SU607638A1 - Sand for making ceramic moulds - Google Patents

Description

(54) MIXTURE FOR THE MANUFACTURE OF CASTING FOUNDRY

FORMS

This is achieved by the fact that the mixture contains ferrochromium so as a binder and, as a boron additive, boric acid in the following ratio of ingredients, w / v:

Ethyl silicate4 - and

Water 2--15

Sol Na Acid

(unit weight. I, 9 g / cm) 0,2--0,4

Ferrochrome slag1-3.5

Borna acid 0,2-1,5

Fireproof fillerEverything.

The use of ferrochromic slag in the composition of the starting components allows the ceramic mass to be cured without the use of solutions of mineral or optic hardeners, which allows for improved working conditions.

In the process of drying to calcining forms, metal oxides, which are part of ferrochromic slag, interact with boric acid to form refractory borates, which have binding properties that increase the strength properties of the forms in both cold and hot conditions.

The table shows examples of mixtures, their physico-mechanical and technological properties.

The mixture is prepared as follows.

Ethyl silicate binder is obtained by hydrolyzing ethyl silicate with water in the presence of hydrochloric acid by vigorous stirring. As a result of hydrolysis, binders with a conditional silicon oxide content of 30-327o are obtained. These binders are diluted with water to 8-107s. conditional silica content.

The solid phase, including a refractory filler, boric acid, ferrochromic slag, premixed, is introduced into the binder and, after averaging, the ceramic mass is cast into molds.

The curing of the ceramic mass proceeds within 7–15 min, depending on the content of ferrochromic slag and boric acid in the composition of the initial components.

The forms are dried for two hours at a temperature of 190 ± 10 ° C.

The forms are calcined at 900 ° C for 6 hours.

During calcination, boric acid, interacting with metal oxides, which are part of ferrochromic slag, forms refractory borates with bonding properties that contribute to the improvement of cold and cold properties.

As an example, the table shows some compositions of the ceramic mass and the strength properties of the forms obtained on their base.

As can be seen from the table, the optimal composition is composition No. 4, since a further increase in the content of ferrochromic acid to boric acid leads to an insignificant increase in the strength properties of the forms, and a decrease in their number leads to a decrease in the strength characteristics.

An increase in the strength properties of the forms in the hot state ensures the joint use of ferrochromic slag and boric 5 acid in the composition of the initial components, while each of them, separately, does not give the desired effect (see compositions No. 1.5, 9).

Molds made on the basis of the proposed composition make it possible to obtain castings with a degree of higher dimensional accuracy and without burns.

The expected economic effect when using the proposed composition under the conditions of the Kuibyshev Steel Plant is 150-180 thousand rubles. at the expense of reducing the length of ethyl silicate by 50% bo / o and reducing the rejects of forms by 3-4% compared with the existing process.

In the manufacture of castings of a simple configuration of carbon steel, the molds withstand 5-7 castings without reducing the dimensional accuracy of the reflux.

Claims (1)

Invention Formula Mixture for the manufacture of casting ceramic forms according to permanent models, including refractory filler, ethyl silicate, hydrochloric acid, boron additive, water, hardener, characterized in that, in order to increase the strength of the forms in the hot and cold state, to improve the quality surface castings as a hardener contains ferrochromic slag, and as a boron-containing additive, boric acid in the following ratio of ingredients, w / v:. Ethyl silicate4-I Water12-15 Sol on acid 0,2 ° -1,2 Slag ferrochrome 1-3,5 Borna acid 0,2-1-1,5 Fireproof fillerEverything.