航空材料学报

2013, 33(4): .

[Abstract](965) [PDF 284KB](81)

Abstract:

Preparation of Silica Based Ceramic Core in Casting of Nickel-Based Alloy Hollow Blade

KANG Hai-feng, LI Fei, ZHAO Yan-jie, XU Hua-ping, SUN Bao-de

2013, 33(4): 1-8.

[Abstract](1293)

Abstract:
The silica based ceramic cores were formed by hot pressure molding method. The composition, porosity, expansion coefficient, microstructure and mechanical property of the sintered ceramic cores were characterized. The test results show that the pores of the ceramic cores are distributed in multiple peaks, and mainly locate from 0.1m to 5 m. With the temperature increasing to 1400℃, the expansion coefficient is decreased and the downtrend is suddenly intensified between 1170℃ and 1350℃.The -cristobalite phase and amorphous quartz coexist in the ceramic cores sintered at 1200℃. Heated at 1550℃ for 2h, the compactness of the ceramic cores increases, and the pore structure is more distinct, furthermore, both the quantity and the length of the cracks at the exterior and interior of the ceramic cores increase. Besides, the nickel-based alloy hollow blade was casted using the ceramic cores manufactured at the temperature of 1550℃ successfully.

Effects of Boron on Microalloying and Grain Refinement in Nb-40Ti-15Al Alloy

WANG Yan-qing, LIU Zhao-gang, SUN Ben-shuang, WANG Jing-ming

2013, 33(4): 9-13.

[Abstract](1205) [PDF 1501KB](131)

Abstract:
The effect of grain refinement and distribution of boron in Nb-40Ti-15Al alloy was studied by using OM,XRD,SEM and EDS. The result indicates when the addition of boron is above 0.5 %, the effect of grain refinement is apparent, it is estimated that the brittleness and other performances of these kinds of alloys shall be improved to a certain degree. The BSE results show the boron are mainly distributed at grain-boundaries. It demonstrates the reason of boron effect on grain refinement is the low solid solubility of boron in B2/ matrix that leads to a front constitutional supercooling.

Effects of Solution Heat Treatment on Microstructure and Corrosion Properties of 7050 Al Alloy

SONG Feng-xuan, ZHANG Xin-ming, LIU Sheng-dan, BAI Tan, HAN Nian-mei, TAN Ji-bo

2013, 33(4): 14-21.

[Abstract](1301) [PDF 4276KB](359)

Abstract:
The effects of different solution heat treatments on the microstructure and corrosion resistance of 7050 Al alloy hot-rolled plate were investigated by optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscope (TEM), electrochemical measurements, immersion corrosion tests and slow strain rate techniques (SSRT). The results show that (MgZn2) phase is fully dissolved into Al matrix after the single-step solution heat treatment, while S (Al2CuMg) phase isn't dissolved at all. As a result, the supersaturation degree of the alloy is low and the precipitation density of second phase in the Al matrix after aging treatment is small. Through the two-step solution treatment, S phase is partially dissolved and the size of recrystallization grains in the alloys grows larger resulting in the increase of recrystallization volume fraction. By treating with step-to-step solution, and S phase are completely dissolved into the matrix contributing to the high precipitation density in the Al matrix after aging treatment. Meanwhile, the alloy with low recrystallization fraction is obtained because of full recovery. The resistance to stress corrosion cracking (SCC) for the samples with solution and aging treatments decreases in the order: step-to-step solution two-step solution single-solution.

Microstructure and Mechanical Properties of TZM Plate Fabricated by Accumulative Roll Bonding

WANG Hua, ZHANG Yun-peng, CHEN Xing-you

2013, 33(4): 22-26.

[Abstract](1256) [PDF 2706KB](167)

Abstract:
Based on the test prepared by powder metallurgy TZM alloy sintered and then rolled into 2mm thick plate, the four times rolling compound for TZM plate by accumulative roll bonding technology (ARB) was successfully completed. And the properties tests and structural analysis of different times of TZM composite board was made. The results show that: with cumulative deformation increasing, the grain is refined, and the tissue is distributed homogeneously. The tensile strength and interface state are the best after the three time cumulative compound. During rolling process, the grain size of the sample is elongated and broadened, the grain section diameter is 200-500nm, tensile strength increases by 50%, the maximum tensile strength of 2mmTZM composite board reaches 968 MPa; but its fracture feature is a brittle fracture, elongation rate does not change obviously, and the elongation rate of the composite plate is only 2%.

Friction Stir Welding Microstructure of SiC_p/2024Al MMC

FENG Tao, YU Zhen-qi, HAN Yang, ZHANG Yong-ang, WANG Yin-zhen

2013, 33(4): 27-31.

[Abstract](1228) [PDF 2060KB](179)

Abstract:
SiCp/2024Al aluminum matrix composites were welded by Friction Stir Welding. The teleport move behavior of the base metal was analyzed by use of the emergent stopexperiment. The joint structure was observed by metallographic microscope and SEM. The microstructure analysis indicated that V style structure was found in the brazing joint. And SiC particles distributed unevenly in different parts of the welding joints. SiC particles presented segregation phenomenon in the SMAZ, SiC particles were less in the centre of the welding joints. The reinforcement particles might disappear if the welding parameters were inappropriate. The TEM analysis of different parts of the welding joint showed that SiC/Al interface was bounded clearly, no brittle phase formed, and the crushed SiC particles were found.

MIG Arc Brazing of Dissimilar Metals between Pure Aluminum and Zinc-Coated Steel

GUO Xu-ming, WANG Jian-mei, XU Rong-zheng

2013, 33(4): 32-36.

[Abstract](1198) [PDF 1131KB](130)

Abstract:
MIG arc brazing of dissimilar metals between pure aluminum and zinc-coated steel in a lap joint was investigated using Al-Mg, Al-Si filler wires. The interface structure and the mechanical properties of the fusion-brazing joint were characterized. The results show that the high quality welded joint is successfully achieved with Al-Mg, Al-Si filler wire in the suitable welding parameters. The intermetallic compound layer (IMC) is composed of -Al3Fe, -Al5Fe2 and AlFeSi phases by using Al-Si filler wire. It is thinner and denser than that obtained by using Al-Mg filler wire. The growth of IMC layer is suppressed due to the addition of Si element. The shear strength of welded joint nearly reaches that of pure aluminum. The cracking position occurs in weld zone.

Finite Element Simulation of Residual Stress Field in TB6 Titanium Alloy Induced by Laser Shock Peening and Shot Peening

HU Zheng-yun, LI Man-fu, XIE Lan-sheng

2013, 33(4): 37-42.

[Abstract](1295) [PDF 4242KB](227)

Abstract:
Two 3D finite element models for laser shock peening(LSP) and shot peening(SP) were established. To indicate the effects of the process parameters, and the composite processing, and the stress wave decay laws, the tests were carried out. The results show that the plane wave induced by LSP forms deeper stress affected layer with the depth reaching 1.5 mm; the spherical waves induced by SP form a larger residual stress with the maximum reaching 1.1 times of the yield strength. The greater plastic strain causes the greater of residual stress, the depth of strain and the depth of residual stress affected layer were similar. In the composite process, the depth of residual stress affected layer was close to that of LSP, and the maximum residual stress reaches 1.2 times of the yield strength.

Effects of Deposition Temperature on Microstructure and Wear Resistance of Mo Coating Prepared by Glow Plasma Deposition on TC4 Titanium Alloy

TIAN Xiao-dong, WANG Li-jie, SUN Bo

2013, 33(4): 43-47.

[Abstract](1258) [PDF 2783KB](132)

Abstract:
Mo coatings on TC4 alloy were prepared by glow plasma deposition technique at 850-1050℃ for 1-5 hours. Structure, wear rate and mechanics of the coatings were studied by using XRD, SEM, EDS, microhardness device and friction wear testing machine. The results reveal that the coatings are mainly consisted of Mo layer and an interdiffusion zone composed of Mo-Ti solid solution. The coating average grain size increases with rising deposition temperature, which causes the decrease of Mo coating hardness and wear resistance. Wear tests demonstrate that the wear rate of the Mo coating prepared at 950℃ for 5h is about 1/45 of the TC4 substrate wear rate under simple sliding and dry friction condition with a load of 98N.

Effects of Interface Structure between Aluminosilicate Glass and Polyurethane on Optical Properties of Laminated Glass

FENG Zhi-jun

2013, 33(4): 48-52.

