Method for producing a molten salt corrosion resistant alloy

Abstract

The application provides a preparation method of a molten salt corrosion-resistant alloy, and the preparation method is characterized in that the preparation method comprises the following steps: respectively taking Ni, Al, Cr and Ti metal particles, performing ultrasonic cleaning and drying; weighing the dried metal particles according to the mass proportion, and uniformly mixing; vacuum arc melting the mixture to obtain an alloy ingot, and performing vacuum annealing treatment on the alloy ingot to obtain the molten salt corrosion-resistant alloy. The preparation method of the molten salt corrosion-resistant alloy is characterized in that Al, Cr, Ti and other elements with low prices and good corrosion resistance are used to dope and modify a Ni-based alloy, so that a high-performance-price-ratio protective material suitable for being used in a high-temperature chlorine-containing environment such as waste incineration can be prepared.

Description

Technical Field

[0001] This invention relates to the field of high-temperature molten salt corrosion resistant alloy design technology, and particularly to a method for preparing a molten salt corrosion resistant alloy. Background Technology

[0002] With the acceleration of urbanization and the improvement of people's living standards in China, a large number of people have concentrated in cities, providing inexhaustible impetus for the country's prosperity and development. However, this has also brought a series of challenges to cities. Among them, the difficulty in disposing of large amounts of urban household waste has become a prominent problem. Waste incineration is a generally recommended method for handling urban household waste. However, the incineration process produces a large amount of corrosive gases, such as HCl, Cl2, and SO2. Among these corrosive factors, Cl... - Considered one of the most destructive elements, it can react with metals through an "activated oxidation" mechanism to form low-boiling-point, high-vapor-pressure metal chlorides, accelerating the corrosion process. Simultaneously, during waste incineration, a large amount of fly ash accumulates on the surface of the pipes, containing significant amounts of alkali metal chlorides and sulfides. Combined with the products and characteristics of gas corrosion, molten salt corrosion easily forms on the pipe surface. This molten salt corrosion, containing elements such as Cl, S, and K, causes severe damage to the pipe surface, far exceeding the damage caused by chlorine-containing atmospheres.

[0003] Studies have shown that Inconel 625 nickel-based alloys exhibit good corrosion resistance in material protection for waste incineration plants. However, the high price of Inconel 625 limits its widespread application in practical conditions. On the other hand, the variety of alloys or coating materials that can be used in high-temperature chlorine corrosion environments is very limited. Summary of the Invention

[0004] Based on this, the purpose of this invention is to propose a method for preparing a molten salt corrosion resistant alloy. By doping and modifying Ni-based alloys with inexpensive and corrosion-resistant elements such as Al and Cr, a high-performance protective material suitable for use in high-temperature chlorine-containing environments such as waste incineration can be prepared.

[0005] According to the present invention, a method for preparing a molten salt corrosion resistant alloy includes:

[0006] Ni, Al, Cr and Ti metal particles were taken separately and subjected to ultrasonic cleaning and drying.

[0007] Weigh the dried metal particles according to their mass percentage and mix them evenly.

[0008] The mixture is subjected to vacuum arc melting to obtain an alloy ingot, and the alloy ingot is subjected to vacuum annealing to obtain the molten salt corrosion resistant alloy.

[0009] In a preferred embodiment of the present invention, the molten salt corrosion resistant alloy is composed of the following elements by mass percentage: Ni 66%-76%, Al 11.5%-12.5%, Cr 9.5%-10.5%, and Ti 2%-12%.

[0010] In a preferred embodiment of the present invention, the mass percentage of Ti in the molten salt corrosion resistant alloy is 2%, 9%, 10%, or 12%.

[0011] In a preferred embodiment of the present invention, the metal purity of the Ni, Al, Cr and Ti metal particles is 99.99%.

[0012] In a preferred embodiment of the present invention, in the step of taking Ni, Al, Cr and Ti metal particles respectively and performing ultrasonic cleaning and drying:

[0013] The ultrasonic medium used for ultrasonic cleaning is a mixed solution of acetic acid and ethanol, and V 乙酸:乙醇 =1:1.

[0014] In a preferred embodiment of the present invention, in the step of obtaining an alloy ingot by vacuum arc melting of the mixture:

[0015] The conditions for vacuum arc melting are an argon atmosphere and one atmosphere of pressure, and the current for vacuum arc melting is 180A-220A.

[0016] In a preferred embodiment of the present invention, in the step of vacuum annealing the alloy ingot:

[0017] The annealing temperature is 850℃-950℃, and the annealing time is 20h-28h.

[0018] In a preferred embodiment of the present invention, the molten salt includes NaCl, KCl and K2SO4, wherein the mass ratio of each component in the molten salt is NaCl:KCl:K2SO4 = (4.5-5.5):(4.5-5.5):(1.5-2.5).

[0019] In a preferred embodiment of the present invention, the corrosion conditions of the molten salt corrosion resistant alloy are as follows: the molten salt corrosion resistant alloy is placed in a prepared molten salt, heated to 650℃-750℃, and the corrosion time is 110h-130h.

[0020] In summary, based on the above-mentioned preparation method of molten salt corrosion resistant alloys, a novel Ni-based molten salt corrosion resistant alloy is prepared by doping and modifying Ni-based alloys with inexpensive and corrosion-resistant elements such as Al, Cr, and Ti. This also improves the alloy's resistance to high-temperature chlorine corrosion, and it is expected to be applied to high-temperature oxidizing chlorine-containing atmospheres, such as as a protective coating material for water-cooled wall tubes in waste incinerators.

[0021] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by means of embodiments of the invention. Attached Figure Description

[0022] Figure 1 This is a flowchart of the preparation method of the molten salt corrosion resistant alloy of the present invention;

[0023] Figure 2 The X-ray diffraction spectra of the molten salt corrosion resistant alloys in Examples 1-4 of this invention are shown below.

[0024] Figure 3 Metallographic photographs of the molten salt corrosion resistant alloys of Examples 1-4 in this invention;

[0025] Figure 4 This is a schematic diagram of cross-sectional SEM / EDS analysis of the samples obtained in Examples 1-4 after corrosion. Detailed Implementation

[0026] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Several embodiments of the invention are illustrated in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0028] Please see Figure 1 The diagram shows a flowchart of the preparation method of the molten salt corrosion resistant alloy of the present invention, which includes steps S01 to S03, wherein:

[0029] Step S01: Take Ni, Al, Cr and Ti metal particles respectively, and perform ultrasonic cleaning and drying;

[0030] It should be noted that in this step, the Ni, Al, Cr and Ti metal particles selected are all of high purity, with a purity of 99.99%. During the ultrasonic cleaning of the mixed metal particles, the ultrasonic medium used is a mixed solution of acetic acid and ethanol, with a volume ratio of acetic acid to ethanol of 1:1.

[0031] Step S02: Weigh the dried metal particles according to their mass percentage and mix them evenly;

[0032] The final molten salt corrosion resistant alloy is composed of the following elements in mass percentage: Ni 66%-76%, Al 11.5%-12.5%, Cr 9.5%-10.5%, Ti 2%-12%. For example, the mass fraction of Ni can be 66%, 70%, or 76%, etc., the mass fraction of Al can be 11.5%, 12%, or 12.5%, etc., the mass fraction of Cr can be 9.5%, 10%, or 10.5%, etc., the mass fraction of Ti can be 2%, 7%, or 12%, etc.

[0033] Preferably, when the mass percentage of Ti in the molten salt corrosion resistant alloy is 2%, 9%, 10%, or 12%, the resulting molten salt corrosion resistant alloy exhibits better corrosion resistance.

[0034] Step S03: The mixture is subjected to vacuum arc melting to obtain an alloy ingot, and the alloy ingot is subjected to vacuum annealing to obtain the molten salt corrosion resistant alloy;

[0035] It should also be noted that in this step, the arc melting conditions for vacuum arc melting are an argon atmosphere with an argon pressure of one atmosphere, and the current for vacuum arc melting is 180A-220A. For example, the current for vacuum arc melting can be 180A, 200A, or 220A, etc.

[0036] During the vacuum annealing process, the annealing temperature is 850℃-950℃ and the annealing time is 20h-28h. For example, the annealing temperature can be 850℃, 900℃ or 950℃, and the annealing time can be 20h, 24h or 28h, etc.

[0037] Understandably, after obtaining the molten salt corrosion resistant alloy, the corrosion behavior of the obtained NiAlCrTi alloy in mixed molten salt will be tested. Specifically, the molten salt corrosion resistant alloy is placed in the prepared molten salt, heated to 650℃-750℃, and the corrosion time is 110h-130h. The mass ratio of each component in the molten salt is NaCl:KCl:K2SO4 = (4.5-5.5):(4.5-5.5):(1.5-2.5). Preferably, the molten salt temperature can be heated to 650℃, 700℃, or 750℃, etc., and the corrosion time can be 110h, 120h, or 130h. The mass ratio of each component in the molten salt can be NaCl:KCl:K2SO4 = 4.5:4.5:1.5, or NaCl:KCl:K2SO4 = 5:5:2, or NaCl:KCl:K2SO4 = 5.5:5.5:2.5.

[0038] Examples 1-8

[0039] First, high-purity Ni (99.99%), Al (99.99%), Cr (99.99%), and Ti (99.99%) metal particles were taken and ultrasonically cleaned and dried. The metal particles were then weighed according to the specified dosage and uniformly mixed to prepare Ni12Al10Cr-2Ti alloy, Ni12Al10Cr-9Ti alloy, Ni12Al10Cr-10Ti alloy, Ni12Al10Cr-12Ti alloy, Ni11.5Al10Cr-10Ti alloy, Ni12.5Al10Cr-10Ti alloy, Ni12Al9.5Cr-10Ti alloy, and Ni12Al10.5Cr-10Ti alloy, respectively.

[0040] Next, argon-protected arc melting was performed under the following conditions: argon atmosphere at 1 atmosphere, current 200A. This yielded alloy button ingots, which were then vacuum-annealed at 900℃ for 24 hours. The ingots were wire-cut into 2.5×5×10mm samples, which were then ground and polished. Afterward, XRD and metallographic analysis were conducted on the samples to determine the alloy's microstructure, composition, and other characteristics. Please refer to [link to relevant documentation]. Figure 2 and Figure 3 The figures show the X-ray diffraction pattern and metallographic image of the obtained molten salt corrosion resistant alloy, respectively. Figure 2 and Figure 3 It is possible to determine the microstructure, composition, and other characteristics of the molten salt corrosion resistant alloy.

[0041] Then, high-temperature chloride corrosion tests were conducted on the various molten salt corrosion-resistant alloys obtained: Each sample was weighed, and its precise dimensions were measured with vernier calipers. The samples were placed in a quartz crucible and embedded in a mixed salt solution (mass ratio NaCl:KCl:K₂SO₄ = 5:5:2). The crucible was then placed in a muffle furnace, the furnace temperature of which needed to be preheated to 700℃. The furnace was held at this temperature for 5 hours, then the furnace was turned off. After the samples cooled with the furnace, they were removed and weighed. This process was repeated until the corrosion period was 120 hours.

[0042] Please refer to Table 1 below, which shows the chemical element composition and corrosion resistance data of the molten salt corrosion resistant alloy (Ni12Al10Cr-xTi):

[0043] Table 1 Chemical elemental composition of NiAlCrTi alloy

[0044]

[0045] As shown in Table 1, the corrosion resistance of the new molten salt corrosion resistant alloy is better when the Al content is 11.5%-12.5%, the Cr content is 9.5%-10.5%, and the Ti content is 10%-12%, with the Ni12Al10Cr-10Ti alloy exhibiting the best corrosion resistance.

[0046] For example, please refer to Figure 4 The image shows a schematic diagram of cross-sectional SEM / EDS analysis of the samples obtained in Examples 1-4 after corrosion. Figure 4 It can be seen that during corrosion detection, the addition of Ti significantly altered the microstructure of the Ni12Al10Cr alloy, reducing dendrite continuity and increasing the content of the black phase. Combined with XRD phase analysis, it is evident that the relative concentration of AlNi2Ti in the alloy increases with increasing Ti content. When the Ti addition is 2wt%, the surface oxide of the alloy after corrosion is mainly Al2O3. This type of oxide can effectively resist Cl ion corrosion, thus protecting the matrix. With further increases in Ti content, the surface corrosion products are dominated by a mixture of Al2O3 and Cr2O3 oxides, while the inner corrosion products are dominated by a mixture of Al2O3 or Cr2O3 and NiO oxides. The addition of Ti promotes the formation of Cr2O3 in the corrosion products. Similar to Al2O3, the Cr2O3 product layer typically exhibits better corrosion resistance in the alloy.

