DE202015105368U1 - Casting molds and kits for the suppression of pitted surfaces on castings - Google Patents

Abstract

A chemically bonded mold base mold having surfaces defining a mold cavity for producing a GJS or GJL casting, the chemically bonded mold base comprising one or more acid-cured binders and quartz sand, wherein at least one mold cavity defining region of the mold is an infiltration product which reacts basicly to at least an infiltration depth of 2 mm on contact with water, measured from the surface of the casting mold.

Description

Disclosed is a use of a basic composition as an infiltrant for the molding material of a mold comprising quartz sand and an acid-cured binder, and a method of making a GJS or GJL casting. The present invention relates to corresponding molds and kits.

Most products of the iron and steel industry and the non-ferrous metal industry undergo casting processes for the first shaping. In this case, the melt liquefied materials, ferrous metals or non-ferrous metals are converted into shaped objects with specific workpiece properties. For the shaping of the castings must first be made in part very complicated molds for receiving the molten metal. The casting molds are divided into lost molds that are destroyed after each casting, and permanent molds, with each of which a large number of castings can be produced. The lost forms usually consist of a refractory, granular molding material, which is solidified with the aid of a hardenable binder.

Shapes are negatives, they contain the emptying cavity, which results in the casting to be produced. The inner contours of the future casting are formed by cores. In the manufacture of the mold, the cavity is shaped into the molding material by means of a model of the casting to be manufactured. Inner contours are represented by cores formed in a separate core box.

For the production of casting molds both organic and inorganic binders can be used, the curing of which can be effected by cold or hot processes. Cold processes are processes in which the curing takes place essentially at room temperature without heating the molding material mixture. The curing is usually carried out by a chemical reaction, which can be triggered, for example, by passing a gaseous catalyst through the molding material mixture to be cured, or by adding a liquid catalyst to the molding material mixture. In hot processes, the molding material mixture is heated to a sufficiently high temperature after molding to drive off, for example, the solvent contained in the binder, or to initiate a chemical reaction by which the binder is cured by crosslinking.

The production of the casting molds can be carried out in such a way that the molding material is first mixed with the binder, so that the grains of the refractory molding material are coated with a thin film of the binder. The molding material mixture obtained from molding material and binder can then be introduced into a corresponding mold and optionally compacted in order to achieve a sufficient stability of the casting mold. Subsequently, the mold is cured, for example by heating it or by adding a catalyst which effects a curing reaction. If the mold has reached at least a certain initial strength, it can be removed from the mold.

As already mentioned, molds for the production of metal bodies are often composed of so-called cores and molds. Different requirements are placed on the cores and molds. In molds, a relatively large surface area is available to dissipate gases that form during casting by the action of the hot metal. In cores usually only a very small area is available, through which the gases can be derived. If there is too much gas, there is a risk that gas will pass from the core into the liquid metal and lead to the formation of casting defects. Often, therefore, the internal cavities are imaged by cores solidified by cold box binders, a polyurethane based binder, while the outer contour of the casting is represented by lower cost forms, such as a green sand mold, a furan resin, or a phenolic resin bound form or by a steel mold.

For larger molds, organic polymers are mostly used as the binder for the refractory, granular molding material. As a refractory, granular molding material is often washed, classified quartz sand used, but also other molding materials such. B. Zirkonsande, Chromitsande, chamottes, olivine sands, feldspathaltige sands and Andalusitsande. The molding material mixture obtained from mold base and binder is preferably present in a free-flowing form.

At present, for the production of molds often organic binders such. For example, polyurethane, furan resin or epoxy-acrylate used in which the curing of the binder by addition of a catalyst.

The choice of suitable binder depends on the shape and size of the casting to be produced, the conditions of production and the material used for the casting. For example, in the production of small castings that are produced in large numbers, polyurethane binders are often used because they allow fast cycle times and thus also a series production.

Processes in which the curing of the molding material mixture by heat or by subsequent addition of a catalyst, have the advantage that the processing of the molding material mixture is not subject to any special time restrictions. The molding material mixture can first be produced in larger quantities, which are then processed within a longer period of time, usually several hours. The curing of the molding material mixture takes place only after molding, with a rapid reaction is sought. The mold can be removed immediately after curing from the mold so that short cycle times can be realized. However, in order to obtain a good strength of the mold, the curing of the molding material mixture must be uniform within the mold. If the curing of the molding material mixture by subsequent addition of a catalyst, the mold is gassed after molding with the catalyst. For this purpose, the gaseous catalyst is passed through the casting mold. The molding material mixture cures directly after contact with the catalyst and can therefore be removed very quickly from the mold. As the size of the mold increases, it becomes more difficult to provide an amount of catalyst sufficient to cure the molding material in all sections of the mold. The gassing times are prolonged, but can still arise sections in the mold, which are achieved very poorly or not at all by the gaseous catalyst. The amount of catalyst therefore increases sharply with increasing size of the mold.

Similar difficulties occur in hot curing processes. Here, the mold must be heated in all sections to a sufficiently high temperature. As the size of the mold increases, on the one hand, the times for which the mold must be heated to a certain temperature for curing are extended. Only then can it be ensured that the casting mold also has the required strength in its interior. On the other hand, the curing with increasing size of the mold is also very expensive from the apparatus side.

In the field of large casting, the weight of the cores is often about 1000 kg or more. With methods in which the hardening with gas or by heat, such large cores are difficult or impossible to produce from a technical point of view. Here then preferably cold-curing methods are used.

In the production of molds for large castings, such as engine blocks of marine diesel engines or large machine parts, such as hubs of rotors for wind power plants, so-called "no-bake binder" are used for the reasons mentioned mostly. In the "no-bake process", the refractory base molding material (eg sand) is often first coated with a catalyst (hardener), then the binder is added and evenly distributed by mixing onto the already catalyst-coated grains of the refractory molding base material. In this process is often worked with so-called continuous flow mixers. The resulting molding material mixture can then be shaped into a shaped body. Since binder and catalyst are evenly distributed in the molding material mixture, the curing is largely uniform even with large moldings.

Alternatively, in the no-bake process, the refractory base molding material (eg sand) may first be mixed with the binder and then the hardener added. In this process, it may, especially in the production of molds for large castings, come because of a partial, local too high concentration of the curing agent to partial hardening or crosslinking of the binder, whereby an inhomogeneous molding material would be obtained.

Since the catalyst (hardener) is added to the molding material mixture before molding, the curing of the molding material mixture begins immediately after its preparation. In order to achieve a suitable processing time for an industrial application, therefore, the components of the molding material mixture should be coordinated. Thus, the reaction rate can be influenced for a given amount of the binder and the refractory base molding material, for example, by the type and amount of the catalyst or by the addition of retarding components. On the other hand, the processing of the molding material mixture should be carried out under very controlled conditions, since the rate of curing is influenced for example by the temperature of the molding material mixture.

The "classic" no-bake binders are often based on furan resins and phenolic resins. They are often offered as systems (kits) wherein one component comprises a reactive furan resin and the other component comprises an acid, which acid acts as a catalyst for the curing of the reactive resin component.

Furan and phenolic resins show very good disintegration properties during casting. Under the action of heat of the liquid metal, the furan or phenolic resin decomposes and the strength of the mold is lost. After casting, therefore, cores, possibly after prior shaking of the casting, pour out very well from cavities.

"Furan no-bake binders" contain reactive furan resins, which regularly comprise furfuryl alcohol as an essential component. Furfuryl alcohol can react with itself under acid catalysis and form a homopolymer. Furfuryl alcohol is generally not used alone for the preparation of furan no-bake binders, but further compounds are added to the furfuryl alcohol which are copolymerized into the resin. Examples of such compounds are aldehydes, such as formaldehyde or furfural, ketones, such as acetone, phenols, urea or polyols, such as sugar alcohols or ethylene glycol. The resins may be added with other components that affect the properties of the resin, such as its elasticity. Melamine can be added, for example, to bind still free formaldehyde.

Furan no-bake binders are most often prepared by first producing precondensates of, for example, urea, formaldehyde, and furfuryl alcohol under acidic conditions. These precondensates are then diluted with furfuryl alcohol.

Likewise, urea and formaldehyde can be reacted alone. This produces so-called UF resins ("urea formaldehyde" resins, "aminoplasts"). These are usually subsequently diluted with furfuryl alcohol. Advantages of this manufacturing method are a higher flexibility / variability in the product range and lower costs, because it is cold mixing processes. The disadvantage is often that certain chemical and performance properties can not be achieved. Furthermore, UF resins are often cloudy, so that usually made therefrom binder are also cloudy and inhomogeneous.

Resoles can also be used to prepare furan no-bake binders. Resoles are prepared by polymerization of mixtures of phenol and formaldehyde. These resoles are then often diluted with a large amount of furfuryl alcohol.

Furan no-bake binders are regularly cured with an acid. This acid catalyzes the crosslinking of the reactive furan resin. It should be noted that, depending on the type of binder, certain amounts of acid should not be exceeded, since alkaline components, which may be present in the refractory base molding material, can partially neutralize the acid.

Frequently used acids are sulfonic acids, phosphoric acid or sulfuric acid. In some specific cases, combinations of these are used, inter alia, in combination with other carboxylic acids. Further, certain "curing moderators" can be added to the furan no-bake binder.

Phosphoric acid is often used as an acid catalyst for curing in concentrated form, i. H. used at concentrations greater than 70%. However, it is (with some exceptions) only for the catalytic curing of furan resins with a relatively high proportion of urea, since essentially the curing of the aminoplast content in the furan no-bake binder responds. The nitrogen content of such resins is usually more than 2.0% by weight. Sulfuric acid, as a relatively strong acid, can be added as a starter for the curing of furan resins to weaker acids. During casting, however, a smell typical of sulfur compounds develops. In addition, there is a risk that the casting material sulfur is absorbed, which affects its properties.

The selection of the acid catalyst for curing has a significant influence on the curing behavior of the binder, the properties of the molding material mixture and the casting mold or the core obtainable therefrom. Thus, the rate of curing can be influenced by the amount and the strength of the acid. High amounts of acid or stronger acids lead to an increase in the curing rate. In the case of too fast setting, the processing time of the molding material mixture is shortened too much, so that the processability is greatly impaired or even a Processing is no longer possible. When using too large amounts of acid catalyst, the binder, such as a furan resin, also become brittle upon curing, which adversely affects the strength of the mold. When using too small amounts of acid catalyst, the resin is not completely cured (or the curing takes a long time), resulting in lower strength of the mold.

In the manufacture of molds, new sand is often used for the cores, while frequently recycled mold base material (eg sand) is used for the molds. Refractory mold raw materials, which have been solidified with furan no-bake binders, can be worked up very well again. The workup is carried out either mechanically by mechanically rubbing off a shell formed from residual binder or by thermally treating the used sand. With mechanical workup or with combined mechanical / thermal processes, return rates of up to almost 100% can be achieved.

Phenolic resins, the second large group of acid-catalyzed curable no-bake binders, contain resoles as reactive resin components, ie phenolic resins prepared with a molar excess of formaldehyde. Phenolic resins show lower reactivity compared to furan resins and require strong sulfonic acids as catalysts. Phenolic resins show a relatively high viscosity, which increases even more with prolonged storage of the resin. After the phenol no-bake binder has been applied to the refractory base molding material, the molding compound should be processed as promptly as possible so as not to suffer deterioration in the quality of the molding compound due to premature curing, resulting in deterioration of the strength of the molding compound mixture produced molds can lead. When using phenol no-bake binders, the flowability of the molding material mixture is usually worse than a comparatively produced molding material with a furan no-bake binder. In the production of the mold, the molding material mixture must therefore be carefully compacted in order to achieve a high strength of the mold can.

