SU1360871A1 - Sand for making cores - Google Patents

Abstract

The invention relates to foundry and can be used for the manufacture of cores, mainly ceramic, gating systems, for casting on melted models. The purpose of the invention is to reduce the strength of the mixture after drying and prevent slag inclusions from entering the mold increasing the strength of the mixture after calcination at a temperature 800-1000 ° C, which is achieved by introducing into the mixture a three-component hardening additive consisting of marshalite, sodium silicofluoride and a lacquer based on n ntaftalevoy resin. The mixture contains, wt%: marshalite 25.0-30.0; sodium silicofluoride 6.0-10.0; liquid glass 9.0-16.0; varnish based on pentaphthalic resin, modified with vegetable oil 0.3-1.0) refractory filler based on silicon dioxide - the rest. The introduction of a three-component hardening system (marshalite, sodium silicofluoride and oil varnish) into the mixture contributes to the increase in the strength of the liquid-glass system, the reduction of burnability in contact with the liquid melt and the refractoriness of the mixture. 2 tab. with "b (L from 05 o 00

Description

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The invention relates to foundry and can be used for the manufacture of cores, predominantly ceramic gating systems, when casting on melted models.

The purpose of the invention is to reduce the crushability of the mixture. After drying and preventing slag inclusions from entering the mold, the strength of the mixture is improved after calcining at 800-1000 ° C.

The mixture contains quartz sand in the form of a refractory filler, the bond is liquid glass and a complex strengthening additive, which uses marshall, sodium silicofluoride and oil varnish.

To prepare the mixture, marshalite (powdered quartz), lacquer oil PF-283, technical sodium fluorofluoride, quartz sand and liquid glass of the composition,%: mass fraction of dioxide 30.95j sodium oxide 10.58; sulfuric anhydride 0.12 j calcium oxide 0.20, iron oxide and aluminum oxide 0.25. The silicate module is 2.93, the density is 1.48 g / cm.

The marshalite introduced into the mixture increases the strength of the mixture in its raw state, increasing the geometric accuracy of the ceramic rods after being removed from the core hook, reduces the stickiness of the rods in contact with the liquid steel, while increasing the strength characteristics of the rods. Sodium silicofluoride (), introduced into the mixture, leads to sintering of ceramics in the temperature range of 800-1000 ° C, and it is considered that an increase in refractoriness and strength at high calcination temperatures occurs due to the gradual dissolution of the refractory filler in the glassy link.

The introduction of oil lacquer into the mixture contributes to the formation of a lacquer film located mainly along the grain boundaries of quartz sand. Drying of the oil in the varnish film at room and elevated temperatures occurs due to evaporation of the solvent, complex processes of polymerizing the oil and oxidizing it with oxygen. Drying varnish films are completely non-soluble in water.

one

alcohol and others, when heated, does not soften, which ensures high strength of the rods and eliminates crumbling of the mixture after prolonged storage at room and high temperatures.

Prepare the mixture as follows.

Marshalite, silicofluoride sodium and quartz sand fall asleep in a metal container and mix thoroughly. Then liquid glass and lacquer are poured into glass or porcelain dishes and kept until a homogeneous suspension composition is obtained, after which the mixture components are poured into dry glass containers and mixed thoroughly until a homogeneous composition is obtained.

From the prepared mixture in the metal core rods are made, which are dried at 150-250 C, and then calcined at 800-1000 C.

The compositions of the mixtures are given in Table 1; their properties are given in Table. 2

From the data table. 2 it can be seen that the proposed mixtures have high strength after calcination (4-5 times more than the known ones), while shedding is also reduced by two orders of magnitude, which makes it possible to reduce the scrap of castings for slag inclusions and blockages by 8- ten%.

Claims (1)

Invention Formula The mixture for making rods, predominantly ceramic gating systems, when casting on melted models, contains a refractory filler based on silicon dioxide and water glass, in order to reduce the shedding of the mixture after the substance and prevent slag inclusions from entering into the casting mold, increasing the strength of the mixture after calcining the rods at 800-1000 ° С, the mixture additionally contains marshalite, sodium silicofluoride and lacquer based on foam taftal resin modified with vegetable oil with the following ratio of ingredients, wt.%: Marshalite25.0-30.0 Fluorosilicate sodium6.0-10.0 Liquid glass 9.0-16.0 Varnish based on pentaphthalic resin, modified with vegetable oil Rest Table 1 table 2