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By Sugui Tian

By means of the T6 treatment, the measurement of creep curves and microstructure observation, the influence of T6 heat treatment on the microstructure and creep properties of Ti-6Al-4V alloy is investigated. Results show that the microstructure of the forged alloy consists of the banded-like a phase and networks b phase. After sub-temperture T6 treated, the microstructure of alloy consist of the block a phase and ?networks basket? structure. Under the conditions of the applied stress of 575 MPa at 4000C, the forged alloy displays a lower creep lifetimes, after T6 treated the creep lifetimes of the alloy is enhanced to 548 h from 66 h, which is attributed to the formation of the network basket structure in which the needle-like phase are dispersedly distributed. As creep goes on, the denser dislocations in the a phase are concentrated to occur the dynamic recrystallization for refining grain. which is a main reason of the alloy displaying a better creep lifetimes and plasticity. Thereinto, the creep mechanism of the forged alloy is thought to be the slip of the straight <a> and <a+c> dislocation are activated on the prismatic planes and pyramidal planes, while the creep mechanism of T6 treated alloy is that wave-like <a+c> dislocations are activated on the pyramidal planes.

Jan 1, 2009

By Neale R. Neelameggham, Brian R. Davis

Organic agriculture is using natural materials such as degrading plant matter to replenish soils. This includes use of naturally degraded plant components such as peat, humus and weathered brown coals. Another important natural organic matter which has not been applied in agriculture thus far has been the black coal, Here we show that reversing the coal formation reaction by combined hydro-oxidation principles of biochemical engineering in natural conversion methods in an accelerated fashion. The modified coal soil additive can convert arid lands into farm lands for the future to sustain the population growth. In addition, the development of this new use of black coal will revive economically deprived areas from phasing out coal in the USA and Europe. This will show how the Stored energy in coal can be made renewable in helping plant growth under the soil to facilitate above ground photosynthesis.

Mar 1, 2018

By D. A. Hayman, J. D. Steenkamp, G. M. Denton

Design of furnace containment systems can be based on one of two design philosophies: Insulating or conductive lining designs. In insulating lining designs, management of the compatibility between refractory materials and process materials (typically liquid metal and/or slag) is an important criterion for furnace design, and an important process parameter to control during furnace operation. In conductive lining designs, management of the integrity of the layer of frozen material (freeze lining) on the interface between the liquid process material, and the refractory lining, is important. For example in ferrochromium production, both lining design philosophies are applied. The work presented here discusses the significance of lining design philosophy in the context of ferrochromium production.

Mar 1, 2017

By Toshiyuki Hashida, Victor M. Lopez-Hirata

"Small-punch tests and determination of fracture toughness JIC were conducted at 4 and 77 K on new cryogenic JN1, JJ1 and JK2 austenitic stainless steels, after isothermal aging. Equivalent fracture strain ?qf determined by measuring the reduction of thickness in the small-punch test specimen. A linear dependence of JIC on ?qf was found in these new materials. Regression analysis of experimental data produced the following linear relation JIC = 1304.1 ?qf + 8.09 [kJm-2]. An analysis of present work relation was pursued on the basis of material properties and evaluation method of he. Results showed that the slope value has a strong dependence on material yield strength and JIC evaluation method. This linear relation is useful for the evaluation of fracture toughness JIC, measuring the equivalent fracture strain ?qf by means of small-punch test. Thus it can be useful for assessing the degradation of fracture toughness in small areas such as, the heat-affected zone in welded components.IntroductionCryogenic structural materials for superconducting magnets of fusion nuclear reactor are required to possess a good combination of strength and toughness. The mechanical properties are required beyond the capability of conventional austenitic stainless steels [1]. New cryogenic JN1, JJ1 and JK2 austenitic stainless steels were developed by the Japan Atomic Energy Research Institute (JAERI) [1]. The structure of superconducting magnets is constructed by welding of 200 = thick plates of these steels, which are solution treated at high temperatures and then water-quenched to avoid intergranular precipitation. However, the welding process involves heating and cooling [2], which cause microstructural changes in both base metal and weld. In this heterogeneous microstructure, it is important to estimate the fracture toughness of these materials at cryogenic temperatures. Therefore, it is necessary to evaluate the effect of aging process on the fracture toughness behavior of these new steels. To determine the cryogenic fracture toughness, the elastic-plastic JIC value has been co=only used [2]; however, the specimen size is much larger than heat-affected zones in welded components. Small-punch (SP) testing method, employing miniature specimens, has permitted to evaluate the fracture toughness behavior at different temperatures in different nuclear reactor materials [3,4]. Mao et al. [5,6] and Misawa et al. [7] found a linear relation between JIC value and equivalent fracture strain ?qf, determined by SP method in non-ferrous alloys and ferritic steels at room temperature and austenitic stainless steels at 4 and 77 K, respectively. So that, this kind of correlation would be very useful to assess the fracture toughness JICe values by means of SP test in small zones of welded components."

Jan 1, 2012

By Mingchun Lu, Yunjin Yan

"This paper describes a new type of bell-less top installed on two relined blast furnaces at Tianjin Iron Works and another new-built at Echeng Steel Works in China. A compact installation was presented for existing furnace top innovation with the least reformation of existing top structure. A water cooling and sealing gearbox used for driving the chute discards completely the traditional idea about necessity of continuous supply of cooling gas for the gearbox. A multiring spreader and its dozens of selectable charging patterns enables an operator to achieve optimal burden distribution easily under the condition of a minimum investment of control equipment. Some useful conclusions have been made through a small-size model and a full-scale model tests. The excellent characteristics and the superiority of the new top have been fully proved at both works.IntroductionIt is known that there are some advantages with the bell-less top of a blast furnace: suitable for furnace to operate at high top pressure, capable of realizing optimal burden distribution, less investment and maintenance costs, etc. But why do most of blast furnaces in the world still remain using conventional bell top. One of the concerns is that current bell-less tops still have some shortcomings:1) The height of a current bell-less top might be lower than three or four-bell top or two-bell plus valve seal top, but still much higher than an ordinary two-bell top.2) The gearbox for driving the rotating chute is positioned onto the lip of the furnace. It is subject to attack by crude hot bf gas. Continuously pumping cooling gas (pressurized nitrogen or clean bf gas) into the gearbox is indispensable to withstand such a harsh working environment. Therefore, a plant furnished with blower8 and its ancillaries has to be built, It involves a large sum of investment and much expense in its annual running costs.3) Although the current bell-less charging device as a means of controlling burden distribution possesses a wide range of freedom, it is difficult to realize optimal burden distribution. There are some large blast furnaces realized better burden distribution, but sophisticated control means is indispensable so that the investment of control means is much higher."

Jan 1, 2000

By Stein Tore Johansen, Fionn Iversen, Jon Arne Bakken

"A new marker chain front tracking method is used for modelling the meniscus movement during DC casting of aluminium ingots. Modifications have been made to an earlier method developed by Popinet and Zaleski [12] to adapt the model for simulations of meniscus dynamics in the casting process.Initial casting simulations show that wetting conditions in the mould greatly influence the meniscus stability. Controlling the wetting conditions seems to be important for improving the cast ingot surface quality.IntroductionIn conventional direct chill (DC) hot top casting of aluminium extrusion ingot with gas-slip poor surface quality of the cast ingot can be a problem. In the worst cases pronounced surface wrinkling occurs coupled with periodic zones of reduced grain size, macrosegregation and exudation at the surface. The observed surface irregularities are believed to be linked to Periodic surface oscillations or folding of the meniscus resulting in varying solidification conditions.The focus of this work is to gain a better understanding of the dynamics of the meniscus and the influence it has on the finished cast ingot surface through numerical simulations of meniscus movement during the casting process.A two phase marker chain front tracking technique[12] using cubic spline surface reconstruction is applied for modelling the meniscus movement. The advantage of this type of model is its accuracy in the calculation of surface tension forces. Also the wetting can be implemented directly as a boundary condition on the surface spline function. The method is applied in the FLUENT solver, which is based on a finite volume method using the SIMPLE algorithm."

