New measurement of melting and thermal conductivity of iron close to outer core conditions

The amount of literature on both melting and thermal conductivity of iron at Earth’s core conditions is overwhelming and the discrepancies are very large.There is a broad range of experimental techniques each of which is flawed to a certain degree,which may explain the discrepancy.In this report,we present new data using a different method for determining the phase behavior and resistivity of iron in the laser-heated diamond cell by measuring the electrical resistance of both solid and liquid iron wires.The experiment avoids some of the major flaws of previous experiments,the most important of which is the detection of the onset of melting.These measurements confirm a shallow melting curve found earlier and the resistivity data imply a trend towards low thermal conductivity in the liquid outer core.

Geostatistics Studies and Geochemical Modeling Based on Core Data,Sheytoor Iron Deposit,Iran

In general,the purpose of the mineralization modeling is the advancement of a mineral exploration project and ultimately,the extractive design of a deposit,which is one of the most important stages in mining engineering.Mineralization modeling is divided into two general categories,superficial and deep modeling.In surface modeling,the aim is finding abnormal locations in terms of mineralization at the study area,which is commonly used in the early stages of exploration as one of the means for locating exploratory boreholes.After drilling in the study area with the aim of identifying mineralization and reserve estimation it is necessary to obtain deep mineralization position and its geometric features,using statistical and modeling methods.Using mathematical,statistical and modeling methods,we can predict the position of iron mineralization in places where drilling is not done and eventually reach a three-dimensional model of the mineral materials underground.As a case study,the deep information about the boreholes of the sheytoor mining area in Yazd province of Iran was investigated.Iron mineralization was modeled as 2D cumulative model and 3D block model,and the results were presented.Finally the geochemical threshold and the anomalous limit of iron element are calculated by concentration-volume(C-V)fractal method in this deposit.Geochemical threshold and the anomalous limit for Fe in this deposit are 24.7%and 34.3%respectively.

Calculation of Magnetic Field in J-TEXT with an Unsaturated Iron Core

A study of the magnetic field with an unsaturated iron core in tokamak equilibrium using a spool model is described in detail. The application of this model to the J-TEXT tokamak shows that the calculated results are in good agreement with those measured experimentally. At present this scheme is used to give the plasma configuration during J-TEXT＇s operation.

Analysis and Design of the Iron Core as the Arc Snubber in the EAST NBI System

A special winding iron-core is designed to act as the snubber for the neutral beam injection （NBI） power supply （PS） system in EAST, which will limit the fault current and energy caused by occasional sparking in the NBI ion source. 50-50 Ni-Fe is chosen as the high-frequency magnetization material for the iron-core. Equations for the snubber is derived from the design of the iron-core. The iron-loss factor and eddy-current losses are found to increase in a sample experiment at a frequency from 1 kHz to 20 kHz. A 1：10 miniature of the iron-core is tested and performs well with a fine capability.

Raman Spectroscopic Core Scanning for Iron Ore Characterisation

Automated core scanning technologies for mineralogical characterisation of diamond core, drill chips pulps is now an established technique, particularly in the Australian iron ore industry, for mineral analysis in exploration and mining. Application of reflectance spectroscopy over the 400–2500 nm, visible to near-infrared wavelength range, has been used to characterise the iron ore oxide mineralogy of bedded iron deposit (BID) derived iron ores in India (Thangavelu et al., 2011) and Brazil (da Costa et al., 2009), and used to define the ore and gangue (e.g., clay) mineralogy in ironstone or channel iron deposits (CID) in the Pilbara region of Western Australia (e.g., Haest et al., 2012).

The anisotropy of hexagonal close-packed iron under inner core conditions: the effect of light elements

In recent decades,global seismic observations have identified increasingly complex anisotropy of the Earth’s inner core.Numerous seismic studies have confirmed hemispherical variations in the inner core’s anisotropy.Here,based on ab initio molecular dynamics calculations,we report how the anisotropy of hexagonal close-packed(hcp)-iron,under inner core conditions,could be altered when alloyed with light elements.We find that light elements in binary allows with iron-hcp-Fe-X(X=C,O,Si,and S)-could have significant effects on density,sound velocities,and anisotropy,compared with the behavior of pure hcp-iron;the anisotropy of these binary alloys depends on combined effects of temperature and the particular alloying light element.Furthermore,the change in anisotropy strength with increasing temperature can be charted for each alloy.Alloying pure iron with some light elements such as C or O actually does not increase but decreases core anisotropy at high temperatures.But the light element S can significantly enhance the elastic anisotropy strength of hcp-Fe.

