CN112899512A

CN112899512A - Aluminum-titanium-carbon alloy grain refiner and preparation method thereof

Info

Publication number: CN112899512A
Application number: CN202110068771.4A
Authority: CN
Inventors: 曹刚; 马志伟; 高文娟; 方超群
Original assignee: Hefei Bolin Advanced Materials Co ltd
Current assignee: Hefei Bolin Advanced Materials Co ltd
Priority date: 2021-01-19
Filing date: 2021-01-19
Publication date: 2021-06-04
Anticipated expiration: 2041-01-19
Also published as: CN112899512B

Abstract

The invention discloses an aluminum-titanium-carbon alloy grain refiner and a preparation method thereof, wherein the preparation method of the material comprises the following steps: will KAlF₄、K₂TiF₄Adding NaCl and TiC into a dispersing agent, uniformly dispersing to obtain a mixture, drying to obtain mixed powder, pressing the mixed powder into a block sample, and preheating to obtain a preheated sample; heating and melting the aluminum block to obtain molten aluminum, adding the preheated sample into the molten aluminum, uniformly mixing to obtain a mixture, fishing out scum on the surface of the mixture, and pouring the mixture into a mold to form to obtain a target product. The mixed powder prepared by the invention contains KAlF₄、K₂TiF₄NaCl, which melts immediately into molten salt upon heating, and Al₂O₃A reaction occurs such that the molten salt is in direct contact with the molten Al. Because TiC is in the meltThe wettability of Al is better than that of Al in molten salt, so TiC can permeate into Al melt, and the aluminum-titanium-carbon alloy with better dispersion is obtained.

Description

Aluminum-titanium-carbon alloy grain refiner and preparation method thereof

Technical Field

The invention belongs to the technical field of metal material manufacturing, and particularly relates to an aluminum-titanium-carbon alloy grain refiner and a preparation method thereof.

Background

In many fields such as new energy automobile, aerospace, etc., the light weight of parts has become an important future development direction, and the aluminum alloy is a key material for realizing the light weight. However, the poor mechanical properties of aluminum alloy limit its industrial application. The method of improving the mechanical properties of the crystal grain refiner by adding the crystal grain refiner has become a hot point of research. Grain refinement is one of the important methods for improving the mechanical properties of aluminum and aluminum alloy, reducing segregation and improving the compactness of castings. The method for refining the crystal grains is more, wherein the addition of the refiner has the advantages of convenient operation, quick action, stable effect, simple equipment and the like, and is the most economical, effective and practical refining method. At present, the grain refiner which is most applied is Al-Ti-B, has better grain refining effect and improves the mechanical property of the aluminum alloy to a certain extent. However, borides in the Al-Ti-B refiner are easy to aggregate and precipitate in the aluminum melt, which greatly reduces the refining effect, and easily generates defects in the subsequent processing process, especially generates serious quality problems in the production process of aluminum foil, and causes a large amount of waste products; meanwhile, some elements, such as Zr, Cr, V and the like, are easy to poison and reduce the refining effect. Therefore, there is an urgent need in the aluminum casting industry to develop new aluminum and its alloy refiners to replace the Al-Ti-B grain refiners.

As TiC in the Al-Ti-C grain refiner is not easy to aggregate and precipitate and has an 'immune' function on Zr, Cr, V and other elements causing Al-Ti-B 'poisoning', the Al-Ti-C grain refiner is one of grain refiners with good industrial application prospect.

However, the conventional preparation process of the Al-Ti-C grain refiner has the following difficulties: (1) the Al-Ti-C alloy prepared by the common process can not control the grain size of TiC, and the uniformity of the grain size is poor; (2) because the TiC and Al have poor wettability, the TiC is difficult to be directly dispersed into the Al melt; (3) al oxide film is very easily formed on the surface of molten Al₂O₃Resulting in difficulty in direct addition of TiC.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide the aluminum-titanium-carbon alloy grain refiner and the preparation method thereof, the preparation method has the advantages of simple preparation equipment, short process flow, high preparation efficiency and the like, and the prepared Al-Ti-C grain refiner has a good grain refining effect.

In order to achieve the purpose, the invention adopts the technical scheme that:

the preparation method of the aluminum-titanium-carbon alloy grain refiner comprises the following steps

(1) Will KAlF₄、K₂TiF₄Adding NaCl and TiC into the dispersing agent, and then sequentially carrying out mechanical stirring and ultrasonic dispersion to obtain a mixture; preferably, the dispersant is ethanol, the KAlF₄、K₂TiF₄And the mass ratio of NaCl to TiC is 70: 10: (10-18): (2-10).

(2) Drying the mixture to obtain mixed powder, pressing the mixed powder into a block sample, and preheating to obtain a preheated sample; alternatively, the pressing pressure is 50-200MPa, such as 50MPa, 100MPa or 200 MPa.

(3) And (3) heating the aluminum block to melt the aluminum block to obtain molten aluminum, adding the preheated sample obtained in the step (2) into the molten aluminum, mechanically stirring to uniformly mix the preheated sample and the molten aluminum to obtain a mixture, fishing out floating slag on the surface of the mixture, and pouring the mixture into a mold to obtain a target product. Preferably, the heating temperature is 1000-.

As a preferable technical scheme, in the step (2), the drying temperature is 100-200 ℃, and the drying time is 6-12 h; for example, the drying temperature may be 100 ℃, 15 ℃ or 200 ℃ and the drying time may be 6h, 10h or 12 h.

As a preferable technical scheme, in the step (2), the preheating temperature is 100-200 ℃, and the time is 1-3 h; for example, the preheating temperature can be 100 ℃, 15 ℃ or 200 ℃ and the like, and the time can be 1h, 2h or 3h and the like.

The second purpose of the invention is to provide the AlTiC grain refiner prepared by the preparation method, wherein the AlTiC grain refiner comprises Al and TiC particles, and the size of the TiC particles is 100-500 nm.

Compared with the prior art, the invention has the beneficial effects that:

(1) the mixed powder prepared by the invention contains KAlF₄、K₂TiF₄NaCl, when the mixed powder is placed on the surface of molten aluminum, the mixed powder is heated to be immediately melted into molten salt, and fluoride in the molten salt can be mixed with Al on the surface of the molten aluminum₂O₃Chemical reaction occurs, and the molten salt is directly contacted with molten aluminum due to strong capability of removing an oxidation film. Since the wettability of TiC in Al is better than that in molten salt, TiC will penetrate into molten aluminum to obtain well-dispersed aluminum-titanium-carbon (Al-Ti-C) alloy. In addition, TiC can be prepared in advance as required, and the powder size is also easy to control.

(2) According to the invention, the mixture is mixed by two mixing modes of mechanical stirring and ultrasonic dispersion, so that the agglomeration of nano-particle TiC can be avoided; the TiC is primarily dispersed in the dispersing agent by mechanical stirring, and then the nano-particles TiC are further uniformly dispersed in the mixture by utilizing the cavitation effect of ultrasonic so as to prepare mixed powder with uniformly dispersed TiC.

(3) The method provided by the invention has the advantages of simple preparation equipment, short process flow, high preparation efficiency and the like, and the prepared Al-Ti-C grain refiner has a good grain refining effect.

Drawings

FIG. 1 is a metallographic structure diagram of an Al-Ti-C alloy obtained in example 1.

FIG. 2 is a scanning electron micrograph of TiC particles in Al-Ti-C alloy.

Detailed Description

The present invention will be further described with reference to the following examples. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

(1) Weighing the following substances in percentage by mass: 70% KAlF₄、10％K₂TiF₄15% NaCl and 5% TiC, then adding the mixture into ethanol, and mechanically stirring the mixture for 30min at the rotating speed of 280 rpm; continuing ultrasonic stirring for 15min, wherein the ultrasonic power is 500W, and obtaining a mixture;

(2) putting the mixture into an oven, keeping the temperature at 200 ℃ for 12h, drying to obtain mixed powder, and pressing the mixed powder into a block sample under the pressure of 10 Mpa; placing the block sample at the temperature of 200 ℃ for heat preservation for 2h for preheating to obtain a preheated sample;

(3) and (3) heating the aluminum block at the temperature of 1000 ℃ to melt the aluminum block to obtain molten aluminum, adding the preheated sample obtained in the step (2) into the molten aluminum, mechanically stirring to uniformly mix the preheated sample and the molten aluminum, fishing out scum on the surface of the aluminum, pouring the scum into a mold, and forming to obtain a target product, namely the aluminum-titanium-carbon alloy grain refiner.

The product prepared in example 1 is polished and polished, and then observed by a scanning electron microscope, and a large amount of TiC particles exist in the product and are uniformly distributed among Al crystal grains, so that an Al-Ti-C structure with uniform distribution is obtained.

Example 2

(1) Weighing the following substances in percentage by mass: 70% KAlF₄、10％K₂TiF₄Adding 12% of NaCl and 8% of TiC into ethanol, and mechanically stirring at the rotating speed of 280rpm for 30 min; continuing ultrasonic stirring for 15min, wherein the ultrasonic power is 500W, and obtaining a mixture;

The product prepared in example 2 is polished and polished, and then observed by a scanning electron microscope, a large amount of TiC particles exist in the product, the size of the TiC particles is 50nm, the TiC particles are uniformly distributed among Al crystal particles, and an Al-Ti-C structure with uniform distribution is obtained.

Example 3

(1) Weighing the following substances in percentage by mass: 70% KAlF₄、10％K₂TiF₄10% NaCl and 10% TiC, then adding the mixture into ethanol, and mechanically stirring the mixture for 30min at the rotating speed of 280 rpm; continuing ultrasonic stirring for 15min, wherein the ultrasonic power is 500W, and obtaining a mixture;

(3) and (3) heating the aluminum block at 1200 ℃ to melt the aluminum block to obtain molten aluminum, adding the preheated sample obtained in the step (2) into the molten aluminum, mechanically stirring to uniformly mix the preheated sample and the molten aluminum, fishing out scum on the surface of the aluminum, pouring the scum into a mold, and forming to obtain a target product, namely the aluminum-titanium-carbon alloy grain refiner.

The product prepared in example 3 is polished and polished, and then observed by a scanning electron microscope, and a large amount of TiC particles exist in the product and are uniformly distributed among Al crystal grains, so that an Al-Ti-C structure with uniform distribution is obtained.

Example 4

(1) Weighing the following substances in percentage by mass: 70% KAlF₄、10％K₂TiF₄15% NaCl, 5% TiC, then added to ethanol, rotated at 280rpmMechanically stirring for 30 min; continuing ultrasonic stirring for 15min, wherein the ultrasonic power is 500W, and obtaining a mixture;

The product prepared in example 4 is polished and polished, and then observed by a scanning electron microscope, and a large amount of TiC particles exist in the product and are uniformly distributed among Al crystal grains, so that an Al-Ti-C structure with uniform distribution is obtained.

Comparative example 1

Comparative example 1 differs from example 2 in that: the melt temperature of Al in comparative example 1 was 800 degrees.

Comparative example 1 the test results are: the alloy has less TiC and uneven distribution.

Comparative example 2:

comparative example 2 differs from example 2 in that: in comparative example 2, ultrasonic agitation was not applied at the time of mixing the powders.

The test results for comparative example 2 were: larger bulk material is present in the alloy and is detected as TiC blocks, with dimensions between 20 and 100 microns.

As can be seen from the above examples and comparative examples, it was found from the results of SEM test that as the amount of TiC in the mixed powder increased, the amount of TiC in the Al-Ti-C grain refiner also gradually increased. When the temperature of molten Al is lower (800 ℃), the TiC content in the alloy is less. This is because TiC has poor wettability with Al at low temperature, and TiC is difficult to permeate into Al, so that it is difficult to obtain a good Al-Ti-C alloy. When no ultrasonic agitation is applied, TiC is present in bulk in the alloy, suggesting that nano-scale TiC is difficult to disperse under mechanical agitation, resulting in its aggregation in Al.

The embodiments described above are intended to facilitate one of ordinary skill in the art in understanding and using the present invention. It will be readily apparent to those skilled in the art that various modifications can be made to the embodiments and the generic principles defined herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the embodiments described herein, and those skilled in the art should make modifications and alterations without departing from the scope of the present invention.

Claims

1. A preparation method of an aluminum-titanium-carbon alloy grain refiner is characterized by comprising the following steps: comprises the following steps

(1) Will KAlF₄、K₂TiF₄Adding NaCl and TiC into the dispersing agent, and then sequentially carrying out mechanical stirring and ultrasonic dispersion to obtain a mixture;

(2) drying the mixture to obtain mixed powder, pressing the mixed powder into a block sample, and preheating to obtain a preheated sample;

(3) and (3) heating the aluminum block to melt the aluminum block to obtain molten aluminum, adding the preheated sample obtained in the step (2) into the molten aluminum, mechanically stirring to uniformly mix the preheated sample and the molten aluminum to obtain a mixture, fishing out floating slag on the surface of the mixture, and pouring the mixture into a mold to obtain a target product.

2. The method of claim 1, wherein: in the step (1), the dispersant is ethanol.

3. The method of claim 1, wherein: in the step (1), the KAlF₄、K₂TiF₄And the mass ratio of NaCl to TiC is 70: 10: (10-18): (2-10).

4. The method of claim 1, wherein: in the step (2), the drying temperature is 100-200 ℃, and the drying time is 6-12 h.

5. The method of claim 1, wherein: in the step (2), the preheating temperature is 100-200 ℃, and the time is 1-3 h; the pressing pressure is 50-200 MPa.

6. The method of claim 1, wherein: in the step (3), the heating temperature is 1000-1200 ℃.

7. The method of claim 1, wherein: in the step (3), the material of the die is iron or copper.

8. The method of claim 1, wherein: in the step (3), the mechanical stirring is performed in an argon atmosphere.

9. An Al-Ti-C alloy grain refiner made by the method of any one of claims 1 to 8, wherein: the aluminum titanium carbon alloy grain refiner comprises Al and TiC particles, and the diameter of the TiC particles is 100-500 nm.