材料期刊网

MICROSCOPIC CORROSION STUDIES OF DUPLEX STAINLESS STEELS

C.Leygraf , J.Pan , M.Femenia

金属学报(英文版)

Electrochem,cal scanning tunneling microscopy and scanning electrochemical microscopy have been used for in situ monitoring of localized corrosion processes of different Duplex stainless steels (DSS) in acidic chloride solutions. The techniques allow imaging of local dissolution events with micrometer resolution, as opposed to conventional electrochemical techniques, which only give an overall view of the corrosion behavior. In addition, combined scanning Kelvin probe force microscopy and magnetic force microscopy were used for mapping the Volta potential variation over the surface of DSSs. A significant difference in Volta potential between the austenite and ferrite phases suggests galvanic interaction between the phases. A compositional gradient appears within 2 micrometers across the phase boundary, as seen with scanning Auger microscopy (SAM). In all, the studies suggest that higher alloyed DSS exhibit a more homogeneous dissolution behavior than lower alloyed DSS, due to higher and more similar corrosion resistance of the two phases, and enhanced resistance of the ferrite/austenite phase boundary regions.

关键词: duplex stainless steel , null , null

湿法纺丝Amid-CNT/PAN复合纤维的结构与性能

张海龙 , 靳玉伟 , 徐樑华

复合材料学报

通过溶液聚合得到胺化碳纳米管(Amid-CNT)/聚丙烯腈(PAN)复合溶液,采用湿法纺丝技术制备了Amid-CNT/PAN复合纤维.利用红外光谱、拉曼光谱、差示扫描量热仪、热失重仪和扫描电镜等方法分析Amid-CNT对PAN纤维结构的影响.结果表明:Amid-CNT与PAN大分子之间有很强的化学作用力;Amid-CNT在复合纤维中具有很高程度的取向,使PAN纤维中氰基的取向从1.61提高到了2.30;复合纤维在空气中的起始放热温度相对PAN纤维从212.30℃提前到206.01℃,反应放热量从3054 J/g降低到2346 J/g;复合纤维比PAN纤维的起始失重温度提前了3.7℃,在700℃时的剩余质量提高了13.5%;复合纤维的断面比PAN纤维具有更多的絮状结构.

关键词: 碳纳米管 , 聚丙烯腈 , 取向 , 湿法纺丝 , 复合纤维

Spin waves in a four-sublattice Heisenberg ferrimagnet or ferromagnet with different exchange constants (J(ab)=J(cd)not equal J(bc)=J(da))

Physical Review B

The Hamiltonian for a four-sublattice Heisenberg ferrimagnet or ferromagnet with different exchange constants (J(ab) = J(cd) not equal J(bc) = J(da)) was established. An extended Bogoliubov transformation was developed by solving an equation group, consisting of 20 equations and 20 unknowns. The procedure for solving the equation group was carried out by introducing a simple way of reducing the numbers of the equations and the unknowns. The spin-wave spectra in the present system have been determined by performing the standard Holstein-Primakoff transformation and the Bogoliubov one. It has been found that the spin-wave spectra of the present system depend on the exchange constants and that the degeneracy of the spin-wave spectra remains. The results for a special case (J(ab) = J(bc)) i.e., an antiferromagnet are discussed briefly. The spin-wave spectra of the four-sublattice Heisenberg antiferromagnet are found to be degenerative also and they are linear in k for small k.

关键词: model

PAN基炭纤维经济规模分析

夏春霞 , 闫亚明 , 邓蜀平 , 白光君 , 蒋云峰 , 宋惠森 , 王钰

新型炭材料 doi:10.3969/j.issn.1007-8827.2001.04.013

聚丙烯腈(Polyacrylonitrile缩写为PAN)基炭纤维市场需求旺盛,但由于我国PAN基炭纤维生产企业规模小、产品性能低,产品占领不了市场,企业效益欠佳.通过经济规模方法的分析,就国内现有技术状况和两个样本生产线,用工程技术法对PAN基炭纤维的经济规模进行分析,为我国炭纤维产业化发展提供参考.分析表明,国内PAN基炭纤维经济规模的起点为200t/a～275t/a.

关键词: PAN基炭纤维 , 经济规模 , 工程技术法

PAN/PI复合纤维的结构

李常清 , 袁姗 , 罗荣 , 郭雅明 , 徐樑华

高分子材料科学与工程

将聚酰亚胺(PI)加入丙烯腈-衣康酸-二甲基亚砜体系进行聚丙烯腈(PAN)溶液聚合,湿法纺丝制备了PAN/PI复合纤维.利用流变仪、红外光谱、X射线衍射仪、扫描电镜、差示扫描量热仪等研究了PAN/PI溶液的性质和复合纤维的结构特点.研究发现,加入PI后,聚合物溶液的稳态黏度降低,弹性和粘性模量在低剪切速率区降低;PI作为成核剂,引起初生纤维结晶度增大、晶粒尺寸减小;PI与PAN的溶解性差异导致凝固加快,初生纤维形成皮芯结构;引起原丝体密度减小.PAN/PI纤维在N2下放热量较少,在空气中由于结构疏松放热量较大.

