SU761110A1 - Suspension for producing casting ceramic moulds - Google Patents

Description

The invention relates to foundry, in particular to investment casting.

Known suspension for the manufacture of molds by the method of investment casting [5]. Such a suspension provides for an increase in the strength of ceramics and the possibility of its use immediately after its preparation. The tattoo that is closest to the technical essence and the result achieved is a suspension for the manufacture of ceramic molds obtained by investment casting, which contains a refractory filler, ethyl silicate, ethyl alcohol, inorganic acid, water and 15 cryolite {2].

The use of this suspension requires a long process of calcination, due to the fact that during the melting of the model composition from the cavity of 20 ceramic forms, it partially remains in the pores of the forms. The presence of residues of the model composition is unacceptable, as it leads to the formation of casting castings associated with gas emission and boiling. 25

To remove residual model composition, calcination is used at high

temperatures (900–1000 ° С) for

4-6 hours

The aim of the invention is to reduce 30

temperature and duration of calcining the molds and improving the quality of casting.

To achieve this goal, the suspension additionally contains bertolet salt, fluoroflogopite in the following ratio of ingredients (weight. -%):

Ethyl silicate 11-13

Alcohol 14-16

Inorganic acid 0.6-1.5

Water 1-2

Cryolite 0,2-2,4

Fluoroflogopit 0.01-1.4

Bertolet salt 0.01—0.3

Refractory filler Rest

This composition suspension is used to

1st layer of ceramic form. Bertolet salt in suspension has the function of an oxidizing agent, fluoroflogopite is fused, crystalline mica.

When heated to the temperature of smelting with any of these elements does not occur. When calcining, the oxidizer decomposes: KC103 = 3 [O] + KC1 At the temperature that occurs when the mold is poured, fluoroflogopite decomposes with release of active gas.

The presence in the surface layer of atomic oxygen contributes to intensive

3

the process of combustion of residues of the model composition.

Consequently, instead of the evaporation process of the model composition, the combustion process of the model composition is realized. Considering that the combustion process is much more intensive and at a lower temperature than the evaporation process, the calcining time and the calcination temperature are significantly reduced.

Bertolet salt (CCS ₃ ) was chosen as the oxidizer, based on the following: the melting and decomposition temperature of CCU ₃ —300 ° C, i.e., at the melting temperature, the oxidizer does not decompose and decomposes at the calcination temperature; the decomposition of this oxidizing agent does not form stable non-metallic compounds that clog up the metal and reduce the properties of castings.

With the introduction of the oxidizing agent in the suspension in an amount of less than 0.01%, the effect is practically not noted, since the amount of released oxygen is clearly not enough for the combustion of residues of the model composition.

With an increase in the amount of oxidant over 0.3 weight. % marked complete combustion of residues of the model composition. However, an excess amount of oxygen leads to an increase in the depth of the decarburized layer of castings due to the excess oxygen released during the decomposition of the oxidant and remaining in the volume of the crust and cavity forms. In addition, with an increase in the oxidizing agent over 0.8%, there is a decrease in the strength of the peel.

Fluoroflogopita introduction due

76111Y

as follows: the distribution of the oxidant in the suspension is uniform, and the distribution of residues of the model composition is uneven. By virtue of this, in some volumes an excess of oxygen is formed, contributing to the decarburization of the metal.

To eliminate the possibly harmful effects of excess oxygen, fluoroflogopite is introduced in certain areas, which, when heated, during the pouring process decomposes with the release of fluorine, which blocks atomic oxygen. With a quantitative content of fluorophlogopite of less than 0.01%, practically no effect of eliminating the decouple5 gave birth. With an increase in the amount of input over 1.6%, a deterioration in the surface of the casting due to excessive gas evolution is noted.

The optimal technological process for preparing the suspension is as follows. The oxidant KSYu _{3 is} dissolved in water. Then water with solvent is added during the preparation of the suspension to cover the 1st layer of the peel. Fluorofloid5 pit fractions of not more than 0.5 mm are added directly to the suspension. The application of the remaining 3-4 layers of the crust is carried out by serial technology. After removal of the model composition in hot water and drying 0, the crusts molded in the filler were heated. The temperature of calcination decreased from 950 ° C to 700 ° C, and the time of calcination decreased to 90–110 minutes. instead of 420 min. Corky poured steel 50L for

5 manufacturing special products.

Suspension was tested in the manufacture of ceramic forms. The data of these studies are shown in Table. 1 and 2.

Table I

Ingredients Control suspension (prototype) The compositions of suspensions in weight. % № 1 № 2 Number 3 № 4 № 5 № 6 № 7 № 8 Number 9 Number 10 Fireproof filler (magnesite) 69.9 66,99 69,89 66.6 69.9 67.5 66.5 99.9 99.4 98.6 98.5 Ethyl silicate eleven 12 AND 12 12 13 12 - - - - Alcohol 15 14 15 15 sixteen 15 ¹⁵ - - - - Inorganic acid 0.6 0.6 0.6 1.5 0.6 0.6 0.6 - - - - Water 2 2 2 2 one 2 2 - - - - Cryolite 1.5 2.4 1.5 1.5 0.2 1.5 1.5 - - - - KSYu ₃ - 0,008 0.01 1.4 0.3 0.35 0.3 - - - - Fluoroflogopit - - - - - 0.01 0.1 0.6 1.4 1.5

The introduction of fluoroflogopite in an amount of 0.01–04 contributes to reducing the carburization depth to 0.1 mm.

As follows from the table. 1 and 2, the introduction into the suspension of bertolet salt, which is obvious, was found to introduce 40

the oxidizer KS1O ₃ in an amount of 0.01—

0.3% helps reduce temperature

calcining up to 700–760 ° C, and the time of calcination up to (1.5–1.8) - (2.3–3.5 g).

table 2

761110

five

No suspensions Physico-mechanical and technological properties of molds and castings Gas mist after calcination, cm ³ / m ² Peel strength 700 °, kg / cm ² Depth of bezugl. layer, mm Temperature calcining Duration calcining hour Quality surface forms one 0.28 27— 3.0 28-30 0.1-0.3 0.1 920—940 ° 880-900 6 6 porous 2 0.25 28-, 30 0.1 720-760 2.3-3.5 _I 3 0.48 27–31 0.1-0.2 700-750 2.0-2.5 four 0.89 27—30 0.1-0.2 700 1.5-1.8 I five 1.25 24—26 0.3-0.7 700 1.5-1.8 6 1.44 26-28 0.3—0.65 700 1.5-1.8 about G ⁷ 1.68 26-28 0.1-0.3 700 1.5-1.8 ί 8 1.76 26-28 0.1-0.2 700 1.5-1.8 ί ⁹ 2.78 26–27 0.1 700 1.5-1.8 But 3.44 22-24 0.1 700 1.8-1.8 •

It becomes an oxidizing agent of oxygen, helps reduce calcining to 700–760 ° C, and the holding time during calcination is up to 1.5—

3.5 hours

The introduction of fluoroflogopite reduces the carburization depth to 0.1 mm.

Claims (1)

Claim Suspension for the manufacture of foundry ceramic molds, obtained by investment casting, including refractory filler, ethyl silicate, alcohol, water, inorganic acid, cryolite, which differs from contains bertolet salt and fluoroflogopite with the following ratio of ingredients, weight. %: Ethyl silicate 11-13 Alcohol 14.0—16.0 5 Inorganic acid 0.6-1.5 Water 1.0-2.0 Cryolite 0.2-2.4 Fluoroflogopit 0.01-1.4 Bertolet salt 0.01—0.3 Yu Refractory filler Else