航空材料学报

Effect of Mn on Microstructures and Mechanical Properties of 2519 Aluminum Alloy

LI Hui-zhong, ZHOU Gu-xin, ZHANG Xin-ming, CHEN Ming-an, LIANG Xiao-peng, GAO Hui

2007, 27(1): 1-5.

[Abstract](1479) [PDF 904KB](360)

Abstract:
The effect of Mn on the microstructures and mechanical properties of 2519 aluminum alloy was investigated by means of microhardness test,tensile test,transmission electron microscope and scanning electron microscope.The results show when the content of Mn is less than 0.29wt%,the strength of 2519 aluminum alloy increases with the increase of Mn content;when the content of Mn is greater than 0.29wt%,the strength of 2519 aluminum alloy decreases.The hardening effect of the aged alloy is accelerated at 170℃ and the time to peak-aged is reduced,but the plasticity of the alloy gradually decreases with the increases of Mn content.However,the hardening effect of the aged alloy decreases with the increases of Mn as the content of Mn is over 0.29wt%.The optimal content of Mn of 2519 aluminum alloy is 0.29wt%,at which the alloy has best tesile strength and plasticity.

Influence of Rare Earth on Structure and Properties of High Carbon High Speed Steel

JIANG Zhi-qiang, FENG Xi-lan, FU Han-guang

2007, 27(1): 6-10.

[Abstract](1417) [PDF 1120KB](404)

Abstract:
Some rare earth(RE) is added to high carbon high speed steel whose compositions are as follows: Fe-5%V-5%W-5%Mo-5%Cr-3%Nb-2%Co-2%C.The effects of RE on the as-cast microstructure,heat treatment microstructure and mechanical properties of high carbon high speed steel have been investigated.Results show that, when suitable RE is added into high carbon high speed steel,the austenite and eutectic carbides have been changed.The austenite grains and coarse eutectic structure are refined,and flake carbides in eutectic structure become short and thinner.After heat treatment,most of eutectic carbides are spheroidized and distributed(uniformly.) The hardness and hot hardness of modified high carbon high speed steel are slightly increased,impact toughness is greatly(increased) by 37.81% and reaches 10.17J/cm2.The mechanism that RE improves the structure and properties of high carbon high speed steel is analyzed.

Researches of Microstructures and Properties of Spray-Formed Al-Zn-Mg-Cu Alloy

BAI Pu-cun, YUAN Cai-ping, ZHANG Xiu-yun, CHEN Wei

2007, 27(1): 11-14.

[Abstract](1416) [PDF 663KB](311)

Abstract:
An Al11.3Zn2.4Mg1.1Cu alloy has been prepared by spray forming equipment manufactured by Ospray company.The spray-formed alloy was extruded, and then heat treated with solid solution and aging.Mechanical properties of the experimental alloy were examined by material test machine.The ultimate tensile strength,yield strength and elongation rate are 849 MPa,796 MPa and 3.3%,respectively.Microstructures of the spray formed alloy have been investigated by transmission electron microscopy(TEM) and scanning electron microscopy(SEM).It was shown that micron and nano-scale grains existed in the alloy,and high strength of the alloy resulted from nano-scale grains strengthening,solid solution strengthening and precipitation strengthening.Feature of fracture of the tension sample was type of intergrain fracture in terms of analyses of SEM.

Influence of γ-Aminopropyltriethoxy on Shear Strength of Adhesion Bonded Aluminum Sheet/Polypropylene/Aluminum Sheet

CHEN Ming-an, LI Hui-zhong, XIE Xuan, ZHANG Xin-ming, YANG Xi

2007, 27(1): 15-19.

[Abstract](1451) [PDF 2034KB](376)

Abstract:
The effect of the content of γ-aminopropyltriethoxy(γ-APS) solution on shear strength of adhesion bonded aluminum sheet/polypropylene/aluminum sheet has been investigated for 10% and 20% maleic anhydride grafted polypropylene(PP-g-MAH) in blend of PP and PP-g-MAH.For aluminum sheet with surface pretreatment by sand grinding,the adhesion strengths are 10.03 and 10.76MPa respectively.The adhesion strength and the displacement show obvious promotion with pretreatment of γ-APS after sand grinding,and reach the maximum values at 3% γ-APS solution.The pretreatment of γ-APS transforms the surface of aluminum sheet into amino group-NH2.The covalent bond between carboxyl groups,-COOH on PP-g-MAH and amino group-NH2 are formed at the interface.With further high content of γ-APS,both of the adhesion strength and the displacement decrease due to the formation of weak layers of γ-APS and PP-g-MAH at the interface.

