CN116021188A - Brazing material for copper-aluminum flame brazing and preparation method and application thereof - Google Patents
Brazing material for copper-aluminum flame brazing and preparation method and application thereof Download PDFInfo
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- CN116021188A CN116021188A CN202211717355.3A CN202211717355A CN116021188A CN 116021188 A CN116021188 A CN 116021188A CN 202211717355 A CN202211717355 A CN 202211717355A CN 116021188 A CN116021188 A CN 116021188A
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Abstract
The invention belongs to the technical field of copper-aluminum dissimilar metal brazing materials, and particularly relates to a brazing material for copper-aluminum flame brazing as well as a preparation method and application thereof. The brazing material for copper-aluminum flame brazing consists of the following components in percentage by mass: 15-20% of Al, 1-3% of Mn, 0.5-1.5% of Sr and the balance of Zn. The brazing material for copper-aluminum flame brazing can improve the oxidation resistance of the brazing filler metal and refine the brazing filler metal structure, can effectively improve the mechanical strength of copper-aluminum joints when being used for flame brazing copper-aluminum dissimilar metal joints, has the shearing strength of braze lap joint copper-aluminum joints reaching 95.2-105.3 MPa, and has good application prospects in the field of brazing copper-aluminum joints.
Description
Technical Field
The invention belongs to the technical field of copper-aluminum dissimilar metal brazing materials, and particularly relates to a brazing material for copper-aluminum flame brazing as well as a preparation method and application thereof.
Background
The copper-aluminum is connected to form the copper-aluminum dissimilar metal joint, so that the consumption of rare metal copper can be reduced, the weight of a component can be reduced, the respective performance advantages of copper and aluminum can be exerted, and the copper-aluminum dissimilar metal joint has been widely applied to the fields of electric power and refrigeration equipment and the like.
At present, in the manufacturing process of electric power and refrigeration equipment, flame brazing is often adopted to realize copper-aluminum welding of the Cu/Al joint. In the flame brazing process of copper-aluminum composite, the adopted brazing filler metal mainly comprises Sn-Pb brazing filler metal, sn-Zn brazing filler metal, al-Si brazing filler metal and Zn-Al brazing filler metal. Soft solder such as Sn-Pb, sn-Zn and the like needs to be matched with ZnCl 2 、NH 4 The corrosive solution with lower melting point such as Cl is used as the brazing flux, the process is complex, the cost is high, and the application of the brazing flux is limited. Compared with the Al-Si solder, the soldering temperature of the Zn-Al solder is generally 100 ℃ or more lower, which can provide a wider process window for the soldering process of aluminum and copper and can reduce the thermal stress of the joint and the generation amount of intermetallic compounds. In addition, the melting point of the Zn-Al solder is between that of the soft solder and that of the hard solder, so that the melting point of the Zn-Al solder can be conveniently adjusted, and the Zn-Al solder has excellent processability and mechanical properties. Therefore, the flame brazing is matched with the Zn-Al brazing filler metal to braze the copper-aluminum dissimilar metal, and the dissimilar metal is gradually applied in the industry, and currently, the dissimilar metal is commonly used in the aspects of Zn-2Al, zn-10Al, zn-15Al and Zn-22 Al. Because the melting point of the Zn-2Al, zn-10Al and Zn-15Al solders is relatively low, the brazing filler metals are the same as the CsF-AlF which is most commonly used at present 3 The corrosion-free brazing flux has poor suitability, so Zn-22Al is the most commonly used choice.
Although Zn-22Al solder achieves a certain effect in Cu/Al flame brazing, some problems still exist and are difficult to solve: firstly, the oxide on the surface of the Zn-22Al solder is basically composed of ZnO, and the ZnO film layer structure is loose and cannot play a role in protecting the solder; while the presence of such oxides in large amounts during brazing also deteriorates the brazing properties of the filler metal. Secondly, because the content of Al in Zn-22Al is higher, the Al can react with Cu parent metal to generate brittle compound phase inevitably, so that the mechanical strength of the soldered joint is obviously reduced, and the mechanical property of a soldered component is affected.
Therefore, how to optimize the composition of the Zn-22Al solder to further improve the mechanical properties of the copper-aluminum joint obtained by brazing the Zn-22Al solder becomes a technical problem to be solved.
