SU1404152A1 - Method of preparing modified molten glass for manufacturing moulds and cores - Google Patents

Abstract

The invention relates to a foundry, in particular, to methods for preparing modified liquid glass binder materials used in self-hardening mixtures with a hardener — dicalcium silicate (ferrochrome slag) in the manufacture of molds and cores. The goal is to improve the physicochemical properties of the molds and rods during the curing of the dicalcium forces with 1kat, reducing the consumption of the binder, as well as facilitating the knockability. The essence of the method based on electrophysical processing in the process of dissolving a modifying additive in liquid glass is the implementation of electrophysical processing by pulsed electric discharges in the amount of 200-400 pulses with an energy of one pulse of 1.6-2.2 kJ per 1 kg of binder. At the same time, sodium polyphosphate with a degree of polymerization of n 10-27 is used as a modifying additive. The implementation of the method makes it possible to increase the strength of the molds and cores by 50-60% or else to reduce the binder content in the mixture from 6.5 to 5.0 wt.% Without loss of strength, and also to significantly ease; knocking the mixture out of lyrek. 1 hp f-ly, 2 tab. S (L with about 4 SL IsD

Description

The invention relates to a foundry industry, in particular, to methods for preparing modified liquid glass binder materials used in the composition of self-hardening mixtures with a curing agent — ferrochromic slag for fabricating and casting molds and cores.

The purpose of the invention is to improve the physicomechanical properties of the molds and cores during curing with dicalcium silicate, reducing binder consumption, as well as facilitating knockout.

When pulsed processing by electric discharges under the influence of factors arising from this process, such as a powerful shock wave, a high-speed jet having a cavitation | genesis, acoustic radiation, a high discharge current, electromagnetic radiation, the polyphosphate is likely to be broken up into fine particles and subsequently rhenium it into the structure of liquid glass

- To modify it, laboratory equipment, which includes a typical pulse current generator (HIT), uses it. And the control panel from the electrohydraulic cleaning unit, voltage regulation on the input HIT is dried using a three-phase regulator torus tension The discharge chamber is a specially made stainless steel device. Vacuum rubber and polyethylene are used to electrically insulate electrodes. Sodium polyphosphate with a degree of polymerization of n 10-27 is used as a modifier.

The parameters of electrohydraulic processing, which determine the specific energy expended on one discharge, and also the value of the working discharge gap 5 affecting the efficiency of ebrabok, are determined using the mathematical planning of the experiment: and 50-55 kV,, 2 µF; 1, (7.5-8.5) - 10% 1, where U is the voltage between the electrodes; С - capacity of discharge capacitors .; L is the magnitude of the working bit gap.

The specific energy expended on one breakdown of the working discharge gap,

  M where m is the mass of the material, kg.

,

Q 5

0 5

0 d

e

five

A change in the frequency of the discharge pulses within 0.5–5.0 Hz does not significantly affect the properties of the mixture. However, with an increase in the frequency of the discharge, the performance of the modification process increases. Therefore, it is advisable to carry out processing with the highest frequency that can be provided by the GIT.

B tab. Figure 1 shows the features of modifying the binders and the compositions of the mixtures prepared with these binders, in table. 2 - the properties of these mixtures.

The binder is prepared as follows.

A chamber for electro-hydraulic treatment in the indicated ratios is supplied with liquid glass and lumpy sodium polyphosphate (PFN), after which the treatment with pulsed electric discharges is carried out. The prepared binder in a mixer is mixed with water and a surfactant. As the surfactant used DS-PAC in the amount of 1.5% by weight of liquid glass.

When making the binder in a laboratory mixer, first mix the dry components of the mixture for 1 minute, after which the liquid-glass composition is added and the mixture is mixed for 2 minutes.

In determining the strength, flowability and fallability using the standard method, Iku. The knockout operation is assessed by a known technique, only standard samples of 50x50 cm are used for the tests,

Quartz sand of 1K02A grade is used as a refractory filler.

As can be seen from the above results, by modifying liquid glass with solid sodium polyphosphate with a degree of polymerization of 10-27, together with treatment with pulsed electrical discharges, you can increase the strength of the liquid self-hardening mixture by 50-60% or reduce the binder content in the mixture from 6.5 to 5 % without loss of strength, reduction of current and fallability, significantly facilitating the work of knocking out.

Similar results are obtained in the manufacture of a liquid plastic self-hardening mixture.

Formulas; i and о b p € t e n and

Claims (1)

1. A method for preparing a modified glass binder for manufacturing casting molds and cores, including electrophysical treatment of liquid glass in the process of modifying it with an additive, characterized in that, in order to improve the physicomechanical properties of the forms and cores during curing with dicalcium silicates, the descent of At the same time, as well as facilitating knockout, the electrophysical treatment of ocyniecTB- is applied with a total electrical discharge of 200-400 pulses at an energy of one pulse 1.6– 2.2 kJ per kg binder. 2, the method according to claim 1, 1 and 2, so that sodium polyphosphate is used as a modifying additive. Table 1 1.9 2.2 2.5 100 200 400 500 1.9 1.9 300 300 17 0.115 88.50 5.75 4.42 1.33 0.29 0.58 0.173 0.230 5.34 4.93 4.51 4.10 1.51 3.77 3.43 1.7J 0.115 1.89 90.73 4.08 3.09 2.09 Table 2