DE2010323B - Method and device for producing corrosion protection on a casting mold - Google Patents

Description

1 2

The invention relates to a method of production. To date, however, the fundamental disadvantage is the

a corrosion protection on coatings with liquid metal, namely the insufficient adhesion of the

surfaces in contact with an iron coating on those with liquid metal in contact

Containing casting mold for the aluminum casting as well as an upcoming surface has not been fixed. It

Casting mold made of iron or ferrous material for 5, there is a risk that the coating on the mold

the cast aluminum. wall torn away by the inflowing metal

Aluminum tends to get along with others and thereby the protective effect is lost

To connect elements and different chemical or even the risk of adhesion of the coating to the

To enter into connections. Due to this property casting, so that after removal of the casting

of the aluminum it results that aluminum pieces from the casting mold parts of the casting mold wall

alloys that leave copper, silicon, magnesia, nickel, unprotected (German patent

Manganese and similar substances contain to better 543 044).

mechanical strength or other properties The invention is based on the object

to make casting or machining easier. Corrosion from contact with liquid metal

tern, do not have the desired properties, 15 coming surfaces of a ferrous casting mold

if the alloy is contaminated, to prevent the aluminum casting. About it

Mix. in addition, it aims to absorb impurities

In addition, the substances that are used must be prevented during the casting process. With the position of the container or other components that are part of the invention, the aim is to provide a casting of pure aluminum or aluminum corrosion protection that is easy to apply to alloys and to cast ingots from which the surfaces are Serve even in very molten material, be designed in such a way that complicated shapes can be brought into it.
The object is achieved according to the invention in that molten aluminum or its alloys are deposited on the casting mold surfaces at least to prevent corrosion of the elemental boron liquid metal that diffuses into them will. In this case, the vessels, casting molds or other components should preferably be excluded from excretion of the boron by melt-flow electrolysis. In order to prevent corrosion and the absorption of essentially borax at a temperature of more than 900 ^° C. for impurities in the molten metal. The casting mold to prevent, usually such substances 30 invention made of iron or ferrous material for lining the casting vessels, casting molds and the aluminum casting is characterized by the fact that other at least the casting mold surfaces that are used with the melt components that are used in the casting process are used come into stable contact with high temperatures, have a layer of 40 micron thick boron, quartz, magnesia, lime, etc., applied according to the above, for example heat-resistant Oxydverbin- process of the invention, or carbonaceous substances, like graphite. With the invention, the advantage is achieved that it is part of such linings that they are difficult to manufacture the life of the casting mold and that with liquid rig, are easy to damage and surfaces that come into contact with metal can be displaced. It is also known that it is considerably prolonged and that permanent corrosion is provided to improve productivity and strengthening protection. Impurities can no longer use the continuous casting process from the casting mold, die casting and chill casting from the casting mold into the melt. Im get. The corrosion protection by the action the application of this method of the invention makes use of the physico-chemibesondere transport devices for seeing meltable fact is utilized that borides used for the high-like liquid metal, complicated shapes include 45-melting metallic hard substances ^ own. It is very difficult or even impenetrable metal character and very feasible to have a surface coating on such hard and scale-proof. They only melt at high, "casting facilities or pipes, if the temperatures not reached in aluminum casting, conventional materials are used. Although the properties of borides as such are long

There are also various finishes and more than 50 known finishes and finishes for a long time trains known for casting molds for aluminum casting. are previously known for metallurgical molds that Such coatings for metallurgical casting molds made of borates, boric acid, borax and boron oxides besind to stand as coatings on the mold wall, the proposal of the invention is surprising, see which form a separate, separate layer. So far, borides have only been used for production Essential for the quality and suitability of the 55 high-performance cutting alloys for corrosion, in radiation protection The finishing used is the static drive technology, for the manufacture of turbine blades, ability of this layer on the mold wall. Nozzle heating conductors, etc. used, where although The adhesion is protected against corrosion by various additives, but not by the boride intended for the actual protective agent, and provided it against molten metals Attempts are constantly being made to reach this age of 60.

To improve adhesion. However, it is still within the scope of the production of the invention not successful, a casting mold for the corrosion protection is based on a size Permanent protection for those with liquid metal in base cast aluminum or the cast of aluminum alloy The next wall for the cast aluminum stanchions are provided with a thin layer of boron, to create, although various attempts have been made 65 The mold itself is made of iron or is iron, by adding boric acid, borates, borax and containing material, which without the boron oxides on it a better and more uniform adhesion of the divorced elemental boron with the molten one bring about the size on the mold wall. Aluminum or the aluminum alloy in

Claims (2)

3 4 tion would come. The depth of the corrosion was flattened at both times deposited elemental boron diffused measured specimens. The test piece with the at least partially into this and connects layer of boron corroded only to a depth with the simultaneous presence of iron the 0.1 mm after a period of 30 hours. The Casting mold with this to form a boride. 5 untreated test piece corroded up to For the deposition of the boron on the mold - a depth of 0.8 mm in about 5 hours, and the Surfaces can undergo various processes, the corrosion reaching a depth of 30 hours are known, can be used, for example 1.7 mm. using gaseous, solid or experiment II liquid media. When using liquid io Media can also be an electrolytic process. A test piece was also used in this test can be applied. Used for surface treatment in stainless steel, which the same The frame of the cast aluminum comes, for example, with the same dimensions as in the previous experiment wise crucibles, ladles, gutters, pipes, casting and which are coated in a similar way with boron molds and the like, which was made of ferrous 15. As a counterpart, a test part was made Material such as chrome stainless steel or FC20 cast iron (JIS-Japanese Industrial Standard) from 18-8 stainless steel are made. Used by the 20mm diameter and 30mm length. Invention is provided, these casting devices The cast iron has the following composition: or components as a whole, or at least the ττς pr.OQ Areas that come into contact with the melt, 20, -,, up to 3 50 to be coated with boron. _si "'^ _{90 to 24Q} As examples of the advantages that arise when applying- »j _n q '^ qu: _s o'gß tion of the method according to the invention result in ρ up to 0 20 ' may the following experimental results serve. At ς lj _s q '^ q test pieces were made of rust 25 ρ remainder ' free steel tested, some of which with a Layer of boron were provided. Both test pieces were in a lot of about 3 kg of aluminum immersed, its temperature Experiment 1 _{to 75} o _{c geha} i _{th WUR (e}.} From experience values is There were test pieces from SUS 27 B (JIS-Japa- 3 ° known that cast iron from ferrous metals niche industrial standard) with the dimensions 10 x 14 x 30 mm have the highest level of resistance to corrosion used. It is a rust in molten aluminum. The results free steel of the following composition: the experiment show, however, that the cast iron JIS SUS-27 search piece to a depth of about 2 mm C until 0 08 ^{35 an} immersion time of 20 hours was corroded, c; uj _s 1'qq whereas the test piece coated with boron j ^ kj _s 2'on made of stainless steel only to a depth of 0.1 mm ρ was corroded until 0.04. g uj _s o'o3 Since the period of time during which the meltedo £ _r 18 Oo 'to 20 00 ⁴ ° Aluminum or its alloy in direct contact jqj g'oQ kj _s ii'oo with the surfaces of the containers or other structural p _e £ _e ' _st ' parts come during the casting process, much shorter is than the period on which the test cases are based A test piece was placed in a molten salt bath that is the amount of impurities that are in the consisting of 90 parts by weight of borax and 10 pieces of 45 ingots or other castings, without any practical zirconia, at a temperature of critical importance. The useful life of the 950 ⁰ C immersed. There was an electrolysis of 2stün- casting molds or components that made a coating long duration at a current density of 0.5 A / cm ² boron is longer than usual, and each made, with the test piece as a cathode possible contamination of the aluminum or the worked. In this way, 50 alloy was prevented from being applied to the surface. of the test piece a fine layer of boron in view of the various processes that are involved applied about 40 microns thick. Then were suitable for applying the boron, for example by means of the test pieces, one with, the other without gaseous, solid or liquid media, can do that Boron layer, in a molten aluminum alloy most effective process due to the shape of the too AC 4 B (JIS-Japanese Industrial Standard) can be selected from about 55 coated articles. 2 kg weight submerged and at a temperature In addition, the addition of boron to aluminum is content. The aluminum alloy has to recommend the following at least or aluminum alloys, Composition: because this admixture is suitable for further improving the quality of the JIS AC 4 B casting. The addition of boron Cu 2.00 to 4.00 δο to aluminum and its alloys causes one Si 7.00 to 10.00 Refinement of the metallurgical structure. Mg up to 0.60 _ .., Zn up to 1.00 claims: Fe up to 1.20 1. Process for the production of a corrosion Mn up to 0.80 65 protection on contact with liquid metal Ni up to 0.50 surfaces of a ferrous casting Ti up to 0.20 form for aluminum casting, thereby Al remainder indicates that on the mold surfaces at least partially into this 3. Casting mold made of iron or ferrous diffusing elemental boron is deposited. Material for the cast aluminum, thus marked 2. The method according to claim 1, characterized in that at least the casting mold surfaces, indicates that the deposition of the boron comes into contact with the melt; Melt flow electrolysis of - essentially Borax 5 - a according to the method according to claim 1 Boron-containing layer with a thickness of more than 900 ^{° C. brought forward at a temperature} is taken. of 40 microns.