Jan 1, 2001

By Tianzu Yang, Weifeng Liu, Lin Chen, Wei Chen, DUCHAO ZHANG, HUI XIAO

Oxygen-rich side blow bath smelting (OSBS) technology was developed in 2000 based on Vanyukov process. This technology exceeds the traditional pyrometallurgical methods by its great processing capability, high metal recovery and environmental-friendly property. In the past 15 years, OSBS technology extended its application area from lead industry to bismuth, antimony and waste recycling industries, etc. This paper introduces the history and new developments of OSBS technology. The typical industrial applications examples of the OSBS technology in China, including high lead slag reduction, low grade bismuth-lead concentrate smelting and metallurgical waste recycling, are reviewed. Especially, the unique furnace properties and technical parameters are compared. Finally, the potential research directions of OSBS technology are summarized.

Jan 1, 2016

By A. P. Paiva

Although the advantages of Solvent Extraction for separation/purification of relatively concentrated solutions are well known in Extractive Metallurgy, its use for the recovery of elements present in low levels only recently has been discussed, with particular attention devoted to precious metals. In this work, the extraction behaviour of Cyanex 471X towards silver, from an acidic chloride medium is reported, the extraction and stripping isotherms and related kinetic features analysed. Results on the selectivity of silver extraction against high contents of iron, copper and lead are discussed. Phosphine sulphide extractants are generally associated with solvation mechanisms: analysis of the extraction pathways along with the possibility of reaching a suitable loading in the organic phase are also presented.

Jan 1, 1993

By D. Holdridge, D. Liao, S. Waterfall, N. Strobl, S. Sun

High melting point inclusions, such as spinel, alumina and AlO rich calcium-aluminates, have a strong tendency to agglomerate on the tundish stopper rod and Submerged Entry Nozzle (SEN) during the steel casting process, and eventually to cause SEN clogging. Calcium treatmen by wire injection during steel refining during Ladle Metallurgy (LM) is commonly used to modify these troublesome inclusions to lower melting point inclusions. However, too much Ca injection (Ca over-treatment) can cause operational issue (e.g. slide gate plate erosion),as well as increase Ca cost. Therefore, it is desirable to add an appropriate amount of Ca to avoid either under-or over-treatment. Based on inclusion analysis with an ASPEX® computer controlled scanning electron microscope (ASPEX) instrument, AlO and AlO rich calcium-aluminates were identified as a major cause of SEN clogging at ArcelorMittal Dofasco Electric Arc Furnace (EAF) steelmaking stream. A Ca treatment index was developed to improve the inclusion modification. The improved inclusion control has reduced SEN clogging and enhanced steel quality.

Mar 1, 2017

By Vladyslav P. Yakubovsky, Boris I. Bondarenko, Valentin A. Noskov, Vladyslav M. Sokolov

