航空材料学报

2012, 32(6): .

[Abstract](1382) [PDF 263KB](202)

Abstract:

Advance in High Temperature Polyimide Resin Matrix Composites for Aeroengine

BAO Jian-wen, CHEN Xiang-bao

2012, 32(6): 1-13.

[Abstract](2339) [PDF 2868KB](548)

Abstract:
Advance in thermosetting polyimide and its composites were reviewed. In the last forty years, many kinds of endcap reagent were fund to synthesis polyimide resin matrix for composites, and most of polyimide was endcaped by Nadic anhydride or PEPA anhydride. Many series of polyimide resin were developed to the service in 280-450℃ for aeroengine. Low-cost polyimide, high toughness polyimide and organic/inorganic hybrid polyimide will be the main directions of polyimide study in the future.

New Generation Thermal Barrier Coatings for Ultrahigh Temperature Applications

ZHENG Lei, GUO Hong-bo, GUO Lei, PENG Hui, GONG Sheng-kai, XU Hui-bin

2012, 32(6): 14-24.

[Abstract](2544) [PDF 2110KB](582)

Abstract:
The research background, significance and current status of thermal barrier coatings (TBCs) for advanced gas turbine engines were highlighted. Research progress in new generation TBCs for ultra-high temperature applications was reviewed, which involved new ceramic topcoat materials with excellent high-temperature capability and thermal barrier performance, new metallic bond coat materials with good oxidation resistance at temperatures above 1150℃ and chemical compatibility with the underlying advanced single crystal superalloys, design of novel TBC structure architecture with superior durability, and advanced manufacturing technologies of TBCs. The effects of the deposit under engine environment comprising calcium, magnesium, aluminum and silicon (CMAS) on the TBCs lifetime were discussed. Also, the approaches to mitigate CMAS attack of TBCs were summarized. Eventually, the prospective trends and hot research topics of new generation TBCs for ultra-high temperature applications were forecast.

Theoretical Research on Oxide Film Fracture Behavior during Titanium Particle Ignition

MI Guang-bao, HUANG Xu, CAO Jing-xia, CAO Chun-xiao

2012, 32(6): 25-31.

[Abstract](1833) [PDF 1631KB](372)

Abstract:
Based on thermal self-ignition theory, in combination with theoretical analysis of the stress between oxide film and matrix with experiment fact, the viewpoint that outermost oxide film fractured first without penetrating crack was put forward, and based on this viewpoint, the model, studying the effect of outer oxide film fracture behavior on titanium particles ignition was established. Further, the physical analogue experiments about titanium ignition were carried out. Research results showed that in lower temperature during 673-1373K, titanium particles oxidized thermostatically, and oxidation kinetics curve changed into straight line from parabola due to oxide film fracture. While in higher temperature, ignition temperature was reduced by 45K due to oxide film fracture, which had no obvious effect on ignition process of titanium particles. With increasing in size of titanium particle, there was no obvious change for ignition temperature of titanium particles, which was different from complete fracture of oxide film of aluminum particles. Change of stress in oxide film made crack extension stop after the crack extended to some extent, which accelerated oxygen diffusion in inner layer oxide film and increased ignition sensitivity of titanium particles. Non-isothermal oxidation experiments proved the theoretical research on the effect of nonpenerative crack of outer layer oxide film on titanium ignition indirectly.

Application and Development Trend of Advanced Materials for Fighter Engine

LIANG Chun-hua, LI Xiao-xin

2012, 32(6): 32-36.

[Abstract](2302) [PDF 514KB](598)

Abstract:
Some countries, such as US and UK pay attention to the development of materials for fighter engines, implement a series of advanced materials technology programs, develop and demonstrate lightweight high-strength materials to provide technology base for the engineering manufacture and development of engine. Application of materials in third, fourth and next generation fighter engine is overviewed, the development trend of fighter engine materials is concluded that the application of polymer matrix composite, titanium matrix composite, titanium aluminide, lamilloy, single crystal alloy, powder metallurgy superalloy, ceramic matrix composite, thermal barrier coatings is increased. The materials research trend is concluded that the density becomes lighter to reduce the structure weight, the strength and temperature-resistance become higher to increase the turbine inlet temperature, the integration of materials, process and structure design is obtained to improve materials behavior and reduce the manufacture cost.

