Some considerations on the polarization resistance method

A new mathematical approach aimed at giving light on the polarization resistance method is developed and its basic ideas are discussed to establish a suitable criterion to be used to compute the left bound ΔE₁ and the right bound ΔE₂ of the ΔE interval where the linear approximation works properly with reference to a prefixed degree of accuracy. Examination of the results relating to the theoretical cases, characterized by the Tafel slope values (40, 120) and (80, 100) mV, stresses that the width L() of the interval, where the linear approximation can be considered valid for a given value of , depends on B_a and B_c, their values determining the position of the inflection point ΔE_i of i(ΔE) where G(ΔE)=(αe^αΔE+βe^−βΔE)/(α+β)−1 exhibits a maximum. The maximum per cent value of the relative error μ, that is less than 10, for values ranging from 1 to 15 indicates that it is reasonable to replace i′(0) with the incremental ratio computed at ΔE₁ or ΔE₂. Furthermore, the Newton method was always successful in determining the values of ΔE₁ and ΔE₂. Applications to experimental polarization data refer to the behaviour of iron in 1 N H₂SO₄ solutions containing KCl at various concentrations. All the experimental polarization curves of the current transient type were best-fitted with a polynomial of the fourth degree over the [−50, 50] mV interval to determine the analytical expression of G(ΔE). The good agreement of the values of R_p, R_pa and R_pc, which are computed at ΔE₂ and ΔE₁ respectively for the case =10, underlines the validity of the present approach in providing accurate information on the resistance to corrosion of iron.     

修边模废料切刀产生铁屑的解决方法

分析了汽车外覆盖件修边模产生铁屑的原因,分别介绍了不产生铁屑的外置式废料切刀、浮动式废料切刀和压缩式废料切刀的结构原理、设计要点、适用范围以及优缺点,解决了修边模废料切刀位置产生铁屑的问题,对汽车外覆盖件修边类模具设计具有一定的参考作用。     

我国废钢铁和用整体下滑,逆转艰难——2013年中国废钢铁市场展望及2012年市场回顾

2012年我国废钢铁市场低迷,供需两弱,废钢铁应用总量自2000年以来第一次出现负增长,废钢比大幅度下滑,跌人谷底,创历史新低.废钢铁回收利用市场进入了一个真正的寒冬期,形势严峻.我国废钢铁利用下滑的主要原因,除欧债危机持续发酵及美国经济疲软,全球大宗商品系统性风险全面爆发等世界经济危机的影响外,我国经济的不景气(2012年中国GDP增长率为7.8％、创2000年以来最低),钢材市场长期低价运行,需求市场疲软,钢铁原料配置不合理,环保违法成本过低,政策引导乏力等都是造成2012年废钢铁回收利用下滑的主要刺激因素.     

日本废钢业发展透视:废钢回收业如何实现“绿色重生”

<正>中国钢铁工业经历了数十年的快速发展,钢铁积蓄量不断增加,今后将有大量的废钢资源产生。如何有效利用、管理这些资源或将是未来中国钢铁工业需要解决的一个重大问题。相关资料显示,短流程炼钢比长流程炼钢可减少废气86%、废水76%和废渣97%,与长流程炼钢相比,用废钢炼1吨钢可减少近1.6吨碳排放,因此废钢生产更加清洁和有利于排废减量化,鼓励能耗低、污染小的电炉炼钢发展无疑有利于环境保护。日本钢铁业的发展与中国有很多类似之处,而且日     

Some fundamental considerations for the control of residual flatness in tension levelling

Tension levelling is a process used in the steel industry in order to remove any shape defects present in temper rolled strip. It is generally the final process before the cold rolled product is despatched to the customer, and therefore plays an important rôle in delivering the desired material properties and the product standards required.

In this paper a designed factorial analysis has been employed in order to study the effect that tension levelling process parameters have on the shape characteristics of the levelled product. These characteristics include residual flatness (longitudinal curvature or longbow), centreline elongation and residual (or internal) stress imbalances; criteria which determine whether the customer accepts the material or not. It has been identified that in a basic five-roll leveller the final, adjustable roll wrap angle, has the most significant influence on these characteristics in over 70% of cases. It has also been determined that final flatness is dictated by many second-order process interactions.     