"Each of Ukrainian producers of ferronickel, stainless steel and synthetic diamonds has the same basic problem with recycling their fine Ni-containing secondary materials. The conditions for generation of them along with the correspondent properties were investigated in details. The new approaches for their recycling have been proposed. They are based on application of some pyrometallurgical processes that are used in Ukraine. The proper equipment is also available. It has been shown that the dust from laterite calcining process of ferronickel production should be efficiently recycled by sintering. The stainless steel dust should be smelted after briquetting as a charge addition to the Ni-containing discarded batteries in the elaborated furnace. The sludge after synthetic diamonds production should be pelletized and processed by liquid cast iron with application of induction magnetodynamic forces in the specific furnace.IntroductionThe object of the investigation is recycling the Ni-containing secondary fines in a form of dust and sludge. There are several generators of the fines in Ukraine. Namely they are Pobuzhye Integrated Ferronickel Mill; Electrometallurgical Works “Dneprospetsstal” with stainless steel plant as well as Poltava Diamond Plant that produces synthetic hard materials. Their businesses are the largest in the Commonwealth of Independent States (CIS). However the status of handling with the fines is not perfect since the applied recycling technologies are low efficient. The landfilling option is often adopted for them. At the same in Ukraine there are some nontraditional pyrometallurgical recycling technologies and equipment that should be tried for application in smelting these secondary materials.Recycling the sludge of synthetic diamonds productionThe sludge of “Poltava diamond plant” from production of synthetic hard materials has a following chemical composition, %: iron oxide – 29.7; chromium oxide – 18.97; nickel – 4.27; manganese oxide – 15.2; sulphate – 3.85; natrium – 14.9. The content of moisture is 70-80%. The moisture quite quickly evaporates while keeping sludge out of doors. Sludge returns into the weak agglomerates. The sizing of the dried sludge particles presents the figures from 400 to 1000 µm. The moisture was extracted by sludge pressing. The content of the basic compounds of the moisture is, g/dm3: chromium oxide – 1.6; nickel – 0.001; manganese oxide – 0.002; lead – 0.005; sulphate – 13.6; natrium – 17.0."

Jan 1, 2008

By Binxu Zhaug, Mark Jolly, Xiaojun Dai

"In conventional investment casting process of aluminium alloys for the application of the aerospace industry, to assure the quality of the final casting, usually the foundry uses large runner system which results in low yield, high energy consumption and high GHGs emission. In one case of this investigation, the yield is between 5 ~ 10% which means that the current casting process wastes large amount of energy and generates lots of scraps. By applying a new casting method, the bulky runner system and the melting/holding time are significantly reduced, the quality of the casting is improved, and in the meantime the related energy consumption and GHGs emission are significantly decreased. In the investigation, the energy efficiencies and GHGs emission between the current and traditional processes are calculated and compared.1. IntroductionAs one of the conventional casting process, Investment Casting Process (ICP) and its applications can be traced to thousand years ago [l]. In current casting industry, ICP still plays an important role in the production of small and precious castings with high quality requirements in automobile and aerospace industries. Both casting quality and manufacturing costs which mainly consist of energy costs have crucial effects on the competitiveness of castings in the market. In the production of aluminium alloy castings using ICP, the energy cost and energy efficiency of a casting facility depend mainly on the efficiency of its melting and heat treating performance. In association with the two performances, more than 60 % of the total process energy costs are symbolised in a typical casting facility [2]. Additionally, in conventional ICP of aluminium alloys for the application of the aerospace, to assure the quality of the final casting, typically the foundry uses huge runner system including big risers/feeders which cause low yield, creates lots of scraps and generates high energy consumption. Consequently, there are huge opportunities for casting industry to choose the best practices for potential energy saving. Furthermore, the reasons such as the stringent limitation of environmental legislation in Europe and the pressure of the rising energy price force the casting industry to reduce the energy consumption and greenhouse gases (GHGs) em1ss10n."

Jan 1, 2012

By Sergio N. Monteiro

Lignocellulosic fibers obtained from plants like cotton, flax, hemp, sisal, jute and many others are natural materials used, since long time, in basic items such as textile, baskets, roofing and carpets. These traditional natural fibers as well as some new ones are nowadays replacing synthetic fibers as composite reinforcement owing to environmental advantages. The heterogeneous characteristic of lignocellulosic fibers is, however, a limitation for application in composites. The buriti fiber, extracted from a tropical plant tree, is recently being investigated as a possible reinforcement for polymeric matrix composites but no complete information exists regarding its mechanical behavior. The objective of this work was then to carry out a statistical analysis on the mechanical properties? uniformity of buriti fibers. By precise dimensional measurements in association with tensile tests, it was found that the mechanical properties depend on the range of the fibers? dimension.

