US2776919A - Method of heat treating cerium-iron alloys - Google Patents

Method of heat treating cerium-iron alloys Download PDF

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US2776919A
US2776919A US420191A US42019154A US2776919A US 2776919 A US2776919 A US 2776919A US 420191 A US420191 A US 420191A US 42019154 A US42019154 A US 42019154A US 2776919 A US2776919 A US 2776919A
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alloy
temperature
cerium
treatment
heat treating
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US420191A
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Bungardt Walter
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Evonik Operations GmbH
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TH Goldschmidt AG
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    • CCHEMISTRY; METALLURGY
    • C06EXPLOSIVES; MATCHES
    • C06CDETONATING OR PRIMING DEVICES; FUSES; CHEMICAL LIGHTERS; PYROPHORIC COMPOSITIONS
    • C06C15/00Pyrophoric compositions; Flints

Definitions

  • Pyrophoric metals of the cerium-iron alloy type which are used, for example, for the production of flints for lighters or similar purposes have been known for a long time.
  • Mischmetal may be employed in place of cerium in producing the flint compositions and comprises a mixture of a predominant part of cerium with other rare earth elements such as lanthanum. It is also known to improve the useful properties of such alloys, for example, their resistance to decomposition when stored at room temperature or moderately elevated temperatures or else the form and nature of sparkingetfect and like properties, by further alloying additions or ingredients in relatively small amounts. Copper, magnesium, zinc, silicon, tin and many other elements have previously been proposed for this and similar purposes.
  • Flints can be produced by casting or extrusion. In the former case they are shaped by a special casting process using special moulds. In the case of extrusion the starting material is a suitably composed ingot, as disclosed in U. S. Patent No. 2,660,301, which is converted into the desired final dimensions of the flint in an extrusion press at relatively high and predetermined temperatures and pressures.
  • flints produced from mischmetal or cerium-iron alloys by known methods of manufacture, directly as obtained after shaping and cooling to room temperature.
  • the flints are generally also given special surface treatment, for example, "through application of a protective coating or covering in order to reduce corrosion; for example, fine aluminum tinsel is applied to the surface of the flint and secured thereto by using a lacquer.
  • Still another object of the present invention is to provide means affording a relatively inexpensive treatment step for imparting to the alloy enhanced and desirable qualities whereby the excitability and sparking stimulation of the alloy is markedly improved.
  • the novel after-treatment efiects a decrease in the hardness of the alloys utilized along with a simultaneous improvement in the excitability (pyrophoric sparking) of these alloys.
  • a mischmetalor cerium-iron alloy containing about 10% to 30%.by weight of iron, with or without the customary alloying additions of materials such as copper, zinc, silicon, magnesium, tin, and the like, is subjected to an after-treatment at temperatures ranging'between C. and the melting point of the alloy, the pyrophoric properties are considerably improved while the hardness is somewhat reduced.
  • the preferred temperature range for the after-treatment lies between 300 C. and 450 C. which approaches the softening range of the alloy.
  • EXAMPLE I An alloy containing by weight 18.6% Fe, 1.9% Mg, and 0.8% Sn, the remainder being mischmetal, was subjected to after-treatment at 400 C. As a result of this after-treatment, the hardness was decreased from kg./mm. to 120 kg./mm. As determined at low contact pressures, the excitability of the alloy was increased from 40% to 90%. At high contact pressures, the excitability of the alloy was increased from 84% to 100%. Insofar as could be observed under the microscope, there were no visible changes in the internal structure of the alloy.
  • EXAMPLE II An alloy containing by weight 20.2% Fe, 1.8% Mg, and 0.9% Sn, the remainder comprising mischmetal, exhibited, at room temperature, a hardness of kg./mm. the test being carried out with a 0.625 mm. ball, and 11.7 kg. load at 30 sec. load duration. For comparative purposes, after formation the alloy was brought to different temperature levels and the hardness was determined. In addition, the excitability at both low and high contact pressure was determined. The results are tabulated in the following table:
  • the method of imparting increased. sparking properties to flint alloys which comprises. exposing. said fiint' alloy after final rod. formation thereof, to a thermal aftertreatment at a. temperature. ranging between 100 C. and about. 450 C. at which latter temperature. melting. of said alloy is initiated.

