SU1253706A1 - Self-hardening sand for making moulds and cores - Google Patents

Description

The invention relates to a foundry, namely, to compositions of self-cultivating mixtures on liquid glass binders used for the manufacture of both casting molds and cores.

The aim of the invention is to improve the knockout forms and rods and improve safety of working conditions

The essence of the invention is as follows.

It is foreseen to use liquid glass with a density of 1.48-1.52 g / cm and with a silicate module 2.6-3.0. Caustic soda is preferably administered in the form of an aqueous solution with a density of 1.27 g / cm. Silicon fluoride monosubstituted calcium has the chemical formula CaCHSiFg) and is supplied as per TU-U-310-51. .

In the proposed mixture in the interaction of Ca (HSiF,), with liquid glass

about

acceleration of hardening occurs both due to the action of the formed acid F, and due to the hydroxide Obrazkicese compound

Hjsi

6 calcium.

CaSiOj contributes to the temperature swelling of the silicate phase, with

Liquid glass

Cream-fluoride monosubstituted Kalyschy

An aqueous solution of caustic soda shtotnostyo 1.27 g / cm

Quartz sand

 Corresponds to the content of caustic soda in terms of dry substance of 0.049, 0.066 and 0.086 wt.%.

five

Holding Ca (81HP) j, Ca (SiHF,) b Z

0

five

This liquid-glass solution has a high viscosity, which prevents sintering and adhesion of liquid glass with sand, as well as its hardening during cooling. Thus, an improvement in the strength as well as in the knock-out of the mixture is achieved with an insignificant amount. The content of the mixture leads to an insignificant content of NaF in the reaction products, which in turn improves the working conditions due to the insignificant release of fluorine when metal is poured.

The mixture according to the invention is prepared as follows.

Refractory filler and monofluoric calcium fluorofluoride are introduced into the mixer. Grind 1-1.5 minutes Then water glass is introduced with alkali (sodium hydroxide solution) dissolved in it beforehand and mixed for another 2.0-2.5 minutes, after which the mixture is ready for use.

In tab. 1 shows the compositions of mixtures 1-3 according to the invention; in tab. 2 - their properties.

Table 1

3.0

3.8

,five

0.20

0.32

0.43

0.20 0.27 0.35 96.60 95.61 94.70

Vitality, min

Compressive strength, kgf / cm, at the time of exposure of samples, h: 0.5

1 2 4 24

Bendability (by knockout operation, J)

Thus, the proposed mixture ensures the attainment of improved embossability while maintaining technologically acceptable indicators of the strength of the molds and cores during their curing.

Editor M.Kelemep

Compiled by S.Teplkova

Tehred A. Kravchuk Proofreader E. Sirohman

Order 4664/14 Circulation 757 Subscription

VNSHSHI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

Production and printing company, Uzhgorod, st. Project, 4

table 2

ten

Improved safety of working conditions is provided in view of the reduced soderhan in shchadukhts of the hardening of toxic sodium fluoride and the exclusion of the furyl alcohol from the mixture.

Claims (1)

SELF-SOLID MIXTURE FOR THE PRODUCTION OF CASTING FORMS AND RODS, including quartz sand, water glass and a hardener based on hydrofluoric acid salt, which is coated with the aim of improving the knockability of molds and cores and improving the safety of conditions Labor "mixture, as a hardener based on a salt of hydrofluoric acid, contains monosubstituted calcium silicofluoride and additional sodium hydroxide in the following ratio of ingredients, wt. X: Liquid glass Kremnefteoristy monosubstituted calcium Caustic soda (in terms of dry matter) Quartz sand 3.0-4.5 0.20-0.45 0,049-0,086 Rest