检索结果-南通市图书馆

Phase Formation and Magnetic Properties of Nanocomposite Nd-Fe-b Adjusted by Small Amount of Dy and Co

Journal of Rare Earths 2004年第Z2期22卷 89-94页

作者： T S Jang T W Lim H S aum D H Lee M b kim Division of Materials and Chemical Engineering Sun Moon UniversityKorea Division of Materials and Chemical EngineeringSun Moon UniversityKorea Division of Mechanical EngineeringSun Moon University 100 Kalsan LiTangjung MyonAsan CityChoongnam 336-708Korea Division of Materials and Chemical EngineeringSun Moon UniversityKorea Division of Materials and Chemical EngineeringSun Moon UniversityKorea

In order to improve and stabilize the magnetic properties of nanocomposite Nd2Fe14b/α-Fe magnetic alloys by a compositional adjustment, small amount of Dy and/or Co was added to Nd9Fe84b7 alloys. DTA analysis on the amorphous of the alloys took place as the soft magnetic phases were crystallized, and then the hard magnetic Nd2Fe14b was precipitated from them. While α-Fe and a metastable 1:7 (TbCu7-type) phase were formed simultaneously in Dy and Co-free alloys, they were crystallized separately at different temperatures after Dy or Co was added. This phase separation occurred more clearly in the Dy-treated alloys and the other soft magnetic phase Fe3b was also stabilized by Dy and/or Co. The 1: 7 phase that was stabilized by Dy and/or Co was not eliminated at 700 ℃, decreasing magnetic properties of the alloys. It was eventually disappeared above 725 ℃, but Fe3b was not eliminated even at 750 ℃ when Dy was added more than 0.5 at% or Co was added more than 2.0 at%. Amount of Nd2Fe14b in the alloys tended to increase as Dy addition increased,whereas Co addition did not lead to any appreciable change in the ratio of α-Fe and Nd2Fe14b. Moreover, Dy addition apparently increased coercivity of an alloy while Co addition had a beneficial effect on remanence. The grains in the Dytreated alloys were usually finer than those in the Co-treated alloys. The grain size of both α-Fe and Nd2Fe14b in the alloys exhibiting mr ≥ 0.72 was in the range of 20 ～ 40 nm or even larger 50 nm, which is larger than the theoretical optimum size ( ～ 10 nm). Typical magnetic properties obtained from a Nd7.5Dy1.5Fe82.5Co1.5b7 alloy annealed for 12 min at 725 ℃were iHc=4.85 kOe, br= 11.32 kG, (bH)max = 15.73 MGOe, and mr=0.73.

关键词： nanocomposite Nd-Fe-b magnetic properties remanence coercivity

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

ON FORMATION OF TIDAL FRONTS IN COASTAL SEAS

引用

Journal of Hydrodynamics 1998年第3期10卷 17-28页

作者： Wang Xiao-huaDepartment of Geography and Oceanography, University College, Australian Defence ForceAcademy, Canberra ACT 2600, Australia, Email :h-wang @ adfa.oz. aum. L. HeronPhysics Department, James Cook University Townsville, Q 4811, AustraliaChen WeiThe Second Institute of Oceanography, State Oceanic Administration, Hangzhou 310012,P. R. China Australian Defence Force Acad Canberra Australia

An energy equation which includes the effects of potential energy, turbulent dissipation, heat flux and density flux due to fresh water discharge from estuaries is derived to evaluate the formation of frontal structures in coastal seas. Two different forms of tidal mixing criteria emerge which are the h/u3 of Simpson and Hunter (1974) for openshallow water and the h/u of Nunes et al (1989) for estuaries. The theory is capable ofpredicting tidal fronts in areas where both surface and lateral input of buoyancy are significant. The theory is applied to a tidal estuary and the locations of haline fronts which result from the influence of the fresh water discharge are predicted. The effect of surface heating on the formation and location of the frontal system is also discussed for the estuary.

关键词： tidal fronts coastal sea

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

氮养料和干酒糟对奶牛氮利用率的影响

引用

饲料博览 2011年第10期21卷 20-20页

作者： Greenquist M A Schwarz A k klopfenstein T J Schacht W H Erickson G E V ander Pol k J Luebbe M k brink k R baleseng L b 张树金不详

试验选择135头330±10kg杂交阉牛,采用完全随机区组化设计,旨在评估给在无芒雀麦牧草地放牧的1岁阉牛饲喂含玉米酒精糟(DDGS)替代饲草和氮养料对阉牛氮利用率的影响。分为3个处理组,阉牛按每公顷牧草地6.8头月单位(aum)在不施氮肥的无... 详细信息

试验选择135头330±10kg杂交阉牛,采用完全随机区组化设计,旨在评估给在无芒雀麦牧草地放牧的1岁阉牛饲喂含玉米酒精糟(DDGS)替代饲草和氮养料对阉牛氮利用率的影响。分为3个处理组,阉牛按每公顷牧草地6.8头月单位(aum)在不施氮肥的无芒雀麦牧草地放牧(CONT组);9.9aum在每公顷施90kg氮的无芒雀麦牧草地放牧(FERT组);9.9aum在不施氮肥的无芒雀麦牧草地放牧,每头阉牛每天添加DDGS2.3k(gSUPP组)。以围场作试验单元,每年每个处理3个重复,共3年。在160d放牧期中,围场实行条状放牧,采用减添牛的方法来维持围场之间相似的放牧强度。试验结果表明,阉牛采食较少的饲草(P<0.01),但是SUPP组每头阉牛、每公顷牧草地采食的总氮比FERT组多(P<0.01),而SUPP组和FERT组又比CONT组多(P<0.01)。与CONT组和FERT组相比,SUPP组阉牛的氮滞留提高31%(P<0.01)。SUPP组每公顷氮滞留比FERT组和CONT组分别高30%和98%。SUPP组每头阉牛、每公顷牧草地的氮排泄也比FERT组多(P<0.01),SUPP组和FERT组高于CONT组(P<0.01)。CONT组、FERT组和SUPP组阉牛的氮利用率相似(P=0.29)。与FERT组相比,SUPP组基于系统的氮利用改善144%(P<0.01)。试验结果表明,DDGS提高了1岁阉牛的氮采食量和氮排泄量。不过,由于体增重的提高和牧草地载畜量的增加,DDGS可作为无芒雀麦放牧制度提高氮利用率的有效方法。

关键词：肉用牛玉米酒精糟氮养料氮利用率

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：