DE3512118A1 - METHOD FOR GENERATING AN IMPROVED FINE-NARROWNESS OF THE PRIMARY FABRIC AND / OR THE EUTEKTIKUM OF CASTING PARTS - Google Patents

Description

Essen, April 2, 1985 PZ 3381 Fö / gl

THYSSEN INDUSTRIE AG

At Thyssenhaus 1

4300 Essen 1

Process for producing an improved fine grain size of the primary structure and / or the eutectic of cast parts

BATH

The invention relates to a method for producing an improved fine grain the primary structure and / or the eutectic van Eussteile from: Aluminum, salt-based, nickel-based and iron alloys.

It is known that the fine grain of castings with the help of van Heimen in the molten metal and / or with the help of van Heimen in the pore entrances and affect and improve on the inner surface of the farm shells can.

Usually, when casting aluminum and aluminum-based alloys, a master alloy is added to the molten metal before casting, which z. B. contains titanium diboride as a home, which is present in the molten metal as a chemically stable substance in the manner of a slurry (heterogeneous home). For example, a master alloy is used that contains 5 % Ti, 1% boron, the remainder Al and with 0.2-0.5% wt. B. the molten metal Al - Si7 - Mg O ₁ S is added before casting. About methods for urine refinement of aluminum casting is z. B. van Hissling, R. 3. and üJallace, 3. F. "Grain Refinement of Aluminum Castings" Foundry , June 1963 _; 78-82, reported.

With regard to cast aluminum alloys, it is known that in addition to Ti - boron also Elements dissolved in the melt lead to a reduction in the grain size - im Case of aluminum and aluminum alloys to shrink the dendrites and Dendritic arm distances - contribute. For example, the improved fine grain and / or a refining effect achieved by adding the elements: Li, H, Rb, Cs, Be, Mg, Ca, Sr, Ba, As, Sb, Ga, S, Na, P (endogenous Homes).

The addition of the elements P, V, Ca, Cu, Ag, Ti, and J is known to have one similar effect.

In addition, it is desired that, for. B. in the solidification of the alloy Al - Si7 MgO, 6 finely divided, spherical excretion are formed, which predominantly consist of Si.

With these measures you can achieve z. B. in investment casting according to the üJachs melting process of Al-Si7 -MgO ₁ S tensile strength values of at best approx. ^{280-300 l \ l / mm 2} with approx. 5 % elongation at break.

BATH

The strength properties of aluminum alloys are known to be direct depending on the number and fineness of the smallest possible dendrite arm distances - the secondary dendrite arm distances - and the finest possible distributed spherical precipitates. It is the object of the invention to this Significantly improve properties.

It is also known that nickel, iron and cobalt-based alloys can be used solidify in a fine-grained manner due to homes in or on the surface of the shell mold can leave. Wake up Hortpn, Ashbroak and Feagin. U.S. Patent 3,019, * t97 and U.S. Patent 3,157 ", 926, Schweikert, 111. H-, U.S. Patent 33, 158, 912, as well Feagin, U.S. Patent 3,259,948 is known to have the following chemical Compounds and elements represent medium to highly effective seed catalysts:

Platinum hydroxide, colloidal platinum, silicon carbide, iridium, rhodium,. Ruthenium, cobalt, the cabalt oxides, cobalt hydroxide, nickel oxide, iron oxides, Cobalt silicate, cobalt aluminate (exogenous germs). Εϊηεπ a relatively weaker catalysis effect is obtained when using: Gold, silver carbonate, palladium, titanium carbide, boron carbide, zirconium diboride and others. m.

No or only a very small seed catalysis effect is obtained with the Use of:

Molybdenum, copper oxide, tungsten, tungsten acid, silicon oxide, zirconium silicate, Zirconium hydroxide, zirconium nitride, zirconium cyanonitride, boron nitride. The mentioned Karhides, nitrides and probably also borides are possibly therefore few or not effective because the mold shells in the production z. B. in the investment casting after the ülachsausschmelzverfahren fired and preheated in air before casting so that the nitrides, carbides and of course also borides are superficial be oxidized. It is a further object of the invention to post these substances Possibility to protect against oxidation and so at least their germ effectiveness beyond the preheating temperature of the shell, if possible also beyond the fire of the Shell to get out.