Jan 1, 2009

By Xue Wang, Callie Babbitt, Chelsea Bailey, Matt Ganter, Gabrielle Gaustad, Brian Landi

"Current trends, motivated by fossil fuel dependence and unprecedented greenhouse gas (GHG) emissions, show lithium-ion batteries (LIBs) emerging as a competitive energy storage technology due to higher power and energy densities compared to Pb-acid and Ni-metal hydride chemistries. These trends may be of concern, however, as environmental impacts are not well understood for either the LIB itself, or for the nanoparticles consumed or released during the battery's production, use, or end-of-life. This study combines economic modeling, dynamic material flow analysis, and fundamental material characterization methods in order to quantify some of the economic and environmental trade-offs for LIBs at their end-of-life. As expected, results show that as chemistries transition from Li-Co based cathodes to Li based Fe, Mn, and S cathodes, LIB recovery value correlates to the value of the raw materials used. These initial results aim to inform collection policies being proposed currently as well as enable future deployment of novel recycling techniques.IntroductionGlobal fossil fuel dependence and unprecedented GHG emissions have led to increasing attention on energy alternatives, for both electricity production and personal transportation. However, development of renewable energy systems is contingent on concurrent technological development of energy storage systems, primarily batteries used for power grid load-leveling, renewable energy storage, and hybrid and battery electric vehicles. In this sector, lithium-ion batteries (LIBs) are emerging as a competitive technology due to higher power and energy densities compared to lead-acid and nickelmetal hydride chemistries[!]. LIBs represent close to 20% of the total rechargeable battery market and 75% of the portable rechargeable battery market, which is the fastest growing segment of the rechargeable battery market, with a 20% global growth in 2008 [2].This surge in production ofLIBs indicates a looming waste problem; total waste from Li-ion batteries has likely grown substantially from the 500 metric tons estimated in 2003 [3]. Figure IA shows the substantial increase in world-wide lithium production that has occurred in the last several decades with batteries making up the largest share of applications (Figure lB). California and New York state legislators have attempted to proactively address this looming waste by issuing diposal bans on rechargeable batteries in their states[4, 5]. However, quantification of the costs involved in collection, transportation, and processing of these materials has not been examined in depth."

Jan 1, 2012

By Geoff Matthews, David S. Wong, Linda Wright, Pretesh Patel, Mark Dorreen

This paper examines the development of the new EnPot heat exchanger technology for aluminium smelters and the potential impact it could have on the sustainability and economics of primary aluminium production. The EnPot technology can be used to help the aluminium smelting industry be part of the solution to accommodate increased intermittency in our future renewable energy generation, post COP 21. The EnPot system provides for the first time, dynamic control of the heat balance of aluminium smelting pots across the potline, so that energy consumption and aluminium production can be increased or decreased by as much as plus or minus 30% almost instantaneously. This enables a new way of thinking to emerge when considering the relationship the aluminium smelter plays in connection to the power grid. The EnPot technology provides smelters with the means to free up power back to the grid, transforming the smelter from only an end user of power into a ‘virtual battery’ for the electricity network. This fundamentally changes the way electricity is consumed by the smelter and is a concept already being tested by several smelters.

Mar 1, 2017

By Stéphane Bourg

The SCRREEN project gathers more than 50 European initiatives, associations, organisations or independent experts working on Critical Raw Materials (CRM) into a long-lasting network including stakeholders, public authorities, and civil society representatives. SCRREEN contributes to improve the CRM strategy in Europe by (i) mapping primary and secondary resources and substitutes of CRMs, (ii) estimating the expected demand of various CRMs in the future and identifying major trends, (iii) providing policy and technology recommendations for actions improving the production and the potential substitution of CRM, (iv) addressing specific waste electrical and electronic equipment (WEEE) and other End-of-Life (EoL) product issues related to their mapping and treatment standardization, and (vi) identifying the knowledge gathered over previous years and making the data accessible to those beyond the project. As a first step, SCRREEN worked at providing stakeholders with a comprehensive analysis of the current use of the CRM, the mapping of potential primary and secondary resources, and identification of the key technologies used in their production. Substitution profiles, analysis of European business and policy issues pertinent to CRMs, and an identification of the standards, policies, and regulatory frameworks concerning these CRM was also completed. In a second step, to be conducted between mid-2018 and mid-2019, SCRREEN will provide guidance for improving the CRM market in Europe by identifying opportunities from research, development, and innovation (R&D&I) that could reduce the supply and/or economic risks around the most relevant CRM for Europe.

By Lv Guozhi, Niu Liping, Shi Guanyong, Liu Yan, He Jicheng, Du Yanjun, Dou Zhihe

"We proposed thermit reduction-electroslag remelting method of preparing the large scale CuCr alloy. But there are pores and oxide inclusions in CuCr alloy prepared by thermit reduction process. This paper studied mainly the effects of ratio of reactant and additive on the inclusion type and their occurrences in CuCr alloy. The alloy prepared in different process conditions was characterized via XRD, SEM, OM and TEM and metallographic microscope, in which the existing state and micro-structural defects of inclusions are analyzed. The results show that there are three distinct regions: copper-rich regions, chromium-rich regions and the inclusion regions. Inclusions are mainly in the form of stomata and Alz03 phase, mainly locating in the copper-rich phase and the interface area of chromium-rich phase and the copper-rich phase. Adding Na3AlF6 and heating agent can effectively reduce the inclusion content in the alloy.1 IntroductionIn recent years, with the development ofhigh power vacuum and high-pressure technology ,the CuCr alloy contact material which has many advantages gradually replaced the traditional W-Cu and Cu-Bi series alloy contact material, and become the first choice of material in high-voltage and high-power vacuum switch contacts['-3l. The traditional powder metallurgy method, infiltration method and vacuum arc melting method[4-SJ are using metal Cu powder and Cr powder as raw material by casting molding, and have disadvantages such as high production costs, complicated process, poor product density and low yield, especially in the large size alloy ingots[9-12l. At present, the world regards CuCr alloy new preparation technologies as the first place, and how to achieve a large size the CuCr alloy ingot preparation has become a hot research of CuCr alloy[3l. Zhang Ting-an and Dou Zhihe[l-3l who are supported by national natural science fundation of china successfully successful developed new technologies and core equipment to prepare large-size copper-chromium alloy through aluminum thermal reduction-secondary refining method, and obtained two national invention patents. The method includes two key steps: one is get CuCr alloy consumable ingot by Thermit-SHS with electromagnetic stirring, the other is to refme the CuCr alloy ingot to remove the pores, inclusions and other defects by electroslag remelting technology to get dense and uniform CuCr contact material. The preliminary study results show that means of electromagnetic stirring evidently inhibit effect of alloy ingot macrosegregation during the electromagnetic casting stage, but there are still microstructure defects such as alumina inclusions and pores in the alloy ingots. Therefore, Zhang Ting-an et al refer new ideas of using the electroslag remelting to refine Cu Cr alloy ingots and effectively remove the defects of the ingots such as pores and inclusions [3l _ At present, there is no report of study on the electroslag remelting refining processes of CuCr alloy (the refining slag, remelting current). This article will research mode of occurrence and distribution law of inclusions in the large-size CuCr alloy ingots by Al Thermit-SHS under magnetic field stirring action and provide a theoretical basis for chosing refining slag to remove inclusions by electroslag refining. Meanwhile the article analyses the effect of reduction conditions of Thermit-SHS on the types of inclusions, mode of occurrence and distribution of regular inclusions in alloy ingot, and refer theory for inclusions regulation in the large-size alloy ingots."

Jan 1, 2013

By Sergio N. Monteiro

The interface between the matrix and the reinforcing fiber plays an important role in the efficiency by which an applied load is transmitted through the composite structure. The shear stress at the fiber/matrix interface can be associated with this load transference and,consequently,affects the composite strength. In the present work, pullout tests were used to evaluate the interfacial shear stress of curaua fiber in epoxy matrix composites. A small critical length was found for the curaua fiber embedded in epoxy, which corresponds to a relatively weak fiber/matrix bond and lower interfacial strength.