The preparation and processing of such a molding material mixture should take place at temperatures in the range of 15 to 35 ° C. If the temperature is too low, the molding material mixture can be processed worse because of the high viscosity of the phenol no-bake resin. At temperatures of more than 35 ° C, the processing time is shortened by premature curing of the binder.

After casting, molding mixtures based on phenol no-bake binders can also be worked up again, in which case mechanical or thermal or combined mechanical / thermal processes can also be used.

As already explained, the acid used as catalyst in the case of furan or phenol no-bake processes has a very great influence on the properties of the casting mold. The acid must have sufficient strength to ensure a sufficient rate of reaction in the curing of the mold.

The curing should be well controllable, so that also sufficiently long processing times can be set. This is particularly important in the production of molds for very large castings, the construction requires a longer period.

Furthermore, the acid must not accumulate in the regeneration during the regeneration of used materials (that is to say of mold materials already used for the production of lost molds or cores, for example old sands). If acid is introduced into the molding material mixture via the regenerate, this shortens the processing time and leads to a deterioration in the strength of the casting mold produced from the regenerate.

Therefore, not every acid is suitable for use as a catalyst in no-bake processes. Frequently, toluenesulfonic acid, benzenesulfonic acid or methanesulfonic acid are used, as well as phosphoric acid and sulfuric acid.

Phosphoric acid is, as already explained, only for the curing of certain furan resin qualities. However, phosphoric acid is not suitable for the curing of phenolic resins. As a further disadvantage, phosphoric acid tends to accumulate in the regenerate, making it difficult to reuse the regenerate. Sulfuric acid during casting and during thermal regeneration leads to the emission of sulfur dioxide, which has corrosive properties, is harmful to health and represents an odor nuisance.

Spheroidal graphite cast iron (GJS) is an iron-carbon material whose carbon content is predominantly in globular (globular) form. Cast iron with nodular graphite has steel-like material properties. Due to the globular shape of the graphite, high strengths result with very good, permanent deformation (elongation). Low perlite content increases both machinability and associated tool life. Ductile iron is used, for example, in the automotive industry, mechanical engineering and shipbuilding, in pressure vessels or in wind power. GJS cast iron qualities are in the DIN EN 1563 Foundry - Ballistic graphite cast iron.

Cast iron with lamellar graphite (GJL) also has excellent practical properties and in many cases presents similar requirements to those skilled in the art as GJS. The essential differences between GJL and GJS relevant to the practice are known to the person skilled in the art.

In GJS and GJL casting, casting defects called "pitted surfaces" occur.

These defects are areally occurring, pockmarked roughening and depressions on the casting surface or in the casting skin. They are covered with a white to slightly bluish surface. Therefore, the error is also called "white coating". The lining consists essentially of (fibrous) silicon oxides. When the castings are blasted, the coating is removed, leaving only the pitted surface.

The defect occurs in GJS and GJL castings produced by casting molds and cores made of chemically bonded molding material, which in turn consists of quartz sand and an acid-cured binder. Especially in acid-cured furan resin molds and other acid-cured, cold-curing processes, such as the phenolic resin process, the error occurs. The most common error rate was found in regenerated furan resin sands with an ignition loss between 3 and 4.5%.

The error also occurs in the use of cores and molds made by the croning process as well as in the clay-bonded molding process.

• 1) M. Schrod, H. J. Wojtas, Oberflächenfehler insbesondere bei GJS, 7. Formstofftage, Duisburg Februar 2008
• 2) H. G. Levelink, F. P. M. A Julien, Eigenschaften von regeneriertem Furanharzsand Giesserei 68 (1981) 340
• 3) S. Hasse Guß- und Gefügefehler, Schiele & Schön, Berlin 2. Auflage, 2003, 343

A detailed description of the defect can be found in the following references:

• 1) M. Schrod, HJ Wojtas, surface defects especially at GJS, 7th molding days, Duisburg February 2008
• 2) HG Levelink, FPM A Julien, Properties of regenerated furan resin sand Foundry 68 (1981) 340
• 3) S. Hasse Guß- und Gefügefehler, Schiele & Schön, Berlin 2nd edition, 2003, 343

The white deposits mainly occur in thick-walled parts, ie on medium to heavy castings. Even smaller compact castings with a large module are affected. On the casting, the error mostly occurs in thermally highly stressed zones, such as the radii, but can also be drawn from there over larger areas. Below the surface of the affected zones, the graphite is partially degenerate.

The casting defect leads to increased reworking in the foundry and so far can only be counteracted by an increased oversize of the affected areas. In extreme cases, scarred surfaces lead to rejects of the casting.

Due to the roughening and indentations on the casting surface, the affected areas must first be ground consuming before being subjected to ultrasonic testing or crack testing for quality control of the casting.

In the process of producing GJS and GJL castings by cold-setting mold materials with lost molds, there is a need for a constant process whereby reproducible and cost-effective castings can be made having good cast surfaces. Therefore, solutions are required in which pitted surfaces are avoided even in some areas of the casting surface.

In S. Hasse Guß- und Gefügefehler, Schiele & Schön, Berlin 2nd edition. 2003, 343 some measures are already described with which the casting defects can at least be reduced. However, the measures described are all not yet satisfactory because they, for example, by increasing the Sand waste lead to an increase in the cost of the casting process and therefore are not economically feasible or technically difficult to implement.

In " Contribution to the formation mechanism of the cast surface defect white coating and development of proposed solutions for avoidance, dissertation E. Potaturina, TU Bergakademie Freiberg, March 2014 "Penetration sizing is described. These penetrants contain manganese (IV) oxide (brownstone). Manganese (IV) oxide (manganese dioxide) is insoluble in water and alcohols and reacts amphoterically. The use of impregnating with manganese dioxide has the disadvantage that the manganese dioxide reduces the refractoriness of the molding material. There is a risk of the formation of casting defects. Further, as described by E. Potaturina, these penetrants can at best reduce the "cicatrized surface" casting defect.

The thesis of E. Potaturina also describes a sizing which can suppress the error somewhat when it is applied to the molding surface. This is a size with an inorganic binder.

Usually, in casting processes, penetration sizes are used, i. H. Finishes that penetrate into the molding material and fill the pores in the molding material with their refractory materials. They are particularly suitable for preventing casting defects such as penetration and erosion. These sizes usually contain larger amounts of refractories and may also contain inorganic or organic binders. Commercially available sizes penetrate regularly when applied to the molding material. An effect against scarred surfaces is not known. In our own experiments, for example, with the magnesite size 5848 of the company Hüttenes-Albertus GmbH, Dusseldorf, containing basic refractories, no effect on the formation of pitted surfaces could be observed.

Formcoats which are applied to molding surfaces are also frequently used. These form varnishes are solutions of organic resins in a solvent. They serve to harden the mold surface. An activity against scarred surfaces can not be observed.

The document DE102008025311 A1 discloses an odor and pollutant coating composition for box-bonded cast metal.

The abstract of the document JP 57171540 A discloses a "Preventing Method for Sulfurization of Cast Steel Casting".

The document WO 2009/004090 A1 discloses a method for casting a molten metal.

The publication DE 2407344 relates to a process for the production of foundry molds and cores.

None of these latter documents relates to the casting defect "scarred surfaces" (white deposits); Accordingly, none of the above documents discloses methods or means for controlling such casting defects.

It was a primary object of the present invention to find a way in which the formation of scarred surfaces (white coverings) during the casting process is suppressed or greatly reduced. As a result, it should be possible, for example, that the GJS and GJL castings can be manufactured with conventional oversizes.

• – Vermeidung von Ausschuss
• – Vermeidung von Nacharbeit
• – Vermeidung von erhöhten Bearbeitungszugaben
• – Erreichung von geforderten Oberflächenguten
• – Senkung des Prüfaufwandes z. B. bei einer Ultraschallprüfung/Rissprüfung
• – Verbesserung der mechanischen Kennwerte des fertigen Gussstücks.

Ideally, it should continue to be possible to use the usual foundry processes with the resources normally found in the foundry for core and mold production. It should also be possible to treat only the critical areas of the molds and cores used to make the GJS and GJL castings; This would save production costs. Also, the process of the molding cycle should be minimized as possible in order to avoid costly compensatory measures or Neusandzugaben. It should also be possible to avoid or achieve at least one, preferably several or all of the following points:

• - avoidance of rejects
• - avoid reworking
• - Avoidance of increased machining allowances
• - achievement of required surface quality
• - Lowering the testing effort z. B. in an ultrasonic test / crack test
• - Improvement of the mechanical characteristics of the finished casting.

• – eine basische Komponente bestehend aus einer oder mehreren Basen

sowie

• – eine Trägerflüssigkeit für die basische Komponente

als Infiltrationsmittel für den Formstoff einer Gießform, die Quarzsand und ein mittels Säure gehärtetes Bindemittel umfasst, und zum Unterdrücken der Bildung von narbigen Oberflächen während des Gießverfahrens.This object is surprisingly achieved by the use of a basic composition comprising

• A basic component consisting of one or more bases

such as

• A carrier liquid for the basic component

as an infiltrant for the molding material of a casting mold comprising quartz sand and an acid-cured binder, and for suppressing the formation of pitted surfaces during the casting process.

In the context of this invention, an acid-cured binder is understood as meaning a crosslinked organic polymer which, after curing, has bound a substrate (quartz sand) and in water by the free and necessary acid added for crosslinking (curing) the organic polymer would produce a pH of <7.0.

In the context of this invention, a casting mold is understood as meaning the entirety of outer mold parts and, if present, inner mold parts (eg cores).

In the context of this invention, a base or an acid is understood to mean a Brønsted base (proton acceptor) or acid (proton donor). In addition, for the purposes of this application, bases are compounds which form salts with acids by neutralization or form hydroxide ions in aqueous solutions. For example, in the context of this invention, sodium hydroxide is a base, since sodium hydroxide forms hydroxide ions in aqueous solutions.

Preferred is a use according to the invention, wherein one, more than or all of the bases contained in the composition have a pK _B value in water at 25 ° C of less than 3.0, preferably less than 1.0.

It has been shown in our own investigations that when using compositions which have at least one strong base, ie a base with the pK _B values specified above, the casting defects listed above are particularly well avoided or reduced.

Since many table works instead of the pK _B (Base constant) of the _pKa (acid dissociation constant) is shown the corresponding acid, the specified in the table works _pK a of the conjugate acid having the following formula can be easily in the pK _B - Value of the base to be converted: PK _B = 14 - pK _S

Preferred is a use according to the invention, wherein the basic composition comprises as or in the carrier liquid for the basic component water and wherein the aqueous phase preferably has a pH of> 8, preferably a pH of> 10, particularly preferably a pH Value of> 12, particularly preferably has a pH of> 13.

It has been found that especially when strong bases are used in a concentration sufficient to achieve the above-listed pH values, the use of the basic composition leads to particularly good results. Thus, it can be ensured that the composition in use is able to neutralize the acid remaining in the molding material after infiltrating the molding material of a mold comprising quartz sand and an acid-cured binder.

Preference is given to a use according to the invention as an infiltrant for the molding material of a casting mold comprising quartz sand and an acid-cured binder, the casting acid reacting on contact with water.

Preferably, a use according to the invention, wherein the infiltrant for the molding material of a mold comprising quartz sand and an acid-cured binder is so infiltrated into the molding material, that an infiltrating product is formed, which at least to an infiltration depth of 2 mm on contact reacts basic with water, measured from the surface of the mold, preferably to at least an infiltration depth of 5 mm, more preferably 10 mm, most preferably at each infiltration depth in the range of 2 to 5 mm, the infiltration product reacts basicly on contact with water.

It has been shown in our own investigations that in a use according to the invention surprisingly good results are achieved if at least portions of the mold cavity defining surfaces of the mold react acid on contact with water, wherein the infiltrant infiltrates at least one of said acid-reacting areas.

