材料期刊网

Modelling a Skin-Pass Rolling Process by Means of Data Mining Techniques and Finite Element Method

R Escribano , R Lostado , F J Martínez-de-Pisón , A Pernía , E Vergara

钢铁研究学报(英文版)

An experience is presented using the finite element method (FEM) and data mining (DM) techniques to develop models that can be used to optimize the skin-pass rolling process based on its operating conditions. A FE model based on a real skin-pass process is built and validated. Based on this model, a group of FE models is simulated with different adjustment parameters and with different materials for the sheet; both variables are chosen from pre-set ranges. From all FE model simulations, a database is generated; this database is made up of the above mentioned adjustment parameters, sheet properties and the variables of the process arising from the simulation of the model. Various types of data mining algorithms are used to develop predictive models for each of the variables of the process. The best predictive models can be used to predict experimentally hard-to-measure variables (internal stresses, internal strains, etc) which are useful in the optimal design of the process or to be applied in real time control systems of a skin-pass process in-plant.

关键词: skin-pass rolling , predictive model , finite element method , data mining

通过J/Ψ→N(N-)M衰变研究N*时的核子极点效应

沈彭年 , 梁伟红 , 邹冰松

原子核物理评论 doi:10.3969/j.issn.1007-4627.2004.02.009

研究了J/Ψ→ p(p-)π衰变过程中核子极点图的贡献,特别是由离壳效应带来的贡献.发现衰变宽度对形状因子是敏感的.在通过用J/Ψ→ p(p-)π衰变研究N*时,核子极点图作为背景道的贡献是非常重要的; 在通过J/Ψ→ p(p-)η和 p(p-)η研究N*时,核子极点图的贡献可忽略不计; 在通过J/Ψ→ p(p-)ω研究N*时,核子极点图有明显的贡献.

关键词: J/Ψ衰变 , 核子激发态

S355J2W+N钢激光-MAG复合焊与MAG焊对比

谷晓鹏 , 段珍珍 , 邓钢 , 谷晓燕

材料工程 doi:10.11868/j.issn.1001-4381.2015.02.004

利用激光-MAG复合焊和MAG焊进行了厚板S355J2W+N低碳钢的焊接实验,分析了两种焊接方法接头的微观组织和力学性能.结果表明:复合焊和MAG焊焊缝接头均由焊缝区、过热区、重结晶区和不完全重结晶区构成,复合焊接头截面呈“高脚杯”状特点,焊缝填充量和热影响区宽度较MAG焊明显减小.复合焊由于冷却速率快,过热区魏氏组织略有增多,硬度高于MAG焊,抗拉强度和弯曲性能与MAG焊相比,无显著差异,均能够满足生产标准的要求.

关键词: S355J2W+N , 激光 , MAG , 复合焊 , 接头组织 , 性能

Mechanism of Metal Transfer in DE-GMAW

Kehai Li

材料科学技术（英文）

Modification of conventional gas metal arc welding (GMAW) process is of great potential to achieve high productivity with low cost and strong usability. Double-Electrode GMAW (DE-GMAW) is such a modified arc welding process which is formed by adding a bypass torch (gas tungsten arc welding torch) to a conventional GMAW system. The mechanism of metal transfer in DE-GMAW was proposed and verified in this paper. Experiments show that the critical current is decreased so that spray transfer can be obtained at a lower current level in DE-GMAW. Analysis of this significant change in metal transfer phenomena is conducted, and explanation is given out. It is found that the bypass arc in DE-GMAW lifts the anode point on the droplets such that the electromagnetic force becomes larger and squeezes the droplets so that spray transfer can take
place under welding current lower than that in conventional GMAW.

关键词: Metal transfer , null , null

Formation of Al-doped ZnO films by de magnetron reactive sputtering

Materials Letters

Highly preferred (002) orientation transparent conductive Al-doped ZnO (ZAO) films were successfully prepared by de magnetron reactive sputtering from a Zn target mixed with Al of 2.0 wt.%. The film has a resistivity of 4.80 X 10(-4) n cm and a visible transmittance of as high as 90%. XPS analysis indicates Al-enrichment on the film surface. The asymmetry of Al 2p(3/2) XPS peak is resolved into two components: one centering at 72.14 eV attributed to metallic Al and the other having a binding energy of 74.17 eV due to oxidized Al. (C) 2001 Elsevier Science B.V. All rights reserved.