[Abstract](1253) [PDF 1616KB](219)

Abstract:
The effect of the interface corrosion conditions on optical properties of aeronautic laminated glass was investigated. The transparency and microstructure were analyzed by photoelectric haze instrument, scanning electron microscopy and ultraviolet-visible spectroscopy. Results indicate that with the etchant concentration or time increasing, the transmittance of the aluminosilicate glass reduces in phases and its haze increases first slowly and then rapidly. However, the transmittance of the laminated glass first increased and then decreased with the increasing of the etchant concentration or etching time. There is little effect of the surfactant on the transmittance of laminated glass. When the etchant concentration was 10% and the etching time was 10 minutes, the prepared laminated glass had the better optical performance.

Preparation and Properties of Polyaniline/Ni-Coated Carbon Nanotubes Composites

HE Zheng, QI Shu-hua, QIU Hua, QIN Yun-chuan

2013, 33(4): 53-57.

[Abstract](1295) [PDF 1651KB](158)

Abstract:
By using electroless plating, metal nickel (Ni) was coated on the surface of carbon nanotubes (CNTs) and the composites Ni/CNTs were prepared. Then conductive polyaniline (PANI) was synthesized by in situ polymerization using ammonium persulfate as the oxidant. After that, the composites PANI/Ni/CNTs were prepared through the solution blending method. The morphologies and performance of the composites were characterized by transmission electron microscope (TEM), energy dispersive spectroscopy (EDS), fourier transmission infrared (FT-IR), UV-Visible Spectrophotometer (UV-Vis), X-ray diffraction analysis (XRD) and two probe method. Results show that the lengths of Ni/CNTs are hundreds of nanometer to tens of microns, and the thickness of the coating is about 20-30 nm. With Ni/CNTs contents increasing, the conductivities of the composites PANI/Ni/CNTs also increase. The percolation threshold value of it is about 3.5%.

Ultrasonic Vacuum Resin Infusion Processing and Property of Carbon Nanotube/Glass Fiber/Epoxy Resin Laminates

ZHAO Yan-wen, YE Hong-jun, ZHAI Quan-sheng, GU Yi-zhuo, LI Min, ZHANG Zuo-guang

2013, 33(4): 58-63.

[Abstract](1258) [PDF 3634KB](168)

Abstract:
The carbon nanotube (CNT)-glass fiber/epoxy resin laminates were prepared by traditional vacuum assisted resin infusion molding (VARIM) and ultrasonic vacuum resin infusion processing (UVRIP) respectively. The defects of the laminates processed with two processing methods were examined, and the mechanical properties including flexural property and interlaminar shear strength (ILSS) were measured. In addition, the property of the resin and the adhesion between resin and fiber were analyzed. The effects of CNT and processing method on the property of laminates were discussed. The results show that compared with traditional VARIM, the defects in the fiber bundles decrease because the resin fluidity and the resin infiltration are improved in UVRIP. The mechanical properties of the laminates are enhanced by adding 0.05% mass fraction of CNT, especially for the laminates processed by UVRIP. Moreover, the effect of processing method on the property of laminate is dependent on the structure of the fabric.

Ultrasonic Nondestructive Evaluation of Resin Flow Induced by Temperature Variation

CHEN Ping, LIU Ling, WANG Zhan-ji, HE Shao-gang

2013, 33(4): 64-70.

[Abstract](1290) [PDF 4685KB](118)

Abstract:
Resin flow into dry fibrous webs is the main microstructural change during the process of out-of-autoclave (OOA) prepregs, which influences the air evacuation and porosity formation. An air-coupled ultrasonic nondestructive evaluation (NDE) method was used to measure the variation of resin flow of an OOA prepreg during heating-up and isothermal stage. The OOA prepreg samples were firstly heated up from room temperature to 100℃, and flow variation versus temperature was obtained by C-scan image. Then, the selected OOA prepreg samples were kept at 60℃ and 80℃ respectively, flow change at various time was also obtained by using the air-coupled ultrasound NDE. From the obtained results, the microstructural change in the fibrous webs as well as the flow rate of the resin was quickly achieved by using the NDE method. Also, microscopy image was carried out to demonstrate the effectiveness of the proposed air-coupled NDE. Results show that the variation trend from C-scan image and microscopy image are coherent with each other. Therefore, the proposed air-coupled NDE method is an effective way for monitoring resin flow through the thickness of fibers layers.