Issues in the melting and reclamation of aluminum scrap

The processing of aluminum scrap has been practiced for as long as aluminum has been produced due to the inherent value of the metal and the amount of energy required to produce primary aluminum from bauxite ore. Scrap can be remelted at a fraction of the expense. With the large-scale introduction of aluminum beverage containers in the 1970s, increases in energy costs, and the need to reduce solid waste, aluminum recycling has grown at an increasing rate. This article provides a overview of the technologies and issues that surround the melting and reclamation of aluminum scrap.     

The high-speed identification and sorting of nonferrous scrap

There are various approaches to sorting alloys. Perhaps the most simple method and one which is in greatest use today is hand sortation, which is normally a rather inaccurate process. An opportunity exists to recover low-grade nonferrous scrap by sorting it into various alloys with high accuracy by applying spectrographic analysis techniques. This article presents an alternative method for scrap identification and sortation in which optoelectronics are utilized to make a rapid and accurate identification of the scrap item. The scrap is then sorted automatically without operator intervention. Editor’s Note: A hypertext-enhanced version of this article is available on-line at www.tms.org/pubs/journals/JOM/0504/Spencer-0504.html For more information, contact David B. Spencer, Spectramet, LLC, 7 Alfred Circle, Bedford, MA 01730; (781) 275-6400; fax (781) 275-8612; e-mail ccfwte@aol.com.     

Some necessary considerations for the dynamic performance test proposed by the MTIRA

The MTIRA and other research organizations attempted to establish the standard test conditions for the dynamic performance of machine tools, when using cutting test procedure. However, the scatter of data obtained through their procedures even for the same type of machine are so wide that those standardizations may be considered to be quite far from perfection, because they failed to consider some important chucking conditions, e.g. the chucking force, the chucking length, the relative shape of the inner face of jaws with respect to the testpiece specification and the number of jaws. Moreover, their considerations about some of the cutting conditions, e.g. the length of overhang of the testpiece and the approach angle of the cutting tool are not complete ones. This contribution reveals that through the optimization of both the conditions mentioned above it is quite possible to reach the condition of perfection.     

Melting standardized aluminum scrap: A mass balance model for europe

Although individual aluminum recycling companies have good knowledge of scrap in terms of its characteristic metal yield during melting, an overall view of this industry is still missing. An aluminum mass balance for the aluminum recycling industry in the European Union member states from 1995 to 2004 (EU-15) has been carried out. The objective was to increase the transparency of the complex recycling system and to determine how resource-conservative the industry is when melting aluminum scrap. Results show that in 2002, about 7 million tonnes of purchased, tolled, and internal scrap—with a metal content of 94%—were recycled in the EU-15. By comparing the net metal input to the final product, the study finds a very respectable metal recovery rate of 98%. For more information, contact M. Bertram, European Aluminium Association and Organisation of European Aluminium Refiners and Remelters, 12 Avenue de Broqueville, Brussels, Belgium; +32-2-775-63-61; fax +32-2-779-05-31; e-mail bertram@eaa.be.     

模具修边掉铁屑及预防措施

描述了自动化生产线中出现的多种修边掉铁屑现象对现场生产的影响,分析总结了现场掉铁屑产生的各种原因.针对最易导致产生修边铁屑的模具工艺设计从两方面进行分析,并提出预防措施:一方面,在现有修边模具结构的基础上增加便于排料的装置;另一方面,更改模具修边的方式.通过对模具修边方式的更改及优化,降低了达到修边掉铁屑的现象,使产品的质量和精度得到保证,提高了自动化生产线的生产效率.     

