SU1458058A1 - Self-hardening sand for making moulds and cores - Google Patents

Abstract

The invention relates to foundry and can be used to make casting molds and cores from self-hardening liquid glass mixtures. The purpose of the invention is to improve the quality of the forms by increasing the strength of the mixture and reducing its fallability, as well as improving the knockability. The goal is achieved through the use of silica gel in a mixture — waste from the production of aluminum fluoride used as a bond (it. The mixture contains, in wt%, silica gel — waste from the production of aluminum fluoride, 4.35–6.10; 10% aqueous caustic soda solution, 0.65-0.90, propylene carbonate, 0.30-0.50, silica-based refractory filler — the rest.The use of silica gel in the mixture provides an improvement in the knock-out of the mixture due to its high content; silicon dioxide in relation to sodium oxide. 2 tab. with $ (L

Description

one

The invention relates to foundry and can be used to make casting molds and cores from self-hardening liquid glass mixtures.

The purpose of the invention is to improve the quality of the forms by increasing the strength of the mixture and reducing its fallability, as well as improving the dislodgeability of the mixture.

The mixture contains a refractory filler, a binder, an aqueous solution of caustic soda and a hardener.

Quartz sand of 1K02A grade is used as a refractory filler, and i

silica gel, di-waste by production of aluminum fluoride. The production of silica gel is carried out by the decomposition of aluminum hydroxide with hydrofluoric acid.

The physico-chemical characteristics of silica gel are as follows:

IndicatorsNorm

Appearance Bela loose mass

one

SL

00

about ate

OS

The content of SiOo in the dry product,%

Content%

Not less than 90

No more than 70

No more than 2.5

No more than 4.5

Calcium sulphate content,%

Aluminum hydroxide content,%

The content of aluminum fluoride,% Not more than 3.0

The self-hardening of the mixture is carried out by the interaction of the st. Sukdego and propylene carbonate.

Used caustic soda 10% concentration.

The mixture is prepared in batch or continuous mixers as follows. First, a binder is prepared in a special paddle mixer by mixing and heating to silica gel and caustic soda to PO-SOO to obtain a homogeneous solution, which ensures uniformity of the binder film on the surface

quartz sand grains after curing. Then quartz sand is loaded into the mixer and at the same time a calculated amount of binder and propylene carbonate is supplied. The peremetyani time of the components of the mixture is 0.5-1.0 minutes The finished mixture is discharged into a core box or flask.

The compositions of the mixtures and their technological properties are given in Tables 1 and 2,

Silica gel - waste production of aluminum fluoride

Sodium hydroxide

10% aqueous solution of caustic soda

Propylene Carbonate Molding Peso

Physico-mechanical properties of mixtures

Humidity is original,

% I don't hurt

Gas permeability of dry samples, - units, not less

Compressive strength, MPa, not less

after 1 h

in .4 h

5.22 0.78

6.10 0.90

0.40 93.5

0.50 92.5

Table 2

Test indicators for formulations

A.Z

190

0.7 5.0

The survivability of the mixture, mission not less

Compressive strength after calcining samples at 1273 K and cooling, MPa, not more than

The precipitation of solidified samples,% not more

As can be seen from Table 3 (these mixtures have a 2-3 times better knockability compared to the prototype, while such properties as strength and shedding are improved. S: 1 silicon dioxide for ottopenia to sodium oxide.

The mixture according to the invention can be used in mechanized and automated methods for the production of casting molds and cores to produce ferrous and non-ferrous castings.

Claims (1)

Invention Formula  Self-hardening; a mixture for the manufacture of casting molds and cores containing refractory filler on L1 table 2 g ten ten 1.3 1.8 2.0 0.9 0.7 0.6 0 five 0 five silica-based binder, propylene carbonate, and 10% aqueous sodium hydroxide solution, characterized in that, in order to improve the quality of the forms by increasing the strength of the mixture and reducing its crushability, as well as improving the knockability of the mixture, it is the binder contains silica gel - waste production of aluminum fluoride in the following ratio of ingredients, wt,%: Silica gel - waste production of aluminum fluoride 4.35-6.10. 10% ss-1 caustic water solution natra0,65-0,90 Propylene carbonate 0.30-0.50 Refractory silica-based filler Else