Z.T.Yu1
,
2)
,
L.Zhou1)
,
2)
,
J.Deng2) and H.C.Gu1) 1) College of MaterialScience and Engineering
,
Xi’an Jiaotong University
,
Xi’an 710049
,
China 2) NorthwestInstitute for Nonferrous Metal Research
,
P. O.Box 51
,
Xi’an 710016
,
China
金属学报(英文版)
Thelow cyclefatigue( LCF) propertiesof Ti 2 Al 2 5 Zralloytubeand rod specimens weredetermined at R.T. Thestress～strain curve equation under cyclic and monotonicloading andtherelation of totalstrain vsfatiguelife of Ti 2 Al 2 5Zr alloy were established. Theeffectsofstrain ratio R,strain amplitudeεaandspecimenshapeoncyclicdeformingbehavior and fatigueproperties were analyzed . The fatiguefracture features were also discussed ac cording as SEMobservation. The resultsshow , at R = 0 1 ,thecyclicstress straincurvesof Ti 2 Al 2 5Zr alloytube and rodspecimensappear ascyclesoftening. When Ris 1 ,itsrodspecimen behavesascyclesoftening;atlow εavalues; whereasitbehavesascyclehardeningat high εa values. The LCFproperties determined withtubespecimen islower apparentlythanthat withrod one. Thereare muchirregularrecrystallineconvexin LCFfracturesof Ti 2 Al 2 5Zr alloytubeand rodspecimens, and muchsecondarycracks,fatiguestriationsand holes alsoexistamongthem .
关键词:
Ti 2 Al 2 5 Zralloy
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null
,
null
罗丰华
,
周美玲
,
左铁镛
稀有金属材料与工程
研究了应用于6T51发射管中的碳化La2O3-Mo阴极的制作工艺及电子发射性能.在碳化钍钨阴极的实践基础上,实现了La2O3-Mo阴极的碳化以及碳化La2O3-Mo阴极6T51管的去气和阴极激活.对比碳化钍钨阴极,分析了碳化La2O3-Mo阴极6T51管的发射能力,认为目前碳化La2O3-Mo阴极研究的发射最高水平只达到纯钨阴极的下限值,还不具备取代碳化Th-W阴极的条件.由于碳化Th-W阴极6T51管设计时所选取的阴极发射能力富余量相当大,经过严格的去气、老练处理,碳化La2O3-Mo阴极基本上满足6T51测试的要求,但其发射稳定性不好,发射寿命也不容易掌握.论述了La元素消耗或碳化层消耗是两个影响碳化La2O3-Mo阴极发射稳定性的因素.
关键词:
稀土钼
,
电子管
,
阴极
Solid State Communications
Considering the image potential, we calculate the binding energies of a shallow donor impurity placed on the centre of a quantum box using the variational approach. The results we have obtained show that there is a great difference of the effects of image potential between the cases including impurity ion image potential and including the image potentials of impurity ion and electron simultaneously. The results also show that the image potential is important, especially when the dimensions of quantum box become small.
关键词:
well;gaas-ga1-xalxas;states
王雪俊
,
夏海平
材料导报
制备了χNb2O5-(10-χ)La2O3-60P2O5-10Na2O-19BaO-Eu2O3(以mol%记χ=9、7、5)的玻璃,测定了玻璃的吸收光谱、发射光谱、激发光谱、声子边带谱和差热分析曲线.从发射光谱出发获得了Eu3+光学跃迁的J-O参数Ω2、Ω4,并计算了Eu3+离子5DO→7FJ(J=1,2,4)的自发辐射跃迁几率A以及受激发射截面σp.结果显示,随着La2O3的增加和Nb2O5的减少,玻璃样品的热稳定性降低,强度参数Ω2减小,表明材料的对称性提高,共价性减弱,Eu-O键强减弱;随着La2O3的增加,电-声子偶合减弱,受激发射截面σp减小.
