SU1044407A1 - Parting coat for casting moulds and cores - Google Patents

Abstract

ANTI-DRIVE COATING FOR CASTING FORMS AND RODS, used mainly in the manufacture of large cast iron castings with a wall thickness of more than 150 mm including cryptocrystalline graphite, sulphite-yeast brew, bentonite and water, characterized in that, in order to improve the cleanliness of the surface of large clots, bentonite and water, characterized in that, in order to improve the cleanliness of the surface of large clonds, bentonite and water, characterized in that, in order to improve the cleanliness of the surface of large clonds, bentonite and water, characterized in that, in order to improve the cleanliness of the surface of large clonds, bentonite and water, characterized in that, in order to improve the cleanliness of the surface of large clots, bentonite and water, characterized in that, in order to improve the cleanliness of the surface of large clots, bentonite and water, characterized in that, in order to improve the cleanness of large clogs, bentonite and bentonite and bentonite are more than 150 mm. Due to the increased resistance of the nonstick coating to abrasion and the strength of its adhesion to the form, it additionally contains shungite powder with a content of 25-35 k1 cc.% of carbon with the following ratio ingredients, wt.%: Shung powder with 25–35 wt.% (L C 31–37 carbon Cryptocrystalline graphite 31–37 Sulphite cod 5–7 brew 2-3 Bentonite Water Else 4 O-si

Description

The invention relates to foundry, in particular, to the compositions of nonstick coatings for casting molds and cores used mainly in the manufacture of 1pc pig iron castings with a wall thickness of more than 150 m Known nonstick coating l of the following composition, wt.% Schungite powder containing 60- 72% of natural pi; carbon carbon 48-58 Ben.tonit3-45 Sulfite drozhjeva. However, the composition of the indicated, seemingly, includes a high-carbon shunit, which is currently in deficient materials, and the coating does not provide the required surface quality of large cast iron castings. Coating 2 is also known, which is May. % :. Coke powder Schungite powder. 38-40. Clay -. , 3 Water up to a density of 1270-1300 kg / m. The specified coating has a low strength after drying, which leads to the formation of a burn on the surface of large cast iron castings. The closest to the technical essence and the achieved result to the proposed is an anti-stick coating, containing May. % Latent graphite 58, 6-60 Sulfite yeast brew 4.5.5-6 Bentonite2.5 Water .33 The indicated coating is characterized by insufficient abrasion resistance and low adhesion to form, which leads to the formation of burns on large castings and an increase in roughness their surfaces, especially when the wall thickness of castings is more than 150 mm. The purpose of the invention is to improve the cleanliness of the surface of large cast iron castings by increasing the strength of the nonstick coating to abrasion and the strength of its adhesion to the mold. This goal is achieved by the fact that the nonstick coating for casting molds and cores used mainly in the manufacture of large cast iron castings with a wall thickness of more than 150 mm, including cryptocrystalline graphite, sulphite yeast mop, bentonite and water, additionally contains Schungite powder containing 25- 35 wt.%, Carbon in the following ratio of ingredients, wt.%: Schungite powder, with a content of 25 35 wt.% Carbon (.31-37 Crystalline graphite 31-37 Sulfite-yeast mash5-7 Bentonite 2-3 Water Else Shungite powder containing 25-35% of carbon is cheap and not deficient in materials, unlike shungite containing 60-72% of carbon, which is more expedient to use in coating compositions that serve to obtain small and medium iron castings with a wall thickness of up to 100 mm. Schungite powder used in conjunction with cryptocrystalline graphite as part of the proposed coating has the following chemical composition, wt.% (Table 1). When exposed to high temperatures. Shungite carbon (shungite substance), which is poured into the cast iron form, interacts with amorphous (cryptocrystalline) graphite, thus forming a spatial carbon structure that includes aluminosilicate schungite compounds. The resulting neoplasms have a very high thermochemical resistance and, in addition, have an affinity for the surface of the mold material, which provides increased strength of the nonstick layer. A similar effect is not observed when the schungite substance interacts with ground coke. When the content of shungite in the coating is less than 31 wt.%, The surface roughness of the castings increases, and with a content of more than 37 wt.%, The effect does not increase further. The proposed coating is most appropriately used to obtain a large iron casting, i.e. in the case when large volumes of metal intensively affect the surface layer of the form.

which requires a high mechanical strength and fire resistance from the nonstick coating.

The presence of hydrophobic cryptocrystalline graphite in the proposed coating increases its sedimentation stability.

The sulphite-yeast brew helps to reduce the viscosity of the coating, which ensures its finest covering ability. The interaction of sulphite-yeast brew with shungite powder, having a highly developed surface, also contributes to an increase in the strength of the nonstick coating. For the preparation of the coating, sulphite-yeast grating is used with a density of 1250-1300 kg / m.

The compositions and properties of the coating according to the invention (No. 1 - 3) and the prototype (No. 4) are given in Table. 2 and 3.

The nonstick coating is prepared in the following way.

Water and a sulphite-yeast mash are poured into the mixer, mixed for 3-5 minutes, after which bentonite, graphite and shungite are loaded and the mixing process continues until a homogeneous pasty mass is obtained. In order to prepare the coating suspension, the paste is mixed with water while the moisture content is 1350-1600 kg / m.

The coating applied with a perch or a brush on the surface of a mold or rod is dried at 250–270 ° C for 40–60 min.

The proposed coating has a high strength of the applied layer to abrasion and fire resistance, increased sedimentation stability and good kroni ability. Large cast iron castings produced using this coating have a high-quality non-stick surface.

The use of the proposed coating will increase the strength of the nonstick coating and its adhesion to the surface, which will provide an improvement in the surface quality of large cast iron castings with a wall thickness of more than 150 mm.

T a in l and c a 1

62.90

4.16

2.39 - 0.75

0.24

Shungite powder (2535 wt.% Carbon)

Cryptocrystalline graphite

Sulfite yeast brew

Bentonite

Water

0.20 1.4727.6

0.33

Table

34

37

34 6 2.5

37 7 3

60

6

2.5

23.5

16 31.5

Abrasion resistance, kg / mm

12

Adhesion strength of the layer with the form, MPa

Surface roughness

80 castings, micron

Table 3

14

17

0.09

0.05

0,017 0,016-0,02

85

90

130-160

Claims (1)

NON-COATING COATING FOR CASTING FORMS AND BARS, used mainly in the manufacture of large cast iron castings with a wall thickness of more than 150 mm, including cryptocrystalline graphite, sulphite-yeast mash, bentonite and water, characterized in that in order to improve the cleanliness of the surface of large cast iron castings by increasing the strength of the non-stick coating to abrasion and the strength of its adhesion to the mold, it additionally contains shungite powder with a content of 25-35 wt.% carbon in the following and ingredients, wt.%: < Shungite powder with a content of 25-35 wt.% Carbon Cryptocrystalline graphite Sulphite yeast mash Bentonite Water 31-37 31-37 "4 · *" • m