材料期刊网

Effect of Laminar Cooling on Phase Transformation Evolution in Hot Rolling Process

NING Linxin , YANG Daijun , J Lin , et al

钢铁研究学报(英文版)

In the hot rolling processes, it always uses the laminar cooling system to control the cooling of plate and get the microstructure of different constitution. To investigate the effect of temperature variation due to the cooling pattern, rolling speed and thickness of plate on the microstructure evolution, a thermal-mechanical coupled FE model has been established. A set of constitutive equations of phase transformation is implemented into the commercial FE solver MARC through the user defined subroutine CRPLAW, and the temperature field is calculated by another user defined subroutine FILM. The effect of cooling pattern, rolling speed and thickness of plate on the temperature variation is numerically studied. Furthermore, the effect of temperature variation on the evolution of each phase transformation is investigated for various cooling pattern.

关键词: Hot rolling;Laminar cooling system;Cooling pattern;Thermal-mechanical modelling;Microstructure evolution;constitutive equations;Phase transformation.

ACRT-B法生长的MnxCd1-xIn2Te4晶体的溶质分凝特性

常永勤 , 介万奇 , 郭喜平 , 陈福义 , 安卫军

功能材料

研究了ACRT-B法生长的Mn0.1Cd0.9In2Te4晶体中界面的形状和各组元沿轴向的分布规律及其分凝因数.发现结晶界面为椭球形;采用理想配比生长MnxCd1-xIn2Te4晶体,其4种组元并不按(Mn,Cd):In:Te=1:2:4比例结晶,而是要重新分布;通过数学方法处理实验数据得到Mn,Cd和In的分凝因数在α相区分别为1.286、1.9257和0.7294,在β相区则分别为1.12、1.055和0.985.

关键词: ACRT-B法 , MnxCd1-x In2Te4 , 界面 , 分凝因数

Bridgman法生长的Mn_xCd_1-xIn₂Te₄晶体相形成规律和物理性能研究

常永勤 , 安卫军 , 郭喜平 , 介万奇

无机材料学报

采用Bridgman法生长了x为0.1,0.22和0.4的四元稀磁半导体化合物Mn_xCd_1-xIn₂Te₄晶体.研究了三根晶体中相的形貌、结构、成分和Mn_0.1Cd_0.9In₂Te₄晶体中各组元沿轴向和径向的成分分布.晶体生长初始端的组织为α+β+β₁,随着生长的进行,形成β相的单相区.在晶锭末端,形成In₂Te₃类面心立方结构化合物.组分x增大后,Mn_xCd_1-xIn₂Te₄晶体的吸收边向短波方向移动,禁带宽度则线性增大.磁化率测量结果表明:晶体在高温区的x^-1-T曲线服从居里-外斯定律,在低温区(<50K)则表现出顺磁增强现象.

关键词: Mn_xCd_1-xIn₂T_e4 , compositional distribution , infrared transmission spectra , mag- netic susceptibility

Bridgman法生长的MnxCd1-xIn2Te4晶体相形成规律和物理性能研究

常永勤 , 安卫军 , 郭喜平 , 介万奇

无机材料学报 doi:10.3321/j.issn:1000-324X.2003.02.004

采用Bridgman法生长了x为0.1,0.22和0.4的四元稀磁半导体化合物MnxCd1-xIn2Te4晶体.研究了三根晶体中相的形貌、结构、成分和Mno.1Cd0.9In2Te4晶体中各组元沿轴向和径向的成分分布.晶体生长初始端的组织为α+β+β1,随着生长的进行,形成β相的单相区.在晶锭末端,形成In2Te3类面心立方结构化合物.组分x增大后,MnxCd1-xIn2Te4晶体的吸收边向短波方向移动,禁带宽度则线性增大.磁化率测量结果表明:晶体在高温区的x-1-T曲线服从居里一外斯定律,在低温区(＜50K)则表现出顺磁增强现象.

关键词: MnxCd1-xIn2Te4 , 成分偏析 , 红外透射光谱 , 磁化率

表面包覆法合成的LiN0.8Co0.2O2材料的结构表征

刘欣艳 , 赵煜娟 , 夏定国

功能材料

LiNi0.8Co0.2O2是锂离子电池界公认的最有希望取代商业化正极材料LiCoO2的新型正极材料之一.本文所研究的复合正极材料LiNi0.8Co0.2O2是由细小的晶粒构成的球形颗粒,单一相,属于R3m空间群.对复合材料LiNi0.8Co0.2O2的Co-K和Ni-K的XANES分析可知,在600～850℃范围温度对于钴元素的影响不明显,而对于镍元素的影响比较显著,随着Ni-K边位置向高能量移动LiNi0.8Co0.2O2正极材料的放电容量升高.复合材料LiNi0.8Co0.2O2和LiNiO2的Ni-K边XANES相似,表明少量钴的引入对晶体结构的改变不是太多,但是峰的强度较高和峰的位置向高能量移动,表明钴Co对Ni的局域结构进行了调制.

