SU624694A1 - Composition for making water-soluble core - Google Patents

Description

(54) MIXTURE FOR THE MANUFACTURE OF A VITATIVE STEM

Hjo6peTeHHe relates to foundry, in particular, to mixtures of dd compounds for the manufacture of water-soluble cores used in the casting of aluminum alloys.

Let us know the water-soluble rods manufactured by pressing the dry water soluble inorganic salt, NaCI. or KCI having a residual moisture of less than 1% 1.

The pressing pressure is 1.5-4 cf / cm. Pressed rods calcined at 100-300 ° C. The compressive strength of the obtained rods is more than 1000 kgf / cm. The cores are used to produce castings from aluminum and zinc alloys. Complete removal of the rods occurs in 1 minute when flushing the cooled castings with water.

A significant disadvantage of these mixtures is the low quality of the surface of the rods and the impossibility of obtaining a complex configuration, which in many cases is determined by your use.

Closest to the proposed technical essence and the achieved effect is a mixture for the manufacture of water-soluble rod, including paraffin, stearin, alumina and water-soluble salt (2).

However, the rods of the known mixture have insufficient strength and speed of removal from the cavity of the castings, as well as a large amount of fire shrinkage.

In order to reduce fire shrinkage, increase the strength and speed of removing rods from the cavity of castings, the proposed mixture contains sodium chloride as a water-soluble salt with the following ratio of ingredients, wt.%:

Aluminum oxide 4 - 8

Stearin2.0-2.5

Paraffin 12-16

Sodium chloride

Claims (2)

Sodium chloride with a particle size of up to 100 microns and anhydrous alumina (o AljOj) are used to obtain a core mixture of this composition. These powdered materials are mixed in the indicated amounts with the organic components at 70-80 ° C. The resulting suspension is pressed into the mold. Then the raw rods are burned in the layer of adsorbent at 700-750 ° C. In this composition of the core mixture, sodium chloride is the main refractory component that provides solubility after the manufacture of the casting, aluminum oxide in the specified areas is an addition of stabilizing shrinkage of the rods and increasing the chemical resistance of the core of the mixture. Stearin in this mixture is a surfactant additive (stabilizer), paraffin is a dispersion medium. Their presence makes it possible to obtain rods of complex geometric shape with a slight pressure of the compactor (1.5-3 kgf / cm). In order to obtain the optimal composition of the water-soluble rod, four core MIXTURES were prepared. Mixture 1, wt.%: Sodium chloride82 Aluminum oxide 4 Stearin2 Paraffin12 Mixture 2, wt.%: Sodium chloride78 Aluminum oxide 6 Stearin2.5 Paraffin13.5 Mixture 3, wt.%: Sodium chloride78 Oxide of Aluxix 8 Stearin2 Paraffin12 Mixture4, wt. %: Sodium chloride78 Aluminum oxide 4 Stearin2 Paraffin16 From these compositions of ceramic mixtures, rods were prepared using the above technology. 1and zico-mechanical and technological properties of rods are shown in the table. As can be seen from the test results shown in the table, the optimum composition of the water control of the south rod is mixture 2. The preferred amount of alumina is 6-7%, which helps reduce fire shrinkage and does not affect the rate of dissolution of the ceramic rod. The increased combing of the organic components leads to a significant increase in fire shrinkage, as well as inhomogeneity of the rod in terms of volume. The use of the proposed mixture for the manufacture of water-soluble rods makes it possible to glue the complex cavities of castings of stable geometric dimensions with a surface purity of 6-7 cells. (GOST 2789-73). The formula of the invented Mixture for the manufacture of a water-soluble rod, including alumina, stearin, paraffin, a water-soluble salt, characterized in that, in order to reduce fire shrinkage, increase the strength and speed of removing the rods from the cavity of castings, it contains sodium chloride as a water-soluble salt of the following ratio of ingredients, wt.%: Aluminum oxide 4-8 Stearin 2.0-2.5 Paraffin 12-16 XnopuctbtK sodium Others Sources of information taken into account in the examination: 1. Japan Patent GR 48-17570, CL.11A21, 1973. 2. The copyright certificate K 536004, cl. B 22 from 1/00, B 22 from 9/10, B 22 from 7/02, 06/18/75.