Multi-component aluminum alloy NOCOLOK brazing flux and preparation method thereof

Abstract

The present invention provides a multi-component aluminum alloy NOCOLOK flux and a preparation method thereof, wherein the flux comprises ten fluoride components, namely, KF, NaF, LiF, CsF, MgF2, CaF2, CoF2, ZnF2, CuF2 and AlF3, and the molar ratio of each component is 1: (0.5-1.5): 0.1: 0.02: 0.8: 0.7: 0.01: 0.02: 0.001: (3-5). The multi-component aluminum alloy NOCOLOK flux provided by the present invention has an extremely low melting temperature and can be applied to the brazing of a wide range of aluminum alloy materials.

Description

Technical Field

[0001] The invention relates to the technical field of new materials, and in particular to a multi-component aluminum alloy NOCOLOK brazing flux and a preparation method thereof. Background Art

[0002] Aluminum and its alloys are one of the most important structural materials among nonferrous metals. The specific gravity of aluminum alloys is only one-third of that of steel, with high specific strength, good electrical and thermal conductivity, excellent processing, surface treatment and corrosion resistance. Therefore, aluminum alloys are widely used in fields including modern radar structures, automobile / battery heat dissipation, battery current collectors, etc. The key to the widespread application of aluminum and its alloys lies in the welding of aluminum and aluminum alloys, and brazing is the most precise welding method. The reason why aluminum and its alloys are more difficult to braze than other alloys is that there is an extremely dense oxide film on their surface. The nature of this oxide film is very stable, which can fully resist atmospheric erosion and can generate a new film at any time when the old film is destroyed. This film needs to be destroyed when brazing aluminum and its alloys, otherwise the molten brazing material cannot wet with the base material; after welding, the integrity of the film needs to be maintained and protected, otherwise the joint will be severely corroded. The flux plays the following roles in the brazing process: remove the oxides on the surface of the brazing metal and the brazing filler metal, creating the necessary conditions for the liquid brazing filler metal to spread on the surface of the brazing metal; cover the surface of the brazing metal and the brazing filler metal with a thin liquid layer to isolate them from the harmful effects of oxygen in the air; play an interfacial active role to improve the wetting of the liquid brazing filler metal surface. Therefore, the role of the flux is extremely critical in the brazing process. The most widely used non-corrosive flux (NOCOLOK flux) for aluminum and aluminum alloys is the fluoroaluminate flux, which is composed of potassium fluoroaluminate, rubidium fluoroaluminate or cesium fluoroaluminate, and has the characteristics of no corrosion and no need to clean the residue after welding.

[0003] Conventional KF-AlF 3 The melting temperature of NOCOLOK flux is 558℃, and the corresponding brazing temperature is also relatively high. Generally, the temperature in engineering applications is above 590℃. It can only be used for brazing pure aluminum and a few aluminum alloys such as 3003. Most aluminum alloys, especially high-strength aluminum alloys, cannot be used due to their low solidus temperature. 3 The flux has a melting point higher than KF-A1F 3 Low, ranging from about 440℃-480℃, composition is CsF:AIF 3 (mol%) = 33-74: 67-26. However, the price of CsF-AIFs compound is about KF-A1F 3 CsF-A1F combines the advantages of both 3 -KF ternary flux came into being, but its brazing temperature is still relatively high. Therefore, how to obtain low-cost NOCOLOK flux for aluminum alloy with lower brazing temperature becomes an important issue. Summary of the invention

[0004] In view of the defects in the prior art, the object of the present invention is to provide a multi-component aluminum alloy NOCOLOK flux and a preparation method thereof.

[0005] According to one aspect of the present invention, a multi-component aluminum alloy NOCOLOK flux is provided, wherein the flux comprises KF, NaF, LiF, CsF, MgF 2 , CaF 2 , CoF 2 、ZnF 2 ,CuF 2 and AlF 3 The molar ratio of the ten fluoride components is 1:(0.5-1.5):0.1:0.02:0.8:0.7:0.01:0.02:0.001:(3-5).