关键词: LiNi0.8Co0.2O2 , XANES , 正极材料 , 局域结构

MnxCd1-xIn2 Te4晶体生长研究

常永勤 , 安卫军 , 郭喜平 , 介万奇

功能材料

采用Bridgman法生长四元稀磁化合物半导体Mn0.22Cd0.78In2Te4晶体.当晶体生长到预定长度时,淬火得到固液界面.采用光学显微镜、扫描电镜、X射线衍射仪、ISIS能谱仪以及Leica定量金相分析仪研究了晶体中出现的界面形态、相的形貌和数量以及沿生长方向的相析出规律,并进行了相成分分析.研究发现,淬火得到的Mn0.22 Cd0.78In2Te4晶体中存在两个界面,其中一个为固液相变界面,另一个为由α+β两相区发展到单相β区时的转变界面,二者相对于生长初始端均为凹形;α+β两相区中,β相以条状、花状和近似圆片状形式存在,其中条状β相多分布在晶界处;越接近生长初始端,花状和近似圆片状β相越小,条状β相越细,它们的含量越少;X射线衍射图谱表明,β相为黄铜矿结构,α相为面心立方结构.

关键词: MnxCd1-xIn2Te4 , 相变界面 , β相 , X射线衍射图谱

Composition Distribution in the MnxCd1-xIn2Te4 Ingot Grown by ACRT-B Method

材料科学技术（英文）

关键词:

Improving the electrochemical properties of natural graphite spheres by coating with a pyrolytic carbon shell

新型炭材料

Two kinds of modified natural graphite (MNG) spheres with a pyrolytic carbon shell on smooth or granular surface were obtained using fluidized bed chemical vapor deposition of acetylene by adjusting the reaction parameters. The core of the NING has a highly ordered graphite structure and the shell has a disordered structure. Compared with natural graphite (NG) spheres, MNG with a core-shell structure shows improved first cycling efficiency and cyclability. Especially, the NING spheres with a granular surface possess 84% retention of the first discharge capacity after 41 cycles, owing to effective decrease of the contact resistance and increase of contact area between the NING spheres.

关键词: fluidized bed chemical vapor deposition;core-shell structure;pyrolytic;carbon;modified natural graphite;lithium ion secondary battery;lithium-ion batteries;chemical-vapor-deposition;1st-cycle charge loss;anode material;encapsulated graphite;surface-area;infiltration;performance;improvement;pyrocarbon

THERMODYNAMIC PROPERTIES OF ALPHA-HELIX PROTEIN - A SOLITON APPROACH - COMMENT

Physical Review E

We disagree with the deduction of the equations of motion for the Davydov soliton and of the results in the paper by Jia-Xin Xiao et al. [Phys. Rev. A 44, 8375 (1991)]. The weakness and faults of the Davydov theory are also indicated.

关键词: davydov solitons;vibron solitons;molecules;excitation;system

Heterogenization of Indium for the Friedel-Craft Benzoylation of Toluene

Farook ADAM*, Kei Lin SEK

催化学报 doi:10.1016/S1872-2067(11)60453-1

Indium incorporated silica samples with different indium contents were synthesized using a template free sol-gel method. The silica used was extracted from rice husk (RH) and the resulting catalyst was labeled as RH-xIn (x=5%,10%,15%, and 20%). From the N2 adsorption analysis the presence of type IV isotherm in RH-blank and RH-xIn indicated the mesoporous nature of the catalysts. In the XRD pattern, a broad band at ca.2θ=25° was observed for all the catalysts which showed them to be amorphous. TEM micrographs revealed that the material is composed of nanoparticles. Friedel-Craft benzoylation of toluene was carried out using the RH-xIn catalyst. The optimum conditions for the benzoylation of toluene were determined and at 373 K,100%conversion and 89%selectivity for the para-product (i.e.4-methylbenzophenone) were obtained.

关键词: rice husk , sol-gel , indium , Friedel-Craft benzoylation , Toluene