Z Zhang
,
ZH Tu
,
L.F. Li
,
L.Z. Zhaoand D. Jin (Cryogenic Laboratory Chinese Acaderw of Sciences
,
Beijing 100080
,
China )H.J Lu (Beijing Institute of Aerospace Materials and Technology
,
Beijing 100076
,
China)
金属学报(英文版)
Low temperature may greatly affect the mechanical properties of materials. Some in-teresting mechanical phenomena were detected at very low temperature. In this study,a multi-sample tensile installation was designed to study the plastic deformation be-havior for Ti-5Al-2.5Sn extra-low-interstitial (ELI) alloy at liquid helium temperature.The special geometrical instability phenomena in low temperature, serrated deforma-tion and multi necking, was studied in detail in this project. Slip and twinning were determined in the process of plastic fiow by SEM/TEM analysis. Efficts of temper-ature and sequential straining on load drops in tensile stress-strain curves were also studied. Optical measurement method was used to gauge the geometrical characteristic of multi-necking specimens. The sensitivity of partial thermoplastic deformation and the equivalency of low tempemture with high velocity of this material were studied by using micro-mechanics analysis.The criterion of geometrical instability has been discussed. A computer simulation of the low temperature instability of plastic fiow in Ti-5Al-2.5Sn ELI alloy has been carried out. A computer model has been established which links the hot dtffusion and the plastic fiow of hcp alloys under assumption that the tempemture is homogeneous within the specimen and that the heat exchange with the thermal bath is the control-ling step in the heat release. The computer simulation of the deformation curves as a function of several mechanincal, geometrical and thermal parameters provides a re-alistic description of the experiments. The experimental data available are discnssed in the light of the computer simulation model.
关键词:
mechanical property
,
null
,
null
B.W. Wang
,
H. Shen
金属学报(英文版)
Ni-Cr System solar selective thin solid films were prepared by d.c. magnetron reactivesputtering under the atmosphere of O2 and N2. Ni-Cr alloy was chosen as targetmaterial and copper sheets as substrate. Using SEM, Spectrophotometer and Talystepto analyze the relations between the selective characteristic and the structure, theformation and the thickness of the thin films. The aim is to obtain good solar selectivethin films with high absorptance and low emittance, which is applied to flat plate solarheat collectors.
关键词:
solar selective thin film
,
null
,
null
,
null
A.Akhbarizadeh M A Golozar A Shafeie M Kholghy
钢铁研究学报(英文版)
The effects of the prior austenite grain size in deep cryogenic treatment on the hardness, the structural change and the wear resistance of D6 tool steel were investigated. The wear resistance of the cryogenically treated samples was determined using the pin-on-disk wear machine. The microstructural characteristics and phases present in heat-treated samples were determined bye use of SEM and XRD techniques. The results showed that the retained austenite is completely transformed to martensite during the cryogenic treatment. Besides, there is an optimum grain size in which the maximum wear resistance and hardness are obtained.
关键词:
deep cryogenic treatment;D6;austenizing time;wear;heat treatment
王华林
,
方大庆
,
史铁钧
,
翟林峰
高分子材料科学与工程
聚D,L-乳酸(PDLLA)的合成方法主要有直接法和间接法两种.间接法合成PDLLA的关键在于中间体D,L-丙交酯(DLLA)的制备.文中以D,L-乳酸为原料,在催化剂辛酸亚锡(ZnOct2)的作用下,合成DLLA.研究温度、压力、时间等因素对DLLA产率的影响,利用DSC、XRD、IR等分析测试技术对DLLA的性能和结构进行相关的测试和表征.研究结果表明,在反应体系中加入乙二醇作为稀释剂,能降低DLLA的馏出温度,避免了DLLA在蒸馏过程中产生炭化现象,并使DLLA的平均产率由36.8%提高至51.3%.
