Thermodynamic Behavior Research Analysis of Twin-roll Casting Lead Alloy Strip Process

The thermodynamic behavior of twin-roll casting （TRC） lead alloy strip process directly affects the forming of the lead strip, the quality of the lead strip and the production efficiency. However, there is little research on the thermodynamics of lead alloy strip at home and abroad. The TRC lead process is studied in four parameters： the pouring temperature of molten lead, the depth of molten pool, the roll casting speed, and the rolling thickness of continuous casting. Firstly, the thermodynamic model for TRC lead process is built. Secondly, the thermodynamic behavior of the TRC process is simulated with the use of Fluent. Through the thermodynamics research and analysis, the process parameters of cast rolling lead strip can be obtained： the pouring temperature of molten lead： 360-400 ℃, the depth of molten pool： 250-300 mm, the roll casting speed： 2.5-3 m/min, the rolling thickness： 8-9 mm. Based on the above process parameters, the optimal parameters（the pouring temperature of molten lead： 375-390 ℃, the depth of molten pool： 285-300 mm, the roll casting speed： 2.75-3 m/min, the rolling thickness： 8.5-9 mm） can be gained with the use of the orthogonal experiment. Finally, the engineering test of TRC lead alloy strip is carried out and the test proves the thermodynamic model is scientific, necessary and correct. In this paper, a detailed study on the thermodynamic behavior of lead alloy strip is carried out and the process parameters of lead strip forming are obtained through the research, which provide an effective theoretical guide for TRC lead alloy strip process.

STUDY ON KINETICS OF OXYGEN EVOLUTION ON LEAD ALLOY ANODES

A study was carried out on kinetics of oxygen evolution on lead alloy anodes in sulphuric acidicelectrolyte. The influence of alloy elements Ca, Ag and Sn on the overpotential of oxygen evolution was investigated. All anodes had been subjected to a pre-polarization before the measurement of potential-currentcurves for oxygen evolution. The overpotential of oxygen evolution was found to be decreased when the alloyanode contained Ca and Ag, whereas it remained unchanged when the alloy anode contained Sn. For oxygenevolution on lead alloy anodes the TAFEL equation was valid. The b vulue for Ph and Ph-Ca anodes was approx. 100, for Ph-Ag, Ph-Ag-Ca anodes it was approx. 140. The a value for Ph Ca, Ph-Ag, Ph-Ag-Ca anodes decreased with the increase of Ca or/and Ag content. The a and b value was not influenced by Sn in theanodes.

Behavior of silver and lead in selective chlorination leaching process of gold-antimony alloy

The behavior of silver and lead in the selective chlorination leaching process of gold-antimony alloy was analyzed in detail and appropriate recovery methods were developed.A reduction method by adding gold-antimony alloy powder was adopted to recover silver according to the thermodynamics calculation.The reducing rate of silver can exceed 99%at 80℃for 1.5 h when the dosage of gold-antimony alloy powder is 10%.The dissolution equilibrium curved surfaces of PbSO4 and PbCl2 under different conditions were drawn.The experimental results are well consistent with theoretical analysis that indicate lead may be precipitated in the form of lead chloride.The grade of gold in the residue can be further concentrated to 94.5%after being washed with hot water. These two methods have been applied successfully in the practice.

Effect of Antimony Additions on Corrosion and Mechanical Properties of Sn-Bi Eutectic Lead-Free Solder Alloy

The goal of the present work is to investigate the effects of the addition of Sb (0, 3 and 6 wt%) on structure, melting, corrosion and mechanical properties of Sn-Bi eutectic solder alloys. The mechanical properties of the bulk Sn-Bi-Sb solders were higher as the amount of antimony increases, making compressive strength augment from 65 MPa to 100 MPa when 6 wt% Sb was incorporated to the Sn-Bi eutectic alloy. The three alloys presented a melting temperature that is smaller to the one exhibited by the eutectic alloy Sn-38Pb (Tm = 183°C). According to the electrochemical results, the addition of higher contents of Sb to the Sn-Bi eutectic alloy had a positive effect: it ennobled the Ecorr values.

Addition of Ce as additive to Pb-Ca-Sn-Al grid alloy for lead acid battery

The study on three Pb Ca Sn Al alloys with 0.08%, 0.4% and 1.0% of Ce indicates that the addition of Ce results in an obvious increase in the tensile strength and hardness of the alloys, an increase in the overpotentials of hydrogen and oxygen evolution and the corrosion resistance as well. The study on the corrosion film formed on the alloys by cyclic voltammetry shows that the addition of Ce slows down the formation of corrosion film. It is therefore concluded from the experimental results that the addition of Ce can increase the tensile strength and HB of Pb Ca alloy and the tensile strength and HB of the alloy increase with the increase of Ce; the addition of Ce also increases the hydrogen and oxygen evolution overpotentials of Pb Ca alloy, and when the content of Ce is 1.0%, the alloy has the highest hydrogen and oxygen evolution overpoteatials; the addition of Ce improves the anticorrosion capability of the alloy, and when the content Ce is 1.0%, the alloy has the best anticorrosion capability; and the addition of Ce also slows down the formation of corrosion film.

