Lead-calcium Alloys Research Articles

Optimized batteries for cars with dual electrical architecture

During recent years, the increase in car electrical equipment has led to many problems with traditional starter batteries (such as cranking failure due to flat batteries, battery cycling etc.). The main causes of these problems are the double function of the automotive battery (starter and service functions) and the difficulties in designing batteries well adapted to these two functions. In order to solve these problems a new concept — the dual-concept — has been developed with two separate batteries: one battery is dedicated to the starter function and the other is dedicated to the service function. Only one alternator charges the two batteries with a separation device between the two electrical circuits. The starter battery is located in the engine compartment while the service battery is located at the rear of the car. From the analysis of new requirements, battery designs have been optimized regarding the two types of functions: (i) a small battery with high specific power for the starting function; for this function a flooded battery with lead-calcium alloy grids and thin plates is proposed; (ii) for the service function, modified sealed gas-recombinant batteries with cycling and deep-discharge ability have been developed. The various advantages of the dual-concept are studied in terms of starting reliability, battery weight, and voltage supply. The operating conditions of the system and several dual electrical architectures have also been studied in the laboratory and the car. The feasibility of the concept is proved.

Lead alloys: past, present and future

The most critical non-active component in the lead/acid battery is the grid or substrate. A review of the work on grids and grid alloys in the period 1960–1993 has been carried out by the Advanced Lead-Acid Battery Consortium and, in this paper, the results are analyzed in relation to the effort expended on different alloy systems. Lead-antimony alloys and the effects on them of additions of arsenic, tin, and grain-refining elements (selenium, sulfur, copper), together with lead-calcium alloys and the effect on them of tin additions, have received the greatest attention in the past. Proposals are made for future studies. Possible evolutionary developments include the addition of silver and higher amounts of tin to lead-calcium alloys, more detailed investigations of lead-strontium and lead-lithium alloys containing tin and/or silver, and further work on very-low-antimony alloys. More speculative projects are very rapidly cooled alloys, the use of aluminium as grids or spines, plastic/lead-coated copper negative grids, corrosion-resistant coatings of lead compounds on the grids and, finally, a substrate for a bipolar plate that is based on conductive inorganic compounds.

Advances in the refining and alloying of low-bismuth lead

A programme has been initiated to improve the performance and eliminate the environmental concerns of the traditional Kroll-Betterton process for bismuth removal from lead. The work has resulted in the development of a new generation of debismuthizing reagents that are comprised of a magnesium-calcium alloy, specially designated at Mag-Cal™. The most common Mag-Cal™ alloy contains 70 wt.% magnesium and 30 wt.% calcium. Extensive testing has revealed that addition of Mag-Cal™ to the vortex at approximately 480–500 °C, followed by mixing for 5–15 min, provides the best results. With Mag-Cal™, bismuth levels of 0.005 wt.% Bi, or less, are readily achieved without the need for supplemental calcium and antimony additions. Calcium-aluminum master alloys (known as CAL-AL™) have been developed which enable battery-grid manufacturers to achieve target calcium and aluminum specifications with consistently high and predictable recoveries. A new process has been developed for alloying calcium and aluminum into lead. The process has been proven in an extensive campaign of pilotscale trials. The process uses pure calcium and aluminum in the form of granules of particulates and offers many advantages that will be of significant benefit to lead-calcium alloy producers.

Joining of leadantimony and leadcalcium alloy lugs by a laboratory cast-on-strap process

A laboratory-scale characterization of the cast-on-strap joining process has been conducted using an existing leadantimony strap alloy and low-antimony lead and leadcalcium alloy lugs. Increasing mould temperature in the range from 150 to 250 °C only marginally decreases the initially rapid cooling rate of the strap melt, but considerably decreases the subsequent cooling rate when the strap melt starts to solidify. Increasing the melt pouring temperature from 500 to 550 °C has little influence on the overall cooling characteristics of the strap. Joining of the lug/strap couple can be characterized by lack of fusion, partial fusion and complete fusion from the strap surface to the lug tip. At a mould temperature of 150 °C, a significant lack of fusion and considerable porosity are observed. The degree of fusion increases significantly when the mould temperature is increased from 150 to 200 °C. Pretinning effectively eliminates lack of fusion and considerably reduces the level of porosity. This most likely results from the presence of lower melting point material between the lugs and strap. There is good fusion and low porosity for leadcalcium alloy joints for which a more aggressive acid-based flux is used.

High-resolution electron microscopy of lead and lead-calcium alloys

There are few reports on transmission electron microscopy studies [1, 2] and no referenced work of high-resolution electron microscopy on lead and lead alloys. This is because it is difficult to prepare good thin foil specimens from lead because of its large atomic number and electrochemical stability. High-resolution electron microscopy is useful for direct study of lattice defects and the matrix/second phase interface structure. So far, transmission electron microscopy of lead alloys has been reported using the foils prepared by a microtome method [1, 2]. High-resolution electron microscopy on lead and lead-calcium alloys has been attempted successfully and, for the first time, several high-resolution electron micrographs are reported in this communication.

Scanning laser microscopy studies of grid-paste interfacial areas

Lead/acid batteries with lead-calcium alloy positive grids can exhibit early loss of capacity when subjected to deep-discharge cycling. This has been attributed to the development of a high-resistance layer of α-PbO that separates the grid metal from the active material. Hitherto, direct evidence for such a layer has been difficult to obtain because even minute quantities can exert a potent effect on plate performance. A novel method for studying the distribution of α-PbO via its laser-stimulated photocurrent is presented. In the type of experiment reported, the method is selective for α-PbO since other phases likely to be present in, or on, the grid alloy do not give rise to photocurrents.

The use of scanning photocurrent imaging to study the distribution of lead monoxide in corrosion layers on lead/acid battery grids

Lead/acid batteries with leadcalcium alloy positive grids can exhibit early loss of capacity when subjected to deep-discharge cycling. This has been attributed to the development of a high-resistance layer of α-PbO that separates the grid metal from the active material. Hitherto, direct evidence for such a layer has been difficult to obtain because even minute quantities can exert a potent effect on plate performance. A novel method for studying the distribution of α-PbO via its laser-stimulated photocurrent is presented. In the type of experiment reported, the method is selective for α-PbO since other phases likely to be present in, or on, the grid alloy do not give rise to photocurrents.

Leadcalcium alloys in the production of lead/acid batteries

In current practice, there is a steady tendency for the increase of production of sealed lead/acid batteries using leadcalcium alloys. The mastering of these alloys is, however, difficult due to debilitating phenomena taking place, the main of which is the instability of alloy composition in the process of grid casting because of calcium oxidation. Thus, production conditions experience certain problems associated with the continuous control of alloy composition, increase of slag formation, the increased consumption of calcium, productivity decrease, increase of rejection and decrease of grid resistance to corrosion. This work examines both lead and leadcalcium alloys, methods for their deformation strengthening, the choice of alloy optimal composition, and procedures for stabilizing calcium during long process periods. A technological scheme is presented for wasteless manufacture of leadcalcium grids of stable composition with control of alloy structure, increased corrosion properties and high productivity.

Discontinuous and continuous hardening processes in calcium and calcium—tin micro-alloyed lead: influence of ‘secondary-lead’ impurities

Different transformations in leadcalcium and leadcaciumtin alloys are observed with various complementary techniques such as anisothermal microcalorimetry, optical and electronic microscopy, hardness measurements. Three alloy states are studied: as-cast, rehomogenised/water-quenched, rehomogenised/air-cooled. With binary leadcalcium alloys, three successive discontinuous transformations are observed, namely: an initial and complete discontinuous transformation with regular moving of the front of reaction; a second and incomplete discontinuous transformation (puzzle-shaped); a third and incomplete discontinuous transformation with precipitation of Pb 3Ca. The role of secondary-lead impurities is complex: Ag reduces and Bi accelerates the rate of the discontinuous reaction, while Al refines the grain size. Leadcalciumtin are characterized by the Sn/Ca ratio. For very small values of this ratio, the hardening is similar to that of leadcalcium alloys. For high ratio values, the hardening takes place after an incubation period and proceeds via a continuous micro-precipitation of the (PbSn) 3Ca Compound. For intermediate ratios, the different processes are able to operate separately in sequence. Ag increases the rate of the continuous precipitation and reduces the incubation time. No significant effects are observed with Bi or Al. The kinetic laws of the different transformations are presented and values for the energy of activation are determined.

Behaviour of leadcalcium alloys in positive plates of flooded and recombinant lead/acid batteries

FIAMM has been producing valve-regulated lead/acid batteries utilizing micro-fibre glass (AGM) separators since 1985 for float applications. Due to the success of the product line, FIAMM has been active in evaluating this technology in other areas, particularly consumer, automotive and traction applications. Flooded cells using leadcalcium grids do not perform as well as conventional leadantimony grid cells but AGM valve-regulated cells exhibit very different behaviour. This paper briefly reviews some of the main differences in these characteristics.

A study of the electrochemical properties of lead-strontium alloys for lead/acid batteries

The electrochemical properties of lead—strontium alloys have been investigated by using a dynamic potential technique and scanning electron microscopy (SEM). The results show that the alloys appear more resistant to corrosion than traditional lead—antimony alloys or modern lead—calcium alloys. Perhaps, there is relatively perfect phase-structure in the lead-oxide layer on the alloy surface that is responsible for this corrosion-resistant behaviour.

Thirteen years' experience with expanded leadcalciumtin grids for automotive battery plates

During 1977 to 1979, Magneti Marelli decided to develop an in-house expanded-metal grid technology. The metallurgy of leadcalcium alloys for strip production was investigated extensively and a continuous system was developed. Production problems were solved with machinery of proprietary design and in 1979 about a hundred thousand Fiat cars were equipped with hybrid batteries. After about three years of labour and field tests on the integral use of leadcalciumtin expanded grids, it was decided to convert the whole production (about 3 million batteries/year) to this technology.

Electrochemical investigation of lead-calcium alloys in sulphuric acid

The hydrogen evolution reaction from, and the cycle life (Pb /ar PbSO 4) of, a series of lead-calcium alloys (0 - 0.2 wt.% Ca) in sulphuric acid hav The exchange current density and Tafel slope for the H.R.E. increase with Ca content up to 0.05 wt.% then decrease to a value approaching that of pure The observed results are explained by: (i) preferential adsorption of calcium ions at the electrode surface; (ii) incorporation of Ca, to form a supersaturated solution, with alloys containing < 0.075 wt.% Ca; (iii) formation of an insoluble, non-conducting layer of calcium sulphate on the high content alloy.

Present trends in lead alloys for the manufacture of battery grids — a review

Probable trends in the future requirements for lead acid batteries are briefly reviewed and it is pointed out that the development of maintenance free batteries could have an important place in that future. Such batteries make special requirements on grid materials. Lead—calcium alloys and lead alloys with a low antimony content are favoured for this application. The physical, electrochemical and mechanical properties of these two types of alloy are reviewed together with their respective advantages and disadvantages and the problems that may arise from their use.

Present trends in lead alloys for the manufacture of battery grids - a review

Probable trends in the future requirements for lead acid batteries are briefly reviewed and it is pointed out that the development of maintenance free batteries could have an important place in that future. Such batteries make special requirements on grid materials. Lead-calcium alloys and lead alloys with a low antimony content are favoured for this application. The physical, electrochemical and mechanical properties of these two types of alloy are reviewed together with their respective advantages and disadvantages and the problems that may arise from their use.

The influence of metallurgical factors on the flux distribution in superconductors

Abstract The magnetic flux distribution on the end faces of superconducting discs at 4.2°K has been observed by a Bitter pattern technique and compared with the metallurgical structure of the specimens. Second phase regions of CaPb3 in two-phase lead-calcium alloys, compositional inhomogeneity in single-phase lead-indium alloys, and grain boundaries and surface scratches in V3Si are some of the features that give rise to flux pinning. The results suggest that the effectiveness of any pinning centre depends on its size in relation to the coherence length of the superconducting matrix and on the gradient of the Ginzberg-Landau parameter around the pinning centre.

(33)カーバイドと鉛より鉛カルシウム合金の製造

(33)カーバイドと鉛より鉛カルシウム合金の製造

Rapid Determination of the Calcium Content of Lead-Calcium Alloys by Titrating in the Molten State with Metallic Antimony

Rapid Determination of the Calcium Content of Lead-Calcium Alloys by Titrating in the Molten State with Metallic Antimony

Corrosion and Growth of Lead-Calcium Alloy Storage Battery Grids as a Function of Calcium Content

Corrosion and Growth of Lead-Calcium Alloy Storage Battery Grids as a Function of Calcium Content

Superiorities of Lead-Calcium Alloys for Storage Battery Construction*

Recent investigations, conducted at the Bell Telephone Laboratories and elsewhere, have demonstrated that the lead-antimony alloys almost universally employed in storage cell construction are far from ideal for the purpose from the elect rochemical standpoint. It has been shown that in the course of normal operation of the present type cell, antimony is leached out of the positive electrode, passes through the solution and deposits on the negative. where it promotes “localaction” and self-discharge. Also, it has been demonst rated that stibine is generated in perce ptible amounts by the present type battery on over-charge.