CA2026991A1 - Lead-antimony alloy suitable for making battery grids - Google Patents
Lead-antimony alloy suitable for making battery gridsInfo
- Publication number
- CA2026991A1 CA2026991A1 CA002026991A CA2026991A CA2026991A1 CA 2026991 A1 CA2026991 A1 CA 2026991A1 CA 002026991 A CA002026991 A CA 002026991A CA 2026991 A CA2026991 A CA 2026991A CA 2026991 A1 CA2026991 A1 CA 2026991A1
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- CA
- Canada
- Prior art keywords
- alloy
- antimony
- lead
- less
- temperature
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
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
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Organic Chemistry (AREA)
- Metallurgy (AREA)
- Crystallography & Structural Chemistry (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Cell Electrode Carriers And Collectors (AREA)
Abstract
ABSTRACT
A process for strengthening a lead-antimony alloy which alloy significantly retains its physical properties after mechanical working, the alloy comprising, by weight, about 0.5%-6% antimony, about 0.002%-1% arsenic, about 0.0005% to 1% tellurium, the balance essentially lead, comprising:
(a) working the alloy by rolling to produce a structure containing soluble antimony in the form of antimony-rich eutectic phase bands;
(b) heating the alloy at an elevated-temperature for a sufficient time to provide an alloy having a recrystallized structure which strengthens on aging and which structure contains greater than 50% of the soluble antimony in the antimony-rich eutectic phase bands and less than 50% of the soluble antimony being dissolved in the lead; and (c) quenching the alloy.
A process for strengthening a lead-antimony alloy which alloy significantly retains its physical properties after mechanical working, the alloy comprising, by weight, about 0.5%-6% antimony, about 0.002%-1% arsenic, about 0.0005% to 1% tellurium, the balance essentially lead, comprising:
(a) working the alloy by rolling to produce a structure containing soluble antimony in the form of antimony-rich eutectic phase bands;
(b) heating the alloy at an elevated-temperature for a sufficient time to provide an alloy having a recrystallized structure which strengthens on aging and which structure contains greater than 50% of the soluble antimony in the antimony-rich eutectic phase bands and less than 50% of the soluble antimony being dissolved in the lead; and (c) quenching the alloy.
Description
wo 90!09~62 h '~ !`J ~ ~ Pcr/us90/0o3lo _ LEA~-ANTIMONY ALLOY SUITABLE FOR MAKING B~ITERY GRIDS
BACXGROUND OF THE INVENTION
This invention relates to an improved lead-antimony alloy which is ~trengthened 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 &oft material however, and oxtensive re&earch has developed a number of alloys to provide specific physical properties desired by the battery manufacturers to i~prove the battery and battery making proce~s.
In general the conventional method of preparing grids by cagtinq is relatively inefficient and it is now preferred to use an automated continuous m thod~which produces grid~ by expanding or punching a wrought lead alloy strip as de~cribed in U.S. Pat. No.
`
4,443,918. For example, expanded plates can be obtained by continuously supplyinq a lead alloy strip, expanding it, pastinq the thus produced ~esh-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 ; 25 for making expanded battery plates, the patants being incorporated her~in by reference.
Antimony i~ a common alloying material desirable in battery grids and amounts up to about lIt ~: .. . .
- ~.
, ~ :
. . .
J
BACXGROUND OF THE INVENTION
This invention relates to an improved lead-antimony alloy which is ~trengthened 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 &oft material however, and oxtensive re&earch has developed a number of alloys to provide specific physical properties desired by the battery manufacturers to i~prove the battery and battery making proce~s.
In general the conventional method of preparing grids by cagtinq is relatively inefficient and it is now preferred to use an automated continuous m thod~which produces grid~ by expanding or punching a wrought lead alloy strip as de~cribed in U.S. Pat. No.
`
4,443,918. For example, expanded plates can be obtained by continuously supplyinq a lead alloy strip, expanding it, pastinq the thus produced ~esh-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 ; 25 for making expanded battery plates, the patants being incorporated her~in by reference.
Antimony i~ a common alloying material desirable in battery grids and amounts up to about lIt ~: .. . .
- ~.
, ~ :
. . .
J
hav~ been employed to improve the strength and castability of the lead. Unfortunately, antimony, aside from being relatively exp~nsive, increases the water loss of the battery and i8 of limited use in a maintenance free battery and continuous battery making process.
U.S. Patent Nos. 4,629,516 and 4,753,688 which are assi~ned to the same assignee as the present invention and which are hereby incorporated by reference, disclose a number of lead-antimony alloys useful for making battery grids. The patent notes however that the low antimony alloys require long times to heat treat the alloy for increasing thalr ~trength and a new alloy and short-term heat treatment were developed to enable continuous grid production.
While the alloys and heat treatment methods of the prior art continuous battery making processes produce grids suitable for use in batteries, mechanical working of the alloy durinq the process after the heat-treatment step, particularly in the strip expansion st~p, may recrystallize the alloy under certain circumstances and d~creas~ its physical properties.
It is an ob~ect of the present invention to provide high strength antimonial lead strips or battery grids which exhibit enhanced resistance to 1085 Or physical properties, in particular, strength and hardness due to mechanical working in the process of -~
making the grids. It is a further ob~ect o~ the present invention to provide a continuous process for providing battery grids from a lead alloy strip. Other ob~ects will be readily apparent from the following description.
SUM~RY OF THE_INVENTION
It has now been found that the physical propertie~ Or the lead-antimony-arsenic alloys of U.S.
Patent Nos. 4,629,516, and 4,7S3,688, which alloys have been worked and heat treated according to the patents, may be significantly reta$ned after further mechanical -~
~J3 ~ t~ J ~.
wo9o/os462 PCT/US90/003tO
working by incorporating an effective amount of tellurium in the alloys. Broadly stated, the process ~omprises 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, ~bout 0.5%-6% antimony lo about 0.002-1% arsenic, up to a~out 1%, or more tellurium, up to about o.5% t~n 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 preferàbly greater than 80% or 90% and is preferably reduced by rolling in several successive stages of substantially equal percentage reductions.
DETAILED DESCRIPTIQ~ OF THE I~y~TIQN
The lead-antimony-arsenic-tellurium alloys which may be strengthened by thQ process of tho invention comprise, by weight, antimony in an amount greater than about O.S%, 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% to 0.25%, and most proferably 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%. Tellurium in combination with the antimony and arsenic, has been found to be essQntial to provid~ enhancQd maintenance of the physical properties of the worked, rapidly h-at-treated alloy after further working of the alloy to ; form, for example, battery grid~ by expansion of strips of the heat-treated alloy.
Working and heat treatment of the new alloy is as described in the above-referenced U.S. Patent Nos.
4,629,516, and 4,753,688, With the importanoe of the processing steps and parameter~ being to produce an ' ' . , wosu/os462 ~s~ P~T/US90/00310 alloy having a microstructure such as F~g. 2 of the patents, i.e., a completely recrystallized structure having antimony-rich bands still present and the volume fraction of the antimony-rich regions being approximately the same as the as-rolled alloy of Fig. 1 therein. In general, less than 50%, usually less than 25%, and typically less than 10%, e.g., 5% or 1~ or less of the soluble antimony (black region~-antimony-rich eutectic phase bands) of the as-rolled alloy is dissolved.
Working of the alloys may be performed using conventional procedures well-known in the art, and by working or rolling, extrusion, etc. i8 meant mechanical plastic deformation of the metal and includes cold and hot working. In general, 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 schQdules 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 ll rolls wherein each roll in succession reduced the thickness of the billet by about 25%. Other rolling schedules can suitably be employed.
~eat treatment o~ the alloy i~ performed under time and temperature cond$tion~ which do not result in a conventional solution treatment ~ffect. The heat treatment of the pre~ent invention, which includes the quenching step, when applied to worked lead-antimony alloy~ containing a correlated amount of arsenic, àntimony 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
Desiqnation: E 44-83, means heating an alloy to a suitable temperature, holding at that temperature long enough to cause one or more con~tituents to enter into ~ , .. . , . . .. . ~ . ~ .
i~ .
Wogo/09462 PCT/US90/003tO
J ',1 ~J ~i.'i.
solid solution and then cooling rapidly enough to hold these constituents in solution. The heat treatment of the present in~ention 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 the 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 inc~ thick strip of alloy.
An equivalent heating time for a muf~le furn~ce would be about 2.5 minutes. Por an alloy about 0.25 inch thick, over the broad range of heating workinq, temperatures, 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. AB noted above, heating times will vary depending on the temperature and the thickness of the alloy and, in general, for a strip of alloy about 0.025 inch to 0.1 inch thick, a heating time using a salt bath is about 1-3 seconds, preferably 5 to 30 seconds to less than a~out 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.
Any method and machine may be employed for making thQ worked alloy and/or battery plates and U.S.
Patent Nos. 3,310,438: 3,621,543; 3,94s,097; 4,035,5s6: ~ -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 inlin~ expander, followed by pasting, drying, cutting and accumulating into ~tacks. U.S. Patent No.
4,035,556 disclose~ 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 tb) with (c).
It will be appreciated by those skilled in the art that heat treatment of the alloy may be performed at any convenient interval during preparation or ~anuf~cture of the alloy or battery grid. Preferably, th- alloy can be continuou~ly 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 proce~sing 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.
woso/os462 2 ~ ~ PCT/US90/~310 The following exampleq will further illustrate the present invention. It will be understood that throughout this specification and claims, all parts a~d percentages are by weight and all temperatures in degrees Centigrade unles~ 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~ antimonyl 0.16%
arsenic and 0.23% tin, balance essentially lead.
Tellurium metal was added to the crucible at the le~els 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 3.5 inch x 0.75 inch.
The casting~ were m$11ed to remove surface defects and then rolled at room temperature to 0.045 inch in eight-twelve pas~e~ taking about a 20-30%
reduction per pass. Sample~ for che~ical analysis were cut from the resultant ~trip. Blanks 4 ineh x O.5 ineh for machining to test bara were eut from the strip in the rolling ~lonqitudinal) direction. A Tensilkut Machine was used to eut the test bars to a 1 ineh gage }ength and 0.25 ineh width. Heat treatment wa~
performed by immersion of the bar~ in a molten ~alt bath at 230-C. for 15 seeond~ and quenehed by plunging into room temperature water irmed~ately upon removal from the salt bath. The samples were then stored at room temperature for 10 days. Tensile test~ representing the ultimate ten~ile strength ~UTS) were perforJed on an Instron Maehine using a eros~head ~peed of 0.2 inch/minute and mierohardness testing was employed to obtain Viekers Hardn-ss Numb~rs (VHN) at the grip seetion (un~trained) and the gage length seetions (strained) of the speeimen.
i,': : . ' '., ;'~,.' ,' '' ' ' ' ~"" ' ' ' ~'" '" .~ ' ,, ' TABLE I
As-Rolled Alloy Tellurium _ VHN
No.(ppm) UTS(psi)l ~ UTS(psi~ ~ (Strained) 170 4050 9.4 5450 13.2 13.7 2200 4150 9.9 5280 11.6 13.3 3340 4150 9.4 4870 12.7 12.8 4l 1400 l 42Z0 6380 13.7 13.6 The results in TABLE I clearly show that the tellurium containing alloys retain their heat treated hardness after being pulled in tension to failure (27-40% elongation to fracture). The results als~ indicate the increase in strength of the heat treated alloy versus the as-rolled alloys.
