WO2006109810A1

WO2006109810A1 - Sodium-free flux and process for treatment of molten aluminum alloy with the same

Info

Publication number: WO2006109810A1
Application number: PCT/JP2006/307681
Authority: WO
Inventors: Yukio Kuramasu; Masayuki Ozawa
Original assignee: Nippon Light Metal Company, Ltd.
Priority date: 2005-04-07
Filing date: 2006-04-05
Publication date: 2006-10-19
Also published as: KR20070094837A; JP4274142B2; KR100940376B1; CN100564557C; CN101115852A; JP2006291254A

Abstract

The invention provides a sodium-free flux which is to be used in treating a molten aluminum alloy in a rotary flux injection/ degassing apparatus and which can inhibit the adhesion and build-up of unreacted flux and attain high deslaging effect; and a process for treatment of a molted aluminum alloy with the flux, more specifically, a sodium-free flux which consists by mass of 80 to 95 % AlF3, 2.5 to 10% KCl, and 2.5 to 10 % K2SO4 as the essential components and at most 5 % total of other chlorides, fluorides and nitrates as the balance component; and a process for treatment of an aluminum alloy which comprises keeping the rotor of the above apparatus in a state immersed in a molten aluminum alloy, injecting an inert gas and the above flux into the molten aluminum alloy from nozzles, and rotating the rotor at 200 to 450 rpm to thereby make inclusions contained in the molten alloy float up to the surface of the molten alloy together with fine bubbles and the flux and thus carry out degassing and deslaging.

Description

Non-Natrium Flux and Aluminum Alloy Melting Process Using It ^) Technology Field

The present invention relates to a method for treating molten aluminum, and more particularly, to a method for treating molten aluminum using a flux injection rotary degassing apparatus. Background art

Na has long been used as a eutectic Si improver for porcelain alloys, and a wide range of Na-based fluxes mainly composed of NaF and NaCl are used as fluxes for Na addition. It is used.

However, although Na depends on the alloy composition and forging method, it generally has the effect of promoting the dispersion of gas porosity in aluminum deposits, but molten metal containing Na more than several PPM Due to the reaction with moisture in the air, the hydrogen gas concentration tends to increase, promoting oxidation on the surface of the molten metal and promoting the generation of dross. In addition, it is also known that in a 500-series aluminum alloy containing Mg as a main alloy component, a trace amount of Na causes grain boundary brittleness and significantly deteriorates its properties such as elongation. ing.

Thus, in the forging line that does not like the inclusion of Na, non-sodium flux has been widely used as a flux for the deaeration treatment of molten aluminum alloy. This non- sodium flux mainly contains chloride fluxes that do not contain Na salts, such as Mg C 1 ₂ , C a C 1 _2, and KC 1, which have a denitrifying effect. 'Al KA 1 F 3 A 1 F ₃ K 2 SO to increase the reactivity with the molten metal

4 etc. are mixed.

However, in the chloride flux, Mg C 1 ₂ C a C 1

For 2, since it is hygroscopic, care must be taken for storage. If the moisture absorbed is in direct contact with the molten aluminum, there is a danger of a steam explosion, so if possible, Mg C It is better to avoid using 1 2 a C 1 ₂ . Furthermore, Mg C 1 ₂ C a C 1 ₂ is reacted with an aluminum alloy molten metal. It is used in a closed furnace such as a batch furnace because it emits C-smell and interferes with workability. Except for this, it is widely used.

Therefore, in a production line that does not include Na, the main component is KC 1 which has a denitrifying effect as a flux for the denitrification treatment of the molten metal, and the reactivity with the melt is increased. KA 1 F a ^ Non sodium flux mixed with A 1 F _{3 2} SO ₄ etc., for example, KK 7 6 5 (manufactured by Nippon Light Metal Co., Ltd. (trade name σ Ρ)) KA 1

F ₃ 15% A 1 F 3 10 KSO 4) has been developed and widely used

Incidentally, a rotary degassing apparatus has been known for a long time as a processing apparatus for promoting degassing and degassing of molten aluminum alloy. This is a rotary degassing device that has a nozzle that can supply an inert gas to the center of the rotary port. The rotary rotor is immersed in a molten aluminum alloy, and the nozzle is charged with an inert gas such as argon or nitrogen. The active gas is supplied while being jetted into the molten metal, the rotating rotor is rotated at a rotation speed of 2 0 0 6 5 0 rpm, and inclusions etc. in the molten metal are floated to the molten metal surface with fine bubbles to degas. (In Japanese Patent Publication No. 7-2 0 7 3 7 3).

In recent years, in this 'rotary degassing device' Devices have been developed that have one or more nozzles that can supply inert gas and flux to the unit (US Pat. Nos. 6,375,712,).

By using this flux-injection rotary degassing device, it is possible to further enhance the degassing effect while suppressing as much as possible the generation of gas such as chlorine generated from the flux sprayed in the molten metal. It has become.

However, when the present inventor conducted a test, when the molten metal treatment was performed using the non- sodium flux in a flux injection rotary degassing apparatus, KC 1 as the main component of the flux was rotation

□ Without melting and chlorination without being discharged from the nozzle near

As a result, it was found that 5 questions occurred when the unreacted flux adhered and deposited near the nozzle. Disclosure of the invention

The present invention solves the above-mentioned problems of the prior art, and is used to treat unreacted flux when a molten aluminum alloy is treated with a non-aluminum flux using a flux engine X cushion rotary degasser. Adhesion • An object of the present invention is to provide a non-nitrogen flux that prevents deposition and secures a high denitrification effect, and a method for treating a molten aluminum alloy using the flux.

In order to achieve the above-mentioned hundreds, according to the present invention, a non-nitrogen flux used for treating molten aluminum alloy with a fluxinoxygen 3 rotary degassing apparatus, the mass% So A 1

F 3: 8 0 ~ 9 5 %, KC 1:. 2 5 ~: L 0%, KS o 4: 2

5 to: non-natural sodium, characterized in that L 0% is an essential constituent, and the balance is 5% or less of other chlorides, fluorides, and nitrates. System fluxes are provided.

In addition, a flux-injection rotary degassing apparatus having one or more nozzles capable of supplying an inert gas and a fuchs to the central portion of the rotary rotor shaft can be made of aluminum using the above-described non- sodium flux of the present invention. A method for treating molten Um alloy,

Maintaining the rotating port overnight immersed in the molten aluminum alloy,

Ij The inert gas and the flux are jetted and supplied from the nozzle to the molten metal, and the rotary port is rotated at a rotational speed of 200 to 4500 rpm to intervene in the molten metal. Provided is a molten aluminum alloy treatment method characterized in that degassing and degassing are performed by floating an object etc. to the molten metal surface together with fine bubbles and flux.

In addition, inert gas and flux can be supplied to the center of the rotating rotor shaft.

, ヽ

A method of treating molten aluminum alloy using the non-nitrogen flux of the present invention described above, using a fluxy non-axial rotary degassing apparatus having one or more nozzles,

Maintain the state where the rotary port is immersed in the molten aluminum alloy,

The inert gas and the flux are jetted and supplied from the nozzle into the molten metal, and the rotary lawn is rotated at a rotational speed of 200 to 4500 rpm to finely contain inclusions in the molten metal. A first step of degassing and degassing by raising air bubbles and flux to the hot water surface;

Further, only an inert gas is jetted and supplied from the nozzle into the molten metal, and the rotary rotor is rotated at a rotational speed of 200 to 4500 rpm, so that inclusions in the molten metal are fine bubbles. And a second step of degassing and degassing using a child that floats to the molten metal surface along with residual flux. There is provided an aluminum alloy molten metal treatment method characterized by performing degassing and degassing sequentially.

The non- sodium flux of the present invention is A 1 F ₃ : 80 to 95%, KC 1: 2.5 to 10 0% by mass from the nozzle of the flux injection rotary degasser. _{%, K 2 sO 4: 2.} 5~ 1 0%, the remaining portion total of 5% or less of other chlorides, fluorides, since organic composition from nitrates, KC by the reaction heat of K ₂ S_〇 ₄ and the melt 1 can be melted and chlorinated, and the reaction between A 1 F ₃ and the molten metal smoothly disperses the flux into the molten metal, and the degassing effect is remarkably improved.

