SU1468636A1 - Sand for making cores and moulds the sand being hardened with carbon dioxide - Google Patents

Abstract

The invention relates to foundry and can be used for the manufacture of casting molds and cores from liquid glass mixtures, cured carbon dioxide carbonate 1 The invention relates to foundry manufacturing and can be used to manufacture casting molds and cores from liquid glass mixtures cured by carbon dioxide gas. The purpose of the invention is to improve the quality of the molds and cores by increasing and stabilizing the strength of the mixture, reducing its crushability and improving the knockability. pelvis. The purpose of the invention is to improve the quality of the molds and cores by increasing and stabilizing the strength of the mixture, reducing its density and improving the knockability, which is achieved by introducing into the mixture a 10-20% solution of acid tar in caustic soda. The mixture contains, wt.%: Liquid glass 3.0-5.0 $ caustic soda 0.5-1.0 10-20% solution of acid tar in caustic soda (in terms of acid tar) 0.05-0 ,20; kaolin 1.5-2.5; refractory filler based on silica the rest. The introduction of acidic tar into the mixture promotes the formation of sodium sulphates during its neutralization, which are embedded in the silicate matrix, crush the hardening products, form additional bonds and increase the elasticity between silica gel globules, which leads to a decrease in the strength of the mixture, reducing its crumbling and improve knockout. 1 hp f-ly, 2 tab. The proposed mixture contains a silica-based refractory filler, the binder is liquid glass, kaolin, caustic soda, and an additive to improve the physicomechanical technological properties. As an additive to improve the physicomechanical and technological properties of a 10-20% solution of acidic tar in elk soda was used. (L "a 00 C5 from 05

Description

An acidic tar was used, having the following composition, wt%: organo-arylsulfonic acid 8-15J, dissolved sulfuric anhydride 1.5-3.3, dimethylnaphthalene 0.7-1.2, acenaphthene 0.9-1 , 2, diphenyl 0.4-1.6; naphthacene 0.7-1.9; sulfuric acid the rest.

Liquid glass used sodium with a modulus of 2.30-2.50, density of 1.44 g / cm. Aqueous solution of technical caustic soda density of 1.20 g / cm. Kaolin Turbovsky kaolin plant in accordance with TU 21-238-80.

Quartz sand was used as a non-resistant but filler. You can also use zircon, rutile, kyanene-sillimanite granular

etc.

The procedure for preparing the mixture and adding the ingredients is as follows.

In advance, a 10–20% solution of acidic tar in caustic soda is added and introduced into water glass, stirred mechanically or pneumatically, for 1–2 minutes. The binder thus prepared is capable of maintaining its properties for a long time, does not stratify, does not precipitate, and does not change the binding properties. It has a conventional viscosity according to VZ-4, 2 times lower than the initial liquid glass. Thus, with an initial viscosity of liquid glass of 40 s, it decreases to 20 s with the introduction of neutralized acid tar, which also contributes to the increase in strength properties and reduction of energy consumption for mixing. Kaolin is introduced into the sand, mixed for 20-30 seconds, then the liquid-glass binder is added by the preparation and mixed for another 2 minutes, then the molding sand is prepared for compression and rupture, blown for 10-30 seconds and tested immediately after COg purging after 1 hour , 3 h, 24 h hardening. At the same time, other technological properties are monitored: survivability, friability, residual strength after calcination of the samples for an hour and cooling together with the furnace, Pr 400, 600, 800 and YuOO C.

The proposed compositions of the mixtures are given in tab. 1, their technological properties - in the table. 2

The data given in table. and 2, indicate that the introduction of a solution of acidic tar in caustic soda into the mixture helps stabilize the physicomechanical and technological properties of the mixture, increase its tensile strength at all stages of hardening by 1.5–8.0 times, reduce crumbling 1.5-2.0 times, eliminate the softening during the daily storage of the mixture during its reproduction of COA, reduce the residual strength of the mixture at 400-600 ° C by 20-30%, and in the high-temperature region the residual strengths decrease to zero values and thus ensures easy selection willow mixes from castings.

Increase and stabilization of the strength of the mixture, reduction of its precipitation is achieved due to sulfates.

sodium, which is formed by neutralizing acid tar with caustic soda. Sodium sulfates are embedded in a silicate matrix, crush hardening products, form additional bonds and increase the elasticity between silica gel globules after CO-j treatment. An improvement in the knockout of a mixture of castings during heating Q at low temperatures (300–600 ° C) is achieved due to the destruction of the binder film on quartz grains from the combustion of carbon-containing additives. Improvement of knockout in the high temperature range (700-1000 ° C) is achieved by dehydrating kaolin.

The presence of a number of technical advantages of the proposed mixture and a large

35

40

45

the amount of waste sour tar will ensure its widespread introduction in foundries machine-building plants.

Claims (2)

1. A mixture for the manufacture of casting molds and cores, cured by carbon dioxide, containing refractory filler based on silicon dioxide, water glass, caustic soda, clay mineral and an additive for improving the physicomechanical and technological properties, characterized in that  improving the quality of the molds and cores by increasing and stabilizing the strength of the mixture, reducing its crumbling and improving the knockability, and as well as environmental protection, it contains a 10–20% solution of acid tar in caustic soda as mentioned additive, and kaolin in the following ratio of ingredients, May, as a clay mineral. %: 3.0-5.0 0.5-1.0 0.05-0.20 0 five Kaolin1.5-2.5 Refractory # 1 half pole based dioxide flint rest 2. A mixture according to claim 1, characterized in that the acidic tar has the following composition, in wt.%: Organo-arylsulphonic acid 8.0-15.0 Sulfuric anhydride1, 5-3.3 Dimetipnephthalene Acenaften 0 Diphenyl Naftacene Sulfuric Acid 0.7-1.2 0.9-1.2 0.4-1.6 0.7-1.9 Rest 10 20% solution of acid tar in caustic soda (in terms of acid Tensile strength, MPa, after purging SOCH after 1 h after 3 h after 24 h Vitality, h Humidity,% Strength,% Residual compressive strength after calcining samples, MPa, Table 1 Table 2 0.28 0.37 0.59 0.98 24 2.5 0.01 0.35 0.42 0.67 1.23 24 3.0 0.01