关键词:
聚D,L-乳酸
,
D,L-丙交酯
,
合成
王其坤
,
胡海峰
,
陈朝辉
,
张玉娣
,
罗征
稀有金属材料与工程
针对2D C/SiC复合材料存在碳布层间缺乏纤维增强,层间结合较差的问题,提出通过Z-向穿刺工艺提高碳布层间结合,克服材料使用时可靠性不高的问题,并比较了穿刺工艺对复合材料微观结构和力学性能的影响.结果表明,通过Z-向穿刺工艺制得试样2D C/SiC-Z_(pin)的弯曲强度、弯曲模量和剪切强度分别为247.8 MPa、37.8 GPa和32.1 MPa,而未穿刺试样2D C/SiC的弯曲强度、弯曲模量和剪切强度分别只有219.3 MPa、34.4 GPa和23.3 MPa,由此可见,采用Z-向穿刺工艺能明显提高复合材料的力学性能.微观结构分析认为,试样力学性能提高的根本原因在于采用Z-向穿刺纤维加强了碳布层间结合,使材料具有较好的整体性,克服了复合材料层间结合较弱对力学性能带来的不利影响.
关键词:
2D
,
C/SiC
,
Z-向穿刺
,
微观结构
,
力学性能
钢铁
近日,集团邯钢公司西区冷轧厂1号镀锌线成功生产出9卷主要应用于汽车面板及高档家电外板的IF钢DX56D＋Z、共70多t,产品的屈服强度、抗拉强度、伸长率和表面质量指标均达到客户要求,为批量生产打下了坚实基础。
关键词:
批量生产
,
IF钢
,
冷轧厂
,
邯钢
,
汽车面板
,
屈服强度
,
抗拉强度
,
客户要求
叶龙海
,
邓琼
,
汤忠斌
复合材料学报
采用Hopkinson压杆试验装置,对2D-C/SiC复合材料进行了低温条件下的Z向动态压缩性能试验研究,低温条件通过控制酒精和液氮的配比系数得到,通过改变波形整形器几何尺寸的方法来实现恒应变率加载,以得到准确、可信的试验结果.试验结果表明:由于复合材料内部含有大量初始微缺陷,2D-C/SiC复合材料在低温动态加载条件下呈现伪塑性行为,其破坏时并未表现出典型的脆性破坏,而是在应力达到压缩强度时出现了显著的应变软化现象,在经历了较大的变形后才最终破坏.随着温度的降低,复合材料的动态Z向压缩强度增加,但失效应变减小.2D-C/SiC复合材料在低温环境下,其内部纤维和基体之间界面结合力增强,同时强的界面结合力可以导致高的压缩强度.
关键词:
陶瓷基复合材料
,
Hopkinson压杆试验装置
,
低温
,
动态Z向压缩力学性能
,
界面强度
王建
,
许兴友
,
马卫兴
,
赵宏
,
陆路德
,
杨绪杰
,
汪信
人工晶体学报
新型氨基酸配位聚合物[Zn(L-trp)(D-trp)]n(L-trp和D-trp分别是L-色氨酸和D-色氨酸)通过水热法制备,并进行元素分析、红外光谱、单晶X-衍射等的表征.该化合物属三斜晶系,P-1,a=0.91670(10)nm,b=0.53320(6)nm,c=1.9525(2)nm,Z=2.为二维双链平面结构.此配位聚合物具有中心对称空间群.每个锌离子Zn2+与一对外消旋体配合,而形成内消旋化合物.
关键词:
色氨酸
,
Zn(Ⅱ)配位聚合物
,
混合溶剂热法
,
表征
舒静
,
任丽丽
,
王鹏
,
王鉴
,
王刚
高分子材料科学与工程
研究了中等分子量((M)η=1.10×105)的聚D,L-乳酸在体外不同环境中的可降解性能,包括不同pH值溶液(37℃)和自然土壤.降解性能采用失重率、分子量变化、溶液pH值变化等来进行评价,并对试样表面形貌采用扫描电镜(SEM)进行了观察.结果表明:聚D,L-乳酸在体外环境中具有良好的可降解性,受降解环境的影响较大;失重和分子量的减小并不平行;在不同pH值溶液和土壤中的分子量变化在一定时间内符合一级反应动力学,且随溶液pH值的增大,降解速率减小.
关键词:
聚D,L-乳酸
,
体外可降解性
,
降解动力学