Disclosure of Invention
In order to solve the problems, the invention aims to provide a brazing material for copper-aluminum flame brazing, which has excellent mechanical strength of a copper-aluminum joint obtained by brazing and belongs to the brazing application of the copper-aluminum joint.
The invention also provides a preparation method of the brazing material for copper-aluminum flame brazing, which is simple in process and suitable for industrial production.
The invention also provides application of the brazing material for copper-aluminum flame brazing, in particular application in preparing copper-aluminum composite joints by flame brazing.
In order to achieve the above object, the brazing material for copper-aluminum flame brazing of the present invention adopts the following technical scheme:
the brazing material for copper-aluminum flame brazing consists of the following components in percentage by mass: 15-20% of Al, 1-3% of Mn, 0.5-1.5% of Sr and the balance of Zn.
According to the brazing material for copper-aluminum flame brazing, disclosed by the invention, the novel Zn-Al-Mn-Sr brazing filler metal is prepared by controlling the addition amount of Zn and Al elements and simultaneously introducing Mn and Sr elements into the Zn-Al brazing filler metal, so that the brazing filler metal structure is optimized and the brazing performance is improved. Wherein, the invention introduces alkaline earth metal Sr, and the Sr is easy to generate SrO and SrO with oxygen atoms in the air in the melting process of the solder 2 The film is compact and is extremely easy to adhere to the surface of the solder, and when the solder is melted and enters the heat preservation process, the compact film layer can obstruct the interface reaction process, so that the generation speed of ZnO is reduced, and the oxidation resistance of the solder is improved. The improvement of the oxidation resistance can obviously reduce the viscosity of the solder, and is beneficial to the improvement of the wetting and spreading performance and the brazing performance of the solder. Furthermore, the invention adds the Sr element and the Mn element simultaneously, and the two elements cooperate to achieve the aim of refining the solder structure, so that after the Zn-Al-Mn-Sr solder is used for copper-aluminum brazing, the brittle phase at the interface is also refined, and the interface compound with smaller size is favorable for inhibiting the growth and expansion of cracks, thereby effectively improving the mechanical property of the joint.
In order to further optimize the brazing performance of the brazing material, preferably, the brazing material for copper aluminum flame brazing consists of the following components in percentage by mass: 16.5% Al,1.8% Mn,0.9% Sr and the balance Zn.
The invention relates to a preparation method of a brazing material for copper-aluminum flame brazing, which adopts the following technical scheme:
the preparation method of the brazing material for copper aluminum flame brazing comprises the following steps:
taking Zn, al-Mn intermediate alloy and Al-Sr intermediate alloy according to elements and proportions of a brazing material for copper-aluminum flame brazing; and (3) melting Zn and Al, heating to 740-760 ℃, adding Al-Mn intermediate alloy for smelting, preserving heat, covering by using a covering agent, continuously heating to 950-1050 ℃, adding Al-Sr intermediate alloy for continuous smelting, preserving heat, casting, extruding and reducing the diameter to obtain the brazing material for copper-aluminum flame brazing.
The preparation method of the brazing material for copper-aluminum flame brazing has simple process and is suitable for industrial production. In the method, a mode of adding the intermediate alloy for smelting is adopted, the intermediate alloy can reduce the melting temperature of metal, and the energy consumption in the step-by-step smelting process is reduced; in addition, the intermediate alloy can reduce segregation during metal smelting, avoid segregation phenomenon in the step smelting process, and contribute to the improvement of the strength of the braze welding joint.
Preferably, when Al-Mn intermediate alloy is added for smelting, the heat preservation time is 25-35 min.
Further, when Al-Sr intermediate alloy is added for continuous smelting, the heat preservation time is 15-25 min.
Preferably, the covering agent consists of KCl and NaCl; the mass ratio of KCl to NaCl is 1:1.
Further, the method also comprises the step of blowing argon gas to refine the melt before casting.
The invention relates to an application of a brazing material for copper-aluminum flame brazing, in particular to an application in preparing copper-aluminum composite joints by flame brazing.
Preferably, in the copper-aluminum composite joint, copper is red copper, and aluminum is pure aluminum.
