材料期刊网

NUMERICAL STUDY ON 3-D FLUID FLOW WITHIN THE MOLTEN POOL DURING UNEQUAL DIAMETER TWIN ROLL STRIP CAST-ROLLING

S. W Ma , J.C , He and H.S. Di 1) School of Materials and Metallurgy , Northeastern University , Shenyang 110006 , China 2) The State Key Laboratory of Rolling and Automation , Northeastern University , Shenyang 110006 , China

金属学报(英文版)

In this paper three-dimensional flow field in the molten pool between unequal diameter twin rolls has been studied by BFC technology and SIMPLEC numerical method. From the computed flow pattern,the characteristic of molten steel flow has been discussed. The dynamics generated by the feeding flow and the motivation of counter-rotating twin rolls produces a recirculating flow field nearby the small roll due to the larger room and less resistant here and fluid flows along the roll surface tangential nearby large roll and extends to two side dams. There is faintly flow around the dams of molten pool

关键词: NNSCC , null , null , null , null

MA制备W-Ni-Fe纳米复合粉末的工艺优化

范景莲 , 汪登龙 , 黄伯云 , 曹建虎 , 马运柱

中国有色金属学报

研究了90W-7Ni-3Fe混合粉末在行星式高能球磨机中的机械合金化(MA)工艺.在一定条件下球磨后,采用XRD分析了粉末相变化、晶块尺寸和晶格畸变,采用SEM对粉末形貌进行了分析.研究了球磨时间、球磨机转速、球料比、球装填系数、不同的表面活性剂等因素对粉末性能的影响.确定了机械合金化制备W-Ni-Fe纳米复合粉末的最优化工艺:球磨转速为200r/min,球装填系数为6%～12%,球料比为10∶1,液体介质比为V液体∶V(球+料)=1.4～2.0.不同种类的过程控制剂对MA粉末分散和粉末的成形性有很大的影响,采用8#过程控制剂能在有效分散MA粉末的同时具有好的成形性.

关键词: 机械合金化 , 钨合金 , 工艺优化 , 过程控制剂

253MA(S30815)耐热不锈钢冶炼工艺研究

李国平

钢铁

253MA是在21Cr-11Ni不锈钢的基础上,通过N合金化和添加稀土元素Ce开发的耐热纯奥氏体不锈钢.由于该钢种的熔点与碳钢相比偏低,钢液的流动性差,因此如何解决氮气合金化、稀土添加等问题,是冶炼过程中的工艺难点.通过对不同稀土加入方式、过程脱氧、夹杂物控制以及精确控N模型等的相关参数的研究,成功完成了253MA的冶炼连铸,为生产板材创造了良好的条件.

关键词: 稀土加入工艺 , 氮合金化 , 不锈钢

253MA(S30815)耐热不锈钢冶炼工艺研究

李国平

钢铁

253MA是在21Cr11Ni不锈钢的基础上，通过N合金化和添加稀土元素Ce开发的耐热纯奥氏体不锈钢。由于该钢种的熔点与碳钢相比偏低，钢液的流动性差，因此如何解决氮气合金化、稀土添加等问题，是冶炼过程中的工艺难点。通过对不同稀土加入方式、过程脱氧、夹杂物控制以及精确控N模型等的相关参数的研究，成功完成了253MA的冶炼连铸，为生产板材创造了良好的条件。

关键词: 稀土加入工艺;氮合金化;不锈钢

MA制备93W-4.9Ni-2.1Fe超细预合金粉末的烧结特性研究

刘文胜 , 马运柱 , 黄伯云 , 张林

稀有金属材料与工程

为了改善93W-4.9Ni-2.1Fe合金的力学性能,对MA制备93W-4.9Ni-2.1Fe超细预合金粉末的烧结特性进行了研究.采用比表面吸附法测算了预合金粉末粒度,用X射线衍射仪对粉末晶粒尺寸进行测算,扫描电镜观察球磨粉末和试样拉伸断口的形貌,用金相显微镜对试样显微组织进行观察.结果表明:球磨50 h后可得到粒度为0.29 μm、晶粒尺寸为25.5 nm、各元素分布均匀的超细93W-4.9Ni-2.1Fe预合金粉末;球磨50 h的预合金粉末在1480℃烧结90 min压坯,钨晶粒呈球形或近球形;合金抗拉强度、延伸率和相对密度分别为1025.4 MPa,26.47%和99.45%,合金呈钨晶粒的穿晶解理断裂和粘结相的延性撕裂.

