Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/64—Carriers or collectors
  • H01M4/66—Selection of materials
  • H01M4/68—Selection of materials for use in lead-acid accumulators
  • H01M4/685—Lead alloys
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C9/00—Alloys based on copper
  • C22C9/08—Alloys based on copper with lead as the next major constituent
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
  • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
  • C22F1/12—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of lead or alloys based thereon
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/10—Energy storage using batteries

Definitions

• This invention relates to an improved lead- antimony alloy which is strengthened by an extremely rapid heat treatment method and which is capable of being processed into battery grids on a continuous production line.
• Lead-acid storage batteries have been used for many years as starter batteries for internal combustion engines. Pure lead is a soft material however,, arid extensive research has developed a number of alloys to provide specific physical properties desired by the battery manufacturers to improve the battery and battery making process.
• the conventional method of preparing grids by casting is relatively inefficient and it is now preferred to use an automated continuous method which produces grids by expanding or punching a wrought lead alloy strip as described in U.S. Pat. No. 4,443,918.
• expanded plates can be obtained by continuously supplying a lead alloy strip, expanding it, pasting the thus produced mesh-like strip, drying it and cutting it to form individual grids.
• U.S. Pat. Nos. 3,945,097 and 4,271,586 describes methods and machines for making expanded battery plates, the patents being incorporated herein by reference.
• Antimony is a common alloying material desirable in battery grids and amounts up to about 11% have been employed to improve the strength and castability of the lead. Unfortunately, antimony, aside from being relatively expensive, increases the water loss of the battery and is of limited use in a maintenance free battery and continuous battery making process.
• the process comprises working the alloy and rapidly heat treating (which includes quenching) the alloy for a sufficient time at an elevated temperature to activate a strengthening mechanism in the alloy, the time of the heat treatment step being substantially less than that used to conventionally heat treat lead-antimony alloys.
• the alloy comprises, by weight, about 0»5%-6% antimony about 0.002-1% arsenic, up to about 1%, or more . tellurium, up to about 0.5% tin and the balance being; essentially lead.
• the alloy may be worked, e.g., reduced, by an amount greater than about 15%, preferably greater than about 50% and most preferably greater, than 80% or 90% and is preferably reduced by rolling in several successive stages of substantially equal percentage reductions.
• the lead-antimony-arsenic-tellurium alloys which may be strengthened by the process of the : invention comprise, by weight, antimony in an amount greater than about 0.5%, e.g., about 0.5-6%, preferably about 0.75-3% and most preferably 1-2.5%, arsenic in an amount of about 0.002% to 1%, preferably 0.05% tp 0.25%, and most preferably 0.1% to 0.2% and tellurium- in an amount of about 0.0005% to 1%, preferably 0.003%.to 0.5% and most preferably 0.007% to 0.14%.
• antimony in an amount greater than about 0.5%, e.g., about 0.5-6%, preferably about 0.75-3% and most preferably 1-2.5%
• arsenic in an amount of about 0.002% to 1%, preferably 0.05% tp 0.25%, and most preferably 0.1% to 0.2%
• tellurium- in an amount of about 0.0005% to 1%, preferably 0.003%.to 0.5% and
• Tellurium in combination with the antimony and arsenic has been found to be essential to provide enhanced maintenance * of the physical properties of the worked, rapidly heat- treated alloy after further working of " the alloy to form, for example, battery grids by expansion of-strips of the heat-treated alloy.
• Working of the alloys may be performed using conventional procedures well-known in the art, and by working or rolling, extrusion, etc. is meant mechanical plastic deformation of the metal and includes cold and hot working.
• the alloy is cast into a billet and reduced to the desired size strip by passing it through successive rolls, wherein each roll in succession further reduces the thickness of the alloy.
• Constant reduction rolling schedules in the same rolling direction are preferred whereby, for example, a 0.75 inch thick billet is reduced to a 0.04 inch thick strip by passing it through 11 rolls wherein each roll in succession reduced the thickness of the billet by about 25%.
• Other rolling schedules can suitably be employed.
• Heat treatment of the alloy is performed under time and temperature conditions which do not result in a conventional solution treatment effect.
• the heat treatment of the present invention which includes the quenching step, when applied to worked lead-antimony alloys containing a correlated amount of arsenic, antimony and tellurium, activates a strengthening reaction and a maintenance of the alloy's strength.by means not yet clear.
• Solution heat treatment as defined in ASTM Designation: E 44-83, means heating an alloy to a suitable temperature, holding at that temperature long enough to cause one or more constituents to enter into solid solution and then cooling rapidly enough to hold these constituents in solution.