Usually z. H. in the investment casting of iron, cobalt and nickel-based alloys according to the UJachsauschmelzverfahren in accordance with the patent specifications mentioned (Feagin) worked with the help of cobalt aluminate.

- ³ -. BAD ORJGINAi.

A wax model of the later casting with the necessary supply lines is made from wax; The wax model is provided with a first layer, which consists of a slurry of finely powdered cobalt aluminate and a refractory filler, a binder and a solvent. The layer is dried. Then further layers of aluminum oxide or zirconium silicate and other ceramic materials are applied by aqueous or non-aqueous moistening (dipping) and sanding with ceramic powder and dried after each dip so that a ceramic shell of suitable stability is created. The wax is melted out, the farm shell is burned at a higher temperature - for nickel-based, cabalt-based and iron-based alloys at up to approx. 12DD ⁰ C. If necessary, the cooled farm shell is provided with a suitable thermal insulation material and, before the respective metal alloy is cast, preheated to a temperature which is approx. 200 ^° C. to 500 ^° C. below the temperature of the liquid metal alloy.

It is also common and known to use the nucleating active powder the first Add the dip as a mixture together with the ceramic powder, for example in a fine-grained farm as part of the equally fine-grained filler of the first dip with grain diameters that are predominantly more than 10 m.

A similar procedure, but with fire temperatures of the farm shell of approx. FiOG ⁰ C 900 ⁰ C, is also used in the investment casting of aluminum alloys.

It is known that with very many types of metallic casting that one Lowering the pouring temperature and the mold temperature leads to grain refinement and increases the grain refinement effect of the germ-active substances.

This method is limited by the need for the shell mold having to fill it completely with molten metal. The cause of influenceability the grain size due to the temperatures mentioned lies in the achievable freezing speed is justified by the household budget of the shell - casting system with the properties "thermal conductivity, Heat capacities, geometries "is determined.

ORIGINAL

As is well known, brief supercooling occurs after metallic melts have been poured off the edge zanen of the metal, in which there is no crystallization is, although the molten metal in this zone has assumed a temperature which is lower than the liquidus temperature of the alloy. The germs that are in the molten metal or on the surface of the shell mold reduce this "subcooling temperature interval".

It is also known that particles in the molten metal and / or in the Contact zone molten metal - shell mold can only be germicidal if they have a near wettability.

Körher, K. and Löhherg, K-, "Surface and interface energies of aluminum-silicon melts", Gießereiforsehung 23, Heft 4 (1971) 173-177, give 1% by weight of an IMaCl - IMaF mixture (melting point at 676 ⁰ C with 33.5% MoINaF) liquid aluminum and aluminum-silicon alloys are added to the sample drop by chemical reaction of the aluminum. to refine the Al-Si alloys with metallic sodium. They find that the surface energy and the wetting angle of the drop against a solid base made of metallic silicon are not significantly reduced until about one minute after the salt mixture has been added; the reduction in the wetting angle is supposed to be brought about by the refinement with metallic IMa, which comes from the salt mixture. The aim of this invention is to use the known methods to achieve a finer cast structure, e.g. B. to reduce the dendritic arm distances to find a method in which the metal melt wets the ceramic, parene-containing shell so intensely that it penetrates the pores to there, due to the temperature difference between the preheated shell and the hotter liquid metal, as high as possible To obtain cooling rate. In this way, with the aid of the known seed materials and refinement methods, a particularly fine structure is to be achieved in the branched metal material that has penetrated into the shell mold, uiie z. B. Dendrites with a particularly small arm spacing, so that in the later and slower solidification of the cast body with them as many native germs as possible are present on its surface and are in contact.

■ / -

From the experiences that z. B. with the process for nickel-based alloys and cobalt aluminate as seed material (feagin) is obtained to be expected that the fine grain achieved on the surface of the casting of the structure also continues into the interior of the casting.

The stated object of the invention uiird slacked off by the fact that the molded shell on the surface that forms the cavity for the later casting, with a A layer that contains a salt mixture that contains at least one salt or consists of it, the melting point of the salt mixture or of the individual salt being lower than the liquidus temperature of the respective molten metal lies -and the anions of the salt or the salt mixture predominantly or consist exclusively of halogens, or also the salt or the salt mixture one or more alkali pseudohalogen compounds such as cyanate, Cyanide, Rhodanid-, Tetra- odsr HExacyanoverbindungen and / or similar the contains chemical related alkali compounds mentioned.

The salt or the salt mixture is used for the respective metal alloy to be poured selected so that the metallic melt melts the salt or the salt mixture during casting or it has already been melted by preheating the shell mold is and so the shell as well as the still liquid metal cast body be wetted by it. On the one hand, the molten salt fulfills its function of a flux similar to the method of joining various metals by soldering.

The salt or the salt mixture is after the temperature increase in the liquid state in the pores of the mold shell on the casting side and wetted at the same time the touch points of the casting farm shell. This also improves the heat transfer between the casting and the farm shell.

According to the invention, it is possible to add home material to the salt or the salt mixture - in the dissolved form as well as in the heterogeneous form in the manner of a slurry of a powder.

ORIGINAL BATHROOM

It is also according to the invention that the seed material with the material of the shell mold to connect - for example by applying as a slip and subsequently Sintering, or by flame spraying, plasma spraying and the like known processes. The salt or the salt mixture can be used at the same time or later Uierden applied in any known for the application of layers. Preferably one uses aqueous solutions of the salt or the salt mixture, as well as of the germination material in dissolved or slurried farm for wetting the inner surface and inner pores of the farm shell.

It is possible to use the existing heterogeneous homes - e.g. B .. as part of the surface the farm bowl in an exogenous manner - before loss of activity in the event of a fire and / or when preheating the farm shell, by z. B. Oxidation in air, to protect, sadaß also with nitrides, carbides and barides a high effectiveness can be achieved.

When the farm shell is on fire, advantageously when the shell mold is preheated, the germ-active substance can be protected from oxidation if the Melting point of the salt or the salt mixture is chosen correspondingly low.

With regard to sinter-stable and dissolved, endogenous germs, it is also advantageous to choose salts and salt mixtures with a melting point which is lower than the liquidus temperature of the molten metal. The melting point is chosen as low as possible so that it corresponds approximately to the solidus temperature of the metallic melt. The best results are obtained when the melting point of the salt or the salt mixture is approx. 50 - 90 % of the solidus temperature of the metal alloy to be cast. The lowest possible melting point of the salts and salt mixtures used here promotes the wettability of the metallic melt with respect to the shell mold.

If possible, salts are used which are produced according to the usual production methods and the usual preparations of the shell mold for the casting no water - z. Belly no more water absorbed from the ambient air - contain which for Formation of a bubble-containing surface of the casting can lead. At the same time, however, it is a series production for the production process

* - JSf -

favorable if you work with aqueous or organic-based solutions Salt or the salt mixture can work. In this case the lilac sirloin is used after drying of the first or the first dip including sanding in the Immersed in saline solution and impregnated the pores with the drying. Basically you can use any kind of homogeneous or heterogeneous distribution of the salt in Use a liquid. Solutions of the salt or the salt mixture have the additional advantage over slurries that those of the later Casting facing surface and the pore entrances located there Evenly and thinly with the salt thanks to the drying process or coated with the salt mixture in the preselected quantity ratio. This also applies in the same way, if possible, to the germ-effective Substance.

