed in this study are in good agreement with the experimental results of standard vibration fatigue specimen. Furthermore, the comparison of the present experimental results with the axial-loading fatigue and rotating bending fatigue results for the same material is conducted,and also a good consistency is obtained.

Influences of hydrothermal aging on cracked metallic structure with composite patch

Yue WANG, Shuping ZHAO, Jun YANG, Hui LI, Dongming ZHU

2019, 39(4): 93-100.

[Abstract](2370) [FullText HTML] (1204) [PDF 777KB](31)

Abstract:
Tensile test and fatigue test were performed on aluminum alloy plate containing double-side cracks without patch, aluminum alloy plate containing double-side cracks with glass fiber patch and aluminum alloy plate containing double-side cracks with glass fiber patch immersion in water for 40 days, then the failure mode, failure mechanism, fatigue crack propagation and carrying loading capability were analyzed. The influences of hydrothermal aging on mechanical property of cracked metallic structure with composite patch were assessed. The results show that the hydrothermal aging reduces the ability of composite patches to weaken the interference effect between fatigue cracks, the propagation length from crack of hydrothermal aged specimen is shorter than that of the specimen without hydrothermal aging. After bonding patch to single face of aluminum plate, the fatigue crack propagation rate along the direction of thickness of plate is slow, and the shorter the distance from crack to the patch is, the slower the speed is, so the hydrothermal aging decreases the efficiency of hindering fatigue crack propagation along the direction of thickness of plate. Due to the effect of hydrothermal aging, the recovery rate of carrying loading is decreased to 45%, while the fatigue crack propagation life is decreased to 63.7%. Hydrothermal environment causes the aging of adhesive, resulting in the decrease of cohesive load between aluminum and adhesive, leading to the fall off of composite patch, the failure mode of adhesive layer is changed from cohesive failure to interface failure.

2019 Vol. 39, No. 4