SU1261739A1 - Sand for making moulds and cores in co@ process - Google Patents

Abstract

The invention relates to foundry and can be used to make molds and cores from carbon dioxide-curable liquid-glass mixtures. The purpose of the invention is to increase and stabilize the strength of the mixture, reduce its crumbling and improve the knockout, which is achieved by introducing a complex phosphate additive containing 12–20% solution of an aluminum-chromophosphate binder in caustic soda with a density of 1.25–1.30 g / cm and ferrochromic slag. The mixture includes, by weight, "%: liquid glass 2,, 5; caustic soda 0.6-0.8; 12–20% solution of alum-chromophosphate binder in caustic i (L soda (in terms of aluminum-chromophosphate) 0.072–0.16; ferrochrome slag 0.3–0.5; refractory filler the rest. Table 2.

Description

I The invention relates to a foundry and can be used to make molds and cores from carbon dioxide-curable liquid-glass mixtures. The purpose of the invention is to increase and stabilize the strength of the mixture, reduce its crushability and improve dislodgement. The mixture according to the invention contains a refractory filler, liquid glass, caustic soda, aluminum-chromophosphate binder and ferrochromic slag. As a refractory filler, quartz sand, granular distensillimanite, Alkali, rutile, etc. can be used. The general requirements for limiting the clay component are imposed on the refractory filler used. A sodium liquid glass with a modulus of 2.8-2.9, a density of 1.42-1.48 g / cm, a technical caustic soda with a density of 1.25-1.30 g / cm, an aluminum-chromophosphate binder produced by the Aktyubinsk plant of chromium compounds, self-dissolving ferrochromic is used electrical slag production. The order of preparation of the mixture and the input of the ingredients is elicited. A 12–20% -tn rii solution of an alumina chromophosphate binder 39Z in caustic soda with a density of 1.25–1.2 g / cm is prepared in advance, 1/2 of its part is introduced onto quartz sand simultaneously with ferrochromic sclams and mixed 1.0 - 1.5 min, and then injected liquid glass, modified with 1/2 of a solution of an aluminum-chromophosphate binder in caustic soda, and stirred for another 0.5-1.0 min, after which the mixture was poured into core boxes and sealed manually. Liquid glass is modified as follows; A specified amount of the alumina-chromophosphate binder solution in caustic soda is injected into water glass and mixed for 30-40 seconds. The prepared binder is stable during long-term storage, does not stratify, does not precipitate, and does not alter the binding properties. The prepared molding sand samples are flushed with carbon dioxide for 10-15 seconds and tested for compression immediately after blowing COj, after 1 hour, 3 hours, 24 hours of hardening. At the same time, other technological properties of the mixture are controlled: vitality, crumbling, residual strength after calcining the samples for an hour at 400, 600, 800 and. The compositions of the proposed and known mixtures are given in Table 1, their technological properties in TaOl, 2. j. Table,

Liquid glass

Alumochromophosphate binder

Sodium hydroxide

Ferrochrome putty

Sodium tripolyphosphate 5% salt on sour quartz sand

2.8

4.0

3.5

Ost,

Ost,

Ost,

Properties

Compressive strength, after purging COj

Immediately after blowing

after 1 h

in 3 hours

after 24 h Vitality, h Humidity,% Salinity,%

Residual strength after calcination of samples, MPa, at a temperature, C

The data given in table. 1 k 2 indicate that the introduction of a solution of an aluminum-chromophosphate binder in caustic soda into quartz sand together with ferrochromic slag helps stabilize the physicomechanical and technological properties of the mixture, and increase its overall and surface strength at room temperature. temperature, as this activates the surface of the quartz grain of the filler and when the modified liquid glass is applied to such a surface, the adhesion forces of the adhesion to the similar filler substrate increase. The mixture becomes more free-flowing, easily compacted in a snap. At the same time, when the metal is casting the mixture, the mixture dramatically softens when heated to 400–1000 ° C, since the temperature of the sodium silicate is shifted to a higher area.

1.68

1.87

2.32

6.73

7

2.6

0.01

temperatures due to the introduction of the refractory binder composition. With the introduction of the whole solution of the aluminochromophosphate binder in caustic soda (silica sand or liquid glass, the initial strength of the mixture decreases by 15-30%,

Claims (1)

: From the data in Table 2, it can also be seen that the mixture, compared to the known, has a light knockout from the castings in the area of core heating more, since the residual strength of the mixture in the temperature range is 3-4 times lower than that of the known, and at 400,800 C it is residual durability is lower by 4.5-1.6 times. The initial strength of the proposed mixture is 1.5–5 times higher at all stages of hardening, and friability is 4–12 times lower than that of the known. The presence of a number of technical advantages of the composite mixture will ensure its widespread introduction into foundries in machine-building factories. Formula of the Invention The mixture for the manufacture of casting molds and cores with the CO process includes a refractory filler, liquid glass, caustic soda and a complex phosphate additive, about 1/2. This is so that, in order to increase and stabilize the blending of the mixture, to reduce its crushability and to improve its release, it contains a 1,220% aluminum chromophosphate solution as a complex phosphate additive. it in caustic soda with a density of 3-1.30 g / cm and ferrochromic slag with the following ratio of ingredients, wt,%: 2.0-3.5 Liquid glass Caustic soda (density 1.251, 3 g / cm) 0.6-0, 8 12-20% solution of aluminum-chromophosphate binder in caustic soda (in terms of 0.072-0.16 per aluminum-chromophosphate) 0.3-0.5 Ferrochromic slag Refractory on the Others