Similarly prepared alloys which contained no tellurium were tested in an identical manner. None of the alloys exhibited the permanent hardness retention in the strained region of the tensile specimens as clearly -~
shown in TABLE I, with the hardness decreasing to values ;~
near the as-rolled condition.
Whlle this invention has been disclosed in ~`
terms of specific embodiments thereof it is not intended to be limited thereto and it will be understood that modifications may be made in the improved process of thi~ invention without departing from the scope of the invention defined by the appended claims.
U.S. Patent Nos. 4,629,516 and 4,753,688 which are assi~ned to the same assignee as the present invention and which are hereby incorporated by reference, disclose a number of lead-antimony alloys useful for making battery grids. The patent notes however that the low antimony alloys require long times to heat treat the alloy for increasing thalr ~trength and a new alloy and short-term heat treatment were developed to enable continuous grid production.
While the alloys and heat treatment methods of the prior art continuous battery making processes produce grids suitable for use in batteries, mechanical working of the alloy durinq the process after the heat-treatment step, particularly in the strip expansion st~p, may recrystallize the alloy under certain circumstances and d~creas~ its physical properties.
It is an ob~ect of the present invention to provide high strength antimonial lead strips or battery grids which exhibit enhanced resistance to 1085 Or physical properties, in particular, strength and hardness due to mechanical working in the process of -~
making the grids. It is a further ob~ect o~ the present invention to provide a continuous process for providing battery grids from a lead alloy strip. Other ob~ects will be readily apparent from the following description.
SUM~RY OF THE_INVENTION
It has now been found that the physical propertie~ Or the lead-antimony-arsenic alloys of U.S.
Patent Nos. 4,629,516, and 4,7S3,688, which alloys have been worked and heat treated according to the patents, may be significantly reta$ned after further mechanical -~
~J3 ~ t~ J ~.
wo9o/os462 PCT/US90/003tO
working by incorporating an effective amount of tellurium in the alloys. Broadly stated, the process ~omprises 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, ~bout 0.5%-6% antimony lo about 0.002-1% arsenic, up to a~out 1%, or more tellurium, up to about o.5% t~n 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 preferàbly greater than 80% or 90% and is preferably reduced by rolling in several successive stages of substantially equal percentage reductions.
DETAILED DESCRIPTIQ~ OF THE I~y~TIQN
The lead-antimony-arsenic-tellurium alloys which may be strengthened by thQ process of tho invention comprise, by weight, antimony in an amount greater than about O.S%, 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% to 0.25%, and most proferably 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%. Tellurium in combination with the antimony and arsenic, has been found to be essQntial to provid~ enhancQd maintenance of the physical properties of the worked, rapidly h-at-treated alloy after further working of the alloy to ; form, for example, battery grid~ by expansion of strips of the heat-treated alloy.
Working and heat treatment of the new alloy is as described in the above-referenced U.S. Patent Nos.
4,629,516, and 4,753,688, With the importanoe of the processing steps and parameter~ being to produce an ' ' . , wosu/os462 ~s~ P~T/US90/00310 alloy having a microstructure such as F~g. 2 of the patents, i.e., a completely recrystallized structure having antimony-rich bands still present and the volume fraction of the antimony-rich regions being approximately the same as the as-rolled alloy of Fig. 1 therein. In general, less than 50%, usually less than 25%, and typically less than 10%, e.g., 5% or 1~ or less of the soluble antimony (black region~-antimony-rich eutectic phase bands) of the as-rolled alloy is dissolved.
Working of the alloys may be performed using conventional procedures well-known in the art, and by working or rolling, extrusion, etc. i8 meant mechanical plastic deformation of the metal and includes cold and hot working. In general, 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 schQdules 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 ll rolls wherein each roll in succession reduced the thickness of the billet by about 25%. Other rolling schedules can suitably be employed.
