US2660301A

US2660301A - Process for the manufacture of cerium-iron-alloy flints

Info

Publication number: US2660301A
Application number: US117069A
Authority: US
Inventors: Bungardt Walter
Original assignee: TH Goldschmidt AG
Current assignee: Evonik Operations GmbH
Priority date: 1948-09-28
Filing date: 1949-09-21
Publication date: 1953-11-24
Anticipated expiration: 1970-11-24

Description

Patented Nov. 24, 1953 PROCESS FOR THE MANUFACTURE OF CERIUM-IRON-ALLOY FLINTS Walter Bungardt, Essen, Germany, assignor to Th. Goldschmidt A.-G., Essen, Germany No Drawing. Application September 21, 1949, Serial No. 117,069

Claims priority, application Netherlands September 28, 1948 1 Claim. 1

This invention refers to the manufacture of pyrophoric flint material in rod or like shape and has as one of its primary objects to provide means affording subjection of an ingot of suitable alloy to an extrusion press having a die opening whose cross-section corresponds to that of the finished flint rod.

Cerium-iron alloy flints are usually made by casting. It has been proposedto make flints of this kind by the extrusion process which is more economical than casting. The known attempts in this direction have failed. It was found that the pyrophoric properties of the alloy were lost during the extrusion process hence the process has been described in technical literature as completely useless.

The present invention proceeds from the recognition that the diminution of pyrophoric properties during extrusion is to be attributed to the fact that, on extrusion, the cerium-iron crystals, to which the pyrophoric action of the ceriumiron alloys is to be ascribed, are shattered and that consequently a larger quantity of eutectic matrix is necessary in order to embed sufficiently the fragments of the cerium-iron crystals so that they are protected against braking out when subjected to friction by the friction wheel of the lighter. Researches have shown that the necessary quantity of eutectic matrix increases with increase in thesize of the cerium-iron crystals in the ingot introduced into the extrusion press.

The eutectic matrix has not only the task of embedding the cerium-iron crystals and protecting them from breaking away, but also of making the pyrophoric properties of the cerium-iron crystals readily excitable. The eutectic matrix is readily oxidizable, but oxidation manifests itself not in spark formation on friction but only in heat production; however this heat production favors the flaming of the pyrophoric crystal fragments. The best cerium-iron alloy for flints produced by casting consists of about 30 to 40% iron, the remainder cerium. The amount of eutectic matrix increases with decrease in the iron content.

In the process for the production of pyrophoric films from cerium-iron-alloys, by means of extruding presses according to the present invention, the iron content is therefore lowered to of the total alloyage. It was shown that with ingots with an iron content lowered to from 15 to 25%, when they are produced in a normal manner, such a quantity of eutectic groundmass or matrix is on hand that the fragments or fission products of the cerium-iron-crystals result- 2 ing from the extrusion pressing remain suflicient 1y anchored or tied in it. The required amount of eutectic groundmass or matrix for the extrusion pressing, is much slighter as the ceriumiron-crystals are correspondingly smaller in the ingot used for the extrusion pressing.

The crystals should not be below a minimum size, otherwise they lose their pyrophoric properties. It has been found, however, that by the use of inoculant additions, i. e. additions resulting in the production of more numerous but smaller crystals, or by accelerated cooling of the ingot, such a diminution in size of the ceriumiron crystals can be obtained that, on the one hand, the pyrophoric properties are not substantially influenced, while, on the other hand, the cerium-iron crystals can slip past one another during extrusion without shattering so that an increase in eutectic matrix is not necessary. The

process according to the present invention can therefore be carried out by utilizing cerium-iron alloys with an iron content of more than 25% and up to 40% and an inoculant addition, e. g. zirconium. The amount of this addition must not be so large that it substantially aifects the pyrophoric properties of the alloy. Additions of up to 1% zirconium, for example, are sufficient Particularly advantageous inoculant additions are such elements that do not form with the other alloying elements any alloy constituents which are liquid below the extrusion temperature. Alloying constituents which are liquid at the extrusion temperature have a detrimental effect on the extrusion operation.

As the melting point of cerium-iron alloys decreases with reduction in the iron content, such a reduction has advantages during casting. It diminishes, for example, the loss by burning. On the other hand, it diminishes also the hardness of the alloy so that the friction wheel of the lighter rubs more severely against the flint and therefore uses it up more rapidly. If therefore alloys with a low iron content are used in accordance With the invention, it is useful to add to them hardness-increasing elements, for example tin, magnesium, cadmium or zinc, in a quantity which does not substantially affect the pyrophoric properties of the alloy.

Where reference has been made above to cerium, this term is intended to include the misch metal customary in the trade which, in addition to cerium, is always accompanied by other rare earths, for example lanthanum. Y

The high oxidizability of the cerium-ironaldestroyed in time by oxidation from the air, in particular under the high temperatures of hot and moist climates. Cerium-iron fiints therefore usually have a protecting covering. It has now been found that the lastingness -is increased to an extraordinary degree if the cerium-iron alloy is plunged in oil when in hot condition.

This can easily be effected in the case of ex-- truded flints by leading into oil-the rod=of material delivered hot from the extrusion press; with or without an intermediate passage through an atmosphere of inert gas-"which,- forzexample,

may be argon, hydrogen 0rnitrogen: This method of improving the lastingness,.,however,

not limited to extruded "flints.

The lastingness can also be improved in the case of extruded material by surrounding; the

ingot with a coating metal and then extruding it, so that the emerging rod of cerium-iromalloyj is surrounded by a thin coating of the protecting metaL- Aluminium. has been found. specially suitablefo'r this purpose; The ingot "can either belwrapped. with aluminium foil; introduced "into an. aluminium tube,', or'have' aluminium cast arounditt It'will thusbe recognized' that there'has'been provided, according, to the invention a novel method 0 f producing pyrophoric' flint material inrrodpformation which comprises thesteps of preparing an" ingot of'cerium-iron alloy with an ironcontenti'of approximately, 15% to. 25% by weight, and then subjecting said ingot'which is 0 Numbersteps ofe preparing an ingot of cerium-iron alloy with an iron content of approximately 15% to 25%3by WeightpandFthen subjecting said ingot, which is 'devoid of any outer cover, to extrusion under application of heat and pressure, whereby the resultant extruded material is discharged through an extrusion die opening of a cross-section corresponding to that of the finished flint rod;

WALTER BUNGARDT.

References Cited in-the file of this patent UNITED STATES PATEN'I'S Name Date Welsbach Nov. 22, .1910 Eorcellon Nov. 8,;1921 Winston Dec.- 10;,1935 Van Dusen, Jr., et a1. D'ec. 1,-1936 FOREIGN PATENTS Country; Date? Great Britain Feb. 14; 1945 Number: