US2908569A - Process of producing sintered tungsten electrodes - Google Patents
Process of producing sintered tungsten electrodes Download PDFInfo
- Publication number
- US2908569A US2908569A US485180A US48518055A US2908569A US 2908569 A US2908569 A US 2908569A US 485180 A US485180 A US 485180A US 48518055 A US48518055 A US 48518055A US 2908569 A US2908569 A US 2908569A
- Authority
- US
- United States
- Prior art keywords
- electrodes
- tungsten
- spark
- spark plugs
- producing sintered
- 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.)
- Expired - Lifetime
Links
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 title description 21
- 229910052721 tungsten Inorganic materials 0.000 title description 18
- 239000010937 tungsten Substances 0.000 title description 18
- 238000000034 method Methods 0.000 title description 6
- 230000008569 process Effects 0.000 title description 5
- 239000001257 hydrogen Substances 0.000 description 9
- 229910052739 hydrogen Inorganic materials 0.000 description 9
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 8
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 8
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 7
- 229910045601 alloy Inorganic materials 0.000 description 7
- 239000000956 alloy Substances 0.000 description 7
- 229910052709 silver Inorganic materials 0.000 description 5
- 239000004332 silver Substances 0.000 description 5
- 229910052786 argon Inorganic materials 0.000 description 4
- 238000005470 impregnation Methods 0.000 description 4
- 239000011810 insulating material Substances 0.000 description 4
- 229910052763 palladium Inorganic materials 0.000 description 4
- 229910000831 Steel Inorganic materials 0.000 description 3
- 239000004568 cement Substances 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 239000010445 mica Substances 0.000 description 3
- 229910052618 mica group Inorganic materials 0.000 description 3
- 238000000465 moulding Methods 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- 239000010959 steel Substances 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 238000005219 brazing Methods 0.000 description 2
- 238000001354 calcination Methods 0.000 description 2
- 239000010439 graphite Substances 0.000 description 2
- 229910002804 graphite Inorganic materials 0.000 description 2
- 150000002431 hydrogen Chemical class 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000011159 matrix material Substances 0.000 description 2
- 229910001316 Ag alloy Inorganic materials 0.000 description 1
- 241001387976 Pera Species 0.000 description 1
- 238000005255 carburizing Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 230000000295 complement effect Effects 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000007667 floating Methods 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 230000009191 jumping Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000008961 swelling Effects 0.000 description 1
- 238000011282 treatment Methods 0.000 description 1
- 238000004804 winding Methods 0.000 description 1
- 238000005491 wire drawing Methods 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
- H01T21/00—Apparatus or processes specially adapted for the manufacture or maintenance of spark gaps or sparking plugs
- H01T21/02—Apparatus or processes specially adapted for the manufacture or maintenance of spark gaps or sparking plugs of sparking plugs
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/04—Making non-ferrous alloys by powder metallurgy
- C22C1/045—Alloys based on refractory metals
Definitions
- the invention relates to a new constructional form of spark plugs which are very suitable for ignition by capacity discharge and whose working life is much greater ice and to braze each of the electrodes end-on to a conducting member of, for example, steel.
- FIGS. 1 through 5 are fragmentary sectional views of spark plugs according to the invention.
- Fig. 6 is an elevation 'view of a spark plug element partly insection.
- Figs. 1 and 5 show a spark plug comprising electrodes I 1,2 with insulating material 3 which is for example cethan that of spark plugs which have been constructed heretofore, and of the same order as the life of the currently used high voltage spark plugs.
- the spark plugs according to the present invention are constituted by co-axial circular electrodes machined from special alloys, the dimension of the electrodes being much greater than that of the region subjected to the sparks.
- the metals from which the electrodes are machined are alloys rich in tungsten obtained by impregnation of calcined tungsten bodies of carefully adjusted porosity by another metal or alloy having particular properties which is brought to a molten condition for the impregnation process.
- the tungsten content of the alloys which are suitable is comprised between 65% and 95%.
- the complementary metal added by impregnation in the molten condition can be:
- a moderate melting temperature of less than 1,400 degrees centigrade permitting of the easy impregnation of the tungsten body is reconciled with good properties of resistance to the spark by using alloys containing 70% palladium and 30% silver, or else 50% palladium and 50% silver.
- the height of the spark element With a view to reducing costs, it is possible to reduce the height of the spark element to, for example, 3 mm.
- ment vitrified into position or cement consisting of a refractory mineral charge agglomerated by a heat-hardened organic substance, and a mica ring 4 arranged at the height of the region where the sparks are produced.
- The'mica ring protects the insulating material and supports the fire o f the spark.
- a circular swelling or curvatureS can be formed at the top of one of the cylindrical electrodes in such manner that the shortest distance between electrodes is outside the insulating material and that the spark, jumping beyond the said insulating material, does not damage it.
- electrodes of pure tungsten were employed 7 provided that the volume of pure tungsten was substantiaily greater than that which is subjected to the spark.
- the spark would not be advantageous to cause the spark to jump between two tungsten toruses each constituted by a wire placed in the form of a circle and secured by brazing to a cylindrical steel part.
- the electrodes formed in this known manner can provide, for example in motor cars, only a quite inadequate service life, even if the diameter of the tungsten wire is at the upper limit of approx. 0.25 mm. permissible for winding and brazing to a steel 'n'ng w'hose thickness is of the order of 0.6 mm.
- a spark plug element for a gasoline engine.
- the electrodes 1 and 2 are connected respectively to the electric generator (not shown) by the crown 6 and the cylindrical stem 7.
- the two electrodes are insulated from one another and held in position by the cement 3.
- the spark controlled by the distributor jumps at any point in the inter-electrode space between two points such as A and B situated on the same diameter.
- the small toroidal surfaces which have to be subjected to the spark taken in section at A and B through the plane of the drawing, have a width not exceeding 0.1 mm.
- the tungsten electrodes used by way of example and in accordance with the invention have a thickness of 1 mm. and a height of 5 mm. According to the invention, no material discontinuity of the brazed connection, for example, must exist within each of the electrodes at less than 2 mm. from the line of sparking.
- the tungsten In order that the service life of the electrodes s'hould fulfill the requirements of, for example, automotive use, the tungsten must not be porous and its compactness should be such that its specific weight should be 'greater than 17.5 g./cm. and preferably greater than 18 g./cm. This condition is diflicult to fulfill since the only tungsten products commercially obtainable which exhibit no porosity are those wires whose manufacture has included the preparation of a rod by calcining, then a hammering and a series of wire-drawings, which are mechanical treatments to which spark plug electrodes cannot be subjected during manufacture in view of their form and their size.
- the invention also relates to a method of preparing pure tungsten electrodes for spark plugs operating with capacity discharge, having the compactness necessary for good operation in practice. It comprisesthe following conditions taken necessarily in combination:
- moulding pressure preferably by double compression in a floating matrix, the moulding pressure being greater than 7 kg./mm. although low enough to prevent the appearance of cracks in the moulded article.
- a suitable pressure is one between 7 and 10 kg./mm.
- a graphite resistance furnace in an atmosphere consisting of a mixture of argon and hydrogen, the hydrogen content being less than 10%.
- heat to 1,100" in'an atstrong a content has the result of carburizing the tungsten (probably through the intermediary of gaseous hydrocarmosphere of pure hydrogen, stop the current of hydrogen at this instant and substitute therefor a current of'pure argon.
- Sintering can be carried out by heating the powder electrode in an atmosphere of pure hydrogen up to a temperature between 1,000 centigrade and 1,300 centigrade and then in an atmosphere of argon up to a maximum temperature of 2,100 Centigrade.
- the hydrogen is necessary for ensuring Igood connection between the grains of tungsten, probably because it effects the reduction of oxide traces which may cover the metallic grains. It has been found, moreover, that the use of hydrogen at too high a temperature and in too bons formed by the action of the hydrogen on the graphite of the furnace) and of making it fragile, unmachineable and of low resistance to sparking.
- the electrodes are then machined to their final size.
- the process of making low voltage discharge device electrodes which comprises, providing pure tungsten powder having a specific weight less than three grams per cubic centimeter, molding the powder into electrodes in a matrix under pressure between the limits of seven kilograms per square centimeter and ten kilograms per square centimetergheatinsg the electrodes in the presenceof pure hydrogen to a temperature between 1000 centigrade and 1300 centig'rade and then heating them to approximately 2100 centigrade in the presence of argon thereby to form non-porous electrodes.
Description
L. PERA'S Oct. 13, 1959 PROCESS OF PRODUCING SINTERED TUNGSTEN ELECTRODES Filed Jan. 31, l 1955 FIG 2 FIG 4' FIG 3 surface and the central electrode being held at its United States Patent PROCESS OF PRODUCING SINTERED TUNGSTEN ELECTRODES Lucien Peras, Billancourt, France, assignor to Regie Nationale des Usines Renault, Billancourt, France Application January 31, 1955, Serial No. 485,180 Claim priority, application France February 5, 51954 1 Claim. (Cl. 75-207) This invention relates to improvements in spark plugs, more particularly to spark plugs for mternal combustion engines.
The invention relates to a new constructional form of spark plugs which are very suitable for ignition by capacity discharge and whose working life is much greater ice and to braze each of the electrodes end-on to a conducting member of, for example, steel.
Several constructional forms of spark plugs particularly suitable for electrodes according to the invention are shown in partial axial section in the accompanying drawings purely by way of example.
Figs. 1 through 5 are fragmentary sectional views of spark plugs according to the invention,
Fig. 6 is an elevation 'view of a spark plug element partly insection.
Figs. 1 and 5 show a spark plug comprising electrodes I 1,2 with insulating material 3 which is for example cethan that of spark plugs which have been constructed heretofore, and of the same order as the life of the currently used high voltage spark plugs.
The spark plugs according to the present invention are constituted by co-axial circular electrodes machined from special alloys, the dimension of the electrodes being much greater than that of the region subjected to the sparks. The metals from which the electrodes are machined are alloys rich in tungsten obtained by impregnation of calcined tungsten bodies of carefully adjusted porosity by another metal or alloy having particular properties which is brought to a molten condition for the impregnation process. The tungsten content of the alloys which are suitable is comprised between 65% and 95%. According to the invention, the complementary metal added by impregnation in the molten condition can be:
pure silver, pure palladium,
- palladium-silver alloys in any proportions.
A moderate melting temperature of less than 1,400 degrees centigrade permitting of the easy impregnation of the tungsten body is reconciled with good properties of resistance to the spark by using alloys containing 70% palladium and 30% silver, or else 50% palladium and 50% silver.
For example, in tests carried out on a vehicle having a gasoline engine of current construction, wherein the ignition of the four 748 cm. cylinder engine is effected by low voltage (800 to 1,000 volts approx) The lifedistance of the spark plugs as hitherto used was scarcely more than 5,000 kilometres.
With a spark element wherein the electrodes, spaced from one another by 0.12 mm. by mica whose mechanical action is reinforced by an insulating cement, are formed of an alloy consisting of 85% tungsten and 15% silver, it was possible to travel 18,000 kilometres with the same vehicle under the same running conditions as those in the preceding test before it was necessary to change the spark plugs. The distance travelled could have been increased to 25,000 kilometres with another set of spark plugs wherein the electrodes consisted of an alloy of 80% tungsten, 9.8% palladium and 4.2% silver. In both cases the spark element was held in a mounting which enabled ordinary high voltage spark plugs to be fitted at the appropriate place and time, the peripheral electrode being connected to the frame by its entire outer center by a spindle which is in turn connected to the other pole of the current source.
With a view to reducing costs, it is possible to reduce the height of the spark element to, for example, 3 mm.
ment vitrified into position or cement, consisting of a refractory mineral charge agglomerated by a heat-hardened organic substance, and a mica ring 4 arranged at the height of the region where the sparks are produced. The'mica ring protects the insulating material and supports the fire o f the spark.
In other constructional forms (see Figs. 2, 3 and 4), a circular swelling or curvatureS can be formed at the top of one of the cylindrical electrodes in such manner that the shortest distance between electrodes is outside the insulating material and that the spark, jumping beyond the said insulating material, does not damage it.
In another possible constructional form based on prolonged'tests, electrodes of pure tungsten were employed 7 provided that the volume of pure tungsten was substantiaily greater than that which is subjected to the spark.
For example, it would not be advantageous to cause the spark to jump between two tungsten toruses each constituted by a wire placed in the form of a circle and secured by brazing to a cylindrical steel part. The electrodes formed in this known manner can provide, for example in motor cars, only a quite inadequate service life, even if the diameter of the tungsten wire is at the upper limit of approx. 0.25 mm. permissible for winding and brazing to a steel 'n'ng w'hose thickness is of the order of 0.6 mm.
In order to define precisely the features of the invention, reference will now be made to the example of a spark plug element (Fig. 6) for a gasoline engine. The electrodes 1 and 2 are connected respectively to the electric generator (not shown) by the crown 6 and the cylindrical stem 7. The two electrodes are insulated from one another and held in position by the cement 3. The spark controlled by the distributor jumps at any point in the inter-electrode space between two points such as A and B situated on the same diameter.
Whereas the small toroidal surfaces which have to be subjected to the spark, taken in section at A and B through the plane of the drawing, have a width not exceeding 0.1 mm., the tungsten electrodes used by way of example and in accordance with the invention have a thickness of 1 mm. and a height of 5 mm. According to the invention, no material discontinuity of the brazed connection, for example, must exist within each of the electrodes at less than 2 mm. from the line of sparking.
In order that the service life of the electrodes s'hould fulfill the requirements of, for example, automotive use, the tungsten must not be porous and its compactness should be such that its specific weight should be 'greater than 17.5 g./cm. and preferably greater than 18 g./cm. This condition is diflicult to fulfill since the only tungsten products commercially obtainable which exhibit no porosity are those wires whose manufacture has included the preparation of a rod by calcining, then a hammering and a series of wire-drawings, which are mechanical treatments to which spark plug electrodes cannot be subjected during manufacture in view of their form and their size.
The invention also relates to a method of preparing pure tungsten electrodes for spark plugs operating with capacity discharge, having the compactness necessary for good operation in practice. It comprisesthe following conditions taken necessarily in combination:
Use of a pure tungsten powder of suflicient fineness for the specific weight of the rammed powder to be less than 3 g./cm.
Shaping by moulding under pressure, preferably by double compression in a floating matrix, the moulding pressure being greater than 7 kg./mm. although low enough to prevent the appearance of cracks in the moulded article. A suitable pressure is one between 7 and 10 kg./mm. I
Calcining at a temperature of between 1,800 and 2,100 C. by heating in a graphite resistance furnace in an atmosphere consisting of a mixture of argon and hydrogen, the hydrogen content being less than 10%. In another embodiment it is possible to place the compressed article to be sintered in a cold furnace, heat to 1,100" in'an atstrong a content has the result of carburizing the tungsten (probably through the intermediary of gaseous hydrocarmosphere of pure hydrogen, stop the current of hydrogen at this instant and substitute therefor a current of'pure argon. It is sufficient to maintain this temperature for 15 to 30 minutesv Sintering can be carried out by heating the powder electrode in an atmosphere of pure hydrogen up to a temperature between 1,000 centigrade and 1,300 centigrade and then in an atmosphere of argon up to a maximum temperature of 2,100 Centigrade.
The hydrogen is necessary for ensuring Igood connection between the grains of tungsten, probably because it effects the reduction of oxide traces which may cover the metallic grains. It has been found, moreover, that the use of hydrogen at too high a temperature and in too bons formed by the action of the hydrogen on the graphite of the furnace) and of making it fragile, unmachineable and of low resistance to sparking.
The electrodes are then machined to their final size.
I claim:
The process of making low voltage discharge device electrodes, which comprises, providing pure tungsten powder having a specific weight less than three grams per cubic centimeter, molding the powder into electrodes in a matrix under pressure between the limits of seven kilograms per square centimeter and ten kilograms per square centimetergheatinsg the electrodes in the presenceof pure hydrogen to a temperature between 1000 centigrade and 1300 centig'rade and then heating them to approximately 2100 centigrade in the presence of argon thereby to form non-porous electrodes.
