材料期刊网

THEORETICAL INVESTIGATION ON BY-ONLY-CURRENT ELECTROMAGNETIC SEPARATION OF INCLUSION FROM MOLTEN METALS

B.W. Zhang , Z.M. Ren , Y.B. Zhong

金属学报(英文版)

The electromagnetic field under applied AC and DC current in round and rectangularpipe was systematically investigated, then a concept of "equivalent current density"was proposed for evaluating the inhomogeneous electromagnetic pinch force, and themono-component removal efficiency and the overall removal efficiency of inclusionwere formulated. It is founded that flat pipe is superior to round pipe for the electro-magnetic removal of inclusion, and DC current can get a higher removal efficiencythan AC current due to absence of skin phenomenon. Under usual condition, a re-moval efficiency of 52% for 10μm inclusion or more than 92% for 20μm inclusioncan be achieved by imposing a current density of 3× 106A/m2 in a fiat pipe.

关键词: inclusion , null , null , null

代铬镀层--Ni-W、Ni-W-B非晶态合金镀层性能研究

朱立群 , 李卫平

电镀与涂饰 doi:10.3969/j.issn.1004-227X.2004.05.003

通过在浓硝酸、w=5% NaCl溶液、c＝1 mol/L H2SO4溶液中的浸渍试验,研究了不同基体上的Ni-W非晶态合金镀层的耐蚀性;通过测定在w=5% NaCl溶液及c=1 mol/L的HNO3溶液、H2SO4溶液、HCl溶液中的阳极极化曲线,研究了Ni-W非晶态合金镀层薄膜本身的耐蚀性;采用线性极化方法对Ni-W-B非晶态合金镀层在w=5% NaCl溶液、c＝1 mol/L H2SO4溶液及HNO3溶液中的腐蚀速度进行了测定,并测定了以上2种非晶态合金镀层的硬度与耐磨性.结果表明,非晶态的Ni-W、Ni-W-B镀层比晶态镀层的耐腐蚀性能要好,而Ni-W-B 非晶态合金镀层比Ni-W非晶态合金镀层的耐蚀性能又明显提高;经热处理后,Ni-W-B非晶态镀层的硬度值明显高于Ni-W非晶态镀层,耐磨性能都提高了1倍以上.Ni-W、Ni-W-B非晶态镀层极有望成为一种比较好的代铬镀层.

关键词: 代铬镀层 , 非晶态镀层 , Ni-W , Ni-W-B , 耐蚀性能

B2 precipitates and distribution of W in a Ti-47Al-2W-0.5Si alloy

Intermetallics

The precipitation behavior of B2 particles and the distribution of W in a Ti-47Al-2W-0.5Si alloy were investigated using high-spatial resolution analytical electron microscopy (AEM) and high-resolution electron microscopy (HREM). The ledges at the alpha(2)/gamma interfaces were found to be enriched in W and therefore the preferable nucleation sites for the B2 precipitates. In the B2 phase, as high as one third of Al is substituted by W in comparison with the composition of the 7 phase. The segregation of W to the alpha(2)/gamma and B2/gamma interfaces was also detected. These results provide explanations for the previous observations that additions of tungsten are effective in promoting the creep resistance of TiAl alloys. (C) 2002 Published by Elsevier Science Ltd.

关键词: titanium aluminides, based on TiAl;precipitates;phase interfaces;site;occupany;electron microscopy, transmission;analytical electron-microscope;gamma-titanium aluminides;orientation;relationship;creep deformation;tial alloy;atomic-scale;segregation;microstructure;interfaces;resistance

机械合金化制备Ni-W(B)非晶-纳米晶的粉末特性

马运柱 , 叶晓珊 , 刘文胜 , 张佳佳

稀有金属材料与工程

利用机械合金化(MA)制备了Ni-20.7W和Ni-17.9W-27B (at％)非晶-纳米晶粉末,分别采用扫描电镜(SEM)和X射线衍射(XRD)仪分析了不同球磨时间粉末的微观形貌和结构参数,探讨了B的添加对非晶化过程的影响.研究结果表明:MA过程中,Ni-20.7W样品没有明显发生非晶化,而Ni-17.9W-27B样品在40 h时发生了非晶化,说明B提高了Ni-W合金体系的非晶化形成能力;非晶化过程为W/B首先固溶于Ni中生成Ni(W,B)过饱和固溶体,然后转变为非晶;Ni-20.7W样品球磨30h后Ni的晶粒尺寸为32.9 nm,晶格畸变为0.48％,而Ni-17.9W-27B样品球磨10h后的晶粒尺寸为9 nm,晶格畸变为0.62％.

关键词: Ni-W(B) , 非晶 , 纳米晶 , 机械合金化 , 粉末特性

On structure and crystallization of amorphous Fe-Mo-W-B alloys obtained by electroless plating

Zeitschrift Fur Metallkunde

Quaternary amorphous Fe-Mo-W-B alloy have been deposited by electroless plating. The structure and crystallization processes of the alloys have been studied by X-ray diffraction. It is found that for boron contents of 9.8 to 27.3 at.%, the structure is amorphous, which is wider than the range for the binary Fe-B, but is more narrow than that of ternary Fe-Mo-B amorphous films. A two-step process of crystallization is observed for the deposits. At first, the crystallization phases are alpha-Fe, Fe3B and (Mo, W),B-2, then Fe2B, (Mo, W)B and Fe-2(Mo, W) for high temperatures in the amorphous films.