Microstructures and Mechanical Properties of 5wt% YAl₂p/Mg-14Li-1Al Composite Material

WANG Su-jie, WU Guo-qing, LI Rui-hua, LUO Gen-xiang, HUANG Zheng

2007, 27(1): 20-22.

[Abstract](1477) [PDF 743KB](273)

Abstract:
A new YAl2p/Mg-14Li-1Al composites with 5wt%YAl2p was prepared by stir-casting and its microstructures and properties are investigated systematically.The results show that,the YAl2p particles distribute homogeneously in Mg-14Li-1Al matrix,and a good YAl2p/Mg-14Li-1Al interface was developed.There are no reaction products or obvious elements diffusing on the interface.The tensile strength of the reinforced material is 189MPa,shown to be considerably improved approximately 45.3% compared with matrix alloy,and the composite keeps good ductility property with an elongation of 7%.

Ceramet Composite Coating Synthesized and Deposited from Ti-Ni-C System Composite Powder for Reactive Flame Spray

LIU Hui-yuan, HUANG Ji-hua, WEI Shi-zhong, ZHANG Hua, ZHAO Xing-ke

2007, 27(1): 23-27.

[Abstract](1380) [PDF 988KB](376)

Abstract:
A new process of preparing Ti-Ni-C composite powder for Reactive Flame Spray(RFS)-precursor carbonization-composition process was developed using titanium powder,nickel powder and precursor of carbon(sucrosum) as raw materials.TiCreinforced metal compound coating were synthesized and deposited by RFS.XRD and SEM were employed to analyze the phase composition and microstructure of the composite powder and coating.The results show that: The compound powder prepared by this method has very dense structure,which can solve the problem of raw powder breaking-up in spraying process.The TiC-reinforced Metal Compound Coating by RFS presents typical morphology of thermal spraying coating with two different alternate,laminated layers: The one is the composite reinforcement layer in which round nanoscale TiC particles are dispersed within the metal matrix,the other is the paragentic layers of TiC and Ti2O3.The matrix consists of Ni and Ni3Ti.

3d Needle-Punched Carbon/Silicon Carbide Ceramic Matrix Composites and Tribological Properties

XU Yong-dong, ZHANG Li-tong, CHENG Lai-fei, FAN Shang-wu, YUAN Yi-dong, ZHANG Fu-kuan, TIAN Guang-lai, CHEN Zhi-jun, LOU Jian-jun

2007, 27(1): 28-32.

[Abstract](1513) [PDF 1399KB](468)

Abstract:
Carbon/carbon(C/C) composites with certain density were prepared by chemical vapor infiltration(CVI) of the three-dimensional needle-punched carbon fiber preform.By the reactive melt infiltration(RMI) method as a subsequent densification of C/C composites,the highly densified carbon/silicon carbide(C/SiC) composites were finally obtained.The studies on structure characteristics,braking performance as well as friction and wear mechanisms of C/SiC composites were systematically investigated in this paper.It was found that the CVI-carbon which filled the gap between carbon monofilaments in fiber bundles formed dense carbon/carbon region.The material distributed between fiber bundles were silicon carbide derived from RMI,residual silicon and carbon.C/SiC composites show excellent friction and wear behavior with the typical saddle shape of the coefficient of friction(COF) curve.The average COF obtained is 0.34 and the wear rate is low(1.9μm at a time for one side).The frictional behavior is stable and almost immune to humidity with a decreasing rate of only 2.9% in hygrometric state.In the course of friction and wear,the contact surface of the carbon/silicon carbide brake disk turned to continuous and stable friction surface and grain-abrasion was the main wear form.

Thermally Conductive Silicone Rubber Composites

ZHOU Wen-ying, QI Shu-hua, TU Chun-chao, ZHAO Hong-zhen, WU Bo

2007, 27(1): 33-36.