Particularly preferred is a use according to the invention (as defined above, preferably as described above as preferred), as an infiltrant for the mold material of a casting mold hardened by means of a no-bake binder and for suppressing the formation of pitted surfaces during the casting process, wherein the Bake binder is cured by an acid catalyst for the curing of the reactive resin component of the no-bake binder, wherein the acidic catalyst comprises sulfonic acids, phosphoric acid, sulfuric acid or combinations thereof.

It has proven particularly useful and is preferred (a) to use the acidic catalysts in the liquid phase or (b) to occupy the molding base material (ie preferably quartz sand) with the acidic catalyst (s).

• – anorganischen Basen und organischen Basen.

Preferred is a use according to the invention, wherein one, more than one or all of the bases in the basic component is or are selected from the group consisting of

• - inorganic bases and organic bases.

• – eine, mehr als eine oder sämtliche der anorganischen Basen in der basischen Komponente ausgewählt ist bzw. sind aus der Gruppe bestehend aus anorganischen Verbindungen, die von Wasser ein Proton übernehmen können, und Metallhydroxiden

und/oder

• – eine, mehr als eine oder sämtliche der organischen Basen in der basischen Komponente ausgewählt ist bzw. sind aus der Gruppe bestehend aus Carbonsäure-Salzen und organischen Aminen.

Particularly preferred is a use according to the invention, wherein

• - One, more than one or all of the inorganic bases in the basic component is selected from the group consisting of inorganic compounds that can take over a proton of water, and metal hydroxides

and or

• One, more than one or all of the organic bases in the basic component is or are selected from the group consisting of carboxylic acid salts and organic amines.

Particularly preferred is a use according to the invention wherein one, more than one or all of the inorganic bases in the basic component is selected from the group consisting of alkali metal hydroxide, alkaline earth metal hydroxide and water glass, in particular sodium silicate, potassium silicate or lithium water glass.

Preferred alkali metal hydroxides in accordance with the invention are lithium hydroxide, sodium hydroxide and potassium hydroxide, in particular potassium hydroxide and sodium hydroxide. Alkaline earth metal hydroxides preferred according to the invention are magnesium hydroxide, calcium hydroxide and strontium hydroxide, in particular calcium hydroxide and magnesium hydroxide.

• – Wasser

und

• – organischen Verbindungen mit einem Siedepunkt unter 100°C bei 1000 hPa, wobei vorzugsweise in der Trägerflüssigkeit der Gesamtanteil an Wasser und organischen Verbindungen mit einem Siedepunkt unter 100°C bei 1000 hPa mehr als 50 Gew.-% beträgt, bezogen auf die Gesamtmenge der Trägerflüssigkeit.

Preference is given to a use according to the invention (preferably a use whose design is referred to above or below as being preferred), wherein the carrier liquid for the basic component comprises one or more compounds selected from the group consisting of

• - Water

and

• - Organic compounds having a boiling point below 100 ° C at 1000 hPa, wherein preferably in the carrier liquid, the total amount of water and organic compounds having a boiling point below 100 ° C at 1000 hPa more than 50 wt .-%, based on the total amount of carrier fluid.

An advantage of such a composition in which the carrier liquid for the basic component comprises one or more compounds selected from the group consisting of water and organic compounds having a boiling point below 100 ° C at 1000 hPa, that the carrier liquid after application of the composition at least parts of the mold evaporate faster than comparable ones Compositions whose organic compounds have a boiling point above 100 ° C at 1000 hPa. This makes it possible to shorten the waiting time between application of the composition to the casting mold and the subsequent filling of the casting cavity with a molten iron-carbon alloy.

A use according to the invention is preferred, wherein the carrier liquid for the basic component comprises one or more compounds selected from the group consisting of water, methanol, ethanol, propanol, butanol, acetone and gasoline, preferably in the carrier liquid, the total amount of water, methanol, Ethanol, propanol, butanol, acetone and gasoline is more than 50 wt .-%, based on the total amount of the carrier liquid.

Our own experiments have shown that these compounds or substances have particularly good practical properties. They evaporate quickly enough and are physiologically harmless or less questionable and can be used without high safety precautions in the foundry.

According to a preferred embodiment of the present inventive use, the composition comprises one or more surfactants.

Among other things, the use of surfactants in the composition results in lowering the surface tension of the composition and in wetting the composition, wetting of the casting mold is improved. In addition, the penetration (penetration) of the composition into the upper layers of the mold is improved. In particular, the presence of one or more surfactants is preferred when only water is present as carrier liquids.

Suitable surfactants are anionic surfactants, nonionic surfactants, cationic surfactants and amphoteric surfactants.

Preference is given to a use according to the invention, wherein the composition comprises one or more binders, wherein preferably the one or at least one of the plurality of binders is self-curing in the air and / or dries when the carrier liquid is removed.

It has been shown in our own investigations that the use of binders in the composition has further improved the surface properties of the casting mold and thereby the surface properties of the cast piece produced. The binder serves, inter alia, to solidify ("cure") the infiltrated molding material layer to reduce defects that otherwise occasionally arise in the bonded molding material, possibly through contact with the base (eg, metal hydroxide) of the composition to be used in the invention.

In particular, a use according to the invention is preferred, wherein the composition comprises one or more binders selected from the group consisting of
phenolic resins, preferably resols, more preferably basic aqueous resoles,
Thermoplastics, preferably polyamides, polyvinyl acetates, polyvinyl alcohols and polybutyrals, polyvinylpyrrolidones, more preferably polyvinyl alcohols and polyvinyl acetates,
Carbohydrates, preferably starch and molasses, more preferably starch,
Biopolymers, preferably lignins, celluloses, mucilages, gelatin, pectins and alginates, particularly preferably sulphite liquors,
Dispersions and powders, preferably copolymers, more preferably acrylates,
inorganic binders based on or containing:
Silicate binders, in particular water glass and silica sols,
(basic) polyphosphates, borates, cement binders.

If, in the inventive use, the composition comprises one or more binders which are basic, in particular basic binders which are listed above, the basic binder or the basic binders fulfill the function of the basic component consisting of one or more bases. Other basic components which are not binders may be present in the composition, however, the presence of such other basic components is not mandatory.

Preferred is a use according to the invention, wherein the composition comprises:
organic binders in a concentration of 0.2 to 40 wt .-%, based on the total amount of the composition, preferably 0.2 to 10 wt .-%, particularly preferably 0.2 to 5 wt .-%
and or
inorganic binders in a concentration of 0.5 to 80 wt .-%, based on the total amount of the composition.

Organic binders are understood to mean binders which are based on carbon and, apart from hydrogen, oxygen, sulfur and nitrogen, contain no further atoms. Organic binders may be present as salts; In such cases, in addition to a charged organic binder ion, charged counterions are present, which need not or not exclusively consist of the named elements.

Particularly preferred is a use according to the invention, wherein the composition comprises:
alkaline silicate in a concentration of 5 to 50 wt .-%, based on the total amount of the composition, particularly preferably 10 to 40 wt .-%.

In determining the concentration of the alkaline silicate of the composition, solvent constituents and possible water of crystallization of the silicates are assigned not to the silicates but only to the total amount of the composition.

Also preferred is a use according to the invention, wherein the composition contains one or more solids suspended in the carrier liquid,
preferably one or more solids suspended in the carrier liquid which are inert upon contact with water or have an acidic or basic surface,
wherein preferably one or more solids suspended in the carrier liquid are inorganic solids,
wherein the inorganic solid is preferably not silicate.

Accordingly, a use according to the invention is particularly preferred, the composition containing a proportion of solids suspended in the carrier liquid and having a particle size of less than 0.075 mm,
preferably contains a proportion of suspended in the carrier liquid inorganic solids having a particle size less than 0.075 mm,
preferably contains a proportion of solids suspended in the carrier liquid with a particle size of less than 0.075 mm in the range of> 50% by weight, based on the total amount of solids,
preferably contains a proportion of suspended in the carrier liquid inorganic solids having a particle size of less than 0.075 mm in the range of> 50 wt .-%, based on the total amount of solid.

Also preferred is a use according to the invention, wherein the basic component is completely or partially dissolved in the carrier liquid.

Preference is given to a use according to the invention, wherein the composition contains one or more dyes, preferably contains one or more color pigments and / or dyes dissolved in the carrier liquid.

The use of a composition containing one or more dyes has the advantage that when the composition is applied to the mold or to parts of the mold it can be directly recognized on which areas of the mold the composition has already been applied. In particular, when brushing or spraying the composition, when dipping the mold in the composition or when flooding the mold with the composition, it can be quickly appreciated whether all required areas of the mold are sufficiently in contact with the composition. Also can be seen after breaking the mold optically how deep the composition has penetrated into the molding material surface.

Preference is given to a use according to the invention, wherein the composition contains no graphite and no oxides of zirconium, silicon, aluminum, magnesium and calcium and no mixed oxides of these elements.

A use according to the invention for reducing the formation of casting defects, in particular for reducing the formation of white deposits, is preferred.

• – eine basische Komponente bestehend aus Natriumhydroxid und/oder Kaliumhydroxid,
• – 30 bis 70 Gew.-% einer Trägerflüssigkeit für die basische Komponente, bezogen auf das Gesamtgewicht der Zusammensetzung, wobei die Trägerflüssigkeit Wasser und zumindest einen Alkohol ausgewählt aus der Gruppe bestehend aus Methanol, Ethanol, Propanol und Butanol umfasst,
• – ein oder mehrere Farbpigmente,
• – 20 bis 60 Gew.-% eines oder mehrerer in der Trägerflüssigkeit suspendierter Feststoffs, bezogen auf das Gesamtgewicht der Zusammensetzung, vorzugsweise eines Feuerfeststoffes oder hochfeuerfesten Feststoffes,

sowie

• – 1 bis 15 Gew.-% eines oder mehrerer Bindemittel wie oben definiert, bezogen auf das Gesamtgewicht der Zusammensetzung, vorzugsweise eines basischen wässrigen Resols,

als Infiltrationsmittel (und zum Unterdrücken der Bildung von narbigen Oberflächen) für den Formstoff einer Gießform, die Quarzsand und ein mittels Säure gehärtetes Bindemittel umfasst, wobei die Gießform (oder zumindest Bereiche der den Gießfromhohlraum definierenden Oberflächen) bei Kontakt mit Wasser vorzugsweise acid reagiert. Particularly preferred is a use according to the invention of a basic composition comprising

• A basic component consisting of sodium hydroxide and / or potassium hydroxide,
• From 30 to 70% by weight of a base component carrier liquid, based on the total weight of the composition, wherein the carrier liquid comprises water and at least one alcohol selected from the group consisting of methanol, ethanol, propanol and butanol,
• One or more color pigments,
• From 20 to 60% by weight of one or more solid suspended in the carrier liquid, based on the total weight of the composition, preferably a refractory or high-refractory solid,

such as

• From 1 to 15% by weight of one or more binders as defined above, based on the total weight of the composition, preferably of a basic aqueous resol,

as an infiltrant (and to suppress the formation of pitted surfaces) for the mold material of a mold comprising quartz sand and an acid-cured binder, the mold (or at least portions of the mold cavity defining surfaces) preferably reacting acidically upon contact with water.

Particularly preferred is a use according to the invention, wherein the quartz sand is a regenerated quartz sand, which was preferably prepared by working up a molding material mixture comprising quartz sand and an acid-cured binder.

By using regenerated silica sand, process costs can be reduced and waste is avoided.