• the heat treatment of the present invention comprises only requiring the alloy to be heated to the desired temperature. In general, heating the alloy at the desired temperature does not dissolve any appreciable amount of soluble antimony, e.g., less than 50%, usually less than 25% and typically less than about 10%, e.g., 5% or 1% or less.
• the temperature of the heat treatment is between about 180*C. and the alloy liquidus temperature, preferably, 200*C. to 252*C, and most preferably 220 ⁇ C. to 245"C.
• the time required to bring the alloy to the desired temperature varies according to the thickness of the alloy and the temperature and method of heating, with thinner strips of alloy, higher temperatures and/or higher heat transfer heating means requiring shorter times. It is preferred that the alloy be brought substantially completely to the desired temperature to realize the full effect of the heat treatment on,A ⁇ strengthening of the alloy. In a preferred embodiment, employing a molten salt bath at a temperature of about
• 230 ⁇ C. for about 15 seconds provided excellent strengthening, and retention of the strength after further working, for a 0.040 inch thick strip of alloy.
• An equivalent heating time for a muffle furnace would be about 2.5 minutes.
• a heating time using a salt bath is less .than about 2 minutes, and even 1 minute and for a muffle furnace, less than about 8 minutes.
• heating times will vary depending on the temperature and ⁇ >the.
• a heating time using a salt bath is about 1-3 seconds, pre erably'5 to 30 seconds to less than about 1 minute, and for a muffle furnace, about 1 minute, preferably 2 minutes and most preferably less than about 5 minutes.
• Longer times may be employed, if desired, although the longer times will not typically result in any substantial increased operating efficiencies.
• Other heating means can suitably be employed such as oil, induction heating, resistance heating, infra-red, and the like. Resistance or infra-red heating, for example, would provide almost instantaneous heating thus requiring very short heating times of 30 seconds or less, although longer times could be employed if desired.
• U.S. Patent Nos. 3,310,438; 3,621,543; 3,945,097; 4,035,556; 4,271,586; 4,358,518; and 4,443,918 show representative methods and machines, the disclosures of the patents being hereby incorporated by reference.
• U.S. Patent No. 4,271,586 shows, for example, a ribbon of lead being fed into an inline expander, followed by pasting, drying, cutting and accumulating into stacks.
• 4,035,556 discloses forming of finished storage battery grids from rolled sheet material by (a) slitting and expanding to form an open grid, (b) punching out an open grid, (c) forming an interlocked type of grid and (d) combinations of (a) or (b) with (c) .
• heat treatment of the alloy may be performed at any convenient interval during preparation or manufacture of the alloy or battery grid.
• the alloy can be continuously cast, worked into strip, heat treated, expanded or punched into the grid, pasted, and assembled directly into the battery.
• the worked strip can also be coiled for storage and then heat treated and made into grids or it can be heat treated, coiled and stored for processing at a later time.
• the alloy can also be heat treated after preparation of the grid. Regardless of the method of heat treating and preparing of the grid, it is important that the alloy be worked before the heat treatment.
• the following examples will further illustrate the present invention. It will be understood that throughout this specification and claims, all parts and percentages are by weight and all temperatures in degrees Centigrade unless otherwise specified.
• EXAMPLE I A series of alloys having varying tellurium levels were prepared in a heated graphite crucible by melting a base lead, antimony, arsenic, tin alloy to a final composition containing 1.3% antimony, 0.16% arsenic and 0.23% tin, balance essentially lead, Tellurium metal was added to the crucible at ⁇ tbj__i levels indicated in TABLE I.
• Four alloys were prepared by casting into a graphite book mold at 400 * C.-500'C. to produce a cast block approximately 10 inch x 3. inch x 0.75 inch.
• the castings were milled to remove, surface defects and then rolled at room temperature to 0.045 inch in eight-twelve passes taking about a 20-30% reduction per pass.
• Samples for chemical analyses were cut from the resultant strip. Blanks 4 inqh x 0.5 inch for machining to test bars were cut from the strip in the rolling (longitudinal) direction. J ⁇ .
• Tensilkut Machine was used to cut the test bars to a 1 inch gage length and 0.25 inch width.
• Heat .treatment was performed by immersion of the bars in a molteji salt bath at 230"C. for 15 seconds and quenched by plunging into room temperature water immediately upon removal from the salt bath. The samples were then stored at room temperature for 10 days.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Organic Chemistry (AREA)
• Metallurgy (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Thermal Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Physics & Mathematics (AREA)
• General Chemical & Material Sciences (AREA)
• Electrochemistry (AREA)
• Cell Electrode Carriers And Collectors (AREA)

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• 1990
  • 1990-01-11 AU AU49648/90A patent/AU4964890A/en not_active Abandoned
  • 1990-01-11 CA CA002026991A patent/CA2026991A1/en not_active Abandoned
  • 1990-01-11 EP EP19900902493 patent/EP0408718A4/en not_active Withdrawn
  • 1990-01-11 WO PCT/US1990/000310 patent/WO1990009462A1/en not_active Ceased

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