N.C.Si and S.C.Sun Departmentof Materials Engineering
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Jiangsu University of Science and Technology
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Zhenjiang 212013
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China
金属学报(英文版)
With thehelpofquantitative metallograph ,tensiletest,electron probeandscan electron mi croscope,theinfluencesof mixture rareearth ( RE) on the grain size, dynamics of grain growth and mechanicalpropertiesof CuZnAlshape memoryalloys wereinvestigated . Theex perimentalresultsshowsthat REcanrefinegrainsgreatly,improvethe mechanicalpropertiesremarkably andchangethetensilefracturefrom brittletypebordered grainstoplastictypeinthecondition of maintainingshape memory properties. Moreover microstructuresrevealthatREwhich accumulates on the grain boundariescan restrain grains’growing. In addition, the mechanismsofrefininggrainsizeandimproving mechanicalpropertiesarealsodiscussed.
关键词:
rareearth
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null
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null
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null
N.C.Si and S.C.Sun Departmentof Materials Engineering
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Jiangsu University of Science and Technology
,
Zhenjiang 212013
,
China
金属学报(英文版)
Theinfluencesofthermalcycleson propertiesof CuZnAlshape memory alloysunder differentheatingtemperatures, pre deformation amountεand addition amountofcomplex rareearthmixture wereresearched with X ray diffraction and electron microscope. Theresultsindicate thatthermalcyclescanincreasethetransformationtemperatureofthealloysby 5～6℃.In creasingthe pre deformation amount will decrease the necessary cycle times for stabletwo -wayshape memory property. Howevertheshaperecovery rateofthealloy willdecreaseasthepre deformation amountexceeds3 6 % . Theshape memory propertyofthealloy willchangeinsignificantlyiftheaddition amountofrareearthislessthan 0 10 % . Butthealloys with outrareearth willhave worseshape memory property afterthermalcyclesreach 1800 times.
关键词:
thermalcycle
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null
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null
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null
邱建辉
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中村谕
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川越诚
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森田干郎
无机材料学报
本文主要就Si3N4／S45C连接体在插入软金属及附加热循环的情况下，使残余应力发生变化，而讨论其对抗弯强度的影响．其结果为：（1）Si3N4表面边缘处的拉伸应力是影响连接体强度的主要原因．（2）抗弯强度和残余应力具有σ0＝-1．63σ＋658．1的线性关系．（2）周期性热循环对连接体的残余应力及抗弯强度有较大的影响；即发生加工硬化等使残余应力上升，产生裂纹等导致强度下降．
关键词:
陶瓷
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null
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null
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null
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null
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null
卢国锋
硅酸盐通报
本研究采用CVI方法制备出了以Si-C-N陶瓷为基体以热解碳为界面的碳纤维增强陶瓷基复合材料(C/PyC/Si-C-N).用热膨胀仪和激光导热仪分别测试了C/PyC/Si-C-N的热膨胀性能和热扩散性能.研究结果表明:在25～1200℃范围内,C/PyC/Si-C-N复合材料的平均热膨胀系数为0.638×106 K-1;而热扩散率则随温度的升高而减小,并与温度呈一种指数关系,常温下的热扩散率约为0.00925 cm2·s-1.
关键词:
复合材料
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热膨胀
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热扩散
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Si-C-N陶瓷
Andrej Atrens
材料科学技术（英文）
Corrosion research by Atrens and co-workers has made significant contributions to the understanding of the service performance of engineering materials. This includes: (1) elucidated corrosion mechanisms of Mg alloys, stainless steels and Cu alloys, (2) developed an improved understanding of passivity in stainless steels and binary alloys such as Fe-Cr, Ni-Cr, Co-Cr, Fe-Ti, and Fe-Si, (3) developed an improved understanding of the melt spinning of Cu alloys, and (4) elucidated mechanisms of environment assisted fracture (EAF) of steels and Zr alloys. This paper summarises contributions in the following: (1) intergranular stress corrosion cracking of pipeline steels, (2) atmospheric corrosion and patination of Cu, (3) corrosion of Mg alloys, and (4) transgranular stress corrosion cracking of rock bolts.
关键词:
Stress corrosion cracking
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null
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null
焦桓
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周万城
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罗发
复合材料学报
doi:10.3321/j.issn:1000-3851.2003.04.008
研究了Si/C/N纳米晶须的制备、组成和微波介电性能.利用CVD法制备了化学组成一定的纳米Si/C/N晶须,XRD研究发现晶须的物相主要为β-SiC.热重分析表明该晶须在700 ℃以上开始氧化,具有较好的抗氧化性.测定了Si/C/N晶须的复介电常数与作用频率的关系,并计算了介电损耗角正切.依据介电性能数据,分别设计了单层和双层吸波材料,对所设计材料的吸波性能进行了计算.对Si/C/N纳米晶须的吸波机理进行了初步的探讨.
关键词:
Si/C/N
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抗氧化性
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复介电常数
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吸波材料
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吸波机理
卢国锋
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乔生儒
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焦更生
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徐浩龙
材料工程
doi:10.3969/j.issn.1001-4381.2011.09.016
本研究制备出了以莫来石为界面层的炭纤维增强Si-C-N陶瓷基复合材料(C/Mullite/Si-C-N).使用三点弯曲法研究了复合材料在室温、1300℃和1600℃时的弯曲断裂行为,利用扫描电镜(SEM)和透射电镜(TEM)观察了复合材料的组织和弯曲断口形貌.结果表明:在室温和1300℃时,C/Mullite/Si-C-N复合材料的断口呈现出明显的脆性断裂特征；而在1600℃时,则呈现出韧性断裂特征.1300℃时的弯曲强度高于室温强度,模量则与室温下的基本相等.1600℃时,复合材料的弯曲强度和模量都明显下降.与具有热解炭界面层的C/Si-C-N复合材料相比,采用莫来石界面后,C/Si-C-N复合材料的强度明显下降.
关键词:
弯曲强度
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C/Si-C-N复合材料
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莫来石
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界面层
Ceramics International
The dispersion behavior of laser synthesized Si-C-N nanopowders in 15 pure organic liquids has been studied through particle size analysis and sedimentation test. The Van der Waals potential energy of interaction between the particles and organic liquid molecules, i.e. V-A, is estimated. The results are correlated with the surface composition of powders and the chemical and physical characteristics of the organic liquids. Poor dispersions are found in nonpolar hydrocarbons, whereas in polar organic liquids, the dispersity and stability depend on the functional group, dielectric constant and carbochain length of the organic liquids. After some of the organic groups on the powder surfaces are eliminated by heat-treatment, the dispersity is decreased. The V-A Of the dispersions can be adequately used to predicate the stability of the nonpolar hydrocarbon dispersions. However, in polar organic liquids, the contribution coming from the electric double layers and solvation layers should also be considered. (C) 2001 Elsevier Science Ltd and Techna S.r.l. All rights reserved.
关键词:
suspensions;surfaces;Si-C-N;ceramic materials;silicon;stability;powders;forces
刘晓魁
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周万城
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罗发
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朱冬梅
稀有金属材料与工程
采用化学气相沉积方法,在1200℃～1600℃温度范围内,于不同的NH3流量条件下,合成了Si/C/N纳米粉体,研究了粉体的制备工艺、成分、相组成与其微波介电性能之间的关系.结果表明:NH3流量增加,粉体中N含量升高,随着合成温度的提高,粉体的晶化程度增强,主要为β-SiC相.在SiC晶格中固溶有N原子,且N原子的固溶量随合成温度升高而减少.Si/C/N纳米粉体中SiC微晶含量,以及SiC微晶中固溶的N原子浓度对粉体的ε',ε(")和损耗因子tgδ(ε"/ε')起着重要作用.N原子固溶所导致的极化驰豫损耗和漏导损耗是Si/C/N纳米粉体具有吸波性能的主要机理.
关键词:
化学气相沉积
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Si/C/N纳米粉体
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微波介电性能
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吸波机理
Journal of the American Ceramic Society
The reciprocating sliding friction and wear properties of two novel materials of Zr(2)[Al(Si)](4)C(5) ceramic and Zr(2)[Al(Si)](4)C(5)-30 vol% SiC composite against Si(3)N(4) ball were investigated. The sliding friction process of Zr(2)[Al(Si)](4)C(5) against Si(3)N(4) experiences two different stages under constant normal load and involves friction and wear mechanism transition. The static coefficient of friction increases with an increasing normal load. The friction force mainly comes from the interfacial shear between Si(3)N(4) ball and Zr(2)[Al(Si)](4)C(5), which changes with varied sliding distances and normal loads. In contrast, the friction process of the composite experiences one stage and the friction coefficient is not related to the test durations and normal loads. The friction force between Zr(2)[Al(Si)](4)C(5)-30 vol% SiC composite and Si(3)N(4) is mainly from the plough between SiC particles and Si(3)N(4) ball, which appears not to be influenced significantly by different normal load and sliding distance. In addition, microfracture induced mechanical wear is the rate-control wear mechanism in both Zr(2)[Al(Si)](4)C(5) and Zr(2)[Al(Si)](4)C(5)-30 vol% SiC composite. Adding SiC improves the wear resistance of the single-phase material, because the second phase bears normal load and slows down material removal.
关键词:
thermoelectric properties;crystal-structure;single-crystals;bulk;zr2al3c4;oxidation;carbide;carbon;temperatures;hafnium;ti3sic2