[0006] According to another aspect of the present invention, a method for preparing the above-mentioned multi-component aluminum alloy NOCOLOK flux is provided, the method comprising:

[0007] KF, NaF, LiF, CsF, MgF were taken in a molar ratio of 1: (0.5-1.5): 0.1: 0.02: 0.8 respectively 2 , added to deionized water and stirred to obtain a mixture of KF, NaF, LiF, CsF and MgF 2 The ratio of the total mass of to the mass of deionized water is 15%;

[0008] Take CaF in a molar ratio of 0.7:0.01:0.02:0.001:(3-5) respectively. 2 , CoF 2 、ZnF 2 ,CuF 2 , AlF 3 , add acetone and stir to obtain a mixture of CaF 2 , CoF 2 、ZnF 2 ,CuF 2 and AlF 3 The ratio of the total mass of to the mass of acetone is 20%;

[0009] Add the mixture 2 into a hydrothermal kettle and seal it; heat it to a first preset temperature and keep it warm, then heat it to a second preset temperature and continue the hydrothermal treatment, the second preset temperature is higher than the first preset temperature; after the reaction is completed, cool it to room temperature to obtain a product, which is the mixture 3;

[0010] Adding the mixture 3 to the mixture 1, stirring and sealing; heating to a third preset temperature and keeping the temperature; cooling to room temperature to obtain a mixture 4;

[0011] The mixture is dried and then placed in a tubular furnace, and an inert gas is introduced; the mixture is heated to a fourth preset temperature at a preset heating rate and kept warm; the mixture is cooled to room temperature and ball-milled to obtain a multi-component aluminum alloy NOCOLOK brazing flux.

[0012] Optionally, the mixture is added into deionized water and stirred to obtain a mixture 1, wherein the stirring time is 10 to 30 minutes.

[0013] Optionally, the mixture is added into acetone and stirred to obtain a second mixture, wherein the stirring time is 1 to 3 hours.

[0014] Optionally, the heating to a first preset temperature and keeping it warm, then heating to a second preset temperature and continuing the hydrothermal treatment includes: heating to 75-105°C and keeping it warm for 2-4 hours; then heating to 170-220°C and continuing the hydrothermal treatment for 1-3 hours.

[0015] Optionally, the mixture 3 is added to the mixture 1, wherein: the mass ratio of the mixture 1 to the mixture 3 satisfies MgF 2 With CaF 2 Molar ratio 0.8:0.7.

[0016] Optionally, the mixture three is added to the mixture one, and the mixture is sealed after stirring, wherein the stirring time is 10 to 30 minutes.

[0017] Optionally, the heating to the third preset temperature and keeping it warm includes: heating to 120-140° C. and keeping it warm for 2-4 hours.

[0018] Optionally, heating to a fourth preset temperature at a preset heating rate and keeping the temperature thereat comprises: heating to 230-360° C. at a heating rate of 2° C. / min and keeping the temperature thereat for 3-6 hours.

[0019] Optionally, after cooling to room temperature, ball milling is performed, wherein the ball milling time is 2 hours.

[0020] Compared with the prior art, the present invention has at least one of the following beneficial effects:

[0021] The multi-component aluminum alloy NOCOLOK brazing flux has an extremely low melting temperature through the mutual cooperation of various components and proportions.

[0022] The preparation method provided by the present invention realizes the controllable preparation of multi-component aluminum alloy NOCOLOK brazing flux by combining various steps and controlling the process parameters in the preparation process. The prepared multi-component aluminum alloy NOCOLOK brazing flux has an extremely low melting temperature and is thus applicable to the brazing of a wide range of aluminum alloy materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0024] Figure 1 The figure is a schematic flow chart of a method for preparing a multi-component aluminum alloy NOCOLOK flux in one embodiment of the present invention. DETAILED DESCRIPTION

[0025] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several variations and improvements may be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0026] A multi-component aluminum alloy NOCOLOK flux provided in one embodiment of the present invention includes KF, NaF, LiF, CsF, MgF 2 , CaF 2 , CoF 2 、ZnF 2 ,CuF 2 and AlF 3 The molar ratio of the ten fluoride components is 1:(0.5-1.5):0.1:0.02:0.8:0.7:0.01:0.02:0.001:(3-5).

[0027] Another embodiment of the present invention provides a method for preparing the above-mentioned multi-component aluminum alloy NOCOLOK flux, referring to Figure 1 The process diagram shown in FIG. 1 comprises the following steps:

[0028] S1, KF, NaF, LiF, CsF, MgF in molar ratio 1: (0.5-1.5): 0.1: 0.02: 0.8 respectively 2 , added to deionized water and stirred to obtain a mixture of KF, NaF, LiF, CsF and MgF 2 The ratio of the total mass of to the mass of deionized water is 15%;

[0029] S2, take CaF in molar ratio of 0.7:0.01:0.02:0.001:(3-5) respectively2 , CoF 2 、ZnF 2 ,CuF 2 , AlF 3 , add acetone and stir to obtain a mixture of CaF 2 , CoF 2 、ZnF 2 ,CuF 2 , AlF 3 They all have good solubility in acetone, CaF 2 , CoF 2 、ZnF 2 ,CuF 2 and AlF 3 The ratio of the total mass of to the mass of acetone is 20%;

[0030] S3, adding mixture 2 into a hydrothermal kettle and sealing it; heating it to a first preset temperature and keeping it warm, then heating it to a second preset temperature, and continuing the hydrothermal treatment, wherein the second preset temperature is higher than the first preset temperature; cooling it to room temperature after the reaction is completed, and obtaining a product as mixture 3;

[0031] S4, adding mixture 3 to mixture 1, stirring and sealing; heating to a third preset temperature and keeping the temperature; cooling to room temperature to obtain mixture 4;

[0032] S5. After drying the mixture, place it in a tube furnace and introduce inert gas; heat it to a fourth preset temperature at a preset heating rate and keep it warm; after cooling to room temperature, ball mill it to obtain a multi-component aluminum alloy NOCOLOK brazing flux.

[0033] In some embodiments, in step S1, the stirring time is 10 to 30 minutes to allow the components to be fully mixed.

[0034] In some embodiments, in step S2, the stirring time is 1 to 3 hours to allow the components to be fully mixed.

[0035] In some embodiments, in step S3, the temperature is raised to 75-105°C and the holding time is 2-4 hours; then the temperature is raised to 170-220°C and the hydrothermal treatment is continued for 1-3 hours. The two-stage holding process in this step is conducive to the reaction of each component and the formation of a uniform phase product. If a one-stage holding process is used, the segregation of components and the abnormal growth of the second phase may occur due to the lack of a low-temperature nucleation step.

[0036] In some embodiments, in step S4, the mass ratio of mixture 1 to mixture 3 satisfies MgF 2 With CaF 2The molar ratio is 0.8:0.7. The stirring time is 10 to 30 minutes to fully mix. The temperature is raised to 120 to 140°C and kept warm for 2 to 4 hours.

[0037] In some embodiments, in step S5, the temperature is raised to 230-360° C. at a heating rate of 2° C. / min and kept at this temperature for 3-6 hours. The ball milling time is 2 hours.

[0038] In the above embodiments of the present invention, stirring is required during the heating, hydrothermal treatment and cooling process to ensure the uniformity of the reaction system during the hydrothermal treatment process. The above process parameter settings are conducive to promoting product formation and improving preparation efficiency.

[0039] The principle of the above-mentioned embodiment of the present invention is: adopt a multi-component strategy to achieve disorder and amorphization of the flux, improve the uniformity of the multi-component flux, and reduce the flux ionic bond strength by adding highly electronegative metal elements such as Co, Zn, and Cu, thereby effectively reducing the melting temperature of the flux.

[0040] In the above embodiment of the present invention, the multi-component aluminum alloy NOCOLOK brazing flux has an extremely low melting temperature through the interaction of the components and the proportions. Compared with the aluminum alloy NOCOLOK brazing flux in the prior art, the above embodiment of the present invention reduces the amount of Cs element used, which can reduce the cost of the brazing flux. By combining the various steps and controlling the process parameters in the preparation process, the controllable preparation of the multi-component aluminum alloy NOCOLOK brazing flux is achieved, and the prepared multi-component aluminum alloy NOCOLOK brazing flux has an extremely low melting temperature, so it can be applied to the brazing of a wide range of aluminum alloy materials.

[0041] The scheme of the present application will be explained below in conjunction with specific embodiments and comparative examples. It will be appreciated by those skilled in the art that the following examples are only used to illustrate the present application and should not be considered as limiting the scope of the present application. If no specific technology or conditions are indicated in the embodiments, the technology or conditions described in the literature in this area or the product specification are carried out. The reagents used or the instruments that do not indicate the manufacturer are all conventional products that can be obtained through commercial channels.

[0042] Example 1

[0043] The method for preparing the multi-component aluminum alloy NOCOLOK flux provided in this embodiment comprises the following steps:

[0044] (1) KF, NaF, LiF, CsF, MgF were taken in a molar ratio of 1:0.5:0.1:0.02:0.8 2 , added to deionized water and stirred for 10 minutes to obtain a mixture of KF, NaF, LiF, CsF, MgF 2 The total mass ratio of the deionized water is 15%;

[0045] (2) Take CaF in a molar ratio of 0.7:0.01:0.02:0.001:3 2 , CoF 2 、ZnF 2 ,CuF 2 , AlF 3 , add acetone and stir for 1 hour to obtain mixture 2; CaF 2 , CoF 2 、ZnF 2 ,CuF 2 , AlF 3 The ratio of the total mass of to the mass of acetone is 20%;

[0046] (3) Add the mixture 2 obtained in step (2) into a hydrothermal kettle, seal it, raise the temperature to 75° C., and keep it at this temperature for 2 hours; then raise the temperature to 170° C., and continue the hydrothermal treatment for 1 hour; after the reaction is completed, cool it to room temperature to obtain the product, which is mixture 3;

[0047] (4) Adding mixture 3 to the mixture 1 obtained in step (1) (the mass ratio of mixture 1 to mixture 3 should satisfy MgF 2 With CaF 2 molar ratio 0.8:0.7), stirred for 10 minutes and then sealed; heated to 120°C and kept warm for 2 hours; cooled to room temperature to obtain mixture IV;

[0048] (5) The mixture obtained in step (4) is dried at 80° C., placed in a crucible, and the crucible is placed in a tubular furnace and nitrogen is introduced; the temperature is increased to 230° C. at a heating rate of 2° C. / min, and the temperature is kept for 3 hours; after cooling to room temperature, the mixture is ball-milled for 2 hours to obtain a multi-component aluminum alloy NOCOLOK flux.

[0049] After testing, the melting temperature of the flux is 390℃.

[0050] Example 2

[0051] The method for preparing the multi-component aluminum alloy NOCOLOK flux provided in this embodiment comprises the following steps:

[0052] (1) KF, NaF, LiF, CsF, MgF were taken in a molar ratio of 1:1.5:0.1:0.02:0.8 2 , added to deionized water and stirred for 10 to 30 minutes to obtain a mixture of KF, NaF, LiF, CsF, MgF 2 The total mass ratio of the deionized water is 15%;

[0053] (2) Take CaF in a molar ratio of 0.7:0.01:0.02:0.001:52 , CoF 2 、ZnF 2 ,CuF 2 , AlF 3 , added to acetone and stirred for 3 hours to obtain mixture 2; CaF 2 , CoF 2 、ZnF 2 ,CuF 2 , AlF 3 The ratio of the total mass of to the mass of acetone is 20%;

[0054] (3) Add the mixture 2 obtained in step (2) into a hydrothermal kettle, seal it; heat it to 105° C. and keep it at this temperature for 4 hours; then heat it to 220° C. and continue the hydrothermal treatment for 3 hours; after the reaction is completed, cool it to room temperature to obtain the product, which is mixture 3;

[0055] (4) Adding mixture 3 to the mixture 1 obtained in step (1) (the mass ratio of mixture 1 to mixture 3 should satisfy MgF 2 With CaF 2 molar ratio 0.8:0.7), stirred for 30 minutes and then sealed; heated to 140°C and kept warm for 4 hours; cooled to room temperature to obtain mixture IV;

[0056] (5) The mixture obtained in step (4) is dried at 80° C., placed in a crucible, and the crucible is placed in a tubular furnace and nitrogen is introduced; the temperature is increased to 360° C. at a heating rate of 2° C. / min, and the temperature is kept for 6 hours; after cooling to room temperature, the mixture is ball-milled for 2 hours to obtain a multi-component aluminum alloy NOCOLOK flux.

[0057] After testing, the melting temperature of the flux is 342℃.

[0058] Example 3

[0059] The method for preparing the multi-component aluminum alloy NOCOLOK flux provided in this embodiment comprises the following steps:

[0060] (1) KF, NaF, LiF, CsF, MgF were taken in a molar ratio of 1:1:0.1:0.02:0.8 2 , added to deionized water and stirred for 20 minutes to obtain a mixture of KF, NaF, LiF, CsF, MgF 2 The total mass ratio of the deionized water is 15%;

[0061] (2) Take CaF in a molar ratio of 0.7:0.01:0.02:0.001:3-5 2 , CoF 2 、ZnF 2 ,CuF 2 , AlF3 , added to acetone and stirred for 2 hours to obtain mixture II; CaF 2 , CoF 2 、ZnF 2 ,CuF 2 , AlF 3 The ratio of the total mass of to the mass of acetone is 20%;

[0062] (3) Add the mixture 2 obtained in step (2) into a hydrothermal kettle, seal it, heat it to 90° C., and keep it at this temperature for 3 hours; then heat it to 195° C., and continue the hydrothermal treatment for 2 hours; after the reaction is completed, cool it to room temperature to obtain the product, which is mixture 3;

[0063] (4) Adding mixture 3 to the mixture 1 obtained in step (1) (the mass ratio of mixture 1 to mixture 3 should satisfy MgF 2 With CaF 2 molar ratio 0.8:0.7), stirred for 20 minutes and then sealed; heated to 130°C and kept warm for 3 hours; cooled to room temperature to obtain mixture IV;

[0064] (5) The mixture obtained in step (4) is dried at 80° C., placed in a crucible, and the crucible is placed in a tubular furnace and nitrogen is introduced; the temperature is increased to 295° C. at a heating rate of 2° C. / min, and the temperature is kept for 4.5 hours; after cooling to room temperature, the mixture is ball-milled for 2 hours to obtain a multi-component aluminum alloy NOCOLOK flux.

[0065] After testing, the melting temperature of the flux is 363°C.

[0066] Comparative Example 1

[0067] This comparative example provides a commercially available aluminum alloy NOCOLOK flux (SOLVAY).

[0068] The melting temperature thereof was tested to be 485° C. The melting temperatures of the brazing agents in the above embodiments are all lower than the melting temperature of the brazing agents in the comparative example.

[0069] Comparative Example 2

[0070] Using KF and CaF 2 As raw materials, the molar ratio is 1:0.7. In step (1), KF is added to deionized water to obtain a mixture 1. In step (2), CaF 2 Add acetone to obtain mixture 2, and use the same preparation process as in Example 3 to obtain comparative sample 2.

[0071] The melting temperature of the flux was tested to be 497° C. The melting temperatures of the fluxes in the above embodiments are all lower than that of the comparative sample 2.

[0072] Comparative Example 3

[0073] Using KF, LiF, CsF, MgF 2 , CaF 2 As raw materials, the molar ratio is 1:0.1:0.02:0.8:0.7. In step (1), KF, LiF, CsF, MgF 2 Add to deionized water to obtain a mixture 1, in step (2) CaF 2 Add acetone to obtain mixture 2, and adopt the same preparation process as in Example 3 to obtain comparative sample 3.

[0074] The melting temperature of the flux was tested to be 489° C. The melting temperatures of the fluxes in the above embodiments are all lower than that of the comparative sample 3.

[0075] Comparative Example 4

[0076] Using KF, LiF, CsF, MgF 2 , CaF 2 , CoF 2 、ZnF 2 As raw materials, the molar ratio is 1:0.1:0.02:0.8:0.7:0.01:0.02. In step (1), KF, LiF, CsF, MgF 2 Add to deionized water to obtain a mixture 1, in step (2) CaF 2 , CoF 2 、ZnF 2 Add acetone to obtain mixture 2, and adopt the same preparation process as in Example 3 to obtain comparative sample 4.

[0077] The melting temperature of the brazing agent was tested to be 441° C. The melting temperatures of the brazing agents in the above embodiments are all lower than that of the comparative sample 4.

