SU1380845A1 - Mould coating composition - Google Patents

Abstract

FIELD OF THE INVENTION The invention relates to a foundry, in particular, to the manufacture of forms of non-film vacuum forming. The purpose of the invention is to reduce the air permeability and adhesion of the coating to the model equipment. The coating composition contains, wt%: pyrophyllite 18-22; crystal graphite silvery 18-22; nitrocellulose film-forming varnish based on organic solvent 4-8; acetone - the rest. Due to this composition of the coating, which is characterized by low values of air permeability and adhesion to the model equipment with a low binder content and reduced gas-making ability, it becomes possible to obtain castings with a high-quality surface layer. 2 tab. (L

Description

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FIELD OF THE INVENTION The invention relates to a foundry, in particular, to the manufacture of forms of non-film vacuum forming.

The purpose of the invention is to reduce the air permeability and adhesion of the coating to the model equipment.

In the composition to obtain a coating

a dimensional film that is shaped according to the model and is constantly used.

The compositions and properties of the proposed coating are shown in Tables 1 and 2, respectively.

Compounds 2, 3, 4 have an optimal composition and are characterized by low air permeability and low air permeability.

as filler, use of a supply unit for model equipment, good-quality materials: pyrophyllite (PCT USSR 1343 70); crystalline silver graphite (GOST 5279-74). Pyrophyllite - aluminum silicate

neck heat resistance. Due to the low binder content and lower gas-creating ability, these coating compositions provide castings

The use of the invention allows to dramatically improve the air permeability of the coating to the model equipment and improve its heat resistance, floor

Alj (OH) /, density 2850kg / m, 15 with a qualitative surface layer. melting point 1820 C. The crystalline silver graphite (GOST 5279-74) has a density of 1.9-2.3 g / cm, humidity (percent by weight), not

more than 2. As a refractory coating, castings with a clean siding surface are used: nitrolak-1111-218 (GOST 4676-63); viscosity 60-95 s, heat resistance of a varnish film 70 С; drying time at t 18–20 ° C - 30–40 min; durability 1.5 rubles. for 1 kg; 25 drying time when diluted with acetone 1-3 minutes. Nitrolac is elastic, moisture resistant, characterized by good solubility. Nitrolac is applied without burning and also reduces the consumption of polymer films, since it is used continuously on the model as a separating layer.

Claims (1)

Invention Formula The composition of the coating for foundry forms obtained by the method of vacuum forms with a thin layer on the surface, which includes a fire-resistant, highly resistant, gas- and moisture-proof monolithic solid, elastic film. The film has a mesh structure, infusible and insoluble. Film formation is accompanied by a gradual increase in viscosity due to the volatility of the solvent. NTS-218 nitrolac is used as a binder (nitrocellulose film-forming lacquer based on organic solvent; whom solvent). Acetone (GOST 2768-69) is used as a fast-drying organic solvent. Coating technology. Prepare a mixture of pyrophyllite and graphite 45 of crystalline silver, shut with nitrolac to a paste, then add acetone and mix for 1-2 minutes until a homogeneous suspension with a density of 1.17 50 1.20 g / cm is obtained. The coating is applied with a brush. Hardening time under the action of a jet of air 15-20. As a separating layer, poly- neck heat resistance. Due to the low binder content and reduced gas-making ability, these coating compositions provide castings with high-quality surface layer. The use of the invention makes it possible to dramatically increase the air permeability of the coating to the model tooling and improve its heat resistance, with a semi-qualitative surface layer. clean surface castings clean surface castings without burns, and also to reduce the consumption of polymer films, since they are used continuously on the model as a separating layer. Invention Formula The coating composition for casting molds, obtained by the method of vacuum molds To achieve this, in order to reduce the air permeability and adhesion of the coating to the model equipment, the composition contains pyrophyllite and crystalline silver graphite as a refractory filler, and a nitrocellulose film-forming varnish as a binder for a mass ratio of masses. %: Pyrophyllite Crystal graphite silver Nitrocellulose film-forming varnish based on organic solvent Acetone The content of ingredients, wt.%, Ingredients in the compositions :: ii: ri: izii ::; Pyrofillite17 18 20 22 23 Crystalline graphite silver17 18 20 22 23 Nitrolak NTs-2183,5 4 68 8.5 Nitro-enamel - Acetone 62.5 60 54 50 46.5 table 2 Composition Indicators1111 .-. 1 ± .1-1.1Д-еПосность suspension, kg / m Viscosity (src.), P. tensile strength, MPa Breathability, ml / min Gas permeability Gas ability, cm / g Coating adhesion to equipment, MPa Fracture after heating to 383 K Characteristic of casting surface VNIIPI Order 1142/12 Random polygons pr-tie, Uzhgorod, st. Project, 4 Table I 1270129013101320 1416 1819 0,220,250,250,27 70747981 789 10 4.34.85.35.6 0,0080,010,0120,014 No cracks In separate Defects, Gas wounds are observed Circulation 740 Subscription