Copper-phosphorus Brazing Foil and Preparation Method Thereof

Abstract

The present disclosure provides a copper-phosphorus brazing foil and a preparation method thereof, which relates to the technical field of brazing material. It comprises a copper inner core and a copper-phosphorus alloy layer coating outside the copper inner core, wherein the phosphorus content in the copper-phosphorus brazing foil is over 5 wt %, and the thickness of the copper-phosphorus brazing foil is below 0.5 mm. In the present disclosure, red copper foil is used as the core layer, and the surface of the red copper foil is alloyed with a layer of copper-phosphorus alloy by the eutectic reaction between the core layer and red phosphorus, such that the copper-phosphorus brazing foil is obtained. The present disclosure prepares a copper-phosphorus brazing foil with high phosphorus content and lower thickness. Comparing with the traditional preparation method, the preparation method of the present disclosure has high efficiency and high yield.

Claims

1. A copper-phosphorus brazing foil, wherein the copper-phosphorus brazing foil comprises a copper inner core and a copper-phosphorus alloy layer coating on an outside of the copper inner core, wherein a phosphorus content in the copper-phosphorus brazing foil is more than or equal to 5 wt %, and a thickness of the copper-phosphorus brazing foil is less than or equal to 0.5 mm.

2. The copper-phosphorus brazing foil according to claim 1, wherein the phosphorus content in the copper-phosphorus brazing foil is 7 wt % or more, preferably 7-8.4 wt %.

3. A method for preparing the copper-phosphorus brazing foil according to claim 1, wherein a red copper foil is used as a core layer, and a surface of the red copper foil is alloyed to form a layer of copper-phosphorus alloy by an eutectic reaction between the core layer and red phosphorus, so as to obtain the copper-phosphorus brazing foil.

4. The method for preparing the copper-phosphorus brazing foil according to claim 3, wherein a thickness of the red copper foil is 0.1-0.5 mm.

5. The method for preparing the copper-phosphorus brazing foil according to claim 3, wherein the red copper foil is pretreated, wherein the pretreatment comprises that after the red copper foil is polished with a sandpaper and wiped with alcohol, a surface of the red copper foil is coated with a layer of copper flux.

6. The method for preparing the copper-phosphorus brazing foil according to claim 3, wherein a purity of the red phosphorus is greater than or equal to 99.99%, and the red phosphorus is heated to molten red phosphorus with a temperature of 650-720 C., preferably, the core layer of the red copper foil is enabled to pass through the molten red phosphorus at a speed of 5-15 mm/s.

7. A device for preparing a copper-phosphorus brazing foil, applicable to the method for preparing the copper-phosphorus brazing foil according to claim 2, wherein the device comprises a pay-off reel, an airtight container (9), a take-up reel and a motor, wