Jiang QIN(School of Mechanical Engineering
,
University of Bath
,
Claverton Down
,
Bath BA27AY
,
UK)
材料科学技术（英文）
The variation principle is discussed and Rayleigh-Ritz method is proposed for construction of veloci ty field. A kinematically admissible velocity field based on polynomials was appIied to the determina tion of forging load and deformed buIge profile during upset forging of blocks. Simulation of upsetforging of rectangular blocks under various friction condjtions was performed. Comparison of the computed results with experiments and FEM shows good agreement. It is shown that this techniquecan be used for 3D simulation of metal forming process.
关键词:
周克省
,
刘利强
,
邓联文
,
周一平
,
尹荔松
,
刘宝刚
功能材料
采用柠檬酸溶胶凝胶法制备了稀土W型六角铁氧体Ba0.8La0.2Co2Fe16O27粉晶,用DSC-TGA、FT-IR、XRD、SEM分析了样品的形成过程、微观形貌、粒径和晶体结构,根据微波矢量网络分析仪测试的样品在2～18GHz微波频率范围的电磁参数计算了电磁损耗角正切及微波反射率.研究结果表明, 煅烧2h能得到单一的W型相Ba0.8La0.2Co2Fe16O27 ;晶粒为六角块状结构,大小均为200nm左右;Ba0.8La0.2Co2Fe16O27样品厚度为1.9mm时,12GHz位置处吸收峰为16.2dB,10dB频宽为4.0GHz;微波吸收主要由磁损耗引起.
关键词:
柠檬酸溶胶凝胶法
,
稀土掺杂
,
W型六角铁氧体
,
微波吸收材料
周克省
,
卢玉娥
,
尹荔松
,
秦宪明
,
邓联文
,
翟志彩
,
陈颖
,
夏辉
材料导报
采用溶胶-凝胶法制备了(MnCu)组合掺杂W型钡钴铁氧体Ba(MnCu)xCo2-2x Fe16O27(x=0.1、0.2、0.3、0.4、0.5)样品.用XRD和SEM对样品的晶体结构、表面形貌、粒径进行了表征,用微波矢量网络分析仪测试了该样品在2～18GHz微波频率范围的电磁参数,根据测量数据计算电磁损耗角正切及得出微波反射率与频率的关系,探讨了该材料的微波吸收性能与电磁损耗机理.研究结果表明,Ba(MnCu)xCo2-2xFe16O27晶粉呈微米级六角片状形貌,煅烧温度1235℃以上的晶体结构为W型,是一种宽频带强损耗微波吸收材料.当x=0.3时,厚度为2.3mm的样品在频率为10GHz处的吸收峰为24dB,10dB以上频带宽度达8.8GHz.样品的微波吸收主要来自畴壁共振、磁化弛豫和自然共振引起的磁损耗,介电损耗较弱.
关键词:
溶胶-凝胶法
,
(MnCu)掺杂
,
W型钡铁氧体
,
微波吸收
,
电磁损耗
刘志宾
,
朱正吼
,
徐雪娇
,
颜日成
功能材料
首先采用化学共沉和高温助熔工艺制备铁氧体Ba(Zn0.65CO0.35)2 Fe16O27粉体,用手糊工艺制备铁氧体/M-玻璃纤维/环氧树脂复合材料板,再用波导法测定复合材料的电磁参数.研究表明当铁氧体Ba(Zn0.65CO0.35)2 Fe16O(27)含量不变时,复合材料板的吸波性能随板厚度的增加而提升,且试样反射系数绝对值增加的幅度随试样厚度的增加而变少.将M-玻璃纤维/环氧树脂复合材料置于非晶粉体/M-玻璃纤维/环氧树脂复合材料前端组合成多层复合材料结构,可以改善复合材料板与空气的电磁匹配性能,提高复合材料板的吸波性能.
关键词:
复合材料
,
电磁参数
,
Ba(Zn0.65CO0.35)2
,
Fe16O27
马素云
,
朱正吼
,
徐雪娇
,
刘志斌
功能材料
采用化学共沉+高温助熔工艺制备了铁氧体Ba(Zn(1-x)Cox)2Fe16O27粉体,然后用模压法制备了铁氧体粉体/环氧树脂复合材料板,采用同轴电缆法测定了复合材料的电磁参数.研究表明,随着铁氧体中Co含量增加,铁氧体主相由BaZn2Fe16O27转变成BaCo2Fe16O27,材料磁损耗逐渐加强,复合材料与空气的电磁匹配特性在频率低于12GHz时较好.然后将M-玻璃纤维/环氧树脂复合材料置于铁氧体粉体/环氧树脂复合材料前端组合成多层复合材料结构,复合材料板与空气的电磁匹配性能和吸波性能都有很大提高.数据如下:当复合材料结构中x=0.75铁氧体吸波层厚度为2.0mm,结构总厚度5.3mm时,复合结构反射系数R的绝对值在2～8GHz时＞4dB、在8～18GHz时＞10dB的吸波性能.
关键词:
铁氧体
,
环氧树脂
,
复合材料
,
吸波性能
张跃
,
王洪涛
,
刘建武
,
严生虎
,
沈介发
稀有金属材料与工程
用柠檬酸溶胶-凝胶法制备了铁氧体Ba0.8La0.2(Zn0.5Ni0.5)2-xCoxFe15O27(x=0.8,1.0,1.2,1.4).采用X射线衍射(XRD)分析,扫描电镜(SEM),热重(TG)和差热分析(DTA)对凝胶及铁氧体的晶型和显微结构进行了研究,并用网络分析仪测试了样品在2～18 GHz范围内的的电磁参数.研究发现制备的铁氧体是片状的W型晶体,随着Co2+含量的增多,铁氧体中M晶型的含量逐渐增多;当x为1.0时,铁氧体的损耗角正切达到最大值0.57.
关键词:
柠檬酸
,
溶胶-凝胶法
,
镧六角晶系铁氧体
,
晶体结构
,
电磁性能
X.K. Tao
,
X.Cong
,
R.S. Peng
,
J.Liu and Z.Y. Liu Tianjin Institute of Technology
,
Tianjin 300191
,
China
金属学报(英文版)
This paper investigates the effect of rare earth elements on the kinetic process, microstructure and mechanical properties of vanadization in borax bath. The results show that addition of rare earth elements to vanadizing agent has obvious catalytic effect on the rate of vanadization, which has been enchanced by 30%. The wear and corrosion resistance of vanadium carbide layer were prompted by the addition of rare earth to the agent. Through increasing vanadium potential of the agent, activating the surface of workpieces and decreasing the activation energy of diffusion of carbon, rare earth elements accelerate the rate of vanadization process.
关键词:
rare earth elements
,
null
,
null
QU Ying YANG Jian XU Baomei University of Science and Technology Beijing
,
Beijing
,
China
金属学报(英文版)
By use of the two-component LDA and high speed camera,the water model of the flow field in metal bath under molten slag layer has been tested.On the basis of experimental results,the flow boundary conditions of liquid metal at the slag-metal interface of a gas injecting bath were deduced.The flow field and the turbulent parameters of the metal bath covered with slag were solved by the vorticity-stream function method.The results reveal that the flow velocity, turbulent energy and circulating rate of the melt under slag are lower than that of without slagcover.Another one “dead zone” of the lowest turbulent energy is formed in the top layer under cover of slag near the ladle linning.
关键词:
flow field
,
null
,
null
,
null
Haibin CHENG
,
Shuai XU
,
Wenyu ZHAO
,
Suling ZHAO
,
Pengcheng ZHAI
,
Zhigang SUN
,
Qingjie ZHANG
材料科学技术（英文）
Electroless CoNiWP magnetic films were prepared by varying the bath pH and then characterized by energy dispersive X-ray analysis, X-ray diffraction and magnetic force microscopy. It has been found that the microstructure and the magnetic properties of films were influenced greatly by the bath pH. At the bath pH 8.06, the grain size and coercivity of the films reach maximum, while the squareness (Mr=Ms) of MH curves reaches minimum. The Henkel plots indicates that the exchange-coupling interaction is very weak at this pH, which may be caused by phase-separation and large grain size, and then results in the lowest squareness. At pH above 8.5, obvious exchange-coupling interaction is observed because of the inexistence of phase-separation and the refinement of grain size.
关键词:
CoNiWP magnetic film
,
Bath
,
pH
,
Squarenes
,
Exchang
HE Chun-lai
,
ZHU Rong
,
DONG Kai
,
QIU Yong-quan
,
SUN Kai-ming
钢铁研究学报(英文版)
A transient three-dimensional mathematical model has been developed to analyze the three-phase flow in a 150 t EAF (electric arc furnace) using oxygen. VOF (multiphase volume of fluid) method is used to simulate the behaviors of molten steel and slag. Numerical simulation was conducted to clarify the transient phenomena of oxygen impingement on molten bath. When oxygen jet impinges on the surface of molten bath, the slag layer is broken and the penetrated cavity in molten steel is created. Simultaneously, the wave is formed at the surface of uncovered steel on which the slag layer is pushed away by jet. The result of numerical simulations shows that the area and velocity of uncovered steel created by impingement, jet penetration depth change from 0.10 m2, 0.0125 m/s, 3.58 cm to 0.72 m2, 0.1445 m/s, 11.21 cm, when the flow rate of an oxygen lance varies from 500 to 2000 m3/h. The results have been validated against water model experiments. More specially, the relation between the penetration depth and oxygen flow rate predicted by numerical simulation has been found to agree well with that concluded by water model.
关键词:
electric arc furnace
,
three-phase flow
,
numerical simulation