~eat treatment o~ the alloy i~ performed under time and temperature cond$tion~ which do not result in a conventional solution treatment ~ffect. The heat treatment of the pre~ent invention, which includes the quenching step, when applied to worked lead-antimony alloy~ containing a correlated amount of arsenic, àntimony 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
Desiqnation: E 44-83, means heating an alloy to a suitable temperature, holding at that temperature long enough to cause one or more con~tituents to enter into ~ , .. . , . . .. . ~ . ~ .
i~ .
Wogo/09462 PCT/US90/003tO
J ',1 ~J ~i.'i.
solid solution and then cooling rapidly enough to hold these constituents in solution. The heat treatment of the present in~ention 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 the 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 inc~ thick strip of alloy.
An equivalent heating time for a muf~le furn~ce would be about 2.5 minutes. Por an alloy about 0.25 inch thick, over the broad range of heating workinq, temperatures, 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. AB noted above, heating times will vary depending on the temperature and the thickness of the alloy and, in general, for a strip of alloy about 0.025 inch to 0.1 inch thick, a heating time using a salt bath is about 1-3 seconds, preferably 5 to 30 seconds to less than a~out 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.
Any method and machine may be employed for making thQ worked alloy and/or battery plates and U.S.
Patent Nos. 3,310,438: 3,621,543; 3,94s,097; 4,035,5s6: ~ -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 inlin~ expander, followed by pasting, drying, cutting and accumulating into ~tacks. U.S. Patent No.
4,035,556 disclose~ 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 tb) with (c).
It will be appreciated by those skilled in the art that heat treatment of the alloy may be performed at any convenient interval during preparation or ~anuf~cture of the alloy or battery grid. Preferably, th- alloy can be continuou~ly 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 proce~sing 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.
woso/os462 2 ~ ~ PCT/US90/~310 The following exampleq will further illustrate the present invention. It will be understood that throughout this specification and claims, all parts a~d percentages are by weight and all temperatures in degrees Centigrade unles~ 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~ antimonyl 0.16%
arsenic and 0.23% tin, balance essentially lead.
Tellurium metal was added to the crucible at the le~els 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 3.5 inch x 0.75 inch.
The casting~ were m$11ed to remove surface defects and then rolled at room temperature to 0.045 inch in eight-twelve pas~e~ taking about a 20-30%
reduction per pass. Sample~ for che~ical analysis were cut from the resultant ~trip. Blanks 4 ineh x O.5 ineh for machining to test bara were eut from the strip in the rolling ~lonqitudinal) direction. A Tensilkut Machine was used to eut the test bars to a 1 ineh gage }ength and 0.25 ineh width. Heat treatment wa~
performed by immersion of the bar~ in a molten ~alt bath at 230-C. for 15 seeond~ and quenehed by plunging into room temperature water irmed~ately upon removal from the salt bath. The samples were then stored at room temperature for 10 days. Tensile test~ representing the ultimate ten~ile strength ~UTS) were perforJed on an Instron Maehine using a eros~head ~peed of 0.2 inch/minute and mierohardness testing was employed to obtain Viekers Hardn-ss Numb~rs (VHN) at the grip seetion (un~trained) and the gage length seetions (strained) of the speeimen.
i,': : . ' '., ;'~,.' ,' '' ' ' ' ~"" ' ' ' ~'" '" .~ ' ,, ' TABLE I
As-Rolled Alloy Tellurium _ VHN
No.(ppm) UTS(psi)l ~ UTS(psi~ ~ (Strained) 170 4050 9.4 5450 13.2 13.7 2200 4150 9.9 5280 11.6 13.3 3340 4150 9.4 4870 12.7 12.8 4l 1400 l 42Z0 6380 13.7 13.6 The results in TABLE I clearly show that the tellurium containing alloys retain their heat treated hardness after being pulled in tension to failure (27-40% elongation to fracture). The results als~ indicate the increase in strength of the heat treated alloy versus the as-rolled alloys.