Advance in Manufacture Technology and Mechanism of Aero-Engine Dual Property Disk

GAO Jun, LUO Jiao, LI Miao-quan

2012, 32(6): 37-43.

[Abstract](2060) [PDF 2222KB](378)

Abstract:
Dual property turbine or compressor disk for high thrust-weight ratio areo-engine was in deeply studied due to its dual microstructure and excellent mechanical properties in recent years. The advance in aero-engine dual property disk of superalloy and titanium alloy was introduced. And dual property disks consisting of two alloys and one alloy were compared. Moreover, the encounter problems in the study were analysed with emphasis. In the future, the research focuses on dual property disks of P/M superalloy and titanium alloy which are suitable for dual microstructure heat treatment (DMHT), apparatus improvement for DMHT, ultrafine-grained billet and improving the performance of dual alloy disk joints.

Research Progress of Multiaxial Fatigue Test Methods on Blades of Aviation Engine

MA Nan-nan, TAO Chun-hu, HE Yu-huai, LIU Xin-ling

2012, 32(6): 44-49.

[Abstract](2304) [PDF 1607KB](481)

Abstract:
Based on the failure analysis of blades in recent years, the common failure mode gas turbine blades and compressor blades is caused by fatigue. The blades are required to resist high mechanical load, imposed by the high rotational speed which applies a large centrifugal load and by vibration stress of blades under rotating state. The research progress of biaxial fatigue load test methods in both domestic and overseas academic circles is reviewed, including their merits and demerits. In addition, the representative international research on multiaxial fatigue test methods of blades which can simulate the effects of centrifugal load and blade vibration are emphasized. Finally, the successful experiences of foreign countries in multiaxial fatigue test methods of blades should be learned and the Chinese multiaxial fatigue test system of blades should be formed as soon as possible.

Effect of Hf on Solidification Characterization of IC10 Superalloy

WANG Yan-li, ZHAO Xi-hong, FAN Ying-wei, HUANG Zhao-hui, WANG Qi

2012, 32(6): 50-55.

[Abstract](1644) [PDF 2256KB](270)

Abstract:
The effect of hafnium on the solidification characterization of IC10 superalloy was studied by the method of DSC and isothermal solidification experiment. The solidified structure at different temperature and solidification sequence were obtained. It is found that with the increasing hafnium content,temperatures of liquidus and solidus decrease, in the same time, the solidification range of the alloy and the temperature of eutectic increase. Hafnium narrowed down the temperature range between the lost of interdendritic capillary feeding action and solidus, as well as decreased the liquid content necessary for linking the interdendritic pools in the late solidification. The Hf-rich melts in interdendritic zone had superior fluidity. So the increasing of hafnium content increased the castability of IC10 superalloy.

Molecular Dynamic Simulations of Pressure Effect on Rapid Liquid-Solid Transition Process of Ti-Al Alloy

FU Wei, YANG Xin-hua, ZHOU Chao, YANG Xiong-wei

2012, 32(6): 56-60.

[Abstract](1808) [PDF 1900KB](392)

Abstract:
The interaction between atoms was characterized with the embedded atomic potential. The potential function of Ti-Al was given by Zope and Mishin. An out-of-order Ti-Al solid solution was investigated. Molecular dynamic simulations for rapid liquid-solid transition process of Ti-Al alloy were performed in the conditions of two certain descent rates of temperature and different pressures. The variation laws of the average atomic energy,the average atomic volume,the radial distribution function and the percentage of amorphous H-A bonding pairs were analyzed, so that the rapid liquid-solid transition process of Ti-Al alloy into the crystal or noncrystalline was observed from all conceivable angles.And then, the effects of pressure on the liquid-solid transition process and products were evaluated. It is shown that both the average atomic volume and the average atomic energy decrease, but the crystallization temperature or the glass transition temperature increases with the increasing pressure.

