DE1019949B - Extruded ignition stone made from a pyrophoric cerium (mixed metal) -zinc-magnesium alloy with 4 to 40% iron - Google Patents

Description

GERMAN

In the German patent application G 18480 IV a / 78 f, a method is disclosed, according to which not extrudable se cerium (misch metal) iron alloys with 4 to 40% iron and an alloy content of zinc of more than 0.15 ° / ₀ in the Temperature range between about 400 and 500 ° can be made extrudable by adding magnesium to the alloy at the same time. It is necessary for the effectiveness of the process that the ratio of zinc to magnesium does not exceed 1.2. The process technology thus disclosed removes the previous restriction to zinc-free cerium (mischmetal) -iron alloys for extrusion technology. The advantage achieved in this way only applies to four-component alloys with cerium (mischmetal) as the base, iron as the main alloy partner and zinc and magnesium as third and fourth special alloy additives that improve the pyrophoric character of the alloy.

In the practice of flint production by tube or chill casting processes, however, there are more still other additional elements common, z. B. copper, which has the special task of storage stability to improve the inherently less corrosion-resistant alloy type. There is therefore a Great economic interest in making this possibility usable for the extruded flint make, especially for the complex cerium (mischmetal) -iron alloys, which in addition to the main alloy partner Iron and third and fourth additives of zinc and magnesium also have low copper contents. The present invention provides a solution to this problem by specifying a specific range of alloys in which the extrusion technique is carried out can be.

The practice of making cast, non-extruded flints knows alloys in which use is made of the elements zinc, magnesium and copper as special alloy additives. Table 1 contains some well-known typical examples. _{Tabeüe χ}

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No. Fe Cu Zn Si Mg Sn % % % 7o 0 /
/ ο 1 20th 0.5 _ 1.0 0.5 _ 2 28 0.5 - - 1.5 - 3 12.8 0.73 - 0.45 2.38 - 4th 19.6 1.00 0.04 - 2.30 - 5 23.0 1.5 - - - - 6th 15..18 2.0 2.0 - 2.0 - 7th 25.6 2.01 0.39 0.40 - 8th 20.4 2.38 - - 3.95 - 9 16 4.0 - - 2.0 2.0 10 21.7 4.95 - - 2.71 -

Extruded flint

from a pyrophoric cerium (mixed metal!) -

Zinc-magnesium alloy

with 4 to 40 per cent. iron

Addition to patent application G 18480IVa / 78f
(Interpretation document 1 017 508)

Applicant:

Th. Goldschmidt A.-G. _f
Essen, Heilermannstr. 15th

Dr. Walter Bungardt, Essen-Bredeney,
has been named as the inventor

However, all these alloys are in the most favorable processing range for cerium (mischmetal) iron alloys, namely between 400 and 500 ° C not extrudable, be it that the necessary relationship of the Components zinc to magnesium according to the German patent application G18480IV a / 78 f not fulfilled is, be it that the copper or zinc content is too high to allow technically perfect extrusion. Even the obvious lowering of the pressing temperature does not lead to any result, since it is then sufficient Temperature reduction, although a temperature range can be found in which the to be processed The ingot consists only of solid phases; however, as has been operationally proven, this is the case with this measure sharp increase in the deformation resistance of the alloy linked to the inadequate pressability The durability of even the best extrusion dies fails. The procedure is then compared to that Casting of flints too uneconomical because of the high repair costs for the extrusion press and pressing tools.

In the further development of the process according to the German patent application G 18480 IV a / 78 f, it has now been found that the extrudability of the alloy group disclosed in this application is retained with certain low copper contents. However, it is necessary for this purpose that the copper content 0,35 ° / ₀ not exceed. If they are higher, the pressability is at the upper range of the pressing temperature range due to partial melting of the ingot and at the lower limit of the temperature range mentioned

709 806/81

canceled by too strong deformation resistance. The results given in Table 2 were obtained for the particularly favorable forming conditions at 480 °. The examples refer to pjrfophqre cerium (MischmetaUJ-iron alloys mit'etwa '21%' iron, 2% magnesium and 1 '%' ZmK, which increasing copper levels have been up to 0.35 ° / ₀ alloyed.

Table 2

Chemical composition in ° / " Zn Cu Press pressure Verse. / 0 1.0 (kg / cm ² ) 0.7 0.1 at 480 ° after No. ^: Cerium Fe Mg 0.9 0.23 30 minutes longer (Mischmetal) 20.8 2.0. 1.0 0.30 Preheating 458 76.2 20.9 ^: 1.7 0.9 0.35 3500 460 76.6 20.9 : 1.8 1850 461 76.1 20.8 1.9. 1450 462 76.0 20.9 2.0 1250 462 a 75.75 no longer compressible

IO

The table shows the concept of nutrition, that the compressibility of this complex group of alloys is only possible with certain low copper contents is possible. The extrudability is already lost above 0.35% Cu.

For the choice of the alloying element copper to pyrophoric cerium (mischmetal) -iron alloys is in primarily the observation that copper increases the shelf life of this type of alloy able to improve. The copper content required for this is found in cast flints made of cerium (mischmetal) iron alloys mostly at levels of a few percent (see Table 1); below 0.5% copper is used Improvement of the shelf life of cast flints has not yet been added. been. Surprisingly has now been found that the extrudable, copper-containing cerium (mischmetal) -iron alloys tolerable low copper content on the shelf life of extruded flints, despite the reduction of the alloy content, still have a significantly improving effect. So was z. B. with the help of a simple corrosion test, in which the weight loss of flints of the same size after Storage in 'humid air is measured, found that the shelf life is doubled at 0.3% compared to the copper-free alloy.

The addition of relatively small amounts of copper up to at most 0.35 ° / ₀ has also for the extruded flint. still has the advantage that the compression pressure is reduced very noticeably, as can be seen in the last column of Table 2.

Through the invention is thus achieved that the after German patent application G 18480 IV a / 78 f disclosed alloy group of cerium (Mixed Metal!) Iron alloys with 4 to 40 ° / alloyed ₀ iron as well as zinc and magnesium contents in certain ratios and copper may be, when the copper content from 0.05 to 0.35 ° / _'o remains. Apart from the possibility of using copper as an alloying element, this measure also has the technical advantage that the pressing pressure is reduced and the storage life is increased. The improvement in shelf life can even be achieved with extruded flints with lower copper contents than with cast flints, to which higher copper contents are normally added to achieve this effect.

Claims (1)

Claim: Extruded flint made of a pyrophoric cerium (mischmetal) -zinc-magnesium alloy with 4 up to 40% iron according to German patent application G18480 IVa / 78f, characterized by the addition of an alloy from 0.05 to 0.35% copper. Considered publications:
Austrian Chemiker Zeitung, 40 (1937), p. 302. © 709 806/81 11.57