Jan 1, 2009

By Kazuhiro Asai

Hitachi Refinery of Nippon Mining & Metals Co., Ltd. installed a reverberatory type recycling fumace in 1978 in order to treat the industrial wastes which contain metal elements such as copper, gold and silver. Pyrite and industrial waste materials such as galvanizing sludge, hydroxide slime and dust are smelted. Sulfidized copper, iron and precious metals are transformed into matte and other metallic elements are oxidized into slag This copper matte is transported to Saganoseki smelter and copper and precious metals in the matte are recovered. Recently it is difficult to obtain pyrite economically because of the decrease of pyrite production. Therefore, a new treating process of the liquid waste has been investigated at Hitachi Refinery. In this process, the sulfide or sulfate from the liquid waste are smelted as a source of sulfur.

Jan 1, 1997

By Liangying Wen, Jian Xu, Dongdong Wang, Kaihui Ma, Yang Xu

Slags play an important role in blast furnace operation, and their com- positions are based on the CaO –SiO2–MgO–Al2O3 quaternary system. However, there is not a clear understanding of the effects of gangue on of the formation of FeO-bearing primary-slags process in blast furnace. In this work, the softening and dripping experiments under the blast furnace conditions are designed to explore the influences of CaO-/SiO 2-/MgO-/Al2O3 on the softening and melting properties of FeO respectively. The results indicate that additions of CaO or Al2O3 decrease the starting softening temperature and no dripping behaviors are found in comparison with the base case results when only FeO is used. On the contrary, the addition of SiO2 or MgO rises the starting and ending softening temperature, as well as the dripping temperature. The lowest maximum pressure drop is obtained in the case with addition of SiO2. According to XRD analysis results, the initial phase with CaO addition in the primary-slags should be CaOFe3O4 and that with SiO2, MgO, Al2O3 additions are fayalite (2FeOSiO2), magnesioferrite (MgOFeO), hercynite (FeO2Al2O3), respectively.

Mar 1, 2017

By N. Mizutani, S. Harada, Z. Asaki, T. Tanabe

"The development of lead-free solders is urgent in view of environmental standpoints. In this -work the wettability of tin-bismuth- silver solders on copper was studied. Three kinds of fluxes were used. The wettability of conventional eutectic tin-lead .solder exhibited an excellent level over the other solders of tin-bismuth systems. Poor wettability of the tin-bismuth solders may be caused by the growth or dendritic copper-tin compounds at copper/solder interface, in contrast to the case of tin-lead'· solder. The wettability was improved by the addition· of silver in the solder. In this tin bismuth- silver system, silver was abnormally concentrated at the copper I solder interface even in the initial stage of contact. The wettability of the solder and the thickness of compound formed on the copper have a good correlation; the solder containing 2% silver exhibited the best wettability and the formation rate of copper-tin· compound on the copper was slowest.IntroductionSocial demand to avoid lead use in the industrial fields has been recently promoted· (1) because of the environmental protection of water resources. Especially the lead-bearing solders have been widely used in electronics and automobile products, and it is urgent to replace them with nontoxic materials (2)-(4). Thus the development of lead-free solders becomes an indispensable subject to the new generations and many works (5)(6) have already been carried out on the research and development of new solders. New lead-free solders are expected to have some requirements, for example, moderate melting temperature, proper strength and integrity, and lower prices, as compared with conventional solders. There have been already several alloy systems developed. Among ·these alloy systems, tin-bismuth binary or tin-bismuth-silver ternary alloys have great advantages such as having a wide range of soldering .temperature by controlling con:ipositions, though they have such disadvantages as ""lift-off"" (7)-(9): It is said, on the other hand, that a frequently overlooked property of solders, or one that is typically ignored by the research scientist as an ""issue"" for the manufacturing or product engineer, is wettability (10), although a ·work on the wettability has recently been published (11). In this Work, therefore, the authors selected Sn-Bi-Ag solders and focused mi the effect of Ag-addition to wettability of the solder."

Jan 1, 2000