• (i) Bereitstellen oder Herstellen einer Gießform, deren Oberflächen einen Gießformhohlraum definieren, aus chemisch gebundenem Formgrundstoff umfassend ein oder mehrere mittels Säure gehärtete Bindemittel und Quarzsand, wobei zumindest Bereiche der den Gießformhohlraum definierenden Oberflächen der Gießform bei Kontakt mit Wasser acid reagieren,
• (ii) Infiltrieren zumindest eines der besagten acid reagierenden Bereiche mit einer erfindungsgemäß zu verwendenden Zusammensetzung wie vorstehend, nachfolgend oder in den Ansprüchen definiert, so dass das Infiltrationsprodukt bis mindestens zu einer Infiltrationstiefe von 2 mm bei Kontakt mit Wasser basisch reagiert, gemessen von der Oberfläche der Gießform,
• (iii) Füllen des Gießformhohlraums mit einer schmelzflüssigen Eisen-Kohlenstoff-Legierung,
• (iv) Erstarren lassen der Eisen-Kohlenstoff-Legierung im Gießformhohlraum, so dass ein GJS- oder GJL-Gussstück resultiert.

Another aspect of the present invention relates to a method of making a GJS or GJL casting and suppressing the formation of scarred surfaces, comprising the steps of:

• (i) providing or fabricating a mold whose surfaces define a mold cavity of chemically bonded mold base comprising one or more acid-cured binders and quartz sand, wherein at least portions of the mold cavity defining surfaces of the mold react acid upon contact with water;
• (ii) infiltrating at least one of said acid-reacting regions with a composition to be used according to the invention as defined above, below or in the claims such that the infiltration product is basic to at least an infiltration depth of 2 mm upon contact with water, measured from the surface the mold,
• (iii) filling the mold cavity with a molten iron-carbon alloy,
• (iv) solidify the iron-carbon alloy in the mold cavity to result in a GJS or GJL casting.

Preferably, step (ii) is carried out to form an infiltration product which is basic to at least an infiltration depth of 5 mm, more preferably 10 mm, upon contact with water, measured from the surface of the mold, most preferably at each infiltration depth in the range of 2 to 5 mm, the infiltration product reacts basicly upon contact with water.

• (i) Bereitstellen oder Herstellen einer Gießform, deren Oberflächen einen Gießformhohlraum definieren, aus chemisch gebundenem Formgrundstoff umfassend ein oder mehrere mittels Säure gehärtete Bindemittel und Quarzsand, wobei zumindest Bereiche der den Gießformhohlraum definierenden Oberflächen der Gießform bei Kontakt mit Wasser acid reagieren,
• (ii) Infiltrieren zumindest eines der besagten acid reagierenden Bereiche mit einer erfindungsgemäß zu verwendenden Zusammensetzung wie oben definiert, so dass das Infiltrationsprodukt bei Kontakt mit Wasser an der Oberfläche der Gießform basisch reagiert, vorzugsweise so, dass der infiltrierte Oberflächenbereich der Gießform bei Kontakt mit Wasser basisch reagiert,
• (iii) Füllen des Gießformhohlraums mit einer schmelzflüssigen Eisen-Kohlenstoff-Legierung,
• (iv) Erstarren lassen der Eisen-Kohlenstoff-Legierung im Gießformhohlraum, so dass ein GJS-Gussstück resultiert.

A specific aspect of the present invention thus relates to a method for producing a GJS casting, comprising the following steps:

• (i) providing or fabricating a mold whose surfaces define a mold cavity of chemically bonded mold base comprising one or more acid-cured binders and quartz sand, wherein at least portions of the mold cavity defining surfaces of the mold react acid upon contact with water;
• (ii) infiltrating at least one of said acid-reacting regions with a composition to be used in accordance with the invention as defined above so that the infiltrate reacts basicly upon contact with water at the surface of the mold, preferably such that the infiltrated surface area of the mold upon contact with water basic reacts,
• (iii) filling the mold cavity with a molten iron-carbon alloy,
• (iv) solidify the iron-carbon alloy in the mold cavity to result in a GJS casting.

• (i) Bereitstellen oder Herstellen einer Gießform, deren Oberflächen einen Gießformhohlraum definieren, aus chemisch gebundenem Formgrundstoff umfassend ein oder mehrere mittels Säure gehärtete Bindemittel und Quarzsand, wobei zumindest Bereiche der den Gießformhohlraum definierenden Oberflächen der Gießform bei Kontakt mit Wasser acid reagieren,
• (ii) Infiltrieren zumindest eines der besagten acid reagierenden Bereiche mit einer erfindungsgemäß zu verwendenden Zusammensetzung wie oben definiert, so dass das Infiltrationsprodukt bei Kontakt mit Wasser an der Oberfläche der Gießform basisch reagiert, vorzugsweise so, dass der infiltrierte Oberflächenbereich der Gießform bei Kontakt mit Wasser basisch reagiert,
• (iii) Füllen des Gießformhohlraums mit einer schmelzflüssigen Eisen-Kohlenstoff-Legierung,
• (iv) Erstarren lassen der Eisen-Kohlenstoff-Legierung im Gießformhohlraum, so dass ein GJL-Gussstück resultiert.

And another specific aspect of the present invention relates to a method for producing a GJL casting, comprising the following steps:

• (i) providing or fabricating a mold whose surfaces define a mold cavity of chemically bonded mold base comprising one or more acid-cured binders and quartz sand, wherein at least portions of the mold cavity defining surfaces of the mold react acid upon contact with water;
• (ii) infiltrating at least one of said acid-reacting regions with a composition to be used in accordance with the invention as defined above so that the infiltrate reacts basicly upon contact with water at the surface of the mold, preferably such that the infiltrated surface area of the mold upon contact with water basic reacts,
• (iii) filling the mold cavity with a molten iron-carbon alloy,
• (iv) solidify the iron-carbon alloy in the mold cavity to result in a GJL casting.

The preferred embodiments given above with a view to the use according to the invention apply correspondingly to the process according to the invention; this also applies vice versa.

• (i-a) Bereitstellen eines No-Bake-Bindemittels, wobei das No-Bake-Bindemittel als reaktive Harzkomponente vorzugsweise Furanharze und/oder Phenolharze umfasst.
• (i-b) Bereitstellen von Quarzsand,
• (i-c) Bereitstellen eines sauren Katalysators, vorzugsweise in flüssiger Phase oder als Belag auf dem Quarzsand gemäß Komponente (i-b), für die Aushärtung der reaktiven Harzkomponente des No-Bake-Bindemittels
• (i-d) Herstellen der Gießform aus den bereitgestellten Komponenten gemäß dem No-Bake-Verfahren.

Preferred is a process according to the invention (as defined above, hereinafter or in the appended claims, preferably as preferred), in which the casting mold is produced in step (i), with the following steps for producing the casting mold in step (i):

• (ia) providing a no-bake binder, wherein the no-bake binder as the reactive resin component preferably comprises furan resins and / or phenolic resins.
• (ib) providing quartz sand,
• (ic) providing an acid catalyst, preferably in the liquid phase or as a coating on the quartz sand according to component (ib), for the curing of the reactive resin component of the no-bake binder
• (id) Manufacture of the mold from the provided components according to the no-bake method.

• (i-a-F) Bereitstellen eines No-Bake-Bindemittels, wobei das No-Bake-Bindemittel als reaktive Harzkomponente ein Furanharz umfasst.
• (i-b-F) Bereitstellen von Quarzsand,
• (i-c-F) Bereitstellen eines sauren Katalysators, vorzugsweise in flüssiger Phase oder als Belag auf dem Quarzsand gemäß Komponente (i-b), für die Aushärtung der reaktiven Harzkomponente des No-Bake-Bindemittels, umfassend Sulfonsäuren, Phosphorsäure, Schwefelsäure oder Kombinationen davon,
• (i-d-F) Herstellen der Gießform gemäß dem No-Bake-Verfahren

oder

• (i-a-P) Bereitstellen eines No-Bake-Bindemittels, wobei das No-Bake-Bindemittel als reaktive Harzkomponente ein Phenolharz umfasst,
• (i-b-P) Bereitstellen von Quarzsand,
• (i-c-P) Bereitstellen eines sauren Katalysators, vorzugsweise in flüssiger Phase oder als Belag auf dem Quarzsand gemäß Komponente (i-b), für die Aushärtung der reaktiven Harzkomponente des No-Bake-Bindemittels, umfassend Sulfonsäure,
• (i-d-P) Herstellen der Gießform gemäß dem No-Bake-Verfahren.

Particular preference is given to a process according to the invention (as defined above, hereinafter or in the appended claims, preferably as referred to as preferred), with the following steps for producing the casting mold in step (i):

• (iaF) providing a no-bake binder, wherein the no-bake binder as the reactive resin component comprises a furan resin.
• (ibF) Provision of quartz sand,
• (icF) providing an acid catalyst, preferably in the liquid phase or as a coating on the quartz sand according to component (ib), for curing the reactive resin component of the no-bake binder comprising sulfonic acids, phosphoric acid, sulfuric acid or combinations thereof,
• (idF) Manufacture of the mold according to the no-bake method

or

• (iaP) providing a no-bake binder, wherein the no-bake binder comprises, as a reactive resin component, a phenolic resin,
• (ibP) Providing quartz sand,
• (icP) providing an acidic catalyst, preferably in the liquid phase or as a coating on the quartz sand according to component (ib), for curing the reactive resin component of the no-bake binder, comprising sulfonic acid,
• (idP) Manufacture of the mold according to the no-bake method.

Particular preference is given to a process according to the invention (as defined above, hereinafter or in the appended claims, preferably as preferred), the preparation and processing of the molding material mixture being carried out at temperatures in the range from 15 to 35.degree. Reference is made to the above statements. In practice, for reasons of time and cost, the skilled person will only in rare cases infiltrate all areas of acidic reaction. Often, it will infiltrate only those acidic areas where, in the absence of infiltration / infiltration product, scarce surfaces would most likely occur. Preferred is therefore a method according to the invention (as defined above, hereinafter or in the appended claims, preferably as preferred) with the following steps for the suppression of the formation of pitted surfaces:

(I)

Producing a comparative casting mold whose composition and, in sections or completely, whose geometry is identical to that of the casting mold, wherein the comparative casting mold is not infiltrated with a basic composition, filling the mold cavity of the comparative casting mold with a molten iron-carbon alloy, allowing the iron to solidify Carbon alloy in the mold cavity of the comparative mold, resulting in a GJS or GJL comparative casting, identifying at least one position of a portion of the mold cavity defining surfaces of the comparative mold to which the solidified comparative casting has a pitted surface;
and subsequently

(II)

• (i) providing or manufacturing the mold as above, defined below or in the claims,
• (ii) infiltrating at least one of said acid-responsive regions as defined above, hereinafter or in the claims, wherein said acid-responsive region is positioned as well as at least a portion of the comparative casting mold where the solidified comparative casting has a scarred surface;
• (iii) filling the mold cavity with a molten iron-carbon alloy,
• (iv) solidify the iron-carbon alloy in the mold cavity to result in a GJS or GJL casting.

• – eine basische Komponente bestehend aus einer oder mehreren Basen

sowie

• – eine Trägerflüssigkeit für die basische Komponente.

In the method according to the invention, according to a first aspect, a basic composition is used for infiltrating (and thus suppressing the formation of scarred surfaces)

• A basic component consisting of one or more bases

such as

• A carrier liquid for the basic component.

• – anorganischen Basen und organischen Basen,

und wobei vorzugsweise:

• – eine, mehr als eine oder sämtliche der anorganischen Basen in der basischen Komponente ausgewählt ist bzw. sind aus der Gruppe bestehend aus anorganischen Verbindungen, die von Wasser ein Proton übernehmen können, und Metallhydroxiden

und/oder

• – eine, mehr als eine oder sämtliche der organischen Basen in der basischen Komponente ausgewählt ist bzw. sind aus der Gruppe bestehend aus Carbonsäure-Salzen und organischen Aminen.

Preferred aspects of the method according to the invention are summarized below; the advantages of specific aspects mentioned for the use according to the invention apply correspondingly:
Preferred is a method according to the invention, wherein one, more than one or all of the bases in the basic component of the basic composition for the infiltration is selected from the group consisting of

• - inorganic bases and organic bases,

and preferably:

• - One, more than one or all of the inorganic bases in the basic component is selected from the group consisting of inorganic compounds that can take over a proton of water, and metal hydroxides

and or

• One, more than one or all of the organic bases in the basic component is or are selected from the group consisting of carboxylic acid salts and organic amines.

Particular preference is given to a process according to the invention wherein one, more than one or all of the inorganic bases in the basic component is or are selected from the group consisting of alkali metal hydroxide, alkaline earth metal hydroxide and water glass, in particular sodium silicate, potassium silicate or lithium water glass.

Very particular preference is given to a method according to the invention, wherein the carrier liquid for the basic component comprises one or more compounds selected from the group consisting of water and organic compounds having a boiling point below 100 ° C at 1000 hPa, preferably in the carrier liquid, the total amount of water and organic compounds having a boiling point below 100 ° C at 1000 hPa more than 50 wt .-%, based on the total amount of the carrier liquid.

Most preferred is a process according to the invention, wherein the carrier liquid for the basic component comprises one or more compounds selected from the group consisting of water, methanol, ethanol, propanol, butanol, acetone and gasoline, preferably in the carrier liquid Total content of water, methanol, ethanol, propanol, butanol, acetone and gasoline is more than 50 wt .-%, based on the total amount of the carrier liquid.

In a method according to the invention, the basic composition preferably comprises one or more surfactants.

In a method according to the invention, the basic composition preferably comprises one or more binders, wherein preferably the one or at least one of the plurality of binders is self-curing in the air and / or dries when the carrier liquid is removed. In a preferred method of the invention, the basic composition preferably comprises one or more binders selected from the group consisting of
phenolic resins, preferably resols, more preferably basic aqueous resoles,
Thermoplastics, preferably polyamides, polyvinyl acetates, polyvinyl alcohols and polybutyrals, polyvinylpyrrolidones, more preferably polyvinyl alcohols and polyvinyl acetates,
Carbohydrates, preferably starch and molasses, more preferably starch,
Biopolymers, preferably lignins, celluloses, mucilages, gelatin, pectins and alginates, particularly preferably sulphite liquors,
Dispersions and powders, preferably copolymers, more preferably acrylates,
inorganic binders based on or containing:
Silicate binders, in particular water glass and silica sols,
(basic) polyphosphates, borates, cement binders.

In a very preferred method according to the invention, the basic composition preferably comprises organic binders in a concentration of from 0.2 to 40% by weight, based on the total amount of the composition, preferably from 0.2 to 10% by weight, more preferably from 0.2 to 5% by weight
and or
inorganic binders in a concentration of 0.5 to 80 wt .-%, based on the total amount of the composition.

In a method according to the invention, the basic composition preferably comprises alkaline silicate in a concentration of 5 to 50 wt .-% based on the total amount of the composition, particularly preferably 10 to 40 wt .-%.

In a process according to the invention, the basic composition preferably contains one or more solids suspended in the carrier liquid, preferably one or more solids suspended in the carrier liquid which are inert upon contact with water or have an acidic or basic surface, preferably one or more of which are present in the carrier liquid Carrier liquid suspended solids are inorganic solids, wherein the inorganic solid is preferably not silicate. The composition preferably contains a proportion of suspended in the carrier liquid solids having a particle size of less than 0.075 mm, preferably a proportion of suspended in the carrier liquid inorganic solids having a particle size less than 0.075 mm, preferably a proportion of suspended in the carrier liquid solids having a particle size smaller 0.075 mm in the range of> 50 wt .-%, based on the total amount of solids, preferably a proportion of suspended in the carrier liquid inorganic solids having a particle size of less than 0.075 mm in the range of> 50 wt .-%, based on the total amount of solid.

In a method according to the invention, the basic composition preferably contains one or more dyes, preferably one or more color pigments and / or dyes dissolved in the carrier liquid and / or the composition contains no graphite and no oxides of zirconium, silicon, aluminum, magnesium and calcium and none Mixed oxides of these elements.

The method according to the invention, in all its preferred aspects and embodiments, is equally suitable for the production of a GJS or GJL casting and for suppressing the formation of pitted surfaces on these castings.

It is understood that prior to filling the mold cavity with a molten iron-carbon alloy, the carrier liquid of the composition to be used according to the invention is at least substantially removed. This is usually done by evaporating (drying) the carrier liquid. The process can be by heat input or radiation input (microwave or Infrared radiation) are accelerated. It is also possible to carry out the drying by flaming off combustible volatile carrier liquids such as alcohols.

In addition to the composition to be used according to the invention, a (for example commercially available) size can be applied to the casting mold or to parts of the casting mold. Usually, first the composition and then the size is applied. If no sizing is provided, the dried composition reacted with ingredients from areas of the surface of the mold will contact the molten iron-carbon alloy. When the size is applied to the composition (or the dried composition or the infiltrated area), this size separates the molten iron-carbon alloy from the thus dried and reacted composition.

• – Bereitstellen oder Herstellen einer Gießform, deren Oberflächen einen Gießformhohlraum definieren, aus chemisch gebundenem Formgrundstoff umfassend ein mittels Säure gehärtetes Bindemittel und Quarzsand, wobei zumindest Bereiche der den Gießformhohlraum definierenden Oberflächen der Gießform bei Kontakt mit Wasser acid reagieren,
• – Infiltrieren zumindest eines der besagten acid reagierenden Bereiche mit einer erfindungsgemäß zu verwendenden Zusammensetzung vorstehend oder nachfolgend oder in den Ansprüchen definiert, so dass das Infiltrationsprodukt bis mindestens zu einer Infiltrationstiefe von 2 mm bei Kontakt mit Wasser basisch reagiert, gemessen von der Oberfläche der Gießform, bevorzugt bis mindestens zu einer Infiltrationstiefe von 5 mm, besonders bevorzugt 10 mm, wobei ganz besonders bevorzugt bei jeder Infiltrationstiefe im Bereich von 2 bis 5 mm das Infiltrationsprodukt bei Kontakt mit Wasser basisch reagiert,
• – Füllen des Gießformhohlraums mit einer schmelzflüssigen Eisen-Kohlenstoff-Legierung,
• – Erstarren lassen der Eisen-Kohlenstoff-Legierung im Gießformhohlraum, so dass ein GJS- oder GJL-Gussstück resultiert. (Zu den bevorzugten spezifischen Aspekten betreffend GJS bzw. GJL siehe oben).

Preferred is a method according to the invention with the following steps

• Providing or fabricating a casting mold whose surfaces define a mold cavity of chemically bonded molding base comprising an acid cured binder and quartz sand, at least portions of the mold cavity defining surfaces of the casting being acid on contact with water,
• Infiltrating at least one of said acid-reacting regions with a composition to be used according to the invention, above or below or in the claims, so that the infiltration product reacts to at least an infiltration depth of 2 mm on contact with water, measured from the surface of the casting mold, preferably to at least an infiltration depth of 5 mm, more preferably 10 mm, very particularly preferably at each infiltration depth in the range of 2 to 5 mm, the infiltration product reacts basicly on contact with water,
• Filling the mold cavity with a molten iron-carbon alloy,
• Solidify the iron-carbon alloy in the mold cavity to result in a GJS or GJL casting. (For the preferred specific aspects concerning GJS and GJL see above).

Depending on the grain size of the quartz sand, the binder system and the binder content as well as the compaction of the sand, the composition penetrates the molding material at different depths depending on the application. Especially with larger molds or cores, as they are needed for the production of the vulnerable parts, there are always better and less dense areas into which the infiltrant will penetrate at different depths. Also, depending on the manufacturer, the quartz sands used differ considerably in grain size and shape. This also influences the penetration depth (infiltration depth). In our own experiments it has been shown that a deeper infiltration into the molding material surface causes a better error suppression.

The penetration depth can be determined in practice by penetrating a molding material surface in a suitable manner with the composition to be used according to the invention or, for comparison purposes, with another infiltrant and then breaking or scratching the molding material at a suitable location. The penetration depth can be determined by the discoloration of the sand body z. B. be recognized by the carrier liquid of the infiltrant. For more precise determination, z. Example, to determine the number of penetrated sand layers, a magnifying glass or an optical microscope and a corresponding scale can be used. Alternatively or additionally, the number of discolored sand layers can be determined (see below for method).

The determination of the penetration depth of the infiltrant (for example a composition to be used according to the invention) can also be carried out on well-compacted test specimens. Test specimens are produced for this purpose as described in the VDG leaflet P72, Binder Testing, available from the VDG Information Center, PO Box 105144, D-400042 Düsseldorf. Notwithstanding the requirement P72, however, the test specimens are compacted by means of 5 driving strokes analogous to the VDG leaflet P73 with a pile driver from Simpson Technologies GmbH, Sennweidstrasse 43, CH 6312 Steinhausen. The depth of penetration is determined on the best-compacted side of a test piece produced in this way.

Preferred is a method according to the invention, wherein the quartz sand is a regenerated quartz sand, which was preferably prepared by working up a molding material mixture comprising quartz sand and an acid-cured binder. The process of the present invention allows and promotes the use of recycled / regenerated sand and reduces the casting error commonly associated with such use.

Preference is given to a process according to the invention in which the infiltration of at least one of said acid-reacting regions with a composition to be used according to the invention is carried out by spraying, brushing, flooding or dipping.

Another aspect of the present invention relates to a mold. A casting mold according to the invention is produced on a regular basis by means of a process according to the invention and / or under the use according to the invention of a basic composition as infiltrant; to that extent all above and below as well as in the claims as preferred specified embodiments relating to the inventive method or the inventive use also apply to the mold according to the invention, and vice versa.

A casting mold according to the invention is a mold made of a chemically bound molding base material, the surfaces of which define a mold cavity, for producing a GJS or GJL casting,
wherein the chemically bonded molding base comprises one or more acid-cured binders and quartz sand,
wherein at least one region of the mold defining the mold cavity comprises an infiltration product which is basic to at least an infiltration depth of 2 mm upon contact with water, measured from the surface of the mold.

Such a mold according to the invention surprisingly contributes to suppressing the formation of pitted surfaces on castings (in particular GJS and GJL).

Preferred is such a casting mold according to the invention, wherein the chemically bonded molding base comprises one or more acid-cured no-bake binder and quartz sand, wherein the no-bake binder comprises furan resins and / or phenolic resins. Reference should be made to the above statements.

Preferred is a mold according to the invention, wherein the infiltration product in the at least one mold cavity defining portion of the mold until at least to an infiltration depth of 5 mm on contact with water basic reacts, measured from the surface of the mold, preferably at least to an infiltration depth of 10 mm , wherein very particularly preferably at each infiltration depth in the range of 2 to 5 mm, the infiltration product reacts basicly upon contact with water. Reference should be made to the above statements.

Particularly preferred is a mold according to the invention, wherein from the mold cavity defining surface more than 15 mm remote lying, preferably more than 25 mm away areas of the mold, measured from the surface of the mold, react acid on contact with water. Reference should be made to the above statements. The process according to the invention is preferably carried out such that in step (ii) such a casting mold results; this is then used in subsequent steps.

Particularly preferred is a mold according to the invention, wherein in the mold cavity, a liquid or solidified iron-carbon alloy is arranged, selected from the group consisting of iron-carbon alloys for the formation of GJS and GJL castings. Reference should be made to the above statements.

Particularly preferred is a casting mold according to the invention, wherein the chemically bonded molding base material is a regenerated quartz sand, which was preferably prepared by working up a molding material mixture. Reference should be made to the above statements and advantages.

Another aspect of the present invention relates to a kit. A kit according to the invention, as defined below, is regularly employed in a method according to the invention and / or in connection with the use according to the invention of a basic composition as infiltrant. A kit according to the invention is regularly used for producing a casting mold according to the invention; to that extent all above and below as well as in the claims as preferred specified embodiments relating to the inventive method, the inventive use or the inventive mold also apply to the kit according to the invention, and vice versa.

• (a) einen sauren Katalysator in flüssiger Phase für die Aushärtung der reaktiven Harzkomponente eines No-Bake-Bindemittels sowie
• (b) eine basische Zusammensetzung als Infiltrationsmittel für den Formstoff der Gießform, umfassend
• – eine basische Komponente bestehend aus einer oder mehreren Basen

sowie

• – eine Trägerflüssigkeit für die basische Komponente,

sowie optional

• (c) das No-Bake-Bindemittel, umfassend eine reaktive Harzkomponente, wobei der saure Katalysator gemäß Komponente (a) als Katalysator für die Aushärtung der reaktiven Harzkomponente wirkt. Auf die obigen Ausführungen sei verwiesen.

According to the invention, a kit for use in the manufacture of a casting mold, comprising

• (A) an acidic catalyst in the liquid phase for curing the reactive resin component of a no-bake binder and
• (b) a basic composition as an infiltrant for the molding material of the mold, comprising
• A basic component consisting of one or more bases

such as

• A carrier liquid for the basic component,

as well as optional

• (c) the no-bake binder comprising a reactive resin component, wherein the acidic catalyst of component (a) acts as a catalyst for curing the reactive resin component. Reference should be made to the above statements.

Preferred is a kit wherein one, more than one or all of the bases have a pK _B value in water at 25 ° C of less than 3.0, preferably less than 1.0. Reference should be made to the above statements.

• – anorganischen Basen und organischen Basen,

und wobei vorzugsweise:

• – eine, mehr als eine oder sämtliche der anorganischen Basen in der basischen Komponente ausgewählt ist bzw. sind aus der Gruppe bestehend aus anorganischen Verbindungen, die von Wasser ein Proton übernehmen können, und Metallhydroxiden

und/oder

• – eine, mehr als eine oder sämtliche der organischen Basen in der basischen Komponente ausgewählt ist bzw. sind aus der Gruppe bestehend aus Carbonsäure-Salzen und organischen Aminen. Auf die obigen Ausführungen sei verwiesen.

In particular, a kit according to the invention is preferred in which one, more than one or all of the bases in the basic component is or are selected from the group consisting of

• - inorganic bases and organic bases,

and preferably:

• - One, more than one or all of the inorganic bases in the basic component is selected from the group consisting of inorganic compounds that can take over a proton of water, and metal hydroxides

and or

• One, more than one or all of the organic bases in the basic component is or are selected from the group consisting of carboxylic acid salts and organic amines. Reference should be made to the above statements.

Particular preference is given to a kit according to the invention wherein one, more than one or all of the inorganic bases in the basic component is or are selected from the group consisting of alkali metal hydroxide, alkaline earth metal hydroxide and water glass, in particular sodium silicate, potassium silicate or lithium water glass. Reference should be made to the above statements.

Preferred is a kit according to the invention, wherein the carrier liquid for the basic component comprises one or more compounds selected from the group consisting of water and organic compounds having a boiling point below 100 ° C. at 1000 hPa,
wherein preferably in the carrier liquid, the total amount of water and organic compounds having a boiling point below 100 ° C at 1000 hPa is more than 50 wt .-%, based on the total amount of the carrier liquid. Reference should be made to the above statements.

Particularly preferred is a kit according to the invention, wherein the carrier liquid for the basic component comprises one or more compounds selected from the group consisting of water, methanol, ethanol, propanol, butanol, acetone and gasoline,
wherein preferably in the carrier liquid, the total amount of water, methanol, ethanol, propanol, butanol, acetone and gasoline is more than 50 wt .-%, based on the total amount of the carrier liquid. Reference should be made to the above statements.

Also preferred is a kit according to the invention, wherein the basic composition additionally comprises one or more surfactants. Reference should be made to the above statements.

Also preferred is a kit according to the invention, where the basic composition comprises one or more binders,
wherein preferably one or at least one of the plurality of binders is self-curing in the air and / or dries when the carrier liquid is removed. Reference should be made to the above statements.

In particular, a kit according to the invention is preferred, wherein the basic composition comprises one or more binders selected from the group consisting of
phenolic resins, preferably resols, more preferably basic aqueous resoles,
Thermoplastics, preferably polyamides, polyvinyl acetates, polyvinyl alcohols and polybutyrals, polyvinylpyrrolidones, more preferably polyvinyl alcohols and polyvinyl acetates,
Carbohydrates, preferably starch and molasses, more preferably starch,
Biopolymers, preferably lignins, celluloses, mucilages, gelatin, pectins and alginates, particularly preferably sulphite liquors,
Dispersions and powders, preferably copolymers, more preferably acrylates,
inorganic binders based on or containing:
Silicate binders, in particular water glass and silica sols,
(basic) polyphosphates, borates, cement binders. Reference should be made to the above statements.

Also preferred is a kit according to the invention, the composition comprising:
organic binders in a concentration of 0.2 to 40 wt .-% based on the total amount of the composition, preferably 0.2 to 10 wt .-%, particularly preferably 0.2 to 5 wt .-%
and or
inorganic binders in a concentration of 0.5 to 80 wt .-%, based on the total amount of the composition. Reference should be made to the above statements.

In particular, a kit according to the invention is preferred, the composition comprising:
alkaline silicate in a concentration of 5 to 50 wt .-% based on the total amount of the composition, particularly preferably 10 to 40 wt .-%. Reference should be made to the above statements.

Also preferred is a kit according to the invention, wherein the composition contains one or more solids suspended in the carrier liquid,
preferably one or more solids suspended in the carrier liquid which are inert upon contact with water or have an acidic or basic surface,
wherein preferably one or more solids suspended in the carrier liquid are inorganic solids,
wherein the inorganic solid is preferably not silicate.

In particular, a kit according to the invention is preferred, wherein the composition contains a proportion of solids suspended in the carrier liquid with a particle size of less than 0.075 mm,
preferably contains a proportion of suspended in the carrier liquid inorganic solids having a particle size less than 0.075 mm,
preferably contains a proportion of solids suspended in the carrier liquid with a particle size of less than 0.075 mm in the range of> 50% by weight, based on the total amount of solids,
preferably contains a proportion of suspended in the carrier liquid inorganic solids having a particle size of less than 0.075 mm in the range of> 50 wt .-%, based on the total amount of solid. Reference should be made to the above statements.

Finally, a kit according to the invention is also preferred, wherein the composition contains one or more dyes, preferably contains one or more color pigments and / or dyes dissolved in the carrier liquid
and or
wherein the composition contains no graphite and no oxides of zirconium, silicon, aluminum, magnesium and calcium and no mixed oxides of these elements. Reference should be made to the above statements.

In the context of the present invention, preferably a plurality of the embodiments and / or aspects described above or below as being preferred are realized simultaneously; Particular preference is given to the combinations of such embodiments or aspects and the corresponding features resulting from the appended claims.

The person skilled in the art will combine these with one another as preferred and as particularly preferred embodiments of the present invention.

In the following, the present invention will be explained in more detail with reference to figures and selected examples; Unless otherwise indicated, all figures are by weight.

Description of the pictures:

Figure 1 is a photograph of a conventionally produced casting with a pitted surface and white linings.

: Figure 2 is a photograph of a conventionally manufactured casting with flaws.

Figure 3 is the micrograph of a microstructure beneath the cast defect "scarred surface" of a conventionally produced casting.

Figure 4 is a photograph of Panel 1 treated with Infiltrant 1040 from Comparative Example 1. White surfaces and underlying pore formations on the cast skin can be observed.

Figure 5 is a photograph of an example of a mold for test casts 1-3 of Example 1.

Figure 6 is the photograph of panel 4 from trial 1 of Example 1.

Figure 7 is the photograph of panel 2 from trial 1 of Example 1.

Figure 8 is the photograph of the casting produced in Experimental Cast 2 of Example 1 with the fields 1 to 5.

Figure 9 is the photograph of the casting produced in Test Cast 3 of Example 1 with the fields 1-8.

Figure 10 is the photograph of the casting made in Example 2 with the fields 1 to 4.

Figure 11 is the photograph of the casting produced in Example 3. The left surface of the casting was formed by the molding surface in the top box treated with the infiltrant A.

Figure 12 shows schematically on the left a cross section through the surface of a casting mold. The penetration depth corresponds to the depth into which the infiltrant is penetrated. This illustration also shows a sizing layer. On the right is schematically shown the course of the pH value as a function of the penetration depth.

Comparative casting with pitted surface (GJL)

Casting without pitted surface (GJL)

Examples:

Subsequently, the company Hüttenes-Albertus, Dusseldorf, abbreviated to HA.

Method for determining penetration depth:

The specimens were penetrated per m ² area with the same amount of infiltrant as described in the field trials. The determination of the penetration depth of the infiltrant into the test specimens was carried out analogously to practice. For this purpose, the specimens were broken immediately after the order and the penetration depth was determined by light microscopy with appropriate magnification by means of a scale or by counting the penetrated sand layers. In this case, the infiltration by a darker discoloration of the grains of sand by the carrier liquid, or after drying z. B. to recognize by a discoloration by a color body.

The number of penetrated sand layers is determined as follows: The test specimen is penetrated by means of the desired method with the infiltrant. Then it is broken in the transverse direction. Starting from the middle of the molding material surface, the number of grains of sand from the molding surface counted perpendicular to the test center. It counts the grains of sand, which are discolored by the carrier liquid and / or a color body. A grain of sand that is adjacent to the first grain of sand and overlaps less than half of its own diameter is counted as a new layer of sand. The grains of sand must also be wetted to at least half. The determination is repeated at least 5 times on the best compressed side of the test specimen. Thus, for example, with a sand having a mean grain size of 0.36 mm, a penetration depth of about 2.7 mm results for 10 penetrated sand layers.

Comparative Example 1 (not according to the invention):

• • Eisen:Sand Massenverhältnis: ca. 1:7
• • Formstoffsystem: mechanisch regenerierter Furanaltsand mit einer mittleren Körnung von 0,33 mm
• • Eingesetzter Binder: SRV-1 der Firma HA (Handelsprodukt)
• • Eingesetzte Aktivatoren: Aktivator 7809 der Firma HA (Handelsprodukt)
• • Eingesetzte Schlichten: 1. Lage Disopast 8957C der Firma HA (Handelsprodukt), Auftrag durch Streichen, 2. Lage Disopast 8957C der Firma HA (Handelsprodukt), Auftrag durch Streichen
• • Gießtemperatur: ca. 1360°C

Feld in Form und Gussstück 1 Substanz Infiltrationsmittel Formlack 1940 der Firma HA (Handelsprodukt) Harzanteil 20% Isopropanol 80% The following trial was at a core for a casting EN-GJS 400-15 with a casting weight of 13,000 kg and a piece weight of 11,000 kg.

• • Iron: sand Mass ratio: about 1: 7
• • Mold material system: mechanically regenerated furan sand with a mean grain size of 0.33 mm
• • Binder used: SRV-1 from HA (commercial product)
• • Activators used: Activator 7809 from HA (commercial product)
• Used sizing: 1. Layer Disopast 8957C from HA (commercial product), application by brushing, 2nd layer Disopast 8957C from HA (commercial product), application by brushing
• • Casting temperature: approx. 1360 ° C

Field in shape and casting 1 substance Infiltrating agent Formlack 1940 of the company HA (commercial product) resin content 20% isopropanol 80%

Insertion into the uppermost molding layer of 970 g per 1 m ² molding surface of the infiltrant Formlack 1940. Penetration depth approx. 5-6 mm. Evaluation of the results: infiltrant field Evaluation of the faulty image "scarred surface" Form lacquer 1940 of the company HA 1 White surfaces, including pore formation on the casting skin

shows a photograph of the manufactured font surface.

Example 1:

• • Eisen:Sand Verhältnis: ca. 1:2
• • Formstoffsystem: mechanisch regenerierter Furanaltsand mit einer mittleren Körnung von 0,31 mm
• • Die Kornverteilung des Sandes ist gem. Siebanalyse nach DIN 3310 wie folgt:

Siebfraktion Anteil Kumuliert Siebanalyse > 1,000 mm % 0,06 0,06 Siebanalyse > 0,710 mm % 0,27 0,33 Siebanalyse > 0,500 mm % 3,71 4,04 Siebanalyse > 0,355 mm % 22,50 26,54 Siebanalyse > 0,250 mm % 43,61 70,15 Siebanalyse > 0,180 mm % 23,03 93,18 Siebanalyse > 0,125 mm % 6,04 99,22 Siebanalyse > 0,090 mm % 0,47 99,69 Siebanalyse > 0,063 mm % 0,16 99,85 Siebanalyse < 0,063 mm % 0,14 99,99

• • Der Glühverlust nach VDG-Merkblatt P33 ist wie folgt: 4,7%
• • Die Restsäure [mg NaOH/100) nach HA-Prüfvorschrift QS-Nr. beträgt: 0891: 34
• • Eingesetzter Binder: Kaltharz 8670 der Firma HA (Handelsprodukt)
• • Eingesetzte Aktivatoren: Aktivator 500T2 und/oder 7901 der Firma HA (Handelsprodukte)
• • Eingesetzte Schlichten: 1. Lage Arkofluid 7232 der Firma HA, Auftrag durch Streichen, 2. Lage Arkofluid 7879 der Firma HA (Handelsprodukte), Auftrag durch Fluten.
• • Gießtemperatur: ca. 1330°C

The following experiments were based on a mold for a casting GJS 400-15 with a casting weight of 1050 kg and a unit weight of 916 kg.

• • Iron: Sand Ratio: about 1: 2
• • Mold material system: mechanically regenerated furan sand with a mean grain size of 0.31 mm
• • The grain distribution of the sand is gem. Sieve analysis after DIN 3310 as follows:

sieve fraction proportion of cumulatively Sieve analysis> 1,000 mm % 0.06 0.06 Sieve analysis> 0.710 mm % 0.27 0.33 Sieve analysis> 0.500 mm % 3.71 4.04 Sieve analysis> 0.355 mm % 22,50 26.54 Sieve analysis> 0.250 mm % 43.61 70.15 Sieve analysis> 0.180 mm % 23,03 93.18 Sieve analysis> 0.125 mm % 6.04 99.22 Sieve analysis> 0.090 mm % 0.47 99.69 Sieve analysis> 0.063 mm % 0.16 99.85 Sieve analysis <0.063 mm % 0.14 99.99

• • The ignition loss according to VDG leaflet P33 is as follows: 4.7%
• • The residual acid [mg NaOH / 100] according to HA test specification QS no. is: 0891: 34
• • Binder used: Cold Resin 8670 from HA (commercial product)
• • Activators used: Activator 500T2 and / or 7901 from HA (commercial products)
• Used sizing: 1. Location Arkofluid 7232 HA, order by brushing, 2nd layer Arkofluid 7879 HA (commercial products), order by flooding.
• • Casting temperature: approx. 1330 ° C

For the experiments, the mold surface and thus the resulting casting surface formed by this mold surface was divided into several sections, with one section each being reserved as a reference for the procedure described above. The portions of the casting referred to hereinafter as references are in accordance with the above manufacturing procedure and not additionally treated or infiltrated areas of the test casting. shows an example of a form used for the trial casts 1-3.

Trial casting 1:

Table 1: Composition of infiltrants / test substances in test casting 1: Field in shape and casting 4 2 substance Infiltrant A, (Inventive) / Proportion [% by Weight] reference comment water 17.1 ethanol 17.1 Refractory products 52.3 95% finer than 0.063 mm, determined with air jet sieve color pigment 0.8 99% finer than 0.032 mm, determined with the air jet sieve Rheological additives, modifiers, thickeners, additives 4.0 resin 6.0 KOH 2.7 NaOH

Area 4: Infiltrant A

• Introduction into the uppermost molding layer of 910 g per 1 m ² molding surface of the infiltrant A.
• Penetration of 25 g KOH onto 1 m ² molding material surface (KOH MW = 56.11 g / mol); this corresponds to 0.43 mol OH ^- per 1 m ² molding material surface. Penetration depth of the infiltrant A in the molding material depending on the compression of the molding material: 1.7-2.2 mm
• Penetration on test specimen> 4 sand layers

Results of test casting 1:

Table 2: Evaluation of the results of test casting 1: infiltrant field Evaluation of the faulty image "scarred surface" comment A 4 No pores or scars best result reference 2 Pores and scars in the radius and some pores on the surface

and show photographs of fields 4 and 2 from trial casting 1.

Trial casting 2

Table 3: Composition of the infiltrants / test substances in test casting 2:

Area 1: Infiltrant A

• Incorporation in the topmost molding layer of 1230 g per 1 m ² molding surface of the infiltrant A
• Thus, penetration of 33 g KOH onto 1 m ² molding surface (KOH MW = 56.11 g / mol); this corresponds to 0.59 mol OH ^- per 1 m ² molding material surface.
• Penetration depth of the infiltrant A in the molding material depending on the compression of the molding material of the form: 1.7-2.4 mm
• Penetration on test specimen> 4 sand layers

Area 2: infiltrant B

• Incorporation in the uppermost molding layer of 490 g per 1 m ² molding surface of the infiltrant B
• Thus, penetration of 14.7 g KOH and 1.5 g NaOH onto 1 m ² mold surface (KOH MW = 56.11 g / mol, NaOH MW = 40.00 g / mol); this corresponds to 0.3 mol OH ^- per 1 m ² molding material surface.
• Penetration depth of the infiltrant B in the molding material depending on the compression of the molding material of the form: 0.6-1.0 mm
• Penetration on specimens> 3 sand layers

Area 3: Reference

Area 5: Magnesite size 5848 from HA

• Application of 500 g per m ² onto the unsized molding surface. The penetration depth of the sizing, depending on the compression of the molding material of the form: 0.8-1.2 mm
• Penetration into the test specimen> 3 sand layers

Table 4: Evaluation of the results of test casting 2: infiltrant field Evaluation of the faulty image "scarred surface" comment A 1 No pores or whitewash best result B 2 No pores or whitewash Good result reference 3 Pores and scars in the radius and on the surface Bad result Magnesite size 5848 5 Pores and scars in the radius and on the surface Bad result

shows a photograph of the manufactured casting with fields 1 to 5.

Trial casting 3:

Tabelle 7: Infiltrationsmengen in Versuchsabguss 3: Feld Material Infiltrationsmenge pro m² Formstoff-Oberfläche g KOH/m² Mol OH^– pro m² Penetrationstiefe Form Penetrationstiefe Prüfkörper, Anzahl der Sandschichten 1 Infiltrationsmittel 1010 27 0,49 1,7–2,3 mm > 4 A 3 Infiltrationsmittel 920 19 0,34 1,7–2,2 mm > 4 E 4 Infiltrationsmittel 1430 38 0,71 1,8–2,4 mm > 5 D 5 Referenz n. a. 6 Infiltrationsmittel 950 14 0,26 1,7–2,2 mm > 4 F 7 Infiltrationsmittel 910 6 0,12 1,7–2,2 mm > 4 G 8 Infiltrationsmittel H 90 Ca(OH)₂ 21 g 0,56 1,6–2,3 mm > 6 Tabelle 8: Bewertung der Ergebnisse aus Versuchsabguss 3: Infiltrationsmittel Feld Bewertung des Fehlbildes „narbige Oberfläche” Bemerkung A 1 Keine Poren oder Weißauhaftungen Bestes Ergebnis E 3 Poren und Weißanhaftungen in Radius D 4 Keine Poren oder Weißauhaftungen zweitbestes Ergebnis Referenz 5 Poren und Narben im Radius und etwas auf der Fläche F 6 Poren und Narben im Radius und auf der Fläche, insgesamt besser als Referenz G 7 Poren im Radius, insgesamt besser als Referenz H 8 Wenige Poren im Radius Table 5: Composition of the infiltrants / test substances in test casting 3: Field in shape and casting 1 4 5 substance Infiltrant A (Inventive) / Proportion [% by Weight] Infiltrant D (Inventive) / Proportion [% by Weight] reference comment water 17.1 25.7 ethanol 17.1 - Refractory products 52.3 61.7 95% finer than 0.063 mm, determined with the air jet sieve color pigment 0.8 - 99% finer than 0.032 mm, determined with the air jet sieve Rheological additives, modifiers, thickeners, additives 4.0 3.85 wetting agent 0.05 resin 6.0 6.0 KOH 2.7 2.7 Table 6: Composition of the infiltrants / test substances in test casting 3:

Table 7: Infiltration quantities in test casting 3: field material Infiltration amount per m ^{2 of} molding material surface g KOH / m ² Moles OH ^- per m ² Penetration depth form Penetration depth of specimen, number of sand layers 1 infiltrant 1010 27 0.49 1.7-2.3 mm > 4 A 3 infiltrant 920 19 0.34 1.7-2.2 mm > 4 e 4 infiltrant 1430 38 0.71 1.8-2.4 mm > 5 D 5 reference n / A 6 infiltrant 950 14 0.26 1.7-2.2 mm > 4 F 7 infiltrant 910 6 0.12 1.7-2.2 mm > 4 G 8th Infiltrant H 90 Ca (OH) ₂ 21 g 0.56 1.6-2.3 mm > 6 Table 8: Evaluation of the results of test casting 3: infiltrant field Evaluation of the faulty image "scarred surface" comment A 1 No pores or whitewash best result e 3 Pores and white adhesions in radius D 4 No pores or whitewash second best result reference 5 Pores and scars in the radius and something on the surface F 6 Pores and scars in the radius and on the surface, better overall than reference G 7 Pores in radius, better overall than reference H 8th Few pores in the radius

shows a photograph of the manufactured casting with the corresponding casting surfaces.

Example 2:

• • Formstoffsystem: mechanisch regenerierter Furanaltsand mit einer mittleren Körnung von 0,31 mm
• • Eingesetzter Binder: Kaltharz 8670 der Firma HA (Handelsprodukt)
• • Eingesetzte Aktivatoren: Aktivator 500T2 und/oder 7901 der Firma HA (Handelsprodukte)
• • Eingesetzte Schlichten: 1. Lage Arkofluid 7232 der Firma HA (Handelsprodukt), Auftrag durch Streichen, 2. Lage Arkofluid 7879 der Firma HA (Handelsprodukt), Auftrag durch Fluten.
• • Gießtemperatur: ca. 1330°C
• • ohne Einsatz eines Speisers

Tabelle 9: Zusammensetzung der Infiltrationsmittel/Versuchssubstanzen:

Tabelle 10: Infiltrationsmengen: Feld Material Infiltrationsmenge pro m² g NaOH/m² Mol OH^– pro m² Penetrationstiefe Form Penetrationstiefe Prüfkörper, Anzahl der Sandschichten 1 Infiltrationsmittel W 3390 g 176 4,4 1,0–3,8 mm > 40 2 Infiltrationsmittel J 1530 g 23 0,57 2,0–4,0 mm > 25 3 Infiltrationsmittel A 1100 g KOH = 30 g 0,55 1,5–2,0 mm > 4 4 Referenz n. a. - - . Tabelle 11: Bewertung der Ergebnisse: Infiltrationsmittel Feld Bewertung des Fehlbildes „narbige Oberfläche” Bemerkung W 1 keine Poren oder Weißanhaftungen Bestes Ergebnis J 2 einige flache Poren Besser als Referenz A 3 einige Poren zweitbestes Ergebnis Referenz 4 tiefe Poren und Narben auf der Fläche The following experiments were made on a mold for a casting GJS 400-15 carried out with a unit weight of 866 kg.