Similarly prepared alloys which contained no tellurium were tested in an identical manner. None of the alloys exhibited the permanent hardness retention in the strained region of the tensile specimens as clearly -~
shown in TABLE I, with the hardness decreasing to values ;~
near the as-rolled condition.
Whlle this invention has been disclosed in ~`
terms of specific embodiments thereof it is not intended to be limited thereto and it will be understood that modifications may be made in the improved process of thi~ invention without departing from the scope of the invention defined by the appended claims.
Claims (28)
1. A process for strengthening a lead-antimony alloy which alloy significantly retains its physical properties after mechanical working, the alloy comprising, by weight, about 0.5%-6% antimony, about 0.002%-1% arsenic, about 0.0005% to 1% tellurium, the balance essentially lead, comprising:
(a) working the alloy by rolling to produce a structure containing soluble antimony in the form of antimony-rich eutectic phase bands;
(b) heating the alloy at an elevated-temperature for a sufficient time to provide an alloy having a recrystallized structure which strengthens on aging and which structure contains greater than 50% of the soluble antimony in the antimony-rich eutectic phase bands and less than 50% of the soluble antimony being dissolved in the lead; and (c) quenching the alloy.
(a) working the alloy by rolling to produce a structure containing soluble antimony in the form of antimony-rich eutectic phase bands;
(b) heating the alloy at an elevated-temperature for a sufficient time to provide an alloy having a recrystallized structure which strengthens on aging and which structure contains greater than 50% of the soluble antimony in the antimony-rich eutectic phase bands and less than 50% of the soluble antimony being dissolved in the lead; and (c) quenching the alloy.
2. The process of claim 1, wherein the alloy is worked by reducing it an amount of greater than about 15%.
3. The process of claim 1, wherein the alloy is heated for a time whereby the amount of soluble antimony dissolved is less than about 25%.
4. The process of claim 1, wherein the alloy is heated at a temperature between about 180-C. and the alloy liquidus temperature for less than about 2.5 minutes.
5. The process of claim 4, wherein the temperature is between about 200-C. to 252-C. and the time is less than about 1 minute.
6. The process of claim 5, wherein the heating means is a molten salt bath.
7. The process of claim 6, wherein the heating time is less than about 30 seconds.
8. The process of claim 7, wherein the alloy is worked by reducing it an amount greater than about 80%.
9. The process of claim 1, wherein the rolling is performed by successive multiple reductions
10. An alloy prepared in accordance with the method of claim 1.
11. An alloy prepared in accordance with the method of claim 4.
12. An alloy prepared in accordance with the method of claim 9.
13. An alloy comprising by weight, about 0.5%-6%
antimony, about 0.002%-1% arsenic, 0.0005% to 1% tellurium, the balance essentially lead, the alloy being characterized by having a recrystallized structure containing greater than 50% of the soluble antimony in an antimony-rich eutectic phase in the form of bands.
antimony, about 0.002%-1% arsenic, 0.0005% to 1% tellurium, the balance essentially lead, the alloy being characterized by having a recrystallized structure containing greater than 50% of the soluble antimony in an antimony-rich eutectic phase in the form of bands.
14. The alloy of claim 13, wherein greater than 75% of the soluble antimony is in the form of antimony-rich eutectic phase bands.
15. The alloy of claim 13, wherein greater than 90% of the soluble antimony is in the form of antimony-rich eutectic phase bands.
16. A battery grid prepared from the alloy of claim 13.
17. A battery grip prepared from the alloy of claim 14.
18. A battery grid prepared from the alloy of claim 15.
19. A process for preparing battery grids from a lead-antimony alloy comprising, by weight, about 0.05%-6%
antimony, about 0 002%-1% arsenic, about 0.0005% to 1%
tellurium the balance essentially lead, comprising (a) working the alloy by rolling to a desired size strip, the alloy characterized by having a structure containing soluble antimony in the form of antimony-rich eutectic phase bands;
(b) heating the strip at an elevated temperature for sufficient time to provide an alloy having a recrystallized structure which strengthens on aging and which structure contains greater than 50% of the soluble antimony in the antimony-rich eutectic phase bands and less than 50% of the soluble antimony being dissolved in the lead;
(c) quenching the strip; and (d) forming the strip into a battery grid.