Control of Hot Bending Accuracy and Surface Quality for Inconel718 Thick Plate with Gradual Changed Curvature

GAO Peng, ZHANG Kai-feng, JIANG Shao-song

2012, 32(6): 61-67.

[Abstract](1568) [PDF 2910KB](280)

Abstract:
Based on the Inconel718 thick plate bending product of gradual changed curvature with aerodynamic exterior, the influence of die gap and friction coefficient on dimensional accuracy and surface quality was analyzed by experiment and numerical simulation. The results show that the difference of squeezing leads to the radial deviation rise from small radius end to big radius end as the die gap and friction condition are fixed. In the reasonable range, the influence of die gap on dimensional deviation is more than that of friction coefficient. A method of gradual changed die gap and friction coefficient was brought up to increase the dimensional accuracy. According to the results of the simulation, this method increased the dimensional accuracy and surface quality effectively. The availability of the method was verified by hot bending experiment. The Inconel718 thick plate bending product with the radial deviation less than 0.5 mm, the perfect surface was achieved.

Dynamic Recrystallization Behavior of TB-13 Titanium Alloy

FEI Yue, KOU Hong-chao, WANG Xin-nan, SHANG Guo-qiang, ZHU Zhi-shou, LI Jin-shan

2012, 32(6): 68-71.

[Abstract](1760) [PDF 1296KB](188)

Abstract:
Microstructure characteristic and dynamic recrystallization behavior of TB-13 titanium alloy during hot rolling were studied. The microstructure changes after 32%, 50%, 59% and 75% hot rolling reductions were observed by means of optical microscope (OM) and transmission electron microscope (TEM). The results show that the dynamic recrystallization mechanism of TB-13 titanium alloy is continuous dynamic recrystallization during hot rolling. When the deformation reduction is 32%,the characteristic of microstructure indicates that platy of original β grains which are elongated along hot rolling direction existed. The boundary of grain is straight and there are a quantity of random dislocations and dislocation patterns. With the increase of hot rolling deformation, the sub-grains form in the boundary of grains, and the dislocations aggregate in the boundaries of sub-grains make the angle of sub-grain boundary increased. The fine dynamic recrystallization grains are formed by the low angle grain boundary transforming into big angle grain boundary finally.

Influence of Δ Phase on Hot Deformation Behavior of GH4169 Alloy

WEI Jia-hu, DONG Jian-xin, YU Jian, YAO Zhi-hao, FU Shu-hong

2012, 32(6): 72-77.

[Abstract](2435) [PDF 1921KB](330)

Abstract:
In order to reveal the influent of phase on the hot deformation behavior of GH4169 alloy, various phase sizes and distribution,obtained by the different heat treatment,were investigated. Then, those different samples were hot deformed at 980℃ using Gleeble-1500 hot compression testing machine. The effect of pre-precipitated phase on hot deformation mechanism and microstructure after deformation of GH4169 alloy was systematically studied. The results show that the amount and distribution of phase significantly affect microstructure evolution and recrystallization behavior during hot deformation. The amount of phase increases, the stress of deformation reduce. Besides, phase promotes the nucleation and growth of recrystallization grains, especially precipitation in grain boundary. Furthermore, hot deformation accelerates the dissolution of pre-precipitated phase during deformation at 980℃.

Effect of Adding Y₂O₃ to Filler Material on Microstructure and Properties of TIG Welding Joint of MGH956 Alloy

LEI Yu-cheng, LI Meng-gang, CHENG Long

2012, 32(6): 78-84.

[Abstract](1688) [PDF 3265KB](231)

Abstract:
Through adding rare earth(RE) yttrium oxide (Y2O3, 0%, 2%,4%, and 6%,mass fraction) to the self-contained filler material, TIG was adopted to make the thickness of 1.3mm MGH956 alloy in-situ alloying welding. The effects of different contents of Y2O3 on microstructure and mechanical properties of the welding seam metal were investigated. The results show that the microstructure of the welding seam with Y2O3 was main equiaxed grain, the grains are fine and uniform, without apparent metal oxide clusters and with the new reinforced particles precipitation. That filling Y2O3 in the welding process can refine the grain size and also improve the hardness and tensile strength of the weld-joints, wherein, the weld joint tensile strength of the filler material containing 4% Y2O3 are better than those with 2% and 6%Y2O3(mass fraction), the average value is 605 MPa, reaching 84% tensile strength of the parent material.

Influence of Surface Recrystallization on Intermediate-Temperature Stress Rupture Property and Fracture Behavior of Single Crystal Superalloy SRR99

ZHANG Bing, LIU De-lin, TAO Chun-hu, JIANG Tao

2012, 32(6): 85-89.

[Abstract](1684) [PDF 1828KB](394)

Abstract:
The influence of surface recrystallization on the intermediate-temperature stress rupture property and fracture behavior of single crystal superalloy SRR99 was investigated by shot peening. The results show that the intermediate-temperature stress rupture property of the single crystal superalloy was greatly influenced by surface recrystallization. A recrystallized surface layer with the depth of about 103 m, accounting for about 8% of the fracture surface, resulted in a decrease in stress rupture life by nearly 90%. The recrystallized layers nearly have no bearing capacity, and as a result, the actual stress on the matrix increases, which is the main reason of the remarkable decrease in stress rupture life. In addition, the notch effect resulting from recrystallization makes the stress rupture life decrease further. Under 760℃ /785MPa, the unrecrystallized specimens fracture under the co-effect of microvoid coalescence and shear by slip, while the fracture mode of the recrystallized specimens is pure shear fracture by slip.

Influence of Structural Transformation of Multi-Wall Carbon Nanotubes on Microwave Properties of Multi-Wall Carbon Nanotubes Composites

ZENG Guo-xun, ZHANG Hai-yan, CHEN Yi-ming, XIONG Xuan

2012, 32(6): 90-95.

[Abstract](1709) [PDF 1725KB](319)

Abstract:
The influence of the degree of graphitization of Multi-wall carbon nanotubes (MCNTs) on adjusting microwave properties of MCNTs composites was studied by means of treated (MCNTs) at 900℃,1000℃,1100℃and 1300℃respectively. The structural transformation of the heat treated MCNTs was characterized by Raman spectroscopy. The dielectric spectra of the MCNT/paraffin composites was measured in the frequency range between 0.5-6GHz. Raman scattering measurement results show that the D-line peak intensity (1350 cm-1) to G-line peak intensity (1580cm-1) ratio (ID/IG) of MCNTs samples are almost unchanged when treated below 1000℃, so the complex permittivities and the absorbing properties of corresponding MCNTs composites also kept unchanged. With the increasing of the heat treatment temperature (above 1000℃), ID/IG ratios decreases, the structures of MCNTs are re-arranged, the mean crystallite sizes of the MCNTs increase and the graphitization degree improve. The complex permittivities of MCNTs composites also decreased obviously and the absorbing peaks shifted to high frequence with ID/IG ratio decreasing and the mean crystallite sizes of the MCNTs increasing. The spectra of dielectric and microwave absorbing properties of MCNTs composites can be adjusted through controlling ID/IG ratio and the mean crystallite sizes of the MCNTs by heat treatment.

Compression Failure and Mechanics Behavior of PMMA under Different Loading Strain Rates

GUAN Gong-shun, WANG Shao-heng, CHENG Fang-yuan

2012, 32(6): 96-101.

[Abstract](1719) [PDF 2639KB](295)

Abstract:
The uniaxial quais-static and dynamic compression tests of PMMA in a large range of strain rate were completed to investigate the effect of strain rate on the mechanical properties of PMMA. The microscopic damage modes of deformed PMMA pieces from different loading strain rates were analyzed by SEM. The parameters of viscoelastic constitutive model for PMMA were fitted by simplifying known equation, and the fitted curves from the viscoelastic constitutive model were compared with the experiment data. The results indicate that the ductile failure is shown in the quais-static loading mode and the brittle failure is shown in the dynamic loading mode. The flow stress of PMMA obviously is increased along with the rising of the strain rate. In the dynamic loading mode, the rising rate of peak stress is obviously higher than that in the quais-static loading mode.

2012 Vol. 32, No. 6