Mechanical Behavior of Commonly Used Aeronautical Aluminum Alloys under Dynamic Tension

WANG Lei, LI Yu-long, SUO Tao, GUO Ya-zhou

2013, 33(4): 71-77.

[Abstract](1563) [PDF 1767KB](224)

Abstract:
The dynamic as well as quasi-static tensile response of five kinds of commonly used aluminium alloys (i.e. 2A12-CZ,2A12-M,2024-T351,7050-T74 and 7050-T7451) were investigated by using split Hopkinson tension test (SHTB) and universal test machine. The results show that the yield stress of 7050 aluminium alloys is higher than the others. 2A12-M alloy has the lowest tensile strength among the five kinds of alloys. All of the five kinds of alloys have positive strain-rate sensitivity. The strain-rate sensitivity of 2A12-CZ is high, while the strain-rate sensitivity of 7050-T7451 is low. The dynamic tensile failure strain is much higher than the quasi-static tensile failure strain for all tested alloys. 2A12-M alloy and 2024-T351 alloy have higher dynamic tensile failure strain than the others. Finally, the Johnson-Cook and Cowper-Symonds models were chosen to characterize aluminium alloys' behavior and the parameters were obtained by fitting the experiment data. The models coincide with the experiment results fairly well.

Vibration Fatigue and Fracture Performance of Aluminum Alloy 2024

HU Hai-tao, LI Yu-long, SUO Tao, ZHAO Feng

2013, 33(4): 78-83.

[Abstract](1407) [PDF 3661KB](178)

Abstract:
A series of vibration fatigue tests with the same initial stress amplitude were carried out on aluminum alloy 2024 cantilever beam aimed to explore the effect of excitation frequency on vibration fatigue lives. The experiment results show that the longest-life vibration fatigue of cantilever beam appears, and the least fatigue failure region of fracture surface is found, while the excitation frequency is equal to the natural frequency of sample. The fatigue fracture surface was studied by optical microscope and scanning electron microscope. The results show that the crack initiations mostly derive from the surface flaw or inclusion. The crack propagation regions are characterized by fatigue striation and secondary crack. There are lots of dimples in fatigue failure region of fracture surface. The tiny strengthening phase particles play a role of restraining the propagation of fatigue crack.

Influence of Preformed Angle on Strength and Stress of Reverse-Bent Lap Joint

TANG Yong, HE Xiao-cong, ZHENG Jun-chao, XING Bao-ying, XU Jing-nan

2013, 33(4): 84-89.

[Abstract](1135) [PDF 3934KB](163)

Abstract:
The influence of the preformed angle on the strength and stress distribution of 5052 aluminum alloy reverse-bent bonded joints was investigated using static experiment and finite element method (FEM). Experimental results show that the load bearing ability of adhesively bonded reverse-bent joint increases with the increase of the preformed angle. After the preformed angle reached a certain value, the load bearing ability and actual shear strength started to decrease. The results obtained from the finite element method analysis indicate that the preformed angle obviously affects the peel stress and the shear stress in mid-adhesive. The stress concentration in adhesive fillet decreases greatly when the preformed angle reaches a certain value, and then aggravates with the increase of the preformed angle.

Research Progress of Flexible Nanocomposites with High Thermal Conductivity

FENG Wei, LI Dong-jie, LYU Peng

2013, 33(4): 90-97.

[Abstract](1391) [PDF 1179KB](265)

Abstract:
Flexible thermal conductive nanocomposites have wide application in the fields of micro-electronic, aerospace and intelligent drive. The research progresses of the flexible thermal conductive nanocomposites filled with the nano-fillers of different dimension were summarized. Meanwhile, the main problems and their possible solutions were also summarized. The poor dispersion of nano-fillers can be improved by surface modification. Improvement of thermal conductive theories and establishment of mathematical model would provide important basis for the practical application of flexible thermal conductive nanocomposites. Developing novel nano-fillers, especially hybrid fillers, is an important way to improve the comprehensive performance of flexible thermal conductive nanocomposites.

2013 Vol. 33, No. 4