关键词:
光学材料
,
Eu3+离子掺杂铌镧玻璃
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光谱性质
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J-O理论
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强度参数
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受激发射截面
L. H. Lang
,
D. C. Kang
,
S. H. Zhang
,
Z. R. Wang
,
S. J. Yuan
,
K. B. Nielsen and J. Dancket 1) Department of Materials Engineering
,
Harbin Institute of Technology
,
Harbin 150001
,
China 2) Aalberg University
,
Denmark
金属学报(英文版)
In this paper, the forming features of tapered rectangular box during hydrodynamic deep drawing are studied by means of FEM.The effect rules of square blank corner corner amount on body wrinkling are recognized and corresponding methods are discussed. At last, the results of FEM are verified by experi- ment.
关键词:
sheet metal forming
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null
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null
Qunqiang FU
材料科学技术（英文）
At first, a series of finite element method (FEM) simulation tests were used to find the critical forming conditions of hot-galvanized sheet steel during the rectangular box drawing processing when constant blank holder forces were applied. According the test results, the reasonable alteration scope of initial variable blank holder force (VBHF) was as 1.9~2.3 T. Then, based on the test productions of blank holder force, 12 typical VBHF curves were applied to perform the simulation tests by the simulation software of DYNAFORM. The simulation test results showed that VBHF had great effects on drawing formability of hot-galvanized sheet steel during the rectangular box drawing. However, the different VBHF curves were applied to control the whole drawing and it would get great different effects. At the same tine, the VBHF had great effects on the maximum thick thinning ratio, but had little effect on the maximum thick incrassation ratio. So, reasonable application of the VBHF would greatly decrease the fractures. When the VBHF profile is taken as curve L, the best effect of drawing formability could be obtained. When curve I is used, contrary effect could be gotten. The other types of curves would cause effects between above two types of VBHF curves. Finally, the actual tests were applied to check the validity of the FEM simulation tests. The results show that the FEM simulation tests are good ways for predicting and optimizing the VBHF.
关键词:
Drawing process
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变压边力
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热镀锌钢板
Journal of Alloys and Compounds
The subsolidus phase relations in the system La2O3-B2O3-P2O5 were investigated. The system can be divided into 12 three-phase regions. There are nine binary compounds and one ternary compound in this system. The ternary compound La7O6(BO3)(PO4)(2) has a monoclinic structure, space groups P2(1)/n, with lattice constants a = 7.0172 Angstrom, b = 17.9125 Angstrom, c = 12.6500 Angstrom, beta = 97.516 degrees, V = 1576.39 Angstrom(3), and Z = 4.
关键词:
La2O3-B-3-B2O3-P2O5 system;phase relations;ternary compounds
陈玮
,
姚长江
,
尹周澜
,
刘新红
耐火材料
doi:10.3969/j.issn.1001-1935.2008.04.009
分别对反应前后的p-Al2O3进行XRD及SEM分析,确定反应前后Al2O3的物相及显微结构变化;测定加入添加剂前后浆体温度与时间的关系,从而确定添加剂对p-Al2O3水化速度的影响;测定加入添加剂前后浆体的黏度变化,从而测定出添加剂对p-Al2O3水化过程的影响.结果表明:1)p-Al2O3属于无定形态;2)在没有添加剂的情况下,p-Al2O3的水化速率很快,同时释放出大量热量,水化产物主要是一水软铝石、三水铝石和拜耳石;3)加入碳酸钠及六偏磷酸钠的混合物为添加剂后,p-Al2O3的水化速率显著降低,释放出的热量显著降低,水化产物主要是一水软铝石.
关键词:
p - 氧化铝
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水化硬化
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不定形耐火材料
,
结合剂
Yan GAO
,
Zhenjia WANG
,
Quanyou MA
,
Ge TANG
,
Ji LIANG
材料科学技术（英文）
Epoxy resin modified by nanometric γ-alumina or multi-walled carbon nanotubes (MCNTs) was prepared with solution mixing method, and the wear resistance of the composite was studied. The results show that when an optimum amount of nanometric alumina or MCNTs is filled in epikote51 (E51), the wear resistance of the composite will increase. When 8 wt pct nanometric γ-alumina is filled in E51, the wear resistance of the composite increases to 230%. When 10% MCNTs is filled in E51, the wear resistance of the composite increases to 226%. When nanometric alumina is filled in, the wear resistance of modified epikote51 will increase as the cure temperature is heightened.
关键词:
Epoxy resin
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null
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null
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null
