SU1076179A1 - Nonstick coating for moulds and cores - Google Patents

Description

The invention relates to the foundry industry, in particular to the compositions of nonstick coatings for molds and cores used in the manufacture of castings from ferrous and non-ferrous alloys.

A nonstick coating for casting molds and cores is known, including a refractory filler, a clay slurry, water glass, an emulsol, a surfactant, a sulphite yeast mash and water 1.

This coating has a low resistance to abrasion and increased activity when interacting with the liquid metal due to the presence of sodium silicates in the paint. In addition, the use of DS-RLS as a surface-active substance increases the porosity of the coating that

contributes to the formation of burns on castings.

The closest to the proposed technical essence and the achieved result is a non-stick coating for casting molds and cores, including May.%: Bentonite (clay binder) 1.5-2

Substrate lye

(surface.

active substance 3-4 sulphite bard 3-4 water-soluble sour tar by-product of purification of raw benzene from coke production) 3-10 water 10-13 distansillimanite Remaining 2 However, the known coating has insufficient abrasion resistance and covering ability. The potassium and sodium salts included in the sublum-alkali increase the activity of the coating with respect to the liquid metal. Complex nomplex chemical compounds under the action of high temperatures dissociate into CaCO, and then decompose into oxides, which promotes the formation of burns on castings. In addition, this coating contains harmful substances: toluene, xylene.

The purpose of the invention is to increase the coating ability and abrasion resistance of the coating, to improve the cleanliness of the surface of castings and sanitary-hygienic working conditions.

The goal is achieved by the fact that a nonstick coating for casting molds and cores used in the manufacture of castings from ferrous and nonferrous alloys, including a clay-based binder, a sulfite-yeast masonry surfactant, a crude benzene coke-chemical product purification product, water and Distensillimanite, contains an aqueous solution of the sodium salt of sulfate ester; ethylhexanol sulfirol-8 as a surfactant, and as a product of purification of crude benzene by-product coking zvodstva coating comprises intermediate purification of crude benzene production when kokhimicheskogo sledushchem ratio of ingredients, wt. Clay-based binder. 3-4

Sulfirol-8 0.0-2-0.7 Sulphite-yeast mash3-4 Intermediate product of purification of crude benzene from coke-chemical production2-4 Water 25-39 Dystensillimanite Else In this intermediate product of purification of crude benzene of coke-chemical production contains the following components, wt%: Polymers 1-10 Sulfuric acid 40-55 Benzene carbons 3-15 Sulfonic acids of aromatic hydrocarbons 21-30 Water. The rest and has a pH of 0.01-1 density of 1.45-1.5 g / cm.

The intermediate product of the purification of crude benzene of the coke-chemical production differs significantly in its composition and properties from the water-soluble acidic resin used in the prototype coating, which contains wt.%; polymers 10-20; sulfuric acid 16-19; benzene hydrocarbons 23-36, Sulfonic acids of aromatic hydrocarbons 18-20 and water the rest, its pH is 1.5-2, density 1.15-1.30 g / cm

Compared with the water-soluble acidic tar, the content of ballast polymers in the intermediate product for the purification of crude benzene is 2 times lower. The content of sulfuric acid is increased by 2.5 times, which leads to the complete neutralization of impurities, iron oxides, which are part of the refractory filler of nonstick coating, and thus, to reduce the burn on the surface of the castings.

Benzene hydrocarbons (benzene, toluene, xylene) are harmful and toxic reducing components that worsen the sanitary and hygienic working conditions in foundries. The use of an intermediate product for the purification of raw benzene leads to a 6-fold reduction in the toxic emissions by a smaller amount of the product introduced into the coating and a lower content of these substances. In addition, only benzene is present in the intermediate product for the purification of crude benzene from benzene hydrocarbons, while toluene and xylene are present together with benzene in the water-soluble acidic tar. An increase in the content of sulfonic acids by a factor of 1.5 leads to an increase in the number of hydrophilic groups, an improvement in wettability, and an increase in the depth of penetration of the coating into the pores of the mixture. Of all known anionic type of foaming agents of the main groups: sodium salts of carboxylic acids (including synthetic fatty acids), alkyl sulfates, alkyl sulfonates, alkyl benzene sulfonates, alkyl naphthalene sulfonates, the most suitable for use in anti-burn coatings according to the invention turned out to be sulfuryrole-sulphirol-8. It is an aqueous solution of ethylhexanol sodium sulfate ester-2. It is the most homogeneous foaming agent is an aqueous solution of ethylhexanol sodium sulfate ester-2 sodium salt, which gives a fine foam. with its slight stability. In contrast to DS-PA foaming agents, Petrov’s contact, mylonaph, Progress detergent, and others. Sulfur reduces the surface tension of the solutions (liquid glass, water) most intensively, contributing to a deeper penetration of the nonstick coating into the surface layers of the core or rod, significantly improves strength properties of nonstick coatings (resistance to abrasion and adhesion to the mold material). Sulfirol-8 GOST-77, whose chemical formula is Cgtt -, has eight carbon atoms in the hydrocarbon radical, as well as the side group CH, which reduces the hydrophobicity of the hydrocarbon radical, and, thus, the stability of the foam. It has an alkaline reaction (jpH 9-11 units of sulfirol-8 partially interacts with the sulfonic acids of the crude benzene purification intermediate and forms sulfo groups, increasing the number of hydrophilic groups in the nonstick coating and further reducing the surface tension and reducing the stability of the foam. The components of the intermediate product purification of crude benzene have an identical molecular structure (an aromatic hydrocarbon ring with aliphatic side chains), but in the alkyl radical there are slightly fewer atoms Carbon monoxide (about 3-4 and lower molecular weight. During heat treatment of the nonstick coating (220280 ° C), polymerization of sulphirol-8 with an intermediate product for purifying raw benzene forms a hard spatial framework of the neoplasm around the grains, which significantly increases the strength properties of the nonstick coating When pouring liquid metal from spatial carbon-carbon hydrogen bonds and carbon carbon in the alkyl radical, film carbon formations occur. Deposited on the filler grains, thereby reducing the likelihood of metal oxides interacting with the nonstick coating and mold fillers. The combination of sulphirol-8 and the raw product for purification of raw benzene allows to increase the penetration depth and abrasion resistance of the nonstick coating, to improve the surface finish of the steel castings. As a refractory filler, in addition to dystanselymonite, zircon, marshalite and other refractory materials can also be used. With the introduction of sulfirol-8 to less than 0.02 wt.% And an intermediate product for the purification of raw benzene less than 2 wt.%, The sedimentation stability decreases, the coating capacity deteriorates and the coating strength decreases, and the surface quality of the castings deteriorates. With the introduction of these components in quantities exceeding their upper limits, the foaming of the coating increases, which leads to a decrease in its strength and a deterioration in the cleanliness of the surface of the castings. The compositions and properties of the coating according to the invention (1-3) and prototype (4) are shown in Table 1-2. The preparation of the non-stick coating is carried out in the paint machine by any known method. The application of the coating on the surface of the orms and rods is carried out by conventional methods (spray gun, brush, etc.) depending on the density of the prepared surf, it is used for fine casting (1.48-1.59 g / cm, medium (1.6 -1.69 g / cm) and large D, 7-1.8 g / cm).

The implementation of the invention will improve the covering ability and abrasion resistance of the coating, which will provide an improvement in the cleanliness of the surface of castings from black and colored

alloys, reduction of cast iron castings, reduction in the cost of 1 ton of casting on average by 0.42 rubles, and also will allow to improve the sanitary and hygienic working conditions.

Table 1

Clay

Bentonite

Sulfirol-8

Sul phy no yeast and mash

Intermediate product of purification of raw benzene coke-chemical production

Water

Underground Lye

Water soluble sour tar

Distensillimanite

4.0

3.5

2.0

0.7

0.1

3.5

4.0

3.5

4.0

3.0

13.0 39.0 32.0 3.5

 7.0 71.0

48.3

57.9

.

table 2

Claims (3)

1. NON-COATING COATING FOR CASTING FORMS AND BARS used in the production of castings from ferrous and non-ferrous alloys, including clay binder, surfactant, yeast sulphite, product for the purification of crude benzene by-product coke, water and distensillimanite, characterized in that that, with the aim of increasing the hiding power and abrasion resistance of the coating, improving the surface cleanliness of castings and sanitary conditions, it contains as a surface-active substance aqueous solution of the sodium salt of sulfate ester of 2-ethylhexanol sulfirol - 8, and as a purification product crude benzene coke production it comprises intermediate purification of crude benzene coke production with the following ratio of ingredients, wt.%: Clay based binder Sulfirol-8 Sulfite-yeast mash Intermediate product for the purification of crude benzene by-product coke production Water 3-4 9.02-0.7 3-4 2-4 25-39 Distensillimanite Else 2. Non-stick coating according to claim 1, characterized in that the intermediate product for the purification of crude benzene by-product coke production contains ponents, wt.%: Polymers Sulfuric acid Benzene hydrocarbons Sulfonic acids of aromatic hydrocarbons Water following com 1-10 40-55 3-15 21-30 Else 3. Non-stick coating according to claims 1 and 2, characterized in that the intermediate product for the purification of crude benzene by-product coke production has a pH of 0.01 and a density of 1.45-1.5 g / cm? SU -... 1076179. A forms