Effect of Carbon and Sulfur on Iron Melting at High Pressure:Implications for Composition and Evolution of the Planetary Terrestrial Cores

The presence of light element(s)in the Earth’s core is necessary in order to explain the observed density and velocity discrepancy for the core(Anderson and Ahrens,1994).O,Si,S,C and H were suggested as potential candidates based on cosmochemical considerations(Stevenson,1981).High-pressure experiment results,in conjunction with theoretical and cosmochemical evidences,argued that it is difficult for any one of them to account for the core

CeO_(2)添加量对电弧增材制造铁基形状记忆合金组织和性能的影响

采用粉芯丝材+电弧增材制造技术制备了含不同质量分数(0,1%,2%,3%)CeO_(2)的Fe-14Mn-6Si-9Cr-5Ni铁基形状记忆合金,研究了CeO_(2)添加量对试验合金显微组织和形状记忆性能的影响。结果表明:添加质量分数1%的CeO_(2)后,合金晶内析出相减少,晶界处析出较大尺寸的稀土化合物,组织均匀,弯曲变形后未出现ε马氏体跨晶生长现象,且马氏体交叉状态较少;当CeO_(2)质量分数增加至2%和3%时,晶内析出相增多,分布均匀性变差,且在弯曲变形后ε马氏体跨晶生长和交叉特征增多;随着CeO_(2)添加量增加,试验合金的晶粒尺寸减小,层错概率增大,形状回复率先增大后减小,当CeO_(2)质量分数为1%时晶粒尺寸较小,层错概率较大,形状回复率最大,形状记忆性能最好。

甜玉米芯多糖铁配合物的工艺优化及体外活性

甜玉米芯多糖(SCP80)与三氯化铁共热合成了甜玉米芯多糖铁配合物(SCP),在单因素实验基础上,采用响应面法优化了SCP制备工艺。通过SEM、XRD、TG、纳米粒度及Zeta电位分析仪、UV-Vis和FTIR对SCP进行了形貌和结构表征,并测定了其体外抗氧化及降糖活性。结果表明,50 mL质量浓度为1 g/L的SCP80水溶液合成SCP的最佳合成工艺为:反应温度75℃、反应时间64.6 min、pH=8.5、m(SCP80)∶m(柠檬酸三钠)=3.64∶1。在该条件下制备的SCP中铁质量分数为27.89%±0.35%。与SCP80相比,SCP表面更光滑,粒径从43.8 nm(SCP80)增至164.0 nm,具有更好的热稳定性,更好的清除羟基自由基能力和还原能力,质量浓度为4.0 g/L的SCP对羟基自由基的清除率为57.51%;SCP对α-淀粉酶半抑制浓度(IC_(50))为(1.20±0.11) g/L,对α-葡萄糖苷酶的IC_(50)为(0.92±0.07) g/L,其体外降糖活性明显优于SCP80。

一种适用于随钻核磁天线的磁芯材料

介绍了一种随钻核磁天线的铁粉芯磁芯材料,该材料具备高饱和磁通密度,并具备较低的介电损耗,并具备高绝缘强度,并在强磁环境下不产生磁致伸缩效应,较好的解决了随钻核磁测井仪探头敏感区域设计需求。

新能源驱动电机铁芯防锈包装存在问题及解决方案

针对新能源电机用铁芯储运过程中的防锈包装要求,分析电机用铁芯防锈包装现状,系统梳理当前电机用铁芯防锈包装存在问题,提出解决方案,明确电机用铁芯防锈包装未来发展趋势,为进一步提升新能源电机用铁芯防锈包装洁净度及可靠性提供参考。

