DD213369A1 - UEBERZUGSSTOFF - Google Patents

Abstract

The invention relates to a Ueberzugsstoff, which contains as a refractory filler a refractory mixture of titanium dioxide and quartz sand / quartz powder with or without a share of Glanzkohlenstofftraegern preferably graphite. Due to the TiO 2 content, the coating material according to the invention ensures an increase in the ability to slide and brush or compactness and thus also the packing density and the refractoriness of the applied coating material. At the same time, the structure and composition of the refractory filler used as a refractory filler greatly reduces the propensity of liquid metal alloys to undesirable chemical-physical reactions with the coated coating. The coating material is applicable for coating molds and cores, models, pigs, molds and the like. Manufacturing equipment in the foundry industry and in the metallurgical industry and allows the saving of high-quality refractory import raw materials such as zircon, graphite and others.

Description

coating material

Field of application of the invention

The invention relates to a coating material with special refractory fillers for use in the metallurgical and foundry industry for coating molds, tools, foundry models, pigs, molds u.a. Components of different material types.

The term coating material includes in this complexity, so z. As molding or core coatings, Modellaufgieß- or Anlegemassen, Feingußsuspension u.a. Use cases in the metallurgical and foundry industry.

Characteristic of the known technical solutions

Coating materials with refractory fillers are being used increasingly in the foundry and metallurgical industries. They contain solvents and binders, special auxiliaries and, as the most essential ingredient, refractory, fine-grained fillers, for example. 3. on (xbt based graphite and / or quartz powder.

The scope of application of the coating materials is directly dependent on the properties of the filler used and your specific thermal-mechanical load and application of the coating material.

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In particular, in the production of castings made of steel, the use of pure graphite or quartz powder coating materials as well as their combination is limited to a small field of application. As is known, this depends on the complex technological and chemical-physical properties of these coating materials on the one hand and those of the material to be coated on the other hand.

Due to its chemically acidic character and its physically high surface energy, which is imparted to the quartz grain as a result of the production or grinding process, quartz powder has a high reactivity with hot metals, in particular iron-carbon alloys (SU-PS 94813). Further alloying additions z. As manganese strengthen this effect and make the application of this cheap refractory impossible. (Gartazar, J.L. de, Fundicion Ur. 65, 1965) J

Graphite is used very often as a component of Uberzugsstoffen especially for the production of cast iron (DDR-PS 39108). The formation of radiant carbon creates a chemical atmosphere that prevents the reaction of the mold surface with the hot cast metal. However, in the manufacture of steel castings, the use of pure graphite overlay materials is limited for a variety of reasons. Especially for forms with high surface roughness ζ. B. in chemically curing free-flowing molding materials due to lower packing density than compression molding materials by graphite alone, the closure of the pores, i. the sizing of the mold is not possible, so that penetration phenomena make production impossible.

Another cause of the limited range of application of graphite-containing Uberzugsstoffen particular in steel casting, is their high gas count, which can lead to blistering in the casting.

The combination of quartz flour with graphite is also known. The DDR-PS 45261 describes a blackness on the basis of graphite, quartz powder and clay. The stated ratio of graphite to quartz powder is preferably 2: 1. However, this coating is only applicable to the production of cast iron, as conducted studies show that the combination of the refractory graphite and quartz powder does not cancel their Bach parts. In the production of castings made of steel, the high gas count of graphite limits the scope of application, since the simultaneous use of quartz powder, the pores of the mold are sealed, and thus the gas permeability of the mold surface can be reduced up to ten times.

Furthermore, the addition of graphite does not fundamentally suppress the reactivity of the quartz flour with the liquid steel. The production is also limited for this reason possible z. B. for thermally low loaded forms of compaction molding materials and unalloyed Gußmarken.

In the production of cast iron castings, the combination of quartz flour and graphite is not possible in any quantity relationship. Since the task of the graphite is to prevent the reaction of the molten cast iron with the quartz sand mold, the addition of powdered, surface active quartz particles to graphite blacks counteracts the solution to this problem. Depending on the fineness of the quartz meal and its surface-active state as well as the amount of lustrous carbon produced by graphite or other carbon carriers, the combination of graphite to quartz flour is possible up to a quantity range of 2: 1. If the proportion of quartz powder is further increased, sintering occurs in proportional effect and, in severe cases, sisional diffusion phenomena occur in the molding base material. An inverse ratio of graphite to quartz powder of 1: 2 to 1: 1.0 is currently not feasible.