[0078] Comparative Example 5

[0079] The same raw materials as in Example 3 were used, and the molar ratio of the raw materials was also the same as in Example 3. Step (3) of Example 3 was changed to directly heating the temperature to 195°C and treating with hot water for 2 hours. The remaining processes were the same as in Example 3, and comparative sample 5 was obtained.

[0080] The melting temperature of the flux was tested to be 431° C. The melting temperatures of the fluxes in the above embodiments are all lower than that of the comparative sample 5.

[0081] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various modifications or variations within the scope of the claims, which does not affect the essence of the present invention. The above preferred features can be used in any combination without conflicting with each other.

Claims

1. A multi-component aluminum alloy NOCOLOK flux, characterized in that: The flux comprises ten fluoride components, namely KF, NaF, LiF, CsF, MgF2, CaF2, CoF2, ZnF2, CuF2 and AlF3, and the molar ratio of each component is 1:(0.5-1.5):0.1:0.02:0.8:0.7:0.01:0.02:0.001:(3-5).

2. A method for preparing the multi-component aluminum alloy NOCOLOK flux according to claim 1, characterized in that: include: Take KF, NaF, LiF, CsF, and MgF2 in a molar ratio of 1: (0.5-1.5) : 0.1: 0.02: 0.8 respectively, add them to deionized water and stir to obtain a mixture 1, wherein the total mass ratio of KF, NaF, LiF, CsF, and MgF2 to the mass ratio of deionized water is 15%; CaF2, CoF2, ZnF2, CuF2, and AlF3 are taken respectively in a molar ratio of 0.7:0.01:0.02:0.001:(3-5), added into acetone and stirred to obtain a second mixture, wherein the total mass ratio of CaF2, CoF2, ZnF2, CuF2, and AlF3 to the mass ratio of acetone is 20%; Add the mixture 2 into a hydrothermal kettle and seal it; heat it to a first preset temperature and keep it warm, then heat it to a second preset temperature and continue the hydrothermal treatment, the second preset temperature is higher than the first preset temperature; after the reaction is completed, cool it to room temperature to obtain a product, which is the mixture 3; Add the mixture 3 to the mixture 1, stir and seal; heat to a third preset temperature and keep warm; After cooling to room temperature, a mixture 4 was obtained; The mixture is dried and then placed in a tubular furnace, and an inert gas is introduced; the mixture is heated to a fourth preset temperature at a preset heating rate and kept warm; the mixture is cooled to room temperature and ball-milled to obtain a multi-component aluminum alloy NOCOLOK brazing flux.

3. The preparation method according to claim 2, characterized in that: The mixture is added into deionized water and stirred to obtain a mixture 1, wherein the stirring time is 10 to 30 minutes.

4. The preparation method according to claim 2, characterized in that: The mixture is added into acetone and stirred to obtain a second mixture, wherein the stirring time is 1 to 3 hours.

5. The preparation method according to claim 2, characterized in that: The step of heating to a first preset temperature and keeping the temperature, then heating to a second preset temperature and continuing the hydrothermal treatment comprises: heating to 75-105° C. and keeping the temperature for 2-4 hours; then heating to 170-220° C. and continuing the hydrothermal treatment for 1-3 hours.

6. The preparation method according to claim 2, characterized in that: Adding the mixture three to the mixture one, wherein the mass ratio of the mixture one to the mixture three satisfies the molar ratio of MgF2 to CaF2 of 0.8:0.

7.

7. The preparation method according to claim 2, characterized in that: Add the mixture 3 to the mixture 1, stir and seal, wherein the stirring time is 10 to 30 minutes.

8. The preparation method according to claim 2, characterized in that: The heating to the third preset temperature and keeping the temperature warm includes: heating to 120-140° C. and keeping the temperature warm for 2-4 hours.

9. The preparation method according to claim 2, characterized in that: The step of heating the temperature to a fourth preset temperature at a preset heating rate and keeping the temperature thereat comprises heating the temperature to 230-360° C. at a heating rate of 2° C. / min and keeping the temperature thereat for 3-6 hours.

10. The preparation method according to claim 2, characterized in that: After cooling to room temperature, ball milling is performed, wherein the ball milling time is 2 hours.

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