Further, the methodThe brazing flux used for flame brazing is CsF-AlF 3 No corrosion soldering flux; the brazing flux comprises the following components in percentage by mass: 71.4% CsF,28.6% AlF 3 The method comprises the steps of carrying out a first treatment on the surface of the The temperature of flame brazing is 450-500 ℃ and the heat preservation time is 10-20 min. The invention adopts the non-corrosive brazing flux with the composition, and has low cost. And the brazing material of the present invention can be used with CsF-AlF 3 The corrosion-free brazing flux is effectively matched and has good brazing performance.
The brazing material for copper-aluminum flame brazing can improve the antioxidation capability of the brazing filler metal and effectively improve the mechanical strength of copper-aluminum joints. When the flame brazing process is adopted to braze the copper-aluminum joint, the shearing strength of the braze joint lap joint copper-aluminum joint reaches 95.2-105.3 MPa, and the method has good application prospect in the field of braze welding of the copper-aluminum joint.
Drawings
FIG. 1 is a graph showing the results of thermogravimetric analysis of a brazing material for copper-aluminum flame brazing in example 1 according to the present invention and a Zn-22Al brazing filler metal in comparative example 1 at different oxidation times.
Detailed Description
The technical scheme of the invention is further described below with reference to the specific embodiments. It will be appreciated by those skilled in the art that the following examples are illustrative of the present invention and are not to be construed as limiting the scope of the invention. In the following examples, the materials involved, unless otherwise specified, were all conventional commercial products.
Wherein, in the Al-Mn intermediate alloy, the mass ratio of Al to Mn is 70:30; in the Al-Sr intermediate alloy, the mass ratio of Al to Sr is 60:40.
Example 1
The brazing material for copper-aluminum flame brazing in the embodiment comprises the following components in percentage by mass: 16.5% Al,1.8% Mn,0.9% Sr and the balance Zn.
The preparation method of the brazing material for copper-aluminum flame brazing comprises the following steps:
taking Zn, al-Mn intermediate alloy and Al-Sr intermediate alloy according to elements and proportions of a brazing material for copper-aluminum flame brazing; putting metals Zn and Al into an intermediate frequency furnace for melting, adding an Al-Mn intermediate alloy for melting when the temperature of the molten liquid in the furnace reaches 750 ℃, preserving heat for 30min, covering by using a covering agent which is a mixture of KCl and NaCl in a mass ratio of 1:1, continuously heating to 1000 ℃, adding an Al-Sr intermediate alloy for continuously melting, preserving heat for 20min, cooling, blowing argon for refining, finishing the melting when the temperature is cooled to 700 ℃, pouring the solution into a casting mould to form an ingot, starting a cooling system in the pouring process, enabling the ingot to be rapidly cooled, obtaining a rod-shaped ingot with the diameter of 32mm, extruding the rod-shaped ingot, and processing the rod-shaped ingot into a filament-shaped brazing filler metal by drawing reducing, thereby obtaining the brazing material for copper-aluminum flame brazing.
Example 2
The brazing material for copper-aluminum flame brazing in the embodiment comprises the following components in percentage by mass: 15% of Al,1% of Mn,0.5% of Sr and the balance of Zn.
The preparation method of the brazing material for copper-aluminum flame brazing comprises the following steps:
taking Zn, al-Mn intermediate alloy and Al-Sr intermediate alloy according to elements and proportions of a brazing material for copper-aluminum flame brazing; putting metals Zn and Al into an intermediate frequency furnace for melting, adding an Al-Mn intermediate alloy for melting when the temperature of the molten liquid in the furnace reaches 740 ℃, preserving heat for 30min, covering by using a covering agent which is a mixture of KCl and NaCl in a mass ratio of 1:1, continuously heating to 950 ℃, adding the Al-Sr intermediate alloy for continuously melting, preserving heat for 20min, cooling, blowing argon for refining, finishing the melting when the temperature is cooled to 700 ℃, pouring the solution into a casting mould to form an ingot, starting a cooling system in the pouring process, enabling the ingot to be rapidly cooled, obtaining a rod-shaped ingot with the diameter of 32mm, extruding the rod-shaped ingot, and processing the rod-shaped ingot into a filament-shaped brazing filler metal by drawing reducing, thereby obtaining the brazing material for copper-aluminum flame brazing.
Example 3
The brazing material for copper-aluminum flame brazing in the embodiment comprises the following components in percentage by mass: 20% of Al,3% of Mn,1.5% of Sr and the balance of Zn.
