i力
,
刘聪
,
庄春艳
,
孟德芹
,
方杰
功能材料
摘要：制备纳米硫酸钙（CaSO4）颗粒的关键在于采用适宜的制备工艺条件配制反相微乳液．使CaSO4晶体在理想的环境中生长。采用AOT、OP-10复合表面活性剂／环己烷／正戊醇／水溶液反相微乳液反应体系，在水与表面活性剂的摩尔比（水表比）60=20、反应物浓度n（[Ca^2＋]）／n（SO^2＋]）-0．125mol／L、陈化时间t=10min的条件下，制备出了形貌均一。平均粒径为70nto的球形CaSO4颗粒。用扫描电子显微镜（SEM）对产物形貌和大小进行了表征。实验分析了水表比ω、反应物浓度n（[Ca^2＋]）／n（[SO2/4]）值、陈化时间t等因素对纳米CaSO4颗粒粒径的影响。
关键词:
反相微乳液
,
纳米CaSO4
,
球形纳米颗粒
,
表面活性剂
Zhaojun LIN
,
Zhanguo WANG
,
Wei CHEN and Lanying LIN(Lab. of Sendconductor Materials Science
,
Institute of Semiconductors
,
Chinese Academy of Sciences
,
Beijing 100083
,
China)
材料科学技术（英）
Samples have been prepared at different temperatures by loading I2 molecules into the cages of zeolite 5A, and the measurements of the absorption spectra have been carried out for the prepared samples. It is shown that I2 molecular clusters are formed in the cages of zeolite 5A,and it is also found that moIecuIar clusters which are bonded with intermoIecuIar forces have an important feature, namely, the intermolecular distance in molecular clusters can be changed on different preparing conditions and the blue shift of absorption edges can not be as the criterion of forming molecular clusters.
关键词:
Materials Research Innovations
Polycrystalline copper (I) oxide films were deposited on stainless steel substrate by galvanostatic electrodeposition method and were characterized by Xray diffraction and scanning electron microscopy. The effect of bath temperature, bath pH and current density on the compositon, grain size, surface texture and surface morphology of the electrodeposited films were investigated. The films deposited at low bath pH (less than or equal to 7) consisted of copper (I) oxide and metallic copper; while the films deposited at bath pH between 8 and 12 and bath temperature of 60 degrees C were pure copper (I) oxide. The preferred orientation of the copper (I) oxide films depended on the relative growth rate of (111) and (200) faces and could be controlled by adjusting the bath pH and/or the cathodic current density. (100)-oriented copper (1) oxide films could be deposited at pH=9 and current densities in the range of 0.25-1 mA/cm(2) while (111)-oriented films could be prepared at pH=12 or at pH=9 using the current densities between 1.5-2.5 mA/cm(2). Computer simulated crystallite shapes showed that the crystal shape changed from octahedral for (100)-oriented film to trucated pyramids and cubs for (111)-oriented film. And they were approved by scanning electron microscopy.
关键词:
copper(I) oxide;electrochemical deposition;thin films;microstructure;electrochemical synthesis;thin-films
Fatigue & Fracture of Engineering Materials & Structures
Nominal mode I and mixed mode I/II fatigue tests were carried out using the intermetallic compound Ni3Al(CrB) in the form of single crystal specimens. The effects of crystal orientation and load mode on fatigue crack initiation and growth were studied. The fracture surfaces of the single crystals were characterized by a cleavage-like appearance and cracking occurred either on a single {111} plane or on multiple {111} planes irrespective of whether mode I or mixed mode I/II loadings were applied. It was found that the crack initiation and growth behaviour are dependent on both crystal orientation and applied loading mode. The cracking behaviour predicted by three mixed mode fracture criteria (MTS, SED and G criteria) in polycrystalline materials under mixed mode loading can be understood from the present results on single crystals.
关键词:
fatigue cracking;mixed mode loading;crystallographic orientation;resolved shear stress;Ni3Al(CrB) single crystals;growth;alloy
刘文辉
,
杨迅雷
,
张平
,
陈宇强
,
唐思文
材料热处理学报
采用测力仪,表面粗糙度仪、三维表面轮廓仪、透射电镜等对T6和T6I4态7055铝合金的切削加工性能进行研究,分析了时效工艺对7055铝合金加工性能的影响.结果表明,由于T6I4态7055铝合金的析出更加细小密集,T6I4态7055铝合金硬度和强度高于T6态,T6I4态切削表层显微硬度高于T6态;在相同切削条件下,T6I4态的切削力比T6态的切削力小,T6I4态表面粗糙度较T6态低,具有较好的加工质量;在切削热的影响下T6I4态比T6态更易发生回归,因此T6I4态7055铝合金的切削力小于T6态.
关键词:
7055铝合金
,
加工性能
,
时效处理
,
粗糙度
郑锐
,
席生岐
,
刘新宽
,
周敬恩
材料导报
机械力活化由于能大幅度地降低AlN粉末反应合成温度、缩短反应时间,是制备AlN粉末经济有效的实用化途径之一.简要介绍了机械力活化合成AlN粉末的反应机制,并分析了机械力活化对AlN粉末合成过程的促进作用.
关键词:
机械力活化
,
团聚
,
机械力化学效应
吴双成
,
储荣邦
电镀与涂饰
介绍了人体免疫力与镍过敏的基本知识及治疗方法.指出过分提高免疫力反而会加重镍过敏反应,反对在治疗镍过敏中滥用激素和自行购用激素,提醒切忌滥用药物或轻信打着提高免疫力旗号的广告.
关键词:
免疫力
,
镍过敏
,
镍痒症
,
激素
,
首饰病
吴崇试
,
潘奕
原子核物理评论
doi:10.3969/j.issn.1007-4627.2002.01.001
系统分析了A≈170区正常形变带[521]1/2-中的ΔI=1颤动现象. 根据旋称伙伴带的跃迁能量提取Δ2 Eγ (I)=[Eγ(I)+Eγ(I-2)]/2-Eγ(I-1)值, 表现出旋称相关的规则上下颤动. 其颤动幅度在低自旋端约为50 keV, 而后随自旋而增大或减小, 大体呈抛物线形. 利用改进的ab公式, 提取了相关的脱耦合系数. 运用Nilsson波函数, 探讨了原子核集体哈密顿量中高阶微扰项的可能形式.
关键词:
正常形变带
,
旋称伙伴带
,
ΔI = 1颤动
,
脱耦合效应
,
改进的ab拟合
葛庆麟
,
施天生
,
陈廷国
,
陈源
,
吴自良
金属学报
四种不同Ti浓度的Fe-Ti合金,加氮到N/Ti>1之后,发现有两个内耗峰,并且随氮浓度之增加而同时升高。20℃处的峰是氮的Snoek峰,160℃附近的是s-i峰。s-i峰的峰高和Ti浓度成线性关系,表明起峰的反应只涉及孤立的Ti原子,与Ti-Ti原子对或杂质原子团都无关系。 提出了产生s-i峰的二种缺陷中心——Ti-N对缺陷和N-Ti-N仨缺陷——的模型(图7)。氮占Ti位就构成对缺陷,其中的Ti,N原子亲和力很强,只要合金中尚存有自由Ti原子,就不可能存有自由氮原子,因此N/Ti≤1以下,不会出现Snoek峰或s-i峰。N/Ti>1之后,多余氮原子要在对缺陷的OⅡ位和T_3位之间以约1:10的比例进行分配,直到绝大部分的对缺陷转化为仨缺陷。N/Ti(?)2以后,几乎所有的多余氮都进入了仨缺陷的OⅡ位,此时s-i峰的弛豫强度突然增加10倍。 淬火时冻结在α-Fe基体中的过饱和氮、要扩散到OⅡ位(扩散距离～10(?)),以期达到室温下的再分配,因此引起Snoek峰室温下的迅速衰减。s-i峰的形状,只取决于多余氮的浓度,与淬火温度、冷却速度无关。
关键词:
