SU1289581A1 - Binder for making moulds and cores - Google Patents

Abstract

The invention relates to the field of foundry and can be used to prepare molding and core sands as a binder. The purpose of the invention is to increase the adhesive strength of the binder, the quality of the forms and cores and the improvement of their knockability from the castings. The goal is achieved by introducing sodium polyphosphate into the liquid glass composition, in which the degree of polymerization is 10-27. The binder is composed in May. %: liquid glass 93.0-98.5, sodium polyphosphate 1.5-7.0. By increasing the degree of polymerization, the number of functional groups introduced into the binder increases, which causes an increase in adhesion to the surface of quartz, as well as a decrease and relaxation of stresses in the binder film and an increase in its strength. In addition, the use of polyphosphate with a high degree of polymerization contributes to the improvement of knockout mixtures from castings. 4 tab. sh (L 00 co eel eo

Description

The invention relates to foundry and can be used to prepare molding

core mixtures as a binder.

The purpose of the invention is to increase the adhesive strength of the binder, the quality of the forms and cores and the improvement of their knockability from the castings.

The binder according to the invention contains in its composition liquid glass and sodium polyphosphate with the general chemical formula a O, where n is 10-27.

Sodium polyphosphate, a, is a glassy product consisting of a mixture of unbroken linear (chain) polyphosphates. Structural formula

OO

Мtl F-0-Р.

fI

NaNa

It has a high reactivity which increases with the degree of polymerization of sodium polyphosphate.

The solubility of sodium polyphosphate in water at room temperature is 40 May. %

Binding material was prepared as follows.

Sodium polyphosphate is dissolved in water at room temperature. With vigorous stirring for 3-5 minutes. The resulting 40% solution (density 1400 kg / m.) Is introduced into liquid glass and mixed thoroughly. The binder material is a uniform, colorless, transparent colloidal solution that is stable during long-term storage. Sodium polyphosphate may also be added during the autoclave production of liquid glass. The sodium polyphosphate is introduced into the autoclave as a dry product along with a silicate block.

It is preferable to use liquid glass with a density of 1400-1480 kg / m and a module of 2.6-3.0 for self-hardening mixtures and 2.0-2.4 for the CO-process. Mixtures were prepared with a binder content in an amount of from 3.5 to 6.0%. Sodium polyphosphate is introduced into

binder with a degree of polymerization of 10, 19 and 27.

The compositions and properties of the mixtures with the resulting binders are given in Table. 1-4.

Thus, the experimental data presented in Table. 2, 4 indicate that the optimum composition of the silicate binder is May. %:

Liquid

glass93.0-98.5

Polyphosphate

rub with

degree

polymerization 10-27 1,5-7,0

A significant reduction in the operation of knockout and an increase in the initial and final strength of the mixtures with the proposed binder is achieved due to the fact that it contains sodium polyphosphate with a degree of polymerization of 10-27, which has reactivity and changes the structure of the liquid glass film. A higher degree of polymerization of the above-mentioned sodium polyphosphate compared to sodium tripolyphosphate Ma, .PDO, o, having a polymerization degree of three, is the main reason for the greater efficiency of the proposed

technical solution. It is non-toxic.

The implementation of the invention for the manufacture of casting molds and cores in production leads to an increase in the adhesive strength of the binder, an improvement in the quality of the molds and cores and, respectively, castings, a reduction in labor and energy consumption during finishing operations.

Claims (1)

Invention Formula Binder for the manufacture of foundry molds and cores, including liquid glass and sodium phosphate, characterized by the fact that, in order to increase the adhesive strength of the binder, the quality of the molds and cores and improve their knock-out of castings, it contains sodium polyphosphate with the general formula , „„ 31289581 where n is 10-27. at the next corresponding polyphosphate wearing ingredients, may. %: Sodium ester Liquid glass 93,0-98,5nuty formula 1.5-7.0 Table 1 7.0 3.5 1.5 7.0 3.5 1.5 Composition Ingredients, May. % 1493.0-6.033 1594,00,5 4,53,5 table 2 1.0 1.0 95.5 94.0 94.0 94.0 94.0 94.0 94.0 94.0 94.0 94.0 94.0 1.0 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 3.5 4.5 A.5 4.5 4.5 4.5 4.5 4.5 4.5  5 4.5 Composition Physical and mechanical properties Compressive strength, MPa after 3 h in 24 hours 1.3-1.45 1.18-1.25 0.80-0.90 . 1.35-1.50 X 1.20-1.35 0.90-0.98 7.0 3.5 1.0 7.0 3.5 1.5 1.0 1.0 1.0 1.0 1.0 1.0 J.O 1.0 1.0 1.0 1.0 Table 4 Mortification Work knockout after calcination of the samples, J, at T, s 800 1000 1200 16 3 ABOUT 20 7 3 thirty 15 6 26 0.90-g1.00 1.00-1.05 Editor N.Slobod nickname Compiled by V.Shuvalov Tehred V.Kadar Order 7846/10 Circulation 763 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab. 4/5 -Production and printing company, Uzhgorod, st. Project, 4 0.35-0.40 39 48 70 Proofreader A.T. sko