The development of this non-sodium-based flux (fluoride-based flux) makes it possible to uniformly disperse the flux in the aluminum melt and to perform high-efficiency degassing using a flux injection rotary degasser. It was. At the same time, we were able to establish a low-pollution aluminum molten metal treatment method that can maintain a high defatting effect even if the amount of flux used is minimized. BEST MODE FOR CARRYING OUT THE INVENTION

As a result of studying the above-mentioned conventional problems, the present inventor has found that non- sodium-based flux typically contains 60% KC 1 in KK 7 65, but KC 1 is The melting point is relatively high, and it does not melt immediately when it comes into contact with the molten metal. In addition, it contains only 15% of A 1 F ₃ which has good reactivity with the molten metal, so the flux is dispersed in the molten metal. It was estimated that unreacted flux was deposited near the nozzle and the degassing effect was significantly hindered.

As a result of repeating various experiments from this point of view, in order to prevent unreacted flux from accumulating near the nozzle, (1) the chloride flux melted and chlorinated, and (2) the reactivity between the flux and the molten metal. Rako ' And found that is necessary.

In order to realize these, (1) In order to melt chloride the chloride flux, it must contain an appropriate amount of K ₂ so 4 which has high reaction heat with the molten aluminum, and (2) the molten and salified flux. It was concluded that it was necessary to use A 1 F ₃ which is highly reactive with molten aluminum as a main component in order to disperse it in the molten metal.

[Reason for limiting flux composition]

A 1 F ₃ which is a main component in the flux of the present invention has an effect of promoting the dispersion of the flux into the molten metal by reacting with the molten aluminum. When the mixing ratio of A 1 F ₃ is less than 80%, the flux adheres and accumulates in the vicinity of the nozzle at the rotation port overnight, and the flux is smoothly dispersed in the molten aluminum alloy. In other words, the above-described defatting effect is inhibited. If the composition ratio of A 1 F ₃ exceeds 95%, the flux will adhere to the nozzle of the rotating rotor by promoting the dispersion of the flux into the molten metal due to the reaction between the flux and the aluminum melt. No, but the flux itself is extremely inferior. Therefore, a preferable mixing ratio of A 1 F ₃ is in the range of 80 to 95%.

KC 1 which is an essential component in the flux of the present invention is finely dispersed in the molten aluminum, and as a result, gradually floats as a fine molten salt and floats on the molten metal surface with inclusions etc. Significantly enhances the effect of drought. When the composition ratio of KC 1 is less than 2.5%, the flux dewetting effect is remarkably inferior. If the composition ratio of KC 1 exceeds 10%, the composition ratio of A 1 F ₃ will decrease accordingly, and unreacted flux will adhere and accumulate near the nozzle of the rotary loader. Become The flux is not smoothly dispersed in the molten aluminum alloy

The defatting effect is inhibited. Therefore, the preferable mixing ratio of K C 1 is in the range of 2.5 to 10%.

_{_{<K 2 SO 4: 2. 5~}} : 1 0 wt%>

K ₂ S ₄ , which is an essential component in the flux of the present invention, acts as a reaction accelerator between the molten aluminum and the flux. When K ₂ so ₄ reacts with molten aluminum, a reaction such as K ₂ SO ₄ + A 1 → A 1 SO ₄ + K proceeds, generating a large amount of heat of reaction. With this reaction heat, KC 1 can be easily melted and salified to enhance the denitrification effect. If the composition ratio of K ₂ S ₄ is less than 2.5%, KC 1 is not sufficiently melted and the flux adheres and accumulates in the vicinity of the nozzle of the rotating rotor, thus hindering the defatting effect. When K ₂ S_〇 _fourth set composition ratio is more than 1 0%, Ri to put the exothermic reaction between the flux and molten aluminum, it is promoted in the molten chloride KC 1, nozzle near one flux rotating port Isseki The dross that floats and separates burns violently due to an exothermic reaction, generating smoke and deteriorating the working environment. Therefore, a preferable mixing ratio of K ₂ SO ₄ is in the range of _2.5 % to 10%.

Other chlorides, fluorides, and nitrates: 5% or less in total>

In addition to the components specified above, the flux of the present invention should contain a chloride other than KC 1, a fluoride other than AlF 3, or a nitrate as long as it is within the range of 5 mass% or less. Can do. These chlorides, fluorides, and nitrates are typically as follows.

Chlorides other than KC 1: Na C l, C a C 1 2, Mg C 1 ₂ A Fluorides other than A 1 F ₃ : Na F, KF, Mg F ₂ , C a F ₂ Nitrate: KNO 3, N a NO 3

When the total amount of these exceeds' 5 mass%, Incorporation of N a to the _{medium, C a C l 2, M} g C l 2 is not accompanied hygroscopic, fluorides and nitrates, such as N a F occurs a problem that will leave increase the flux deposition.

Therefore, the total of other chlorides, fluorides and nitrates should be 5% by mass or less. Example

[Evaluation test of flux deposition]

Using flux with a composition within and outside the range of the present invention, a flux injection rotary degasser was used to treat the molten aluminum alloy, and the adhesion and deposition of the flux at the lower part of the row was evaluated.

Table 1 shows the composition of the flux used. Flux A and B are invention examples having compositions within the scope of the present invention, and fluxes C to I are comparative examples having compositions outside the scope of the present invention. Table 1 Composition of each flux (mass%)

2 30 kg of AC 4 C alloy melt was held at 7 40 in a holding furnace, and the melt was processed in one direction at a rotation speed of 300 rpm using a flux injection rotary degasser. It was. As the first stage, Flux treatment was performed for 5 minutes by supplying N ₂ gas from the nozzle at a flow rate of 30 L / i η simultaneously with a flux having a predetermined composition at a feed rate of 40 / in and uniformly dispersing the flux in the molten metal. As the second stage

Then, with the rotor still rotating, only the flux supply was cut off, and only the N ₂ gas was supplied from the nozzle at a flow rate of 30 L / min, and the degassing process was performed for 10 minutes.

After the molten metal treatment, the rotor was pulled up from the molten metal, and the deposition length of the flux adhered to the lower part of the rotor around the nozzle was measured. Table ₂ summarizes the deposition judgment results for each flux.

Table 2 Evaluation of flux accumulation

(note)

(* 1) Lower part of rotor (* 2) Criteria

[Evaluation test of flux removal effect]

Similarly, in order to evaluate the degassing effect using the flux with the composition shown in Table 1, a crucible experiment was conducted without using a flux injection rotary degasser, and the cleanliness of the melt before and after the flux treatment was measured. did.

# 30 kg of crucible with 7 kg of AC 4 C alloy melt held at 7 40 ° C In this state, one of the fluxes shown in Table 1 was wrapped in 14 g (0.2 wt%) aluminum foil and added into the molten metal with a phosphorizer.

For inclusion evaluation, K mold sampling (n = 3) was performed before and after flux treatment. The inserted thin plate (5 mm thick x 40 mm wide) sample was struck with a hammer to make 6 pieces. A total of 6 pieces of the total 12 surfaces were visually observed to count the number of inclusions, oxides, and other foreign matters, and the value = the number of foreign matters Z 6 was calculated. Calculate the reduction rate = (Κ 0-Κ 1) ZK 0, where K value before flux treatment is K 0 and K value after flux treatment is K 1, and the flux removal effect is calculated based on this reduction rate. evaluated. Table 3 summarizes the evaluation results of the defatting effect for each flux. Table 3 Defatting effect of each flux

Table 4 summarizes the overall evaluation based on the results of the above deposition evaluation and evaluation tests. Table 4 Comprehensive judgment of each flux

Comprehensive judgment is based on sedimentation evaluation and

The lower judgment level was used.

(◎ Best, ○ Good, △ Acceptable, X-defect) Details of the overall evaluation were as follows.

Flux A and B of the present invention embodiment is a composition within the specified range of the present invention, because it contains the _{A 1 F 3 8 0~ 9 5} %, variance the A 1 F ₃ of the flux into the solvent water And the flux is hardly attached to the rotor. In addition, since KC 1 and K ₂ S Ο ₄ are contained in appropriate amounts, KC 1 melts and chlorinates due to the exothermic reaction between K ₂ S Ο ₄ and the molten aluminum.

