CZ2016764A3 - A sizing medium for application to porous mould surfaces and/or cores for metal casting - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to a wash for application on a porous surface of metal casting molds and / or cores, particularly for casting iron and steel. This wash contains airgel as an ingredient.

Description

Technical field

BACKGROUND OF THE INVENTION The present invention relates to a size for application to a porous surface of molds and / or cores for casting metals, particularly for casting iron and steel. In particular, the cores are coated with a sizing.

BACKGROUND OF THE INVENTION

The composition of the sizing as well as the type and purpose of their use as a coating material for the coating of molds and cores in the foundry industry are described in detail, for example, in DE 10 2009 032 668.

SUMMARY OF THE INVENTION

SUMMARY OF THE INVENTION It is an object of the present invention to provide a size that is applied to the porous surface of metal casting molds and / or cores and to improve the casting process and the results of the casting process.

This object is achieved by a sizing according to claim 1, i.e. a sizing for application to a porous surface of molds and / or cores for casting metals, in particular for casting iron and steel, according to the invention which is characterized by the addition of an airgel.

Thus, according to the invention, the size, which serves for application to the porous surface of molds and / or cores for casting metals, in particular for casting iron and steel, comprises an addition of an airgel.

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Aerogels, which exist as hydrophilic and as hydrophobic aerogels, are highly porous solid bodies, which in their volume consist of more than 95 percent of pores. Due to this high porosity, the thermal conductivity of the aerogels is very low, so that the size according to the invention has a very good thermal insulation due to the added aerogels. This reduces the formation of gases inside the mold or inside the core.

Such formation of gases can lead to casting failure. In addition, due to their high porosity, airgels can adsorb gas to a large extent. Thus, the gases formed during casting are adsorbed by the aerosol contained in the sizing. This can reduce the proportion of gases that are discharged into the environment, or reduce the cost of the existing exhaust gas scavenging and purification devices, which dispense gases into the environment, in order to reduce the burden on the environment. Therefore, the upper emission limits can be easily observed.

The use of aerogels in the size also leads to a reduction in the cost of cleaning and post-casting of castings. The wettability of the mold or core is reduced by the aerosol contained in the size. This makes it easier to knock the core out of the casting.

Preferably, the addition of airgels to the wash is added as a granulate or powder. For this purpose, a suitable dispersant is advantageously added to promote the wetting of the airgels with the sizing.

The pore size of the airgels is preferably designed such that magnesium-reactive elements or magnesium-reactive compounds such as sulfur and sulfur-containing compounds can be adsorbed by airgel. · _T · * · · · · · · · · · · .....

·················· This leads to a reduced consumption of magnesium on the surface of the mold or core and hence to an improvement in the casting crust, especially when casting spheroidal graphite cast iron, also called ductile cast iron. The graphite formations produced by this ductile iron are reduced.

Preferably, the added amount of airgel 2 is from about volume percent to about 40 volume percent of the size.

Particularly suitable as an additive are carbon aerogels, resorcinol formaldehyde aerogels, silica aerogels, silica carbide aerogels or zirconia aerogels or a combination of these types of aerogels.

Claims (9)

A size for application to a porous surface of molds and / or cores for casting metals, in particular for casting iron and steel, characterized by the addition of an airgel. A wash according to claim 1, wherein the airgel addition to the wash is added as a granulate or a powder. The size of claim 1 or 2, wherein the pore size of the airgel additive is formed such that magnesium-reactive elements or magnesium-reactive compounds, such as sulfur and oxygen compounds, can be adsorbed by the airgel additive. The size of one of the preceding claims, wherein the amount of airgel is from 2 volume percent to 40 volume percent. A wash according to one of the preceding claims, wherein a dispersant is added to promote wetting of the airgel with the wash. A wash according to one of the preceding claims, wherein the carbonogel is used as an airgel additive. A wash according to one of the preceding claims, wherein resorcinol-formaldehyde airgel is used as an airgel additive. A wash according to one of the preceding claims, wherein the silica airgel is used as an airgel additive. • ·· · A wash according to one of the preceding claims, wherein a silica carbide airgel is used as an airgel additive.