RU2287604C1 - Complex modifying agent for aluminum-silicon super eutectic alloys - Google Patents

Abstract

FIELD: casting manufacturing.

SUBSTANCE: invention relates, in particular, to manufacturing modified super eutectic aluminum-silicon alloys. Modifying agent comprises components in the following ratios, wt.-%: aluminum phosphate, 19-20; potassium chloride, 65-68.5; hexachloroethane, 11-13, and sulfur, 1-2. Invention provides the development of the modifying agent composition provides grinding primary silicon crystals with improved stability, to enhance rapid effect of the modifying agent and to prolong time wherein the modifying effect is retained.

EFFECT: improved and valuable properties of agent.

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Description

The invention relates to the field of foundry, in particular to the production of modified aluminum-silicon alloys containing silicon more than 13%.

In a modern foundry, hypereutectic silumins are cleaned from oxide captures and dissolved gases before casting and modified to refine the structure.

A complex modifier is known for the treatment of hypereutectic silumins in the form of tablets and containing 10-25% hexachloroethane, the rest is strontium (USSR author's certificate No. 376472, IPC C 22 C 21/04, B 22 D 21/04).

The closest in technical essence and the achieved effect to the claimed composition of the modifier is a modifier that contains the following components, wt.%: Hexachloroethane 30-36%, phosphorous copper 55-65%, sodium fluoride 3-75% and cryolite 1-2.5 % (USSR copyright certificate No. 532644, IPC C 22 C 21/04).

The disadvantage of these modifiers is that when modifying aluminum-silicon alloys, unstable grinding of crystals of primary silicon occurs; the effect of modification persists for a short time; it is necessary to extract after processing in order to completely dissolve the ligature and in addition, the sodium salts included in the modifier significantly reduce the effect of the modification.

The purpose of the invention is improving the quality of the metal by obtaining a more stable grinding of crystals of primary silicon, increasing the speed of the modifier, increasing the time at which the modifying effect is maintained.

This goal is achieved due to the fact that instead of the ligature as a phosphorus-containing element, aluminum phosphate is added to the alloy with the addition of potassium chloride, hexachloroethane and pure sulfur in the following ratio of components,%

Aluminum phosphate 19-20 Potassium chloride 65-68.5 Hexachloroethane 11-13 Sulfur 1-2

The limits of the content of components in the flux are selected based on the following considerations:

Aluminum phosphate. When the content of aluminum phosphate is less than 19%, the effect of grinding grain of primary silicon does not give the desired result, due to the lack of introduction of phosphorus. In the case when the content of aluminum phosphate is more than 20%, the effect of the modification does not increase significantly due to the fact that the assimilation of phosphorus in aluminum is limited (not more than 0.08%).

Potassium chloride. When the content of potassium chloride is less than 65%, the maximum speed of the modifier is not achieved, an increase in the mass fraction of more than 70% is not advisable due to a significant increase in the mass of the modifier.

Hexachloroethane. The presence of hexachloroethane is due to its high refining ability.

Sulfur. The sulfur content within the specified limits is necessary to drain the slag.

The component components of the modifier in the form of powders were dried and compressed into tablets. The modifier in the amount of 1.5% by weight of the treated metal was introduced by a bell at a temperature of 850-870 ° C.

Aluminum phosphate and potassium chloride form a low-melting mixture, and phosphorus is released during the chemical reaction. Hexachloroethane is the main refining element, and sulfur drains the slag (USSR copyright certificate No. 530913, IPC С 22 В 9/00). Thanks to the introduction of potassium chloride modifier into the composition, it became possible to reduce the content of hexachloroethane and, consequently, reduce harmful emissions into the atmosphere during the modification process.

The new modifier gives a stable effect immediately after the end of the reaction and saves it for a long time (see table). At the end, dry slag is formed, which is easily removed with minimal metal loss.

To determine the optimal composition of the modifier, the tests are carried out, the results are shown in the table. Testing was carried out on an alloy AK21M3N.

Table.
Examples of modifier compositions The composition of the modifier,% The average value of the crystals of primary silicon, microns (200-300 measurements) The spread of crystal sizes of primary silicon, microns (200-300 measurements) The duration of the modifier, h The exposure time after entering the modifier. h Al (PO ₃ ) ₃ Kcl C ₂ Cl ₆ S 19.0 69 eleven one fifty 30-70 1,5 0,03 19.5 68.5 eleven one 55 30-80 1,5 0,03

19.5 67.5 eleven 1,5 40 30-50 1,5 0,03 19.5 67 12 1,5 35 30-40 1,5 0,03 19.5 66 12.5 2 35 30-40 1,5 0,03 20,0 65 13 2 40 30-50 1,5 0,03 Prototype CuP C ₂ Cl ₆ NaF Na ₃ AlF ₄ 60 36 3 one 55 30-80 one 0.3

The table shows that the modifier, the use of which gives the maximum grinding of crystals of primary silicon, has the following composition:

Aluminum Phosphate 19.5%

Potassium chloride 67%

Hexachloroethane 12%

Sulfur 1.5%

The proposed modifier can be used in the production of aluminum-silicon hypereutectic alloys.

Claims (1)

A complex modifier for aluminum-silicon hypereutectic alloys containing hexachloroethane, potassium chloride and a phosphorus-containing element, characterized in that it additionally contains sulfur, and aluminum phosphate as a phosphorus-containing element in the following ratio, wt.%: Aluminum phosphate 19-20 Potassium chloride 65-68.5 Hexachloroethane 11-13 Sulfur 1-2