一起低端换流变压器油中缓慢产生乙炔故障分析

本文作者分析了一起低端换流变压器运行中产生乙炔气体的故障,介绍了现场检查情况,分析认为铁心紧固件松动是引起故障的原因,提出了现场维修理方案并实施,最后消除了故障。

通过优化偶联剂含量改善磁粉芯综合性能

磁粉芯在工程应用中会遇到体积变化引起的开裂、磁性能低等问题,目前未见关于这方面的研究。通过在羰基铁粉磁粉芯(包含磁环、磁片和一体成型电感)中加入不同含量KH550硅烷偶联剂,研究其成型性、磁性能和力学性能,并利用SEM、TMA和LCR等测试分析偶联剂对磁粉芯性能影响的作用机理。研究表明偶联剂能将树脂“约束”在磁粉表面,并在固化过程中带动磁粉颗粒重排,从而增加磁粉芯的膨胀系数。添加0 wt.%和0.1 wt.%偶联剂的磁粉芯具有负的膨胀系数,容易收缩开裂。当偶联剂含量达到0.3 wt.%、0.5 wt.%和0.7 wt.%时,树脂固化过程中磁粉芯的膨胀系数升高,从而增加磁粉芯的体积,有效抑制磁粉芯的开裂倾向。但是,体积的增加会降低磁粉芯的密度、磁导率、Q值和力学性能,增加损耗。综合考虑磁粉芯的成型性和其他性能,偶联剂添加的最佳比例是0.3 wt.%。揭示了偶联剂对磁粉芯膨胀系数等综合性能的影响规律,可为高性能磁粉芯的工程化应用提供重要理论依据。

核壳式球形铁基磁性磨料的制备及其抛光性能

[目的]混合式和镶嵌式磁性磨料的尺寸效应,以及磨粒出刃高度不一致所引起的抛光硬冲击问题亟待解决。[方法]将不规则铝粉与球形羰基铁粉均匀混合,通过加热扩散在接触界面生成金属间化合物并均匀分布在球形羰基铁粉表面,从而形成铁/铝核壳式球形磁性磨料,随后用它对氟化钙基片进行抛光。[结果]通过单因素试验优选出制备该核壳式铁基磁性磨料的最佳工艺参数为:反应时间4 h,反应温度770℃,Al含量质量分数12%。X射线衍射(XRD)、扫描电镜(SEM)观察、能谱(EDS)分析和磁化强度测试表明所得磁性磨料以羰基铁粉为内核,Fe Al、Fe_(3)Al、Fe_(0.4)Al_(0.6)等金属间化合物为壳,粒度符合正态分布,磨料相外壳分布均匀且出刃高度较为一致。氟化钙晶体经铁/铝核壳式磁性磨料抛光后表面变得光滑、平坦,粗糙度均方根值由初始的1.102μm下降到33 nm。[结论]所制备的核壳式球形铁基磁性磨料可用于软脆材料的磁力抛光。

非晶合金-取向硅钢组合铁心结构设计及其磁-振动特性分析

非晶合金和取向硅钢是制作配电变压器铁心常用的两种软磁材料,各有优劣。采用非晶合金-取向硅钢组合铁心结构可以综合两者的优势。该文以非晶合金和取向硅钢铁心并排的组合结构为基础,选取组合铁心的取向硅钢占比和尺寸参数为自由变量,提出一种基于自由参数扫描法的组合铁心结构设计方法。首先,根据非晶合金-取向硅钢组合铁心结构特点,建立组合铁心的等效双非线性磁路模型;其次,采用磁路法迭代求解组合铁心的磁通密度分布,并制定组合铁心的结构设计流程;最后,根据结构设计结果制作了组合铁心的实验模型,采用实验和有限元仿真结合的方法分析了其磁-振动特性,验证了所提设计方法的准确性,并与传统纯非晶合金和纯取向硅钢铁心进行对比分析,阐述了组合铁心的优势。

高铬铸铁叶片堆焊工艺研究进展

高铬铸铁因良好的耐磨损、强度、韧性及抗高温、耐腐蚀性能,常被应用于抛丸机叶片、大型挖泥泵叶轮、水泥球磨机耐磨衬板等受磨损冲击的器件,通常采用堆焊工艺对高铬铸铁工件的磨损表面进行修复,以延长其使用寿命,降低制造新工件时产生的资源消耗。本文综述了高铬铸铁叶片堆焊过程中焊接电流、层间温度、冷却条件等工艺参数对高铬铸铁堆焊层组织结构、晶粒大小的影响,讨论了钒、钛、铌、稀土纳米颗粒等合金粉末及由合金粉末制成的药芯焊丝对高铬铸铁堆焊层组织成分、组织结构的影响,对比了现有传统堆焊工艺缺陷,指出了堆焊加工工艺未来发展的方向。

TiC对亚共晶高铬铸铁堆焊合金组织及磨损性能的影响

农机触土部件在作业过程中会受到土壤中沙石、杂草、植物的秸秆、根茬及其他有机质物体的磨损和冲击,极易发生失效报废。为解决农机触土部件耐磨性差、使用寿命短等问题,采用药芯焊丝电弧焊的方法在Q235钢基体上进行堆焊,制备含TiC的亚共晶高铬铸铁堆焊耐磨层。通过金相显微镜、洛氏硬度计、X射线衍射仪(XRD)、扫描电子显微镜(SEM)、能谱仪(EDS)、MLS-225型湿式橡胶轮磨粒磨损试验机和自制叶轮-滚筒冲击磨损试验装置,分析原位合成TiC和粉芯中直接添加TiC两种方法对亚共晶高铬铸铁堆焊合金微观组织、硬度、抗磨粒磨损性能及抗冲击磨损性能的影响。结果表明:耐磨堆焊合金主要由γ-Fe、α-Fe、M_(7)C_(3)和TiC组成,TiC的加入细化了组织中的先析出奥氏体,使得堆焊层宏观硬度增加,磨粒磨损后共晶碳化物的开裂和剥落现象减少,冲击磨损表面材料的脱落减少,磨损失重降低。TiC可以显著提高堆焊合金的抗磨粒磨损性能和抗冲击磨损性能,其中原位合成方式添加TiC的堆焊层性能更加优异,可为TiC在农机触土部件耐磨涂层中的研究和应用提供参考。

一种变压器硅钢卷料精准排样的设计与实现

为提高变压器硅钢卷材纵剪利用率,本文作者讨论了一种二维下料问题,提出了一种改进型动态规划算法,可以将计算精度与计算量优化结合,使卷材排样利用率逼近最优。

球墨铸铁冷却壁心部性能研究

球量铸铁件的心部性能成为衡量球墨铸铁冷却壁内部质量的一个重要指标。技术要求为心部抗拉强度R_(m)≥350 N/mm^(2),伸长率A≥8%;心部金相组织球化率≥70%,铁素体含量≥80%。由于球墨铸铁冷却壁属于厚大铸件,受凝固特性、冷却速度和合金元素等因素的影响,心部性能不稳定,通常无法达到技术协议的要求。本文分析了心部性能较低的原因,提出了工艺改进措施,进行了冷却壁解剖试验,验证了试验效果。

不同纳米晶铁芯结构下高频变压器空载铁耗特性

为了研究高频变压器采用不同纳米晶铁芯结构时的铁芯损耗分布特性,以工作频率为10kHz,容量为20 kVA的U型、三角型和O型结构纳米晶铁芯为研究对象,对比了3种铁芯空载运行时铁芯不同位置磁密和铁耗分布情况,进一步研究了拐角内径对铁芯局部损耗特性的影响。结果表明:O型铁芯损耗密度分布较均匀,U型和三角型铁芯的损耗密度在磁路直线区域分布均匀;在拐角区域径向方向上,损耗密度减小速度先快后缓,切向方向上损耗密度先增大后减小;U型和三角型铁芯拐角处损耗密度最大值显著大于直线区域,适当增大拐角内径,能够显著降低铁芯的最大损耗密度;实验测得U型、三角型和O型铁芯空载损耗分别为37.3 W、50.5 W和20.5 W,局部热点温度最高分别为46.5℃、55.2℃和35.0℃,明显高于铁芯最高平均温度。