The preparation method of the brazing material for copper-aluminum flame brazing comprises the following steps:
taking Zn, al-Mn intermediate alloy and Al-Sr intermediate alloy according to elements and proportions of a brazing material for copper-aluminum flame brazing; putting metals Zn and Al into an intermediate frequency furnace for melting, adding an Al-Mn intermediate alloy for melting when the temperature of the molten liquid in the furnace reaches 760 ℃, preserving heat for 30min, covering by using a covering agent which is a mixture of KCl and NaCl in a mass ratio of 1:1, continuously heating to 1050 ℃, adding the Al-Sr intermediate alloy for continuously melting, preserving heat for 20min, cooling, blowing argon for refining, finishing the melting when the temperature is cooled to 700 ℃, pouring the solution into a casting mould to form an ingot, starting a cooling system in the pouring process, enabling the ingot to be rapidly cooled, obtaining a rod-shaped ingot with the diameter of 32mm, extruding the rod-shaped ingot, and processing the rod-shaped ingot into a filament-shaped brazing filler metal by drawing reducing, thereby obtaining the brazing material for copper-aluminum flame brazing.
Comparative example 1
The brazing material of the comparative example is Zn-22Al brazing filler metal and consists of the following components in percentage by mass: 22% of Al and the balance of Zn.
Comparative example 2
The brazing material of the comparative example is Zn-Al brazing filler metal and consists of the following components in percentage by mass: 16.5% Al, the balance Zn.
Comparative example 3
The brazing material of the comparative example is Zn-Al-Mn brazing filler metal and consists of the following components in percentage by mass: 16.5% Al,1.8% Mn, the balance Zn.
Comparative example 4
The brazing material of the comparative example is Zn-Al-Sr brazing filler metal and consists of the following components in percentage by mass: 16.5% Al,0.9% Sr and the balance Zn.
Test examples
1. Thermogravimetric analysis test
The test was performed using a Pyris Diamond thermogravimetric/differential thermal comprehensive thermal analyzer from Perin-Elmer. In the test, the heating rate is 20 ℃/min, the initial weight of the brazing filler metal is 20mg, the final heating temperature is 530 ℃, the heat preservation time is 30min, the test atmosphere is air, and the change curves of the brazing filler metal mass along with the temperature and time in the heating process are recorded respectively. The thermal weight loss mass of the Zn-Al-Mn-Sr braze of example 1 and that of the conventional Zn-22Al braze of comparative example 1 at different oxidation times were analyzed. The results are shown in FIG. 1.
As can be seen from FIG. 1, the weight of the Zn-22Al filler metal continuously increased with the increase of the heating time during the heat preservation, indicating that the oxidation process of the Zn-22Al filler metal was continuously performed during the heating process. The weight of the Zn-Al-Mn-Sr brazing filler metal added with Sr and Mn elements has the tendency of rising and then gradually stabilizing, this is presumably due to the formation of SrO and SrO by the Sr element in the Zn-Al-Mn-Sr solder and the oxygen atom in the air 2 The compact film layer can obstruct the interface reaction process and reduce the oxygen atom diffusion speed, thereby reducing the ZnO generation speed and effectively improving the oxidation resistance of the solder.
2. Brazing performance test
The brazing performance test adopts pure aluminum and red copper as parent materials, the size is 60mm multiplied by 25mm multiplied by 3mm, the lap joint length of the lap joint is 3mm, the joint is placed in a normal clearance (about 0.15 mm), and the brazing flux is CsF-AlF 3 The brazing flux has a composition of 71.4% CsF and 28.6% AlF 3 Flame brazing temperature is 475 ℃, and heat preservation time is 15min. The shear performance test of the soldered joint is implemented by referring to national standard GB/T11363-2008 "method for testing strength of soldered joint", the device is a SANS-CMT5105 universal tensile testing machine, and the loading rate in the tensile process is 3mm/min. The brazing materials of examples 1 to 3 and comparative examples 1 to 4 were flame-brazed to obtain copper-aluminum joints of the same specifications. The results are shown in Table 1.