[0047] Furthermore, the alloy with 2wt% Ti added obtained a single Al2O3 product layer during corrosion, and the cross-sectional morphology of the sample showed that the corrosion cross-section was undulating, indicating that the corrosion process was not uniform. The alloy with 9wt% Ti added failed to obtain a continuous protective oxide product layer, and the sample was severely corroded, with obvious cracking and peeling of the corrosion layer. Compared with the sample with 12wt% Ti added, which had a similar corrosion product layer composition, the corrosion cross-section of the sample with 10wt% Ti added was straighter, indicating that the corrosion process was uniform, and the microstructure and composition of the alloy effectively inhibited the corrosion process.

[0048] Ultimately, the corrosion resistance order of the alloys is Ni12Al10Cr-10Ti>Ni12Al10Cr-12Ti>Ni12Al10Cr-2Ti>Ni12Al10Cr-9Ti. Based on this, by doping and modifying Ni-based alloys with inexpensive and corrosion-resistant elements such as Al, Cr, and Ti, it is possible to effectively prepare high-performance protective materials suitable for use in high-temperature chlorine-containing environments such as waste incineration.

[0049] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0050] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for preparing a molten salt corrosion resistant alloy, characterized in that, The preparation method includes: Ni, Al, Cr and Ti metal particles were taken separately and subjected to ultrasonic cleaning and drying. Weigh the dried metal particles according to their mass percentage and mix them evenly. The mixture is subjected to vacuum arc melting to obtain an alloy ingot, and the alloy ingot is subjected to vacuum annealing to obtain the molten salt corrosion resistant alloy. The molten salt corrosion resistant alloy is composed of the following elements in mass percentage: Ni 66%-76%, Al 11.5%-12.5%, Cr 9.5%-10.5%, and Ti 2%-12%.

2. The method for preparing the molten salt corrosion resistant alloy according to claim 1, characterized in that, The mass percentage of Ti in the molten salt corrosion resistant alloy is 2%, 9%, 10%, or 12%.

3. The method for preparing the molten salt corrosion resistant alloy according to claim 1, characterized in that, The metal purity of the Ni, Al, Cr, and Ti metal particles is 99.99%.

4. The method for preparing the molten salt corrosion resistant alloy according to claim 1, characterized in that, In the step of separately taking Ni, Al, Cr, and Ti metal particles and performing ultrasonic cleaning and drying: The ultrasonic medium used for ultrasonic cleaning is a mixed solution of acetic acid and ethanol, and V 乙酸:乙醇 =1:

1.

5. The method for preparing the molten salt corrosion resistant alloy according to claim 1, characterized in that, In the step of obtaining alloy ingots by vacuum arc melting of the mixture: The conditions for vacuum arc melting are an argon atmosphere and one atmosphere of pressure, and the current for vacuum arc melting is 180A-220A.

6. The method for preparing the molten salt corrosion resistant alloy according to claim 1, characterized in that, In the step of vacuum annealing the alloy ingot: The annealing temperature is 850℃-950℃, and the annealing time is 20h-28h.

7. The method for preparing the molten salt corrosion resistant alloy according to claim 1, characterized in that, The molten salt includes NaCl, KCl, and K2SO4, and the mass ratio of each component in the molten salt is NaCl:KCl:K2SO4 = (4.5-5.5):(4.5-5.5):(1.5-2.5).

8. The method for preparing the molten salt corrosion resistant alloy according to claim 7, characterized in that, The corrosion conditions for the molten salt corrosion resistant alloy are as follows: place the molten salt corrosion resistant alloy in the prepared molten salt, heat it to 650℃-750℃, and the corrosion time is 110h-130h.

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