直击:“中枪”《加工贸易禁止类商品目录》的废塑料

<正>2014年12月19日,商务部和海关总署公告2014年第90号公布《加工贸易禁止类商品目录》,并于2015年1月1日实施,同时商务部、海关总署2009年第37号公告和2010年第63号公告所附目录停止执行。该目录对先前的加工贸易禁止类商品目录进行了调整,意在保持外贸稳定增长、优化进出口商品的结构。其中,     

科技创新：为废钢加工产业的发展提速

近年来,国家倡导建设“资源节约型、环境友好型”的社会,提出“到2020年前我国单位国内生产总值二氧化碳排放比2005年下降40％-45％的减碳目标”。作为节能减排重点行业之首的钢铁工业,无疑将在其中担当主要角色。从生产源头考虑,优化原料结构,合理采用铁矿石,增大载能、环保的废钢铁原料的使用比例,     

修边模二次废料切刀结构设计

阐述了普通修边模的基本结构,重点介绍了二次废料切刀的结构设计、应用范围、注意事项及工作过程。设计的二次废料切刀在传统废料切刀基础上进行了改进和创新,有效减少了汽车外板件修边时容易产生铁屑和毛刺的问题。     

冲模切边碎屑产生原因及解决方法

根据修边碎屑的不同形状对修边碎屑进行了分类,并对不同类型碎屑的产生机理进行了分析,针对不同类别的碎屑制定了不同的解决方案,与传统的解决方案相比,新方案更简单可靠,并且降低了模具制造成本。     

Preparation and characterization of tungsten nanopowders from WC scrap in molten salts

Tungsten carbide (WC) scrap was used as a consumable anode to prepare tungsten powder in NaCl–KCl melt at 1023 K for the first time. The electrolysis process was investigated. Results showed that the tungsten component in WC anode was dissolved as W^2 + into the NaCl–KCl melt. The cathode reaction was controlled by the diffusion of tungsten ions. The effect of electrolysis parameters, including the anode–cathode distance, cathode current density and different electrolysis ways (galvanostatic and potentiostatic electrolysis), on the purity and grain size of the cathode deposits was studied. It showed that a large anode–cathode distance was beneficial to the formation of pure tungsten powder at the cathode. With increasing the cathode current density, the tungsten grain size first decreased and then increased. When the cathode current density was 0.125 A cm^− 2, tungsten powder with a diameter of smaller than 100 nm was obtained. Deposits prepared through galvanostatic and potentiostatic electrolysis was compared in the end.     

成形顶盖的废料切刀设计

介绍某车型成形顶盖采用新型切边工艺及上、下模切刀结构,以保证切边模具在自动化生产线上能稳定顺畅地使废料滑落。经生产现场验证,一次合模切断的整块废料能稳定地滑落到废料切刀上,二次合模时完成切断,切断后的废料滑落顺畅,验证了该工艺方案的可行性。     

Recycling of metal bearing electronic scrap in a plasma furnace

The recycling of electronic waste and the recovery of valuable components are large problems in the modern world economy. This paper presents the effects of melting sorted electronic scrap in a plasma furnace. Printed circuit boards, cables, and windings were processed separately. The characteristics of the obtained products (i.e., alloy metal, slag, dust, and gases) are presented. A method of their further processing in order to obtain commercial products is proposed. Because of the chemical composition and physical properties, the waste slag is environmentally inert and can be used for the production of abrasives. Process dusts containing large amounts of carbon and its compounds have a high calorific value. That makes it possible to use them for energy generation. The gas has a high calorific value, and its afterburning combined with energy recovery is necessary.     

武钢：废钢铁应用管理的蜕变方略

废钢铁是节能环保、可循环利用的炼钢冶炼的重要原料,废钢铁在钢铁工业发展中起着举足轻重的作用。钢铁_T业的原料是铁矿石和废钢,铁矿石是自然资源,而废钢是再生资源,在炼钢生产中,能源消耗和污染排放主要集中在烧结、焦化、炼铁等工序,占炼钢能耗总量的60％以上。     

新型碎边剪的设计与分析

设计了一种新型碎边剪,分析了刀盘在刀轴上的几种安装方式及安装方式对刀片侧间隙调整的影响。根据设计结构,推导出了侧间隙调整数学模型,为剪刃侧间隙调整机构自动化奠定了基础。对新机型与旧机型进行了对比分析,便于剪切设备的选型。