SU801963A1 - Coating for casting moulds and cores - Google Patents

Description

(54) COATING COLLECTION OF CASTING FORMS AND STEM

The invention relates to foundry production, namely, to compositions of self-hardening strengthening anti-burn coatings for drinking molds and sterols, and can be used both under single and mass production conditions for castings from ferrous and non-ferrous alloys. Coatings are known which contain organic compounds as a binder, for example, dextrin, molasses, sulfite-alcohol bard 1. These binders are cheap and non-refractory, but have low refractoriness. To increase the refractoriness of coatings, organoelement binders are used, for example silicone lacquers and hydrolyzate solutions of ethyl silicate 2. These binders reapply the coating. In terms of reducing the curing time of nl coatings, binders on volatile organic solvents are used, for example polyvinyl acetate, polyvinyl butyral t3. Their application increases fire risk, impairs working conditions, does not provide strength at elevated temperatures. Liquid glass reinforcement coatings are known, which are cured by coal gas blowing or heat treatment 4 J. These coatings are cheap and not deficient, provide high strength properties at elevated temperatures, but do not have expensive anti-adhesive properties. Promising are compositions containing phosphates of some X metals .5. The coatings obtained with the use of these binders have high nonstick and durable properties and properties, however, they require additional heat treatment or have low survivability. Strengthening coatings are known, including alkali metal salts as Hanj: iJCMep KNO and 1 a N oz LGj. Most of these coatings do not require heat treatment, but do not provide a significant increase in the surface strength of the mold, are deposited in a hot state, which worsens the labor conditions.

The closest to the invention to the technical essence and the achieved result is a coating comprising liquid glass, urea, caustic soda and water at a predetermined ratio of ingredients 7. The coating has good physical, mechanical and technological properties, however, heat is required for curing the coating. In order to self-harden the coating, it is necessary to additionally introduce calcium phosphate () in its composition, which increases the cost of the coating and worsens the working conditions.

The aim of the invention is to ensure self-curing of the coating on

First component

liquid glass (М2,7- j а, О У 1.40-1.52 g / cm

Prevocatellum caustic soda

Penetration depth of coating, mm

Time self-hardening coating, min

Flexural strength of the surface layer of the form, kg / cm:

after 1O minutes after coating

after heat treatment

at 35O (for I hour

Harei4H (burn and snakes

surfaces of molds and cores, improving sanitary and hygienic working conditions and reducing the cost of coating.

To achieve the goal

the coating for casting molds and rods, including liquid glass, caustic soda and carbamide, the bulk of the rod contains prevocella, sulfite liquor and ferrosilicon in the following ratio of ingredients, weight. %:

Prevocellos0,3-O, 5

Sulfite particles, 20, O-25, O Urea, O-25, O

Caustic soda 2, O-8.5

ferrosilicon10.0-30.0

Liquid glassH: thal

The compositions and properties of the coating according to the invention are given in table. I and 2. Table I

11.0

32.1 0.5

0.4. 8.5

5.0

Table 2

6.1

2.8

3-10

3-1О

4.7

3.2

47.2 Ao, 1 no

Claims (2)

A coating for it, including sodium and urea, characterized in that, in order to ensure self-hardening of the coating on the surface of the molds and cores, to improve sanitary and hygienic working conditions and to reduce the cost of the coating, it additionally contains precell, sulfite liquor and ferrosilicon with the following ratio of ingredients, wt.%: Prevocell Sulphite liquor Urea Caustic soda Ferrosilicon • Liquid glass molds liquid glass, Sources and Stingy 0.3-0.5 20.0-25.0 15.0-25.0 2.0-8.5 10.0-30.0 Else.