[Abstract](1573) [PDF 807KB](866)

Abstract:
The thermal conductive and electrically insulating silicone rubber was prepared using the methyl vinyl silicone rubber and heat conductive hybrid alumina powder with two different particle sizes.The examinations of effects of alumina filler content on the thermal conductivity,mechanical properties,curing behavior,coefficient of thermal expansion(CTE) and heat stability of the silicone rubber indicated that the thermal conductivity and heat stability increased with increasing the filler content,while CTE and mechanical properties declined;alumina has a slight influence on the curing reaction of silicone rubber.In addition,a novel type of electrical fiberglass reinforced composite silicone rubber with thermal conductivity of 0.92 W·(m·K)-1,good electrical insulation and mechanical properties,was developed based on the alumina filled silicone rubber.The developed composite silicone rubber is a kind of ideal thermal interfacial materials for heat dissipation of higher performance devices.

Experimental Studies of Property of Woven-Fiber Laminates Composite on Hygrothermal Environment

PAN Wen-ge, JIAO Gui-qiong, YANG Jie

2007, 27(1): 37-40.

[Abstract](1387) [PDF 1013KB](309)

Abstract:
Flexural strength and open-hole tensile strength of glass-fiber woven reinforcement epoxy laminates is investigated experimentally at room temperature and hygrothermal environment.The results of experiment indicated that flexural strength of specimens has size effect and linearly reduces along with thickness of specimens.Balanced moisture content of this composite is up to 2.2%,and property of epoxy-resin degrades during moisture absorption,the extent of which depends on specimen thickness.After composites obtain balanced moisture content,average flexural strength retention is 31.7%,and open hole tensile strength linearly increase by 4.2%/mm following to thickness of specimens,and average open hole tensile strength retention is 70.0% at 70℃ with 85% relative humidity.

Syergic Effect of Atomic Oxygen and Vacuum Ultraviolet on Organic Coatings Degradation

CHEN Rong-min, ZHANG Lei, YAN Chuan-wei

2007, 27(1): 41-45.

[Abstract](1374) [PDF 1085KB](364)

Abstract:
An investigation on AO/VUV combination was carried out to surfaces of epoxy resin and Siloxane.The studies show that AO is the dominant factor in AO/VUV combination.VUV have offered high energy photons to cut off the chemical bonds of organic polymer,mean while offering the reacting radicals for AO,which have accelerated the AO interaction with materials.Compared with the result of VUV irradiation,Siloxane with main chain of Si—O—Si has excellent properties to resistant to VUV irradiation and AO erosion.Especially,protective oxide film appears on the surface of the Siloxane after exposure to AO and AO/VUV.So it is greater potentiality to be exploited.atoms.

Interlacing Technique for New Carbon Fiber Lattice Materials

FAN Hua-lin, YANG Wei, FANG Dai-ning, ZHUANG Zhuo, CHEN Xiang-bao, XING Li-ying, LI Bin-tai, JIANG Shi-cai

2007, 27(1): 46-50.

[Abstract](1568) [PDF 893KB](687)

Abstract:
To get lattice materials with higher loading capacity than honeycombs and foams but much lighter,unit lattice cell structures were studied.Rules for stretching dominated structures must be satisfied and the aspect ratio of the lattice struts should be smaller than the critical value.A lattice structure reinforced by carbon fibers was designed.The three dimensional interlacing method was developed to manufacture sandwich structures with lattice cores.The mechanical behaviors of lattice sandwich structures were analyzed comparing with honeycombs and foams.It’s shown that lattice sandwich structures have advantages of higher specific strength and stiffness,integrally manufactured,and no debonding between the face sheets and the cores,which make them attractive for the use in aeronautic and astronautic structures.

Study on M40T-300 Carbon Fiber Reinforced Cyanate Hybrid Composites

REN Peng-gang, LIANG Guo-zheng

2007, 27(1): 51-56.

[Abstract](1504) [PDF 948KB](293)

Abstract:
Interply and intraply hybrid composites based on Bisphenol A Dicyanate ester(BADCy) and T300-M40 fiber were prepared by monofilament press moulding process.Mechanical properties(tensile,flexural and interlaminar shear) and SEM analysis of fracture surfaces of hybrid composites with different fiber content and fiber arrangement were investigated.It was found that the mechanical properties of intraply hybrid composites were mainly dependent on the fiber content.While the mechanical properties of interply hybrid composite mainly rely on the fiber arrangement.The hybrid composites with T300 laid on the outside layers possessed high flexural strength.When M40 was laid on the outside layer and T300 in the middle,the hybrid composite([(M40)x/(T300)y]S) would possess high flexural modulus and high interlaminar shear strength.

Characterization of Pyrocarbon

YU Shu, ZHANG Hong-bo, ZHANG Chuan-fu, LIAO Ji-qiao, DENG Yan-mei

2007, 27(1): 57-60.

[Abstract](1421) [PDF 1020KB](433)

Abstract:
The microstructures,extinction angles of different pyrocarbons are determined.The results show that the microstructures of pyrocarbons can be divided into rough lamina,smooth lamina,regeneration lamina and isotropy.The rough lamina has the high optical feathers,preferred orientation and the highest extinction angles between 16～21.

Nano-SiO₂/ BADCy Composites Prepared by Sol-gel Method

WANG Jun-long, LIANG Guo-zheng, ZHU Bao-ling

2007, 27(1): 61-64.

[Abstract](1506) [PDF 867KB](518)

Abstract:
Nano-SiO2 was synthesized though hydrolyzation-condensation of n-tetraethyl orthosilicate(TEOS) in organic solvent using sol-gel method.The synthesized nano-SiO2 was applied to modify dicyanate ester of bisphenol A(BADCy) resins and the SiO2/BADCy composites were fabricated by casting process.The morphology was investigated by transmission electron microscopy(TEM) and the mechanical properties of SiO2/ BADCy composites were estimated.The results indicate that the nano-SiO2 can dispersed well in the matrix when the size of nano-SiO2 is in the range of 20～50nm,the adhesion strength of nano-SiO2/ BADCy composites was improved.The addition of SiO2 can increase the impact strength and the flexural strength of cured BADCy,and the mechanical properties of composites were the best when the content of nano-SiO2 is 4%.

Investigation of Net-Shaped Pipe Processing for Catalytic Igniter

GAO Shan, CHENG Yi-fei

2007, 27(1): 65-69.

[Abstract](1533) [PDF 912KB](249)

Abstract:
The catalytic net-shaped pipe is the key component of the catalytic in the combustion tube of aero-engine.The effect of processing on the ignition properties of the catalytic net-shaped pipe has been studied and the plate surface morphology is analyzed in this paper.The influences of plating temperature,plating time,electricity density and hydrogenated disposal on the plate surface morphology have been investigated.The ignition property of specimens with fine-crystalline and the increment of the platting should be controlled by platting parameters: the plating time is 1～2h, plating temperature is 30～40℃ and hydrogenated disposal temperature is 500～700℃.

Video-Detecting and Image-Processing the Structure of Cr12 Steel and Hot Working Processes

TANG Gan-min, SHI Zhong-ke

2007, 27(1): 70-75.

[Abstract](1333) [PDF 1401KB](360)

Abstract:
The structure of Cr12 steel was evaluated by comparing to the standard plates under microscope.Such evaluation method is not precision enough for modern industrial requirements.In this paper,the video-detecting and image-processing techniques to carry out the inspection of the microstructure of Cr12 steel,was employed.Based on those results,a series of new hot working processing techniques was designed,i.e.,new forging and heat treatment processes.

Corrosion Fatigue of Die-Cast Magnesium Alloys

LIU Ma-bao, LEI Jun, GAO Yu-xia, ZHANG Ying-jie, QI Yanjie, SUO Jian-qin

2007, 27(1): 76-80.

[Abstract](1355) [PDF 921KB](330)

Abstract:
The fatigue properties of die-cast magnesium alloys AM50HP and AZ91HP were determined in ambient air and in 3.5% sodium chloride solution,respectively.It is found that fatigue cracks initiate from the casting pores within the specimen and near the surface in both environments depending on the relative pore size,and the S-N curves of both alloys are steeper in corrosive environment than in ambient air.Both die-cast magnesium alloys do not have endurance limits in 3.5% NaCl solution,whereas endurance limits could be detected in ambient air,which are about 90MPa and 100MPa for AZ91HP and AM50HP respectively.The die-cast magnesium alloy AM50HP shows a higher sensitivity to the action of 3.5% NaCl solution in comparison with AZ91HP,and the corrosion fatigue behaviour of both die-cast magnesium alloys correlates with their mechanochemical behaviour.The latter was studied by the polarization measurements of the dissolution rate of strained magnesium alloys.

2007 Vol. 27, No. 1