For the reasons mentioned, if possible, salts are selected that have a low value Have an affinity for water, d. H. which, if possible, do not form hydrates, but can be brought into solution in them. These are preferably the fluorides of Alkali and alkaline earth metals, in special cases determined by the conditions of the cast, e.g. B. vacuum casting, are given, including the chlorides, bromides and iodides of alkali, alkaline earth, light and heavy metals.

When using pseudo-halogen compounds, it is the same as before Knowledge level favorable to add them only in small proportions to the halogen salts to lower the liquefaction temperature, provided that the Salt impregnation after firing and before preheating the shell mold undertakes to avoid harmful gas development from their decomposition during casting obtain. However, in the case of cast parts made of Al-Si7-MgO, 6 the Use of additives to halogen salt mixtures .van one of the alkali hexacyanoferrates in the form of an aqueous solution for impregnation before the Brand of the molded shell exposed. In the event of a fire, this will probably result in a albeit hardly measurable, finely distributed, very thin coating of alkali-containing iron oxide, which is wetting by the molten metal additionally promotes and a high sintering activity compared to the farm material owns. Other organic and inorganic iron and iron also have a beneficial effect Nickel salts, which are predominantly oxidized when the shell is Erand, z. B. iron citrate, - acetate, one of the alkali tetracyanonickelates and others. m.

-B-

SAD OfiJG / NAL

■■■■ ■ · / <- ■

In individual cases it has even proven to be advantageous to use the Select the salt or the salt mixture so that one of the salt components or the mixture as a whole with the molten metal chemically reacts, so that a particularly intimate contact between form, Seed and casting material is produced.

A disadvantage of the invention described so far is that Due to the metallic penetration of the shell mold, a rough cast surface that is difficult to separate is obtained. It is now according to the invention possible to equip the inner surface, which forms the cavity for the later casting, with one or more layers, which has very fine pores in large numbers / area unit. The use of a salt or a salt mixture with a suitable one low melting point as a wetting aid and additionally the Use of a material that is inherently easily wettable by molten metal for the production or coating of the pores make it possible that the metal melt is still in these pores of the layers by capillary action penetrates, although they have very small pore diameters, about one Patents of ten and more are smaller than the prior art for Investment molds is common. The metallic ramifications break to a large extent Part of the casting due to different thermal expansion during the cooling process and / or can be cleaned with the remnants of the casting Easily remove the molded shell.

To produce the pores, a slurry of the finest has been used so far Ceramic material with grain sizes of preferably predominantly less than 0.2 μm is used. The slip is preferably applied after baking poured into the shell mold and, if possible, by rotating and swiveling movements applied evenly and thinly (up to approx. 5 μm), the excess liquid is poured off. You can also use the fine layers with the help of a SaI-Gel reaction or by mixing the powder Apply with the model material.

The coating with salts can be done at the same time or afterwards The fine layers are dried and sintered. The fine grain that Presence of salts as sintering aids and those for the slip technique, as well as the exact setting of the ph-lüertes usual for the sol-gel technique have the effect that afterburning of the shell mold high temperatures can be avoided.

BATH

The production of fine-grain ceramic powder and ceramic materials with a narrow, adjustable distribution of the pore diameter is known and is described, for example, by Burggraaf, A. 3., van de Graaf, MACG, "The preparation of special Ceramic microstructure and their properties" DKG eV, Annual meeting in Aachen 1984, 1 to 3 October.
The invention is explained in detail on the basis of the exemplary embodiments.

1. Aluminum alloys

A salt mixture in% mol, 23% BaF ₂ , 41% Li ₂ F ₂ , 29%
MgF ", 7% Na _? F "made by grinding the salts and melting them together. The solidification temperature was around
G30 ⁰ C. The solidified salt mixture was finely ground (grain size smaller than approx. 5 μm) and suspended in water.

The slurry was inputted by pivoting into the prepared by the lost wax finished fired ceramic shell mold, dried, heated for one hour at ⁰ C and then 55G
cooled to 240 ⁰ C. It was thus in a vacuum (10 Torr) with the
Alloy Al - Si7 - MgQ, G incl. Ti-boron grain refinement master alloy cast. The casting temperature was approx. 700 ° C.