• • Mold material system: mechanically regenerated furan sand with a mean grain size of 0.31 mm
• • Binder used: Cold Resin 8670 from HA (commercial product)
• • Activators used: Activator 500T2 and / or 7901 from HA (commercial products)
• Used sizing: 1. Location Arkofluid 7232 HA (commercial product), order by brushing, 2nd layer Arkofluid 7879 HA (commercial product), order by flooding.
• • Casting temperature: approx. 1330 ° C
• • without use of a feeder

Table 9: Composition of the infiltrants / test substances:

Table 10: Infiltration quantities: field material Infiltration amount per m ² g NaOH / m ² Moles OH ^- per m ² Penetration depth form Penetration depth of specimen, number of sand layers 1 Infiltrant W 3390 g 176 4.4 1.0-3.8 mm > 40 2 Infiltrant J 1530 g 23 0.57 2,0-4,0 mm > 25 3 Infiltrant A 1100 g KOH = 30 g 0.55 1,5-2,0 mm > 4 4 reference n / A - - , Table 11: Evaluation of the results: infiltrant field Evaluation of the faulty image "scarred surface" comment W 1 no pores or white adhesions best result J 2 some flat pores Better for reference A 3 some pores second best result reference 4 deep pores and scars on the surface

shows a photograph of the manufactured casting with the corresponding cast surfaces 1 to 4.

Example 3

• • Formstoffsystem: mechanisch regenerierter Furanaltsand
• • Eingesetzter Binder: Kaltharz 7830 der Firma HA (Handelsprodukt)
• • Eingesetzte Aktivatoren : Aktivator 7857 der Firma HA (Handelsprodukt)
• • Eingesetzte Schlichten: Arkofluid 5004F der Firma HA (Handelsprodukt), Auftrag durch Streichen, zweite Lage Arkofluid 7879 der Firma HA (Handelsprodukt), Auftrag durch Fluten.
• • Gießtemperatur: ca. 1318°C

Another attempt was made on a mold for a casting: GJS40.3 with a casting weight of 3.8 tons and a unit weight of 2.92 tons.

• • Mold material system: mechanically regenerated furan sand
• • Binder used: Cold resin 7830 from HA (commercial product)
• • Activators used: Activator 7857 from HA (commercial product)
• Used sizing: Arkofluid 5004F from HA (commercial product), application by brushing, second layer Arkofluid 7879 from HA (commercial product), application by flooding.
• • Casting temperature: approx. 1318 ° C

Part of the mold surface in the top box was treated with the infiltrant A (see above). 1170 g / m ² molding surface was applied.

Result: The casting surface imaged by the mold surface treated with the infiltrant A was almost completely free of scars and pores. The casting surfaces, in the remaining area of the casting depicted on the upper side of the untreated molding material, were traversed by many small pores and scars, especially near radii.

shows the photograph of the casting produced in Example 3. The left surface of the casting was represented by the area of the forming surface in the top box treated with the infiltrant A.

Further examples: GJL castings

Example 3 analogous examples were carried out for GJL castings. Also in this regard, it was found that the formation of pores and scars was surprisingly greatly reduced by infiltrating the molding material with a basic composition to be used according to the invention.

The and are detail shots concerning GJL castings with a respective unit weight of 2,016 kg; the particular casting material was "GG20" (that is, an alloy for making a GJL casting). The casting temperature was identical in both cases and was about 1300 ° C.

relates to a comparative example in which no infiltration of the molding material of the mold took place. Otherwise, in the comparative example, only steps were carried out which correspond to the procedure according to the invention.

relates to an example according to the invention in which the casting mold was infiltrated with a basic composition so that, up to an infiltration depth of about 6 mm, the resulting infiltration product reacted basicly upon contact with water, measured from the surface of the casting mold. Otherwise, the procedure in Comparative Example and Example was identical.

The infiltrant used in the example according to the invention was a basic composition according to Example 3 above.

(relating to the comparative example not according to the invention) shows at the lower edge of the image a surface area with an approximately triangular shape, which has a pronounced pitted surface.

(Concerning the casting produced in accordance with the invention) shows in the corresponding area of the casting a particularly smooth surface structure, which has no disturbing scars or pores.

It should be noted that the casting produced according to the invention according to was produced using a mold whose surface was treated only in some areas with the inventive composition according to Example 3. The treated area was in the mold exactly where, in the comparative example, the triangular area with a scarred surface was adjacent the casting.

The comparison of and shows that the casting defect "scarred surface" by the inventive use, the inventive method and the use of a mold according to the invention can also be suppressed for GJL castings.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102008025311 A1 [0051]
• JP 57171540 A [0052]
• WO 2009/004090 A1 [0053]
• DE 2407344 [0054]

Cited non-patent literature

• DIN EN 1563 [0035]
• M. Schrod, HJ Wojtas, Surface defects especially at GJS, 7th molding days, Duisburg February 2008 [0041]
• HG Levelink, FPM A Julien, Properties of regenerated furan resin sand Foundry 68 (1981) 340 [0041]
• S. Hasse Guß- und Gefügefehler, Schiele & Schön, Berlin 2nd edition, 2003, 343 [0041]
• S. Hasse Guß- und Gefügefehler, Schiele & Schön, Berlin 2nd edition. 2003, 343 [0046]
• Contribution to the formation mechanism of the cast surface defect white coating and development of proposed solutions for avoidance, dissertation E. Potaturina, TU Bergakademie Freiberg, March 2014 [0047]
• EN-GJS 400-15 [0173]
• GJS 400-15 [0176]
• DIN 3310 [0176]
• GJS 400-15 [0185]
• GJS40.3 [0187]

Claims (20)

Mold of a chemically bonded mold base, the surfaces of which define a mold cavity for making a GJS or GJL casting, wherein the chemically bonded molding base comprises one or more acid-cured binders and quartz sand, wherein at least one region of the mold defining the mold cavity comprises an infiltration product which is basic to at least an infiltration depth of 2 mm upon contact with water, measured from the surface of the mold. A mold according to claim 1, characterized in that the chemically bonded molding base comprises one or more acid-cured no-bake binder and quartz sand, the no-bake binder comprising furan resins and / or phenolic resins. A mold according to any one of claims 1 to 2, wherein the infiltration product in the at least one mold cavity defining region of the mold reacts to at least an infiltration depth of 5 mm on contact with water, measured from the surface of the mold, preferably to at least an infiltration depth of 10 mm, with very particular preference at each infiltration depth in the range of 2 to 5 mm, the infiltration product reacts basicly on contact with water. Casting mold according to one of the preceding claims 1 to 3, wherein from the mold cavity defining surface more than 15 mm remote lying, preferably more than 25 mm away areas of the mold, as measured from the surface of the mold, react acid on contact with water. A mold according to any of the preceding claims 1 to 4, wherein in the mold cavity is disposed a liquid or solidified iron-carbon alloy selected from the group consisting of iron-carbon alloys for the formation of GJS and GJL castings. Casting mold according to one of the preceding claims 1 to 5, wherein the chemically bonded molding base material is a regenerated quartz sand, which was preferably prepared by working up a molding material mixture, Kit for use in the manufacture of a mold, comprising (A) an acidic catalyst in the liquid phase for curing the reactive resin component of a no-bake binder and (b) a basic composition as infiltrant for the molding material of the mold, comprising A basic component consisting of one or more bases such as A carrier liquid for the basic component, as well as optional (c) the no-bake binder comprising a reactive resin component, wherein the acidic catalyst of component (a) acts as a catalyst for curing the reactive resin component. The kit of claim 7, wherein one, more than one or all of the bases have a pK _B value in water at 25 ° C of less than 3.0, preferably less than 1.0. The kit according to any one of claims 7 to 8, wherein one, more than one or all of the bases in the basic component is selected from the group consisting of - inorganic bases and organic bases, and preferably: - One, more than one or all of the inorganic bases in the basic component is selected from the group consisting of inorganic compounds that can take over a proton of water, and metal hydroxides and or One, more than one or all of the organic bases in the basic component is or are selected from the group consisting of carboxylic acid salts and organic amines. A kit according to any one of claims 7 to 9, wherein one, more than one or all of the inorganic bases in the basic component is or are selected from the group consisting of Alkali metal hydroxide, alkaline earth metal hydroxide and water glass, in particular soda waterglass, potassium silicate glass or lithium waterglass. Kit according to one of claims 7 to 10, wherein the carrier liquid for the basic component comprises one or more compounds selected from the group consisting of water and organic compounds having a boiling point below 100 ° C at 1000 hPa, wherein preferably in the carrier liquid, the total amount of water and organic compounds having a boiling point below 100 ° C at 1000 hPa is more than 50 wt .-%, based on the total amount of the carrier liquid. Kit according to one of claims 7 to 11, wherein the carrier liquid for the basic component comprises one or more compounds selected from the group consisting of water, methanol, ethanol, propanol, butanol, acetone and gasoline, wherein preferably in the carrier liquid, the total amount of water, methanol, ethanol, propanol, butanol, acetone and gasoline is more than 50 wt .-%, based on the total amount of the carrier liquid. Kit according to one of claims 7 to 12, wherein the basic composition in addition - comprises one or more surfactants. A kit according to any one of claims 7 to 13, wherein the basic composition comprises one or more binders, wherein preferably one or at least one of the plurality of binders is self-curing in the air and / or dries when the carrier liquid is removed. A kit according to any one of claims 7 to 14, wherein the basic composition comprises one or more binders selected from the group consisting of phenolic resins, preferably resols, more preferably basic aqueous resoles, Thermoplastics, preferably polyamides, polyvinyl acetates, polyvinyl alcohols and polybutyrals, polyvinylpyrrolidones, more preferably polyvinyl alcohols and polyvinyl acetates, Carbohydrates, preferably starch and molasses, more preferably starch, Biopolymers, preferably lignins, celluloses, mucilages, gelatin, pectins and alginates, particularly preferably sulphite liquors, Dispersions and powders, preferably copolymers, more preferably acrylates, inorganic binders based on or containing: Silicate binders, in particular water glass and silica sols, (basic) polyphosphates, borates, cement binders. A kit according to any one of claims 7 to 15, wherein the composition comprises: organic binders in a concentration of 0.2 to 40 wt .-% based on the total amount of the composition, preferably 0.2 to 10 wt .-%, particularly preferably 0.2 to 5 wt .-% and or inorganic binders in a concentration of 0.5 to 80 wt .-%, based on the total amount of the composition. A kit according to any one of claims 7 to 16, wherein the composition comprises: alkaline silicate in a concentration of 5 to 50 wt .-% based on the total amount of the composition, particularly preferably 10 to 40 wt .-%. A kit according to any one of claims 7 to 17, wherein the composition contains one or more solids suspended in the carrier liquid, preferably one or more solids suspended in the carrier liquid which are inert upon contact with water or have an acidic or basic surface, wherein preferably one or more solids suspended in the carrier liquid are inorganic solids, wherein the inorganic solid is preferably not silicate. Kit according to one of claims 7 to 18, wherein the composition contains a proportion of solids suspended in the carrier liquid with a particle size of less than 0.075 mm, preferably contains a proportion of suspended in the carrier liquid inorganic solids having a particle size less than 0.075 mm, preferably contains a proportion of suspended in the carrier liquid solids having a particle size of less than 0.075 mm in the range of> 50 wt .-%, based on the total amount of solids , preferably contains a proportion of suspended in the carrier liquid inorganic solids having a particle size of less than 0.075 mm in the range of> 50 wt .-%, based on the total amount of solid. Kit according to one of claims 7 to 19, wherein the composition contains one or more dyes, preferably one or more color pigments and / or dyes dissolved in the carrier liquid and or wherein the composition contains no graphite and no oxides of zirconium, silicon, aluminum, magnesium and calcium and no mixed oxides of these elements.

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