Flux C (comparative example) has a composition of 100% KA 1 F ₄ and its reactivity with aluminum is extremely low compared to A 1 F ₃ , so flux dispersion in the molten metal does not occur and the rotor A large amount of flux adheres and accumulates. Moreover, the KA 1 F _{4 has} a poor defatting effect.

Flux D (comparative example) contains each component of KA 1 F ₄ , KC 1, K 2 S 0 ₄ and has a good defatting effect, but contains A 1 F ₃ As a result, there is no flux dispersion in the molten metal, and a large amount of flux adheres and accumulates on the rotor.

Flux E (comparative example) is a component of 100% A 1 F ₃ , has high reactivity with albumin, and the flux is smoothly dispersed in the molten metal, but there are no other components and Has almost no wrinkle effect.

Flux F, G (Comparative Example) contained the respective components of _{KA 1 F 4, A 1 F} 3, KC 1, K 2 S_〇 _4, has a good leaving debris effects, A 1 F 3 The content of the low, flux dispersion in the molten metal does not occur, a large amount of flux is deposited on the rotor.

Flux H (Comparative Example) does not contain exothermic reaction with molten aluminum because it does not contain KC 1, Mg C l ₂ components ^ K ₂ SO ₄ Not. In addition, since it does not contain A 1 F ₃ , flux dispersion does not occur in the molten metal, and the flux deposits and accumulates overnight.

Flux I (comparative example), KC 1, K ₂ S_〇 but are having good leaving debris effects have each component of _4, the content of A 1 F 3 is slightly lower, flux dispersion in the melt Does not occur sufficiently, and the flux adheres and accumulates on the rotor.

In general, among the fluxes used, the flux with A 1 F ₃ content lower than the specified range of the present invention and showing a tendency to adhere to and deposit on the lower part of the rotor may have a defatting effect. It cannot be used for flux injection. Flax injection containing A 1 F 3 in an amount within the range of the present invention and KC 1 and K ₂ S Ο ₄ in an amount within the range of the present invention and having a defoaming effect Suitable as a flux for rotary degasser Industrial applicability

According to the present invention, when a molten aluminum alloy is processed using a non- sodium flux by a flux injection rotary degassing apparatus, the occurrence of unreacted flux adhesion and deposition is prevented and high desorption is achieved. Provided are a non-nitrogen flux that secures the dredging effect and a method for treating molten aluminum alloy using the same.

Claims

The scope of the claims

1. Non-nutrient flux used when treating molten aluminum alloy with a flux injection rotary degassing device. A 1 F ₃ : 80 to 95% by mass, KC 1: 2.5 ~: L 0%, K ₂ S ○ ₄ : 2.5 ~ 10% are essential components, and the balance is 5% or less of other chlorides, fluorides, nitrates in total A non- sodium flux characterized by comprising

2. A method of treating molten aluminum alloy using a flux according to claim 1 by a flux injection rotary degassing device having one or more nozzles capable of supplying an inert gas and a flux to a central portion of a rotary rotor shaft. Because

Maintaining the rotating rotor immersed in the molten aluminum alloy,

The inert gas and the flux are jetted and supplied from the nozzle into the molten metal, and the rotating rotor is rotated at a rotational speed of 200 to 4500 rpm, so that the inclusions in the molten metal are fine bubbles and flux. And a molten aluminum alloy treatment method characterized by degassing and degassing by ascending to the molten metal surface.

3. A method of treating molten aluminum alloy using a flux according to claim 1 by a flux injection rotary degassing apparatus having one or more nozzles capable of supplying an inert gas and a flux to the central portion of the rotary rotor shaft. Because

Maintaining the rotating rotor immersed in the molten aluminum alloy,

The inert gas and the flux are jetted and supplied from the nozzle into the molten metal, and the rotation port is rotated at a speed of 200 to 4500 rpm. A first step of degassing and degassing by causing the inclusions in the molten metal to float up to the molten metal surface with fine bubbles and flux,

Further, only the inert gas is jetted and supplied from the nozzle into the molten metal, and the rotating rotor is rotated at a rotation speed of 200 to 4500 rpm so that the inclusions in the molten metal become fine bubbles and residual flux. In addition, a molten aluminum alloy treatment method is characterized in that the second step of degassing and degassing is carried out sequentially by floating to the molten metal surface and degassing and degassing are performed.