- 4 Object of the invention

The aim of the invention is therefore to avoid these disadvantages.

Explanation of the essence of the invention

The invention has for its object to provide a coating material based on quartz powder alone or in conjunction with lustrous carbon, preferably graphite, which avoids the previous disadvantages and extends the field of application fundamentally by the mechanical properties of the coating such as the density and thickness, the lubricity and compaction ability of the coating material are increased and improved, and the chemical-physical refractory properties of the fillers are changed such that the reactivity of the refractory coating with the hot metal is considerably limited.

This object is achieved in that the coating material as a refractory filler with or without a share of lustrous carbon supports preferably graphite contains a refractory mixture of titanium dioxide and quartz sand or flour, which is characterized by a particular chemical composition and granulometric structure.

Coating materials with such a titanofield-containing filler are characterized by a number of new or improved properties and thus a considerably greater range of application. The defined addition of titanium dioxide ensures an increased packing density of the applied and solidified coating. On the one hand, this is due to the physically different densities of TiOp, SiO ₂ and graphite and, on the other hand, to the considerably improved covering, sliding and compaction capability as a result of the addition of TiCU. Furthermore, it has been found that coating materials with such

Filler in contrast to conventional quartz powder or quartz powder / graphite coating materials are characterized by an extremely low reactivity in the interface metal coating material and thus have improved Feuerfesteigensohaften.

Overall, it is possible with the application of the coating material according to the invention to increase application breadth and safety over conventional quartz powder or silica flour / graphite coating materials so that, for example, in the production of cast iron castings, the proportion of high-quality foundry graphite or other lustrous carbon carriers up to 95 % by a titandioxidhaltiges Quartz flour can be replaced. In the production of castings from cast steel, the use of such coating materials allows the complete or partial substitution of common in the steel casting sector refractories such as zirconium silicate or corundum.

embodiment

1st example

Sine conventional cast steel sizing exists'

70 % zirconium silicate

3 % rosin 27.% spirit (in % by mass )

The use of the high-quality zirconium silicate is required because conventional quartz flour does not ensure the casting quality of the castings produced by the free-flowing molding technology. With the application of the coating material according to the invention, the substitution of zirconium silicate succeeds:

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5 5δ titanium dioxide 50% quartz powder 3% rosin

42% alcohol (data in %)

2nd example

A conventional blackness for cast iron consists of:

50 % foundry graphite 5 % polyvinyl acetate 45 55 water

By applying a coating according to the invention in the composition:

5 % titanium dioxide 5 # foundry graphite 40 % quartz flour

3 % polyvinyl acetate

4% bentonite

43 % water

a considerable reduction of the graphite content is possible

3rd example

A suspension applicable to the casting of lead for coating the wax models or as a model casting compound has the composition:

70 % quartz flour 30 % ethyl silicate-ethanoi solution

In contrast, "the coating material according to the invention has the following composition:

5 % titanium dioxide 60 % quartz powder 35 % ethyl silicate-ethanol solution

The application of the coating material according to the invention enables improved casting quality and the casting of high-alloyed iron-carbon materials.

4th example

A conventional modeling material consists of β % water glass solution and 94 % corundum.

With a coating material according to the invention for the model coating in the composition:

3 % titanium dioxide 90% quartz sand / quartz powder 7 % water glass solution

The substitution of the high-quality corundum succeeds in a large number of assortments.

Claims (3)

- 8 claims 1 · Coating material consisting of refractory fillers with or without a proportion of lustrous carbon supports preferably graphite and from a binder solvent system preferably based on ethyl silicate or silicone resins, in particular in conjunction with a Aluminiumstearatträgerflüssigkeit characterized in that it contains a titanium dioxide-containing refractory mixture as a refractory filler Composition: 2.5 - 15 % titanium dioxide
97.5 - 80 % quartz sand / quartz flour
0 - 5 % residual components contains. 2. coating material according to item 1, characterized in that the proportion of the refractory mixture based on the total composition of the coating material is preferably 5-70 mass % . 3. coating material according to item 2, characterized in that the granulometric structure of the refractory mixture preferably in the distribution: 0 - 0.063 mm 70 %
0.063 - 0.08 mm 20%
0.08 - 0.1 mm 10 % is present.