关键词: 聚丙烯腈纤维 , 聚酰亚胺 , 原液改性 , 晶态结构

高分子专利j

高分子材料科学与工程

专利名称：具有改进的抗冲击性、尺寸稳定性和吹塑成形性能的热塑性ABS树脂组合物专利申请号：CN200580040787．3公开号：CN101065413申请日：2005．03．31公开日：2007．10．31申请人j韩国第一毛织株式会社根据本发明的热塑性ABS树脂组合物包括：（a）2

关键词: 专利名称 , 高分子 , 树脂组合物 , 专利申请号 , 尺寸稳定性 , 抗冲击性 , 株式会社 , 成形性能

PAN初生纤维拉伸性能试验研究

谢奔 , 朱波 , 王政 , 井敏 , 王进军 , 张春雷 , 吴益民

功能材料

为了提高聚丙烯腈（PAN）初生纤维的可拉伸性能,将溶液纺丝得到的初生纤维进行不同时间的恒温干燥处理,研究其拉伸性能随干燥时间的变化规律。结果表明,干燥处理可以大幅度提升PAN初生纤维的力学性能,其拉伸强力可达10.3cN,断裂伸长可达263.5%;随着干燥时间的延长,纤维的可拉伸性能增强,经过10h干燥后的初生纤维具有最佳可牵伸性能;而拉伸速率的提高可以有效促进未干燥初生纤维的拉伸变形,而对干燥处理后纤维的拉伸性能的影响不大。用SEM观察纤维断裂形貌发现,PAN纤维的致密性随牵伸比的增加而提高。

关键词: 聚丙烯腈 , 初生纤维 , 干燥 , 拉伸性能 , 断裂形貌

PAN废丝接枝聚乙二醇相变材料的制备

郭静 , 相恒学 , 巩学勇 , 张银鹏

高分子材料科学与工程

研究了腈纶(PAN)废丝碱催化水解工艺,用傅立叶红外光谱表征了PAN废丝水解产物的结构.采用正交实验法研究了PAN废丝接枝聚乙二醉制备工艺,用差示扫描童热仪研究了聚乙二醉(PEG)分子量、催化剂用量、接枝反应温度等因素对纶水解产物和聚乙二醉的接枝产物(HPAN-g-PEG)相变性能的影响,用偏光显微镜考察了PEG,HPAN-g-PEG的晶体结构,通过测定步冷曲线观察了接枝产物的保温性能.结果表明,该接枝材料表现出固一固相转变特性,潜热储存能力达105 J/g,并呈现出良好的保温性能.

关键词: 腈纶废丝 , 聚乙二醇 , 接枝 , 相变材料

Effect of carbonization atmosphere on the structure changes of PAN carbon membranes

Journal of Porous Materials

PAN carbon membranes were prepared by carbonizing the initial PAN membranes in vacuum and Ar at different temperatures. FTIR, Raman and XRD were applied to study the influence of carbonization atmosphere on the structure changes of PAN carbon membranes. The variations in adsorption peaks of FTIR, the intensity, position and FWHM of the Raman peaks, and microcrystallite parameters from XRD (e.g., d(002), Lc and La) are correlated with the structure change of PAN carbon membranes. Analyses results reveal that vacuum atmosphere can produce PAN carbon membranes with higher order degree than those in Ar atmosphere, although the structures of PAN carbon membranes prepared in the two atmospheres are both amorphous. In addition, vacuum atmosphere can significantly accelerate the degradation reaction of PAN membranes and favors the preparation of carbon membranes with smaller pore size.

关键词: Carbonization;Atmosphere;Carbon membranes;PAN;Structure;molecular-sieve membranes;gas separation membranes;phenolic resin;pyrolysis conditions;thermal-degradation;polyimide;polyacrylonitrile;deposition;graphite;kapton

Study on the Relationship Between J-Integral and COD

Y.G. Cao , X.Y. Sun

金属学报(英文版)

J-integral and crack opening displacement δ(COD) were important parameters for characterization of fractures in engineering materials. The relationship between J-integral and COD has been investigated for a long time and was enerally represented as J = m σyδ, where σy is the yield strength and m is a function of specimen geometry and material properties. To determine the value of m, extensive studies and experiments have been performed. The method that used the fracture-surface topography analysis (FRASTA) for determining J-integral from fracture surfaces of materials was introduced. On the basis of the relationship between COD and fracture surface average profile, the relationship between J-integral and COD was deduced and compared with the generally used equation. The method was experimentally confirmed to be able to provide a new way to determine the relationship between J-integral and COD.

关键词: FRASTA , null , null