Effect of cerium on microstructure and mechanical properties of Sn-Ag-Cu system lead-free solder alloys

The melting point, spreading property, mechanical properties and microstructures of Sn-3.0Ag-2.8Cu solder alloys added with micro-variable-Ce were studied by means of optical microscopy, scanning electron microscopy(SEM) and energy dispersive X-ray(EDX). The results indicate that the melting point of Sn-3.0Ag-2.8Cu solder is enhanced by Ce addition; a small amount of Ce will remarkably prolong the creep-rupture life of Sn-3.0Ag-2.8Cu solder joint at room temperature, especially when the content of Ce is 0.1%, the creep-rupture life will be 9 times or more than that of the solder joint without Ce addition; the elongation of Sn-3.0Ag-2.8Cu solder is also obviously improved even up to 15.7%. In sum, the optimum content of Ce is within 0.05%-0.1 %.

Mechanical properties of directionally solidified lead-antimony alloys

The Pb-17wt% Sb alloy was directionally solidified under two solidification conditions：with different temperature gradients （G=0.93-3.67 K/mm） at a constant growth rate （V=17.50 λm/s） and with different growth rates （V=8.3-497 μm/s） at a constant temperature gradient （G=3.67 K/mm） in a Bridgman furnace.Microstructure parameters,such as primary dendrite arm spacing （λ1）,secondary dendrite arm spacing （σ2）,and dendrite tip radius （R）,were measured.The microhardness （Hv） and ultimate tensile strength （λ） of the directional so-lidification samples were also measured.The influences of solidification and microstructure parameters on Hv and σwere investigated.The results obtained in this work were compared with similar experimental researches in literatures.It is shown that the Hv and σvalues increase with the increase of G and V,but decrease with the increase of λ1,λ2,and R.

Electromotive force measurements in liquid Ag-In-Pd lead-free alloys

Emf technique was employed to determine indium activities in the liquid Ag-In-Pd alloys using galvanic cells with yttria-stabilised-zirconia as solid electrolyte according to the scheme： kanthal/rhenium, Ag-In-Pd, In2O3 ｜ YSZ ｜ Ni, NiO, Pt. Composition and temperature measurement ranges were limited, because of very steep liquidus surface; 35 compositions for Xpd up to 0.3 were investigated and at temperatures from near-liquidus up to 1700 K. High temperature experiments required special moly furnace to be constructed with unique automatic gas supply system for fumace winding protective atmosphere. Emf readings were taken and recorded by automatic data acquisition system. Linear dependence of emf on temperature was observed for all compositions investigated, and results were approximated by straight line equa- tions. Then In activities were calculated using well-known relations and taking into account correction for thermoelectric power between kanthal and platinum. Results are to be used along with other existing data to perform assessment of the ternary system under accord.

Thermodynamic Behavior of Lead-Antimony Alloy in Vacuum Distillation

The distribution of metals in Pb-Sb ailoy during vacuum distillation was calculated.The composition curve of vapor-liquid phases determined by this work is different from those of. other researchers.The curve intersects the diagonal at C.The compositions of vapor and liquid at C are identical.The antimony content of vapor on the left of C is less than that of liquid,and the vapor on the right-side of C contains more antimony.These characteristics can be applied to the elimination of antimony from crude lead or the elimination of lead from crude antimony.The position of C moves rightwards with temperature increment.The discrepency among the compositions of C suggested by diffrent authors was explained.

Influence of Rare Earths on the Directional Solidification Microstructure of Tin-Lead Eutectic Alloy

The research on the influence of RE on the directional solidified microstructure of tin lead alloy reveals that the addition of RE can cause chopping and irregular lamellar and smaller lamellar spacing. When RE content increases, the microstructure changes to peritectic structure. Moreover, the eutectic point of Sn Pb alloy deviates because the affinity of RE for Sn, which results in the existence of primary Pb rich phases contained hypocutectic grown layers. Sn RE intermetallic compound has no effect on the solidification of Sn Pb alloy.

Dynamic behavior and applicability of lead alloy absorber

The paper describes the damping effect of lead alloy absorber (LAA) by shake table test and finite element method of a kind of high-voltage electrical equipment, LW11-252/Q SF6 Circuit Breaker (LSCB). The strain reduction of the porcelain bushing of LSCB is defined as the damping effect of LAA in the paper based on the damage pattern of test equipment under earthquake. The test results show that LAA has reduced the acceleration response and strain response of the LSCB, at the same time, it does not increase the displacement response of the LSCB. There is a reduction of 30% in the strain of porcelain pipe. Moreover, the stronger the input ground motion is, the larger the reduction will be. The finite element method also indicates the damping effect of LAA, especially under ground motions with significant long period contents and ground motions with velocity pulse. Combined with the test results and calculation results, the paper gives the applicability of LAA finally.

On conversion of plastic work to heat during plastic deformation of tin-lead alloy and mild steel

The temperature rise caused by plastic deformation during the quick upsetting of tin-lead alloy and mild steel was investigated via experiments and numerical simulations aiming at a better understanding of the heat generation mechanism in friction welding. The results show that the compression amount and deformation temperature influence significantly the temperature rise during the upsetting of tin-lead alloy. The temperature rise increases with increasing the compression but decreases with increasing the deformation temperature. The simulation results are in good agreement with the experimental inspection for Sn63A alloy. The simulation results of mild steel present a similar tendency with tin-lead alloy. Moreover, the temperature rise of mild steel at elevated temperatures is comparable to that of tin-lead alloy at low temperatures.

Study on the Effect of Production Parameters and Raw Materials Used on the Mechanical Properties of Leaded Brass (CuZn40Pb2) Alloy

Leaded brass alloys used progressively in many applications such as gas valves production owing to their excellent machinability, corrosion resistance and some other specifications. However, the production processes of these alloys involve some problems appearing in the last activities of production as a result of cumulative defects of previous production processes. Therefore, the current investigation studies the effect of process parameters during casting, hot extrusion and cold drawing production stages of CuZn40Pb2 leaded brass alloy on the mechanical properties. Starting with casting process, two types of charges were used. The first charge consists of 100% recycles while the second contains 30% of pure materials such as Cu, Zn and Pb in addition to the recycles. For each production stage, alloy hardness, micro-hardness, ultimate tensile strength and elongation were examined. The results illustrated that high hardness values are obtained during casting process due to some impurities such as iron and the effect of cooling rate through solidification. The hardness values decrease during extrusion process and then rise again by cold drawing for the charge of 30% pure materials. Micro-hardness values for the fractured tensile test samples appeared higher than others due to work hardening effect. The best mechanical properties as ultimate tensile strength of CuZn40Pb2 alloy products are appeared into cold forming samples with the 30% pure material added.

Microstructures and properties of Sn-Ag-Cu lead-free solder alloys containing La

Trace amounts of La were utilized to improve the melting behaviors,microstructures,tensile properties and microhardness of Sn-3.0Ag-0.5Cu lead-free solder alloy. La has little effect on the melting behavior of Sn-3.0Ag-0.5Cu alloy according to the differential thermal analysis(DTA) tests. The X-ray diffraction(XRD) patterns show that β-Sn,Ag3Sn and Cu6Sn5 coexist in the as-cast solder alloys and LaSn3 phases emerge when adding 0.4% La. The microstructures modified by La are more uniform and much finer than that of baseline alloy,and the coarse LaSn3 particles with complex dendrites are observed by optical microscopy(OM) and scanning electron microscopy(SEM) when the addition of La is up to 0.4%. The composition of the LaSn3 phases is identified by energy-dispersive spectroscopy(EDS). There are considerable improvements in mechanical properties with 0.05% and 0.1% addition,but degenerations by adding 0.4%La. The Vickers microhardness of β-Sn and eutectic area are both enhanced with the addition of La and the microhardness of LaSn3 is much larger than those of β-Sn and eutectic area.

Pb-Ca-Sn-Ba Grid Alloys for Valve-Regulated Lead Acid Batteries

The effect of barium additives on the process of anodic corrosion of lead-tin-calcium alloys in a 4.8 М sulfuric acid solution was studied. Cyclic voltammetry, impedance spectroscopy, weight loss measurements and scanning electronic microscope analysis have allowed exploring the oxidation process and characterizing the formed corrosion layer. According to our results, barium introduction into lead-tin-calcium alloys increases their hardness, reduces their electrochemical activity, and improves their corrosion stability. Reduction of the calcium content in the alloy can be compensated by adding barium. Barium dopation at lead-tin-calcium alloys decreases the resistance of the oxide layer formed on the grid surface, in a deeply discharged state, and raises its resistance during floating conditions and at a charged state of the positive electrode.

MD Simulated Microstructure of Liquid Sodium Alloyed with Lead

The results of molecular-dynamics (MD) simulation are obtained for structural and thermodynamic properties of the molten system, Na1-xPbx (x ≤ 0.1), at 698 K in the model of nearly free electronic gas (NFE approximation). The all numerical experiments are carried out by unified procedure: 1) equilibrating the MD cell 1 ps;2) calculating partial radial distribution functions gab(r) in 1, 5, and 10 ps;3) data handling for calculating other characteristics. It follows from this that lead impurity in liquid sodium at concentration in the range of 1% - 10% is characterized by micro-heterogenetic structure in the form of cluster compounds with variable composition. Just therefore the sodium alloys, Na-MIV, with four-group elements of Periodic table have no eutectic in this range of additive concentrations. This eutectic is needed for modifying sodium coolant of the fast nuclear reactor. Therefore it is reasonable to find an alternative alloy of sodium with additive from adjacent groups which has a eutectic in this range of concentrations, for example, the eutectic, Na0.929Tl0.071, with melting point of 64°C. The modified sodium coolant by isotope, 205Tl, can appear attractive for inhibiting the chemical activity of sodium just as the lead alloyed one.

Enhancing the Creep Resistance of Sn-9.0Zn-0.5Al Lead-Free Solder Alloy by Small Additions of Sb Element

The creep phenomenon is considered as one of the most important deformation mechanisms under working conditions. The present study has examined the microstructure and creep properties of Sn-9.0Zn-0.5Al solder alloy after adding a small amount of Antimony (Sb). Nominal compositions of Sb additions were chosen to be 0, 0.5, 1.0, and 1.5 wt.%. The minimum strain rate was reduced for the Sb containing solder alloy. The stress exponents, n, were found to be around 3.7 for all soldiers at 130°C. The stress exponent increases as the temperature drops from 100°C to 50°C, except for the 1.0% Sb alloy, where n 5.3 - 6.1 at all the temperature range (T = 50°C, 100°C and 130°C). The results reveal that the Sb-containing solder alloys have better creep resistance with greater ductility than the Sb-free alloy due to solid solution strengthening, and intermetallic compound SnSb particle hardening.

Analysis of fixation method of fuel assembly for lead-alloy cooled reactor

As a potential candidate for generation IV reactors, lead-alloy cooled reactor has attracted much attentions in recent years. The China LEAd-based research Reactor(CLEAR) is proposed as the primary choice for the accelerator driven subcritical system project launched by Chinese Academy of Sciences. Lead-bismuth eutectic(LBE) is selected as the coolant of CLEAR owing to its efficient heat conductivity properties and high production rate of neutrons. In order to compensate the buoyancy due to the high density of lead-alloy, fixation methods of fuel assembly(FA) have become a research hotspot worldwide. In this paper, we report an integrated system of ballast and fuel element for CLEAR FA. It guarantees the correct positioning of each FA in normal and refueling operations. Force calculation and temperature analysis prove that the FA will be stable and safe under CLEAR operation conditions.

Structure and Properties of Sn-9Zn Lead-Free Solder Alloy with Heat Treatment

The Sn-9Zn lead-free solder alloy was prepared by conventional casting technique then cold-rolled into long sheets of 1 mm thickness and 3 mm width. It was annealed at 80, 120 and 160°C for 60 min to investigate the effect of isochronal heat treatment on structure and mechanical properties of the cold rolled Sn-9Zn alloy. The results showed that, the crystallite size and lattice strain have opposite behavior with increasing annealing temperature due to recovery and recrystalization processes associated with the heat treatment process. Vickers micro-hardness number increases continuously from 155 to 180 MPa with increasing annealing temperature. Ultimate tensile strength (UTS) was also calculated. It was found that, it is equal to 61.4 MPa for the non annealed sample and slightly decreases to 60.5 and 58.2 MPa for samples annealed at 80 and 120°C, respectively. While, increases to 65.4 MPa for the sample annealed at 160°C. Also, ductility increases with increasing annealing temperature in opposite manor with the UTS. The new method for Micro-creep behavior as well as the creep rate calculated by this method has been characterized at room temperature.

引线框架用高性能铜合金板带材及制备工艺

电子信息产业的飞速发展,对铜及铜合金产品性能提出了更高的要求,其中集成电路封装用引线框架材料代表了铜合金板带材发展的较高水平。本文对近年来引线框架用高性能铜合金板带材及制备工艺进行了综述,介绍了国内外高性能铜合金板带材料的成分和制备加工技术及发展过程,并对其未来发展趋势进行了展望,提出未来高性能铜板带材性能将朝着抗拉强度为700 MPa、导电率为70%IACS的目标发展,其制备工艺将向着智能化、绿色化、高效化等方向发展。