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  • Metallurgy (AREA)
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Description

United States Patent METHOD OF HEAT TREATING CERlUM-IRON ALLOYS Walter Bungardt, Essen-Bredeney, Germany, assignor to Th. Goldschmidt A.-G. Chemische Fabriken, Essen, Germany No Drawing. Application March 31, 1954, Serial No. 420,191
3 Claims. (Cl. 148-13 This invention relates to a method of heat treating cerium iron alloys.
Pyrophoric metals of the cerium-iron alloy type which are used, for example, for the production of flints for lighters or similar purposes have been known for a long time. Mischmetal may be employed in place of cerium in producing the flint compositions and comprises a mixture of a predominant part of cerium with other rare earth elements such as lanthanum. It is also known to improve the useful properties of such alloys, for example, their resistance to decomposition when stored at room temperature or moderately elevated temperatures or else the form and nature of sparkingetfect and like properties, by further alloying additions or ingredients in relatively small amounts. Copper, magnesium, zinc, silicon, tin and many other elements have previously been proposed for this and similar purposes.
It is also known that the mode and quantity of further additions to the alloy, such as those hereinabove mentioned, depend upon the process for manufacturing these flint metal alloys. The extrusion process generally necessitates a diiferent flint composition from that employed in casting. Copper and/or zinc should be excluded from compositions intended for extrusion as they form a molten alloy at the optimum temperature required for extrusion of the basic components constituting the flint alloy.
Flints can be produced by casting or extrusion. In the former case they are shaped by a special casting process using special moulds. In the case of extrusion the starting material is a suitably composed ingot, as disclosed in U. S. Patent No. 2,660,301, which is converted into the desired final dimensions of the flint in an extrusion press at relatively high and predetermined temperatures and pressures.
Hitherto it has been customary to use flints, produced from mischmetal or cerium-iron alloys by known methods of manufacture, directly as obtained after shaping and cooling to room temperature. The flints are generally also given special surface treatment, for example, "through application of a protective coating or covering in order to reduce corrosion; for example, fine aluminum tinsel is applied to the surface of the flint and secured thereto by using a lacquer.
These methods, which are carried out at room temperature or moderately elevated temperatures, are however without influence on the properties of the pyrophoric metal alloy.
It is therefore one of the objects of the present invention to provide means conducive to considerable improvements in highly desirable structural, physical and sparking properties of such pyrophoric material.
It is another object of the present invention to provide means facilitating the preparation of an alloy of the aforesaid type which is homogeneous and of substantially reduced hardness and has increased sparking capa-' bilities.
Still another object of the present invention is to provide means affording a relatively inexpensive treatment step for imparting to the alloy enhanced and desirable qualities whereby the excitability and sparking stimulation of the alloy is markedly improved.
These and other objects of the invention will ensue from the further description thereof and the attached claim or claims.
Referring now more particularly to the present invention in greater detail, it is to be noted that surprising results have been observed when flints produced by either extrusion or casting are subjected in finished form to thermal after-treatment at elevated temperatures up to the temperature at which the respective alloy commences to melt.
The novel after-treatment efiects a decrease in the hardness of the alloys utilized along with a simultaneous improvement in the excitability (pyrophoric sparking) of these alloys.
If, for example, a mischmetalor cerium-iron alloy containing about 10% to 30%.by weight of iron, with or without the customary alloying additions of materials such as copper, zinc, silicon, magnesium, tin, and the like, is subjected to an after-treatment at temperatures ranging'between C. and the melting point of the alloy, the pyrophoric properties are considerably improved while the hardness is somewhat reduced. The preferred temperature range for the after-treatment lies between 300 C. and 450 C. which approaches the softening range of the alloy.
The following example is illustrative of the practice of the present invention:
EXAMPLE I An alloy containing by weight 18.6% Fe, 1.9% Mg, and 0.8% Sn, the remainder being mischmetal, was subjected to after-treatment at 400 C. As a result of this after-treatment, the hardness was decreased from kg./mm. to 120 kg./mm. As determined at low contact pressures, the excitability of the alloy was increased from 40% to 90%. At high contact pressures, the excitability of the alloy was increased from 84% to 100%. Insofar as could be observed under the microscope, there were no visible changes in the internal structure of the alloy.
While a decrease in hardness will produce an increase in excitability as a purely mechanical effect, the increased excitability achieved by the thermal after-treatment herein described is not due solely to the decrease in hardness. Rather, it appears that there may be solubility changes within the mixed crystal components of the alloy which are not detectable by a microscope, but which nonetheless cause enhanced excitability of the alloys.
The following example is a further illustration of. the advantages derived from thermal after-treatment according to the present invention:
EXAMPLE II An alloy containing by weight 20.2% Fe, 1.8% Mg, and 0.9% Sn, the remainder comprising mischmetal, exhibited, at room temperature, a hardness of kg./mm. the test being carried out with a 0.625 mm. ball, and 11.7 kg. load at 30 sec. load duration. For comparative purposes, after formation the alloy was brought to different temperature levels and the hardness was determined. In addition, the excitability at both low and high contact pressure was determined. The results are tabulated in the following table:
As carrbe seen from this" table, the hardnessd'ecreases continuously as the temperature of after-treatment increases to 400 C. In: contrast therewith, the excitability at both high and low contact pressures (against the flint) decreases with increased temperature of after-treatment until a minimum value is attained at' about 300 C. Further increase in the aftentreatment temperature produces a rise in the excitability to a maximum value at about 400 C. after which the excitability levels off; This-table indicates thecomplex nature of the improvement achieved bythe thermal treatments herein de scribed.
It can thus be seen. that there has been-provided according to this invention animproved flint alloy and a. novel method of producing same by subjecting: said alloy (cerium-iron or mischmetal-ironalloy); in its fin ished form to athermal after-treatment at an= approximate temperature ranging between 300 CL and 450 C.
before said alloy is allowed to cool down to room temperature.
While preferred forms of? the invention have been described above, it will be apparent that numerous changes and modifications may be made in the manner of producing .flint and like alloys in accordance with my invention without. departing. fromthespirit and scope thereofl Having thus described the invention, what is claimed as new and desired to besecured by'Letters Patent; is:
1. The method of improving'properties' offii'nts made from cerium-iron alloy, which comprises subjecting said alloy subsequent to=final rod formation to a.heat'.aftertreatment at a temperature within :the range between C. and approximately the temperature at which melting of said alloy starts.
2. The method of improving useful properties of flints made from misehmetal (ceriumQ-iron alloys, which comprises subjecting said alloy, after final formationthcreof into fiint rods, to a. subsequent heat treatment. at a. temperature range between 100 C. and about 400 C.
3. The method of imparting increased. sparking properties to flint alloys, which comprises. exposing. said fiint' alloy after final rod. formation thereof, to a thermal aftertreatment at a. temperature. ranging between 100 C. and about. 450 C. at which latter temperature. melting. of said alloy is initiated.
Hirsch Dec. 31, 19.18

Claims (1)

1. THE METHOD OF IMPROVING PROPERTIES OF FLINTS MADE FROM CERIUM-IRON ALLOY, WHICH COMPRISES SUBJECTING SAID ALLOY SUBSEQUENT TO FINAL ROD FORMATION TO A HEAT AFTERTREATMENT AT A TEMPERATURE WITHIN THE RANGE BETWEEN 100* C. AND APPROXIMATELY THE TEMPERATURE AT WHICH MELTING OF SAID ALLOY STARTS.
US420191A 1954-03-31 1954-03-31 Method of heat treating cerium-iron alloys Expired - Lifetime US2776919A (en)

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Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1290010A (en) * 1917-09-17 1918-12-31 Alpha Products Company Inc Process of making castings of rare-earth metals and their alloys.

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1290010A (en) * 1917-09-17 1918-12-31 Alpha Products Company Inc Process of making castings of rare-earth metals and their alloys.

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