The tensile specimens with B mm 0 produced in this way have, after the usual heat treatment, a tensile strength of approx. 300-320 l / mm ² with an elongation at break of approx. 5%.

2. Aluminum alloys

A salt mixture in% mol of 77% Li ₂ Cl ₂ , 23% BaF was obtained

produced, melted, cooled and finely ground (approx. 5 pm).

The freezing point was around 470 ^° C.

According to the phase diagram, the salt mixture then consists of the reciprocal ones Salt pairs BaF / BaCl- / LiCl / LiF.

The salt mixture was slurried in anhydrous isobutyl alcohol and then the farm bowl in the same way as example 1 inside

coated. After preheating to 430 ⁰ C and holding the temperature for

_2

The shell mold was cooled to 240 ° C. for ² hours in vacuo (10 Torr) and poured off with Al - Si7 - MgO ₁ G in vacuo, after approx.

- 10 -

1 cm ³ / kg Al - alloy made of aluminum boride with a grain size of 1D0pm is deposited at the deepest point of the sprue. The casting was then subjected to a heat treatment in the usual way. The tensile specimens of 8 mm 0 have a strength of approx. 340 l \ l / mm ² and an average elongation at break of approx. 5%.

3., Alumium alloys .

The procedure was as in Example 2, but an amount of about 1 cm ³ aluminum nitride / kg Al alloy was deposited in the sprue. The tensile specimens have a strength of 350 N / mm ² with an elongation at break of approx. 6% on average. The precipitates of the structure, which predominantly consist of Si, are finely distributed and spherical.

About the same strength properties as Example 3 were also obtained obtained by having

a) finely ground SiC, silicon carbide or reaction-bonded Silicon nitride powder with a grain diameter of approx. -10 μm, 10-50 grams / liter, added to the slurry according to Example 2, but none used deposited powder;

b) The aluminum nitride powder - 10 pm '0 with in the salt slurry according to example 2. gave.

The process according to Examples 2 and 3 still shows a few Disadvantages on:

- occasional gas bubble formation due to suspected purple water residues in the salt;

- awkward and uneven coating of the surface of the Shell mold.

H. Aluminum alloys

An aqueous solution of approx. BO g AlF, 60 g PbF, 3 g NaF, 2 k g LiF and 3.5 g BaF ₂ per liter solution at 50 70 ⁰ C was produced.

- ¹¹ - BAD ORIGIN) *.

Aluminum fluoride is used here as an auxiliary substance, according to Bmelin, Band Blei, (C), page 1293, to be able to dissolve larger amounts of lead fluoride. The composition PbF / IMaF / LiF also forms together with BaF "

and smaller proportions of AlF 'early liquid eutectics at approx. 480 -

AlF. Sublimated at temperatures of about 700 ⁰ C in a vacuum for the most part. The salt mixture reacts chemically at the casting temperature based on known thermochemical data with the alloy Al-Si7-MgO, 6.

The first dips were made with a filler made of zirconium silicate flour with predominantly less than 5 μm grain diameter on a wax model, the grave sanding material consisting of zirconium silicate powder in the usual way. After drying, the coated wax model was then dipped into the aqueous salt solution. The other ceramic layers of the farm bowl were applied by dipping on a non-aqueous base and sanding. The shell mold was further dried, dewaxed, calcined at 900 ⁰ C for 1 h and at 240 ⁰ C with Al - Si7 poured off-MgO, G in vacuo, then unterzagen the casting of the usual heat treatment.

The tensile specimens have a strength of approx. 360-380 l / mm ² with elongation at break of approx. 6 %.

5. Aluminum alloys

The procedure of Example 4 was followed, but the aqueous solution of the salts

a) Fine-grained Al 0

with grain sizes of ^ 5 pm and approx. 5 to 10 gr per liter of solution and

c) dissolved platinum chloride with about 0.5 gr per liter of solution

d) cobalt and nickel salts, in the form of potassium hexacyanokabaltate (II) and Sodium tetracyanonickelate (II)

e) 15 g of a water-soluble, trivalent iron salt (iron acetate) added per liter of solution.

- 12 - . ^ ORIGINAL

Using these methods, the spread of the strength properties of example k. can be reduced in size. The favorable allies were obtained with the addition of trivalent iron:

The tensile strength of the samples is approx. 380 N / mm ² with an average elongation at break of approx. 8%. As a disadvantage of the method according to example h. and 5. the roughness of the surface of the castings which sometimes occurs is to be mentioned.

6. Aluminum alloys

Ea was according to Example 4. and 5. e. procedure, the finished fired Farm shell retrofitted with a slurry in isabutyl alcohol consisting of finely ground powder with a grain size of less than 5 μm coated inside by swiveling. The following were added to this Materials used:

a) aluminum oxide i) silicon oxide

b) zirconia j) titanium nitride

c) mullite k) titanium oxide

d) Aluininiunibarat 1) Ilmenite and rutile

e) aluminum phosphate m) aluminum nitride

f) lithium metal aluminate n) reaction-bound silicon nitride

g) zirconium silicate o) halium, sodium and lithium h) Aluminum titanate aluminate and titanate

p) potassium, sodium and lithium

Zirconate q) silicon carbide

The farm dishes were each heated to about 350 ⁰ C in air, cooled, poured the salt solution and distributed by pivoting, post-baked in the terminal at approximately 900 ⁰ C for 1 h. In this way, particularly in the case of zirconium silicate, a suitable smooth surface of the casting was obtained, essentially while maintaining the strength properties of the tensile specimens made of Al-Si7-MgO, 6 according to Example 5.e., the higher strength values tending to be found in materials f ) to p).

13 -

The salt mixture also serves as a sintering aid for the subsequently applied fine grain. The fire temperature was chosen to be high enough to evaporate AlF.

7. Aluminum alloys

It has been shown that one can improve the strength properties and surface quality the cast parts by the method according to Example 6 also thereby can achieve that instead of the fluorides, the corresponding chlorides, Iodides and bromides may be used as a mixture. The aim is to put together the salt mixture so that

- it has a melting point that is below the preheating temperature of the shell mold before the casting in air at removal from the pre-heating below about 400 ⁰ C in the case van Al - alloys is, kratom when handled as little as possible humidity is taken; the desired shell mold temperature of about 180-320 ⁰ C during casting is obtained by cooling in the inert gas pre-dried in air or in the vacuum of Abgußofens.

- the salts not or only a little in the suspension medium of the others Dip's are soluble, so you can only use a small amount for the or the first aqueous dip and the fine-grain layer get by, so that the salt is not washed out further;

- if possible, no auxiliary salts to create a suitable water solubility, such as B. AlF, are necessary.

For example, the following salt solutions were produced:

a) PbF ₂ 10%, PbI ₂ 90% (melting point about 380 ⁰ C);

b) PbBr ₂ 40%, PbI ₂ S0% (melting point about 300 ⁰ C);

c) HBr 16%, PbBr ₂ 42% (melting point - 260 ⁰ C);

HBr is partly washed out by the subsequent non-aqueous dips.

-14 -

The water solubility of the salts can be determined in a known manner with the aid of a

Complex salt or Dappelsalzbildung z. B. with ammonium salts, sodium «.

acetate and much more a. m. be produced or increased. Here were the lead salts with the help of ferric acetate hydrate in their water solubility so increased that a total of 30 grams of lead salts / liter of solution is available

was. The aqueous solution also contained 20 grams of three *

valuable iron acetate per liter. *

The fine grain - internal coating by means of zirconium silicate was prepared as in Example G., but with a refire temperature of about 700 ⁰ C. The grapes ⁰ C the furnace were taken at about kUÜ in vacuo and the furnace only to approximately 300 ⁰ C cooled before pouring.

In this way tensile strengths of approx. 400 N / mm ² with an average of 8% elongation at break and good surface quality were obtained.

B. iron, cobalt and nickel-based alloys

There were üJachstrauben in which several sample basket?

per were arranged, coated on one side with an aqueous dip,>

which in addition to the usual grain refiner cobalt aluminate and a ? -

high proportion of, with grain diameters of predominantly less than 5 pm, Unusual fine grain filler made of zirconium silicate after drying with:

a) sodium fluoride, dissolved

b) barium fluoride, as a fine-grain powder C- 5 pm)

c) barium fluoride, as a fine-grain powder and dissolved sodium fluoride with 65% mol based on the total amount of salt.

d) Calcium fluoride and sodium fluoride, in the proportions as B.c.

was impregnated.

a * The rest of the construction of the shell molds was made on a non-aqueous basis

performed.: .

It was found that the castings from the alloys: - ^ - _x

BAD ORlGlNAL- - 15 -

.5

φ

g IN 100 (ATS 391-G): 63% Ni; 9.5% Cr, 5.5% Al _{1 and} others S 816 (ATS 113-G): 52% Co, 20% Ni, 20% Cr. ATS 117: 67% Co, 11% ld, 21% Cr, etc. 15/5 Ph: 0.04-0.07 C; 13.5-18.5 Cr; 4-6% Ni; 0.2-0.8 Nb; 1.8-2.5 Cu, etc.

_f the salt-treated halves of the grape have an average grain diameter of around 5-10% smaller.
It is preferable to proceed according to example Sd.

⁸⁴⁰

- 16 -

Claims (1)

Expectations:' 1. Process for producing an improved fine grain of "fc Primary structure and / or the eutectic of cast parts from Me- ^ metals and metal alloys, preferably made of aluminum, Cabalt-based, nickel-based and iron alloys, characterized in that the farm shell on the surface that forms the cavity for the later casting, with a layer is equipped, which contains a salt or a salt mixture or bzui from it. it consists, among other things, of the melting point of Salt or the salt mixture is lower than the liquidus temperature of the respective molten metal and the salt is a halide is or the salt mixture predominantly or exclusively of Halogen compounds is formed, or the salt or the salt mixture ude one or more alkali pseudohalogen compounds Cyanate, cyanide, rhodanide or hexa or tetracyano compounds and similar, the alkali cyanides - cyanates and - rhodanides chemically related compounds. 2. The method according to claim 1, characterized in that the shell mold on the surface, which is the cavity for the later casting is provided with one or more layers consisting of one material or a mixture of materials, which or which pores of predominantly less than 5 χ 1D m, -7 -9 preferably in the range from 10 to 10 m, the material or the material mixture having a high wettability, ie at the pouring temperature of the molten metal, the smallest possible wetting angle of less than 100 degrees, preferably less than kO degrees, and the surface formed in this way is additionally coated with the salt or the salt mixture. j 3. The method according to claim 2, characterized in that the pore containing layer on the surface that forms the cavity for the spä- ^a tere casting forms, with the help of a correspondingly fine-grained, ceramic powder is produced. BATH - 17 - H. A method according to claim 2, characterized in that a coarse-grained material, preferably a ceramic, is used to produce the surface which forms the cavity for the later GuB piece. -4 mixed material with grain diameters of predominantly 5 χ 1D to 10 ~ m, the material used itself having pores with a Has a diameter of predominantly less than 5 χ 10 m. 5. The method according to the preceding claims, characterized in, that one mixes the salt or the salt mixture and / or the material forming the fine-pored layer in a fine-grained farm with the Ulachs, which serves as a model for the later casting, so that it settles on the surface when the wax melts and it into the coarser pores of the first inner layers of the shell mold and, if necessary, the inserted ceramic cores and the fine pore-forming material when the shell is burned is sintered with. 6. The method according to the preceding claims when used predominantly more water-soluble, but little or in organic solvents insoluble salts characterized in that the first or the .first Dip's of the üJachs model with the one containing the fine pores or forming material as an additive to the filler on an aqueous basis, or the coarse-grained material containing the pores for sanding of the first dip used on an aqueous basis, the first layer or the first layers produced in this way dries, then the coated wax model in the aqueous solution or slurry of the salts dips, dries, and the dip's of the other layers in the usual way on a non-aqueous basis. 7. The method according to the preceding claims, characterized in that that the material forming the fine-pored layer contains or consists of the following substances: silicon oxide, iron oxide, Titanium nitride, ilmenite, titanium carbide, titanium boride, titanium oxide, zirconium oxide, Zirconium silicate, aluminum oxide, mullite, aluminum nitride, nickel and / or cobalt oxide, aluminum borate, aluminum phosphate, aluminum nitride, Silicon nitride, an alkali aluminate, titanate or zirconate; Magnesium oxide containing substances or mixtures and compounds of the substances mentioned such as z. B. Zeolites and similar ceramics, how they are used to manufacture porous bodies, ζ. Β. Coloring sieves, can be used; preferably zirconium silicate and / or _ 18 - SAD QFoGiNAL Titanium oxide and / or titanium nitride and / or an alkali aluminate in a mixture or coated with iron and / or nickel and / or Kabaltaxid and / or Kabaltaluminat. 8. The method according to the claims provided, characterized in that that one selects a salt or a salt mixture in such a way that its or their melting point about 50% - 100%, preferably less than about 70% the Salidus temperature of the metal melt used. 9. The method according to the preceding claims, characterized in that that a salt or a salt mixture is used whose melting point is below the preheating temperature of the shell mold before the molten metal is poured off. 10.A method according to any preceding claim, characterized in that for the operations department of .Gußteilen from Alumiumlegierungen an alkaline - earth metal - chloro - fluoro mixture having a melting point of less than 650 ⁰ C, preferably from 300 ⁰ C to 600 ⁰ C, are used. H. The method according to the preceding claims, characterized in that that one for the production of castings from aluminum - silicon magnesium containing alloys an alkali - alkaline earth metal chloride - fluoride mixture is used, the BaCl ", BaF" LiCl and contains LiF. 12. The method according to the preceding claims, characterized in that that for the production of castings from aluminum-silicon alloys containing magnesium, a mixture of a fluoride from the Series of sodium, barium, lithium and a heavy metal fluoride from the series lead, silver, cadmium, zinc and mercury or from a mixture of the above-mentioned alkali - alkaline earth fluorides together with one or a mixture of the heavy metal fluorides mentioned is used. 13. The method according to the preceding claims, characterized in that a mixture of IMaF, BaF, PbF, LiF and AlF with a melting point of about 440 to 560 ⁰ C is used for the inner coating of the surface and the pores of the casting mold. - 19 - 14. The method according to the preceding claims, characterized in that that one prepares an aqueous solution of lead and aluminum fluoride, dissolves sodium and barium fluoride in this solution or Barium fluoride slurries with a small urine size, catalytically for the germination of dendrites of the aluminum-silicon-magnesium alloy additionally dissolves or slurries active substances therein, this mixture is poured into the fine-pored precoated casting mold, ensures that the Casting mold is coated or wetted largely uniformly at all points on the inner surface, the casting mold then dries and preheated and finally the liquid Al - Si - Mg alloy is poured into it. 15.Verfahren according to claim 14 and the preceding, characterized in that an aqueous solution or slurry is used which contains 3 to 15% (wt.) Lead fluoride, k - 18% aluminum fluoride, the remainder water, in this aqueous solution 0 to B% wt. IMaF, D - 10% wt. LiF, 0-5% BaF, based on the pale substance used, produced in powder form with a grain size of preferably -2 μm and mixed with a water-soluble iron-containing substance.