关键词: Al-doped;ZnO;XPS;Al-enrichment;oxide thin-films;optical-properties;electrical-properties;rf;dc;transparent;deposition

源气体流量比对a_C:F:N薄膜的影响

张云芳

材料科学与工程学报 doi:10.3969/j.issn.1673-2812.2006.04.036

以CF4、CH4和N2的混合气体为源气体,利用rf-PECVD沉积技术制备了氮掺杂氟化非晶碳(a_C:F:N)薄膜,研究了源气体流量比对a_C:F:N薄膜沉积速率和结构的影响.用椭圆偏振光谱测试仪测量了薄膜厚度,结合沉积时间计算了薄膜的沉积速率(在18～21nm/min之间),随流量比增大,薄膜的沉积速率先升高后降低.FTIR光谱分析表明,随流量比增大,薄膜中含F量降低,交联结构增强.Raman光谱分析发现,薄膜中的碳原子由sp2和sp3两种组态的混合结构组成,并进一步证明,随流量比增大,薄膜中sp2键含量增加,交联程度增强.

关键词: 流量比 , 氮掺杂氟化非晶碳薄膜 , 拉曼光谱

Si₃N₄/BN_(f)复合材料的相界面

许钫钫 , 宋澄宇 , 温树林 , 马利泰

无机材料学报

本文借助高分辨电子显微镜研究了Si₃N₄／BN（f）复合材料的相界面,研究发现，BN纤维的两端与基体结合牢固，界面不易解离，材料断裂过程中纤维很难拔出．材料的韧性主要通过BN纤维自身（001）面上的滑移、撕裂和弯曲以及BN纤维的侧表面与Si₃N₄颗粒的界面上的解离等途径得以提高．

关键词: BN纤维 , composite , interfaces , microstructure

n型掺杂半导体In/Nb-SrTiO3金属异质结变温J～V特性的研究

刘大猛 , 连贵君 , 熊光成

低温物理学报 doi:10.3969/j.issn.1000-3258.2004.04.015

利用Nb替代Ti的导电Nb-SrTiO3(Nb-STO)衬底我们制备得到了Nb-STO/金属异质结并测量了异质结的J～V曲线.氧化物半导体Nb-STO/金属异质结的J～V曲线显示出与由Schottky势垒模型描述的理想半导体/金属二极管有很多不同.利用对数据拟合的结果,我们讨论了与理想半导体模型的差别.在Nb-STO作为新的氧化物半导体材料被引入器件时,偏离理想的半导体模型应该是正常的.

关键词: 氧化物半导体/金属异质结 , Schottky势垒 , 耗尽层模型

TiAl与Si3N4f/Si3N4复合材料钎焊接头界面结构及性能研究

宋晓国 , 曹健 , 王义峰 , 冯吉才

稀有金属材料与工程

采用AgCuTi钎料实现了TiAl与Si3N4f/Si3N4复合材料的钎焊,确定了钎焊接头的典型界面组织结构为TiAl/AlCuTi/Ag(s,s)/TiN/Si3N4f/Si3N4.钎焊过程中,液相钎料在Si3N4f/Si3N4复合材料表面发生较好润湿,钎料中活性元素Ti与Si3N4基体及纤维发生反应形成连续的TiN化合物层.过高的钎焊温度或过长的保温时间导致钎缝中脆性的AlCuTi化合物增加,且由于接头应力的作用在钎缝中产生微裂纹甚至开裂,严重地降低了钎焊接头性能.当钎焊温度T=850℃,保温时间为10 min时,接头抗剪强度达到最大,为9.4 MPa,超过Si3N4f/Si3N4母材层间抗剪强度的60％.断口分析表明:压剪过程中,断裂发生在Si3N4f/Si3N4复合材料一侧.

关键词: TiAl , Si3N4f/Si3N4复合材料 , AgCuTi钎料 , 界面结构 , 钎焊

Bi2Sr2CaCu2O8单晶S-N转变的E-J特性

臧超飞 , 何豫生 , 沈庆飞 , 昌俊 , 李春光 , 张国华 , 罗胜 , 齐志 , 尹道乐 , 丁克俭

低温物理学报 doi:10.3969/j.issn.1000-3258.2001.04.008

我们应用脉冲电流的方法测量了Bi2Sr2CaCu2O8单晶在4特斯拉强场下的大电流时等温E-J特性.我们观察到在大电流时,样品电阻率ρ迅速增大,随着电流的继续上升,经过一段正曲率增长阶段,几乎达到饱和值,最后经过一段负曲率上升,达到正常态,显示出完整的S形.应用尹道乐等人的统一物质方程理论,给出了实验曲线较好的数值拟合.根据拟合结果,讨论了理论中各个参量的物理意义.

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