Table 1 braze material compositions of examples 1 to 3 and comparative examples 1 to 4 and strengths of braze-obtained copper-aluminum joints
As shown in Table 1, the Al/Cu alloy soldered joint obtained by soldering with Zn-Al-Mn-Sr solder shows excellent mechanical properties, and the shear strength of the joint is as high as 95.2-105.3 MPa. While the braze joint strengths of comparative examples 1-4 were all significantly lower than the present invention. Therefore, the invention adds Mn and Sr elements, improves the structure and performance of the solder and the soldered joint, and can greatly improve the strength of the soldered joint.
In conclusion, the brazing material for copper-aluminum flame brazing can improve the antioxidation capability of the brazing filler metal and effectively improve the mechanical strength of the copper-aluminum joint. When the flame brazing process is adopted to braze the copper-aluminum joint, the shearing strength of the braze joint lap joint copper-aluminum joint reaches 95.2-105.3 MPa, and the method has good application prospect in the field of braze welding of the copper-aluminum joint.
Claims (10)
1. The brazing material for copper-aluminum flame brazing is characterized by comprising the following components in percentage by mass: 15-20% of Al, 1-3% of Mn, 0.5-1.5% of Sr and the balance of Zn.
2. The brazing material for copper aluminum flame brazing according to claim 1, comprising the following components in percentage by mass: 16.5% Al,1.8% Mn,0.9% Sr and the balance Zn.
3. A method for producing a brazing material for copper aluminum flame brazing as claimed in claim 1, comprising the steps of:
taking Zn, al-Mn intermediate alloy and Al-Sr intermediate alloy according to elements and proportions of a brazing material for copper-aluminum flame brazing; and (3) melting Zn and Al, heating to 740-760 ℃, adding Al-Mn intermediate alloy for smelting, preserving heat, covering by using a covering agent, continuously heating to 950-1050 ℃, adding Al-Sr intermediate alloy for continuous smelting, preserving heat, casting, extruding and reducing the diameter to obtain the brazing material for copper-aluminum flame brazing.
4. The method for producing a brazing material for copper aluminum flame brazing according to claim 3, wherein the time for heat preservation is 25 to 35 minutes when the Al-Mn master alloy is added for melting.
5. The method for producing a brazing material for copper aluminum flame brazing according to claim 3, wherein the time for heat preservation is 15 to 25 minutes while the addition of the Al-Sr intermediate alloy is continued.
6. The method for producing a brazing material for copper aluminum flame brazing according to any one of claims 3 to 5, wherein the covering agent consists of KCl and NaCl; the mass ratio of KCl to NaCl is 1:1.
7. The method for producing a brazing material for copper aluminum flame brazing according to any one of claims 3 to 5, further comprising the step of refining the melt by blowing argon gas before casting.
8. Use of a brazing material for flame brazing of copper and aluminium according to claim 1 or 2, in the manufacture of a copper-aluminium composite joint by flame brazing.
9. The use of a brazing material for flame brazing of copper and aluminum according to claim 8, wherein in the copper-aluminum composite joint, copper is red copper and aluminum is pure aluminum.
10. The use of brazing material for flame brazing of copper and aluminum according to claim 8, wherein the brazing flux used for flame brazing is CsF-AlF 3 No corrosion soldering flux; the brazing flux comprises the following components in percentage by mass: 71.4% CsF,28.6% AlF 3 The method comprises the steps of carrying out a first treatment on the surface of the The temperature of flame brazing is 450-500 ℃ and the heat preservation time is 10-20 min.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211717355.3A CN116021188A (en) | 2022-12-29 | 2022-12-29 | Brazing material for copper-aluminum flame brazing and preparation method and application thereof |
| ZA2023/01568A ZA202301568B (en) | 2022-12-29 | 2023-02-08 | A brazing material for copper-aluminum flame brazing, preparation method and application thereof |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202211717355.3A CN116021188A (en) | 2022-12-29 | 2022-12-29 | Brazing material for copper-aluminum flame brazing and preparation method and application thereof |
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| CN116021188A true CN116021188A (en) | 2023-04-28 |
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| CN202211717355.3A Pending CN116021188A (en) | 2022-12-29 | 2022-12-29 | Brazing material for copper-aluminum flame brazing and preparation method and application thereof |
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| CN (1) | CN116021188A (en) |
| ZA (1) | ZA202301568B (en) |
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- 2022-12-29 CN CN202211717355.3A patent/CN116021188A/en active Pending
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