SU831332A1 - Mixture for producing casting ceramic moulds - Google Patents

Description

(54) MIXTURE FOR THE MANUFACTURE OF CASTING CERAMIC FORMS

silicate, then pre-mixed powdered quartz, quartz sand and expanded perlite are added, thoroughly mixed for 15 minutes, then a 515% alkaline aqueous solution is introduced, which makes it easy to adjust the mixture survival time from 2 to 15 minutes mixes in forms and core boxes. The relative viscosity of the mixture, as determined by the HIPI-4 booster meter, is 1425 s.

Examples of the proposed formulations are given in table.1.

From a mixture of each composition, two ceramic molds are made for castings, for example glasses. Forms are poured with chromo-nickel-molybdenum steel.

Physico-mechanical and thermophysical properties of mixtures are given in table 2,

where b is the tensile strength,

- compressive strength; x

- heat conduction coefficient;

to

- gas permeability.

As can be seen from Table 2, the proposed formulations have the best combinations of properties as compared with the known ones.

The drawing shows the graphical dependence of the influence of the perlite content on the properties of the mixture.

Curves 1 and 2 depict the dependence of the ultimate strength of the mixture under compression and stretching, respectively, on the content of perlite. Curve 3 shows the effect of perlite on thermal conductivity, and Curve 4 characterizes the change in the gas permeability of the mixture. As can be seen from the graph, with an increase in the content of pearlite from 8% to 35%, the ultimate compressive strength. decreases from 29 to 10 kg / cm; in the case of a tensile strength of 6V, it decreases from 2.2 to 0.3 kg / cm; from 30 to 190 units. Mixtures of 14-28% perlite are optimal. They possess the best complex of properties:

high mechanical properties and gas permeability and low thermal conductivity (GTj ,, 1624 kgf / cm, Gft 0.75-1.7 kgf / cm A - 0.85-0.92 W / m-deg, K 40-100 units. ). J When the perlite content is above 26%, the mechanical properties of the mixture are significantly reduced.

The gas permeability of the form after calcination is 45-90 units. 0 after

Q calcination 0.7 Krc / cM, (kgf / cm.

All castings have a clean surface without poigar and similar defects Pg. . Accuracy class of castings 3. The control of castings by gamma-ray imaging and magnetic defect-5 toscopy methods show the absence of external and internal defects, and the thermal conductivity is not sufficiently low.

The invention allows to obtain a mixture with improved mechanical and

0 thermal characteristics, which makes it possible to carry out directional solidification of castings, to increase the density of the metal and reduce shrinkage defects of castings.

Table 1

Hydrolyzed

30 32

30 30 ethyl silicate 30

Pulverized

3 € quartz

0 5% aqueous solution

0.5

0.5

0.5 alkali

Swollen 23

16 21 5 perlite

Quartz

16.5 16.5

17.5 sand.

Table 2,

Claims (2)

1. USSR author's certificate 595051, cl. In 22 C 1/00, 1975. 2. USSR author's certificate 399286, class, B 22 C 1/00, 1971. G A,  -K 2, X If 1.S 20 160 willow ten 80 000 ji-tind 7 / // t83f Sovereign Permta about.%