antimony, about 0 002%-1% arsenic, about 0.0005% to 1%
tellurium the balance essentially lead, comprising (a) working the alloy by rolling to a desired size strip, the alloy characterized by having a structure containing soluble antimony in the form of antimony-rich eutectic phase bands;
(b) heating the strip at an elevated temperature for sufficient time to provide an alloy having a recrystallized structure which strengthens on aging and which structure contains greater than 50% of the soluble antimony in the antimony-rich eutectic phase bands and less than 50% of the soluble antimony being dissolved in the lead;
(c) quenching the strip; and (d) forming the strip into a battery grid.
20. The process for preparing battery grids of claim 19, wherein the alloy is worked in step (a) by reducing it in an amount greater than about 50%.
21. The process for preparing battery grids of claim 20, wherein the strip is heated in step (b) at a temperature between about 180°C. and the alloy liquidus temperature.
22. The process for preparing battery grids of claim 21, wherein the time of heating in step (b) is less than about 1 minute.
23. The process for preparing battery grids of claim 22, wherein the time of heating in step (b) is less than about 30 seconds.
24. The process for preparing battery grids of claim 23, wherein the alloy is worked in step (b) by reducing it in an amount greater than about 80%.
25. The process for preparing battery grids of claim 24, wherein the strip is heated in step (b) at a temperature between about 200°C. to 252°C. using a molten salt bath.
26. The process for preparing battery grids of claim 25, wherein the alloy is worked by rolling in successive multiple reductions.
27. The process for preparing battery grids of claim 19, wherein step (d) is performed before steps (b) and (c).
28. A battery grid prepared in accordance with the method of claim 19.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US30822189A | 1989-02-09 | 1989-02-09 | |
| US308,221 | 1989-02-09 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2026991A1 true CA2026991A1 (en) | 1990-08-10 |
Family
ID=23193067
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002026991A Abandoned CA2026991A1 (en) | 1989-02-09 | 1990-01-11 | Lead-antimony alloy suitable for making battery grids |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0408718A4 (en) |
| AU (1) | AU4964890A (en) |
| CA (1) | CA2026991A1 (en) |
| WO (1) | WO1990009462A1 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6802917B1 (en) * | 2000-05-26 | 2004-10-12 | Integran Technologies Inc. | Perforated current collectors for storage batteries and electrochemical cells, having improved resistance to corrosion |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB816808A (en) * | 1957-03-07 | 1959-07-22 | British Non Ferrous Metals Res | Improved lead alloys for cable sheathing |
| GB1461266A (en) * | 1973-03-15 | 1977-01-13 | Electric Power Storage Ltd | Electric storage battery grids |
| DE2337708C2 (en) * | 1973-07-25 | 1983-03-24 | Accumulatorenfabriken Wilhelm Hagen Ag Soest-Kassel-Berlin, 4770 Soest | Lead-antimony alloy |
| US4629516A (en) * | 1985-04-01 | 1986-12-16 | Asarco Incorporated | Process for strengthening lead-antimony alloys |
-
1990
- 1990-01-11 EP EP19900902493 patent/EP0408718A4/en not_active Withdrawn
- 1990-01-11 WO PCT/US1990/000310 patent/WO1990009462A1/en not_active Application Discontinuation
- 1990-01-11 AU AU49648/90A patent/AU4964890A/en not_active Abandoned
- 1990-01-11 CA CA002026991A patent/CA2026991A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| WO1990009462A1 (en) | 1990-08-23 |
| EP0408718A1 (en) | 1991-01-23 |
| AU4964890A (en) | 1990-09-05 |
| EP0408718A4 (en) | 1991-07-24 |
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