References Cited in the file of this patent UNITED STATES PATENTS 2,008,617 ,Lampitt July 16, 1935 2,069,951 Hastings Feb. 9, 1937 2,253,533 Ruben Aug. 26, 1941 2,311,647 Doran Feb. 23, 1943 2,491,866 Kurtz Dec. 20, 1949 2,578,754 Smits Dec. 18, 1951 2,625,922 Smits Ian; 20, 1953 2,675,310 Hall Apr. 13, 1954 2,689,556 Smits Sept. 21, 1954 2,712,685 Johnson et a1. July 12, 1955 2,791,022 Stuermer May 7, 1957
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR2908569X | 1954-02-05 |
Publications (1)
Publication Number | Publication Date |
---|---|
US2908569A true US2908569A (en) | 1959-10-13 |
Family
ID=9689841
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US485180A Expired - Lifetime US2908569A (en) | 1954-02-05 | 1955-01-31 | Process of producing sintered tungsten electrodes |
Country Status (1)
Country | Link |
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US (1) | US2908569A (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3599030A (en) * | 1969-07-15 | 1971-08-10 | Brunswick Corp | Annular surface gap spark plug |
US20070262721A1 (en) * | 2006-05-12 | 2007-11-15 | Enerpulse, Incorporated | Composite Spark Plug |
US9640952B2 (en) | 2012-01-27 | 2017-05-02 | Enerpulse, Inc. | High power semi-surface gap plug |
Citations (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2008617A (en) * | 1934-09-05 | 1935-07-16 | Mrs Edwin A Lampitt | Spark plug |
US2069951A (en) * | 1936-01-16 | 1937-02-09 | Jr Arthur C Hastings | Spark plug |
US2253533A (en) * | 1939-01-31 | 1941-08-26 | Ruben Samuel | Electric make and break contact |
US2311647A (en) * | 1940-05-06 | 1943-02-23 | James A Doran | Spark plug and method of making |
US2491866A (en) * | 1942-09-30 | 1949-12-20 | Callite Tungsten Corp | Alloy of high density |
US2578754A (en) * | 1951-12-18 | Sparking plug | ||
US2625922A (en) * | 1949-06-17 | 1953-01-20 | Smitsvonk Nv | Surface discharge spark plug for low voltages and condenser discharge |
US2675310A (en) * | 1949-06-23 | 1954-04-13 | Westinghouse Electric Corp | Consolidation of metal powder |
US2689556A (en) * | 1951-07-31 | 1954-09-21 | Smitsvonk Nv | Surface discharge spark plug for low voltages and condenser discharge |
US2712685A (en) * | 1951-08-06 | 1955-07-12 | Hastings Mfg Co | Method of manufacturing spark plug shell and ground electrode assemblies |
US2791022A (en) * | 1952-05-10 | 1957-05-07 | Gen Motors Corp | Low tension spark plug and process for making same |
-
1955
- 1955-01-31 US US485180A patent/US2908569A/en not_active Expired - Lifetime
Patent Citations (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2578754A (en) * | 1951-12-18 | Sparking plug | ||
US2008617A (en) * | 1934-09-05 | 1935-07-16 | Mrs Edwin A Lampitt | Spark plug |
US2069951A (en) * | 1936-01-16 | 1937-02-09 | Jr Arthur C Hastings | Spark plug |
US2253533A (en) * | 1939-01-31 | 1941-08-26 | Ruben Samuel | Electric make and break contact |
US2311647A (en) * | 1940-05-06 | 1943-02-23 | James A Doran | Spark plug and method of making |
US2491866A (en) * | 1942-09-30 | 1949-12-20 | Callite Tungsten Corp | Alloy of high density |
US2625922A (en) * | 1949-06-17 | 1953-01-20 | Smitsvonk Nv | Surface discharge spark plug for low voltages and condenser discharge |
US2675310A (en) * | 1949-06-23 | 1954-04-13 | Westinghouse Electric Corp | Consolidation of metal powder |
US2689556A (en) * | 1951-07-31 | 1954-09-21 | Smitsvonk Nv | Surface discharge spark plug for low voltages and condenser discharge |
US2712685A (en) * | 1951-08-06 | 1955-07-12 | Hastings Mfg Co | Method of manufacturing spark plug shell and ground electrode assemblies |
US2791022A (en) * | 1952-05-10 | 1957-05-07 | Gen Motors Corp | Low tension spark plug and process for making same |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3599030A (en) * | 1969-07-15 | 1971-08-10 | Brunswick Corp | Annular surface gap spark plug |
US20070262721A1 (en) * | 2006-05-12 | 2007-11-15 | Enerpulse, Incorporated | Composite Spark Plug |
US8922102B2 (en) * | 2006-05-12 | 2014-12-30 | Enerpulse, Inc. | Composite spark plug |
US9287686B2 (en) | 2006-05-12 | 2016-03-15 | Enerpulse, Inc. | Method of making composite spark plug with capacitor |
US9640952B2 (en) | 2012-01-27 | 2017-05-02 | Enerpulse, Inc. | High power semi-surface gap plug |
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