关键词: 93W-4.9Ni-2.1Fe合金 , 机械合金化 , 超细粉末 , 烧结特性

Microstructure and preparation of nano S-W-S new solid lubrication system

Transactions of Nonferrous Metals Society of China

The method for preparing a new solid lubrication system of nano S-W-S was presented. The microstructure of the S-W-S nano cluster was investigated using TEM and XRD. The system is a mixture clusters of both monocrystal and polycrystal of layered hexagonal structure with one tungsten atom linking with two sulphur atoms, and the week Van der Waals' force bonding together the different layers. The changes of electronic structure were studied with XPS. The hybridization of different electronic shelf orbitals of the sulphur atom in the nano cluster is regarded as the quantum size effect. The clusters are found to be of a closed spherical,structure without any dangling bond.

关键词: solid lubrication system;nanometer cluster;quantum size effect;powders

线状MA-AA-MAS聚羧酸陶瓷分散剂的制备工艺及其性能

陈宝璠

硅酸盐通报

采用水溶液聚合法,以异丁烯磺酸钠(MAS)、丙烯酸(AA)和顺酐(MA)为主要合成原料,合成了一种线状MA-AA-MAS聚羧酸陶瓷分散剂.采用FT-IR手段对其官能团结构进行了表征.分别通过正交和单因素试验以确定各单体比例和研究各单体用量及聚合反应条件对陶瓷坯体料浆流动性能的影响.结果表明,合成该分散剂的最佳工艺条件为:n(MAS)∶n(AA)∶n(MA) =1.0∶3.0∶1.0、w(APS)=8％、聚合温度和时间分别为90℃和5h.当分散剂的掺量为0.35％(相对绝干料浆质量)时,料浆体系的黏度仅为78.2 mPa·s.

关键词: 线状MA-AA-MAS聚羧酸 , 陶瓷分散剂 , 聚合 , 性能 , 流动时间

Ni-Fe-W-S刷镀层耐磨性机理研究

张远明 , 惠文华

材料保护 doi:10.3969/j.issn.1001-1560.2001.06.007

采用扫描电子显微镜、X射线光电子能谱(XPS)、俄歇电子能谱(AES)等手段研究了代铬镀层(Ni-Fe-W-S).在磨损前后的成分变化及价态变化,发现WS2具有固体润滑作用,并初步探讨了Ni-Fe-W-S合金层耐磨性的作用机理.研究表明,偏聚的W与S形成立方晶系的WS2作为固体润滑剂可有效地降低摩擦系数,同时,W的偏聚使层错能降低,不易形成磨损裂纹.

关键词: 合金镀层 , 耐磨性 , 偏聚

S355J2W耐候钢的耐腐蚀性能

鲁二敬 , 卢峰华 , 许鸿吉 , 谢明 , 钮旭晶

机械工程材料

通过周期浸润腐蚀试验，对比研究了S355．12W耐候钢和Q345R低合金钢在NariSOs溶液中的耐腐蚀性能，并用扫描电镜对腐蚀产物进行了观察和分析。结果表明：在相同试验条件下，S355J2W耐候钢的腐蚀速率低于Q345R钢的；S355J2W耐候钢会在表面形成黑褐色锈层，而Q345R钢表面形成橘红色易剥落的疏松锈层；S355J2W耐候钢腐蚀产物微观形貌为沿放射性方向生长的针状晶体，Q345R钢为颗粒状聚合物堆积而成，形状无规则，颗粒之间有较大的空隙。

关键词: S355J2W耐候钢 , 周期浸润腐蚀试验 , 耐腐蚀性能

Unusual W-shaped Galvanic Cell Model of ISCC of α-brass in Neutral Mattsson's Solution

WU Shaobin , R. J. Arsenault , I. R. Kramer Metallurgical Materials Laboratory , University of Maryland , USA.

材料科学技术（英文）

Intergranular stress corrosion cracking (ISCC) of α-brass in neutral Mattsson's solution was found to be controlled by an unusual "W"-shaped galvanic cell whose cathode is the grain boundary oxide film (G.B.0. film) and surface film and the anode is fresh metal at the cracked tip on both sides of the G.B.0. film. Redox reactions involved in the cell have been proposed here. According to this mdel, initidtion of ISCC is caused by the rupturing of surface film along grain boundaries, thus forming a galvanic cell. Propagation of ISCC resulted from alternate advances of G.B.0. film and dissolution on both sides of G.B.0. film caused by the effect of electrochemical reaction. This work developed an effective approach to investigate the embrittlement process at the tip of the crack, by increasing the length of the embrittlement region through constant strain test and distinguishing the morphology and the nature of the corrosion products by optical microscopy and scanning electron microscopy (SEH).

关键词: α-brass , null , null , null