关键词: deposition

电沉积RE-Ni-W-B-B4C-MoS2复合镀层的性能研究

郭忠诚 , 朱晓云 , 翟大成 , 徐瑞东 , 曹建春 , 龙晋明

材料保护 doi:10.3969/j.issn.1001-1560.2002.07.012

研究了RE-Ni-W-B-B4C-MoS2复合镀层在不同氧化温度和时间下的抗高温氧化性.结果显示,当温度小于800 ℃时,RE-Ni-W-B-B4C-MoS2复合镀层被氧化的程度较小;温度超过800 ℃,氧化膜的增重呈直线增加.RE-Ni-W-B-B4C-MoS2复合镀层的硬度随着热处理温度的升高而增加,当热处理温度达到400 ℃时,复合镀层的硬度升到极大值(1 368 HV);若继续升高温度,镀层硬度逐渐降低.RE-Ni-W-B-B4C-MoS2复合镀层的耐磨性经400 ℃热处理后最好.工艺条件对RE-Ni-W-B-B4C-MoS2复合镀层的表面形貌影响较大,随着电流密度或镀液温度的升高,复合镀层结晶粗,晶粒大;反之,镀层结晶细,表面晶粒细小.RE-Ni-W-B-B4C-MoS2复合镀层的镀态下以非晶态为主,部分已晶化;当经500 ℃热处理后,复合镀层已晶化;经800 ℃热处理后,CeO2和B4C仍以化合物的形式存在,由此可以说明,CeO2和B4C的加入,可以提高RE-Ni-W-B-B4C-MoS2复合镀层的热稳定性.

关键词: 电沉积 , 复合镀层 , 抗高温氧化 , 耐磨性 , 表面形貌

Cr,Mo,W对非晶态(Fe,B)基合金磁性的影响

詹文山 , 沈保根 , 赵见高 , 潘孝硕

金属学报

本文报道用单辊液淬方法制备的Fe-M-B(M=Cr,Mo,W)非晶态合金的磁性,讨论了Cr,Mo或W元素的加入对非晶态Fe-B合金的磁矩、Curie温度(Tc),Bloch T~(3/2)定律的系数B或自旋波劲度系数(D)等的影响.从热磁测量的结果得到,三个非晶态合金系列中每个Fe原子的平均磁矩都在2.0μ_B左右,每个Cr,Mo,W原子的平均磁矩分别为-3.96,-4.62,-4.08μ_B(与Fe的磁矩反平行,故为负值).Tc随Cr,Mo或W含量的增加分别以20.5K/at.-%Cr,27.7 K/at-%Mo和26 K/at.-%W的递减率下降.在Tc附近的磁短程序的行为由于外加磁场变得更加明显.系数B随Cr,Mo或W含量的增加而增加,说明磁性原子间相互作用的减弱.

关键词:

W对Mo-Si-B合金微观组织和力学性能的影响

徐健建 , 颜建辉 , 汪异 , 刘龙飞 , 王跃明

材料热处理学报

采用放电等离子烧结技术(SPS)在不同温度下制备Mo-12Si-8.5B和(Mo0.9,W0.1)-12Si-8.5B多相合金材料,研究了合金的微观组织和力学性能.结果表明,两种不同成分合金的组成相中都含有α-Mo、Mo3Si和Mo5SiB2相,在(Mo0.9,W0.1)-12Si-8.5B合金中还存在单质W以及含W的固溶体.随烧结温度提高,两种合金的致密度、硬度和抗弯强度都有所增加.在1600 ～1700℃烧结工艺条件下,少量W减少了Mo-12Si-8.5B合金中显微裂纹的数量和尺寸.W加入略降低了Mo-12Si-8.5B合金的硬度,但明显提高了Mo-12Si-8.5B合金的抗弯强度.1700℃烧结制备的(Mo0.9,W0.1)-12Si-8.5B合金的抗弯强度可达441MPa,比Mo-12Si-8.5B提高了18％.

关键词: Mo-Si-B合金 , 钨 , 等离子烧结 , 微观组织 , 力学性能

Ni-W-B-WC复合镀层制备及性能研究

温玉清 , 刘峥 , 尚伟 , 韦德勋

稀有金属材料与工程

以镀层硬度和镀层外观为指标,研究电流密度、镀液中WC的含量、pH值、沉积温度对考察指标的影响.利用正交试验确定了电沉积最佳工艺条件:在超声振荡下,控制电流密度为7 A/cm2,施镀温度50℃,镀液中WC的含量为20 g/L,镀液pH值为5.0时,镀层硬度和镀层外观最佳,同时对Ni-W-B镀层、Ni-W-B-WC镀层的硬度、抗高温氧化性、耐腐蚀性能、表面形貌、镀层结构与成分等进行了测试.结果表明,Ni-W-B-WC复合镀层的综合性能要高于Ni-W-B合金镀层.

关键词: Ni-W-B-WC复合镀层 , 电沉积 , WC粉

电沉积RE-Ni-W-P-B4C-PTFE

郭忠诚 , 陈凌 , 杨显万 , 翟大成

电镀与涂饰 doi:10.3969/j.issn.1004-227X.2000.03.001

研究了RE-Ni-W-P-B4C-PTFE复合镀层的性能.结果表明:热处理温度对RE-Ni-W-P-B4C-PTFE复合镀层的硬度影响很大,当温度达到400℃时,复合镀层的硬度达到极大值(1145 Hv);在同一热处理温度下,当保温时间达到3小时,镀层的硬度值最佳.当热处理温度达到300℃时,RE-Ni-W-P-B4C-PTFE复合镀层的耐磨性最好.高温氧化试验表明:RE-Ni-W-P-B4C-PTFE复合镀层随氧化时间和温度的延长,被氧化的程度增加.

关键词: 电沉积 , RE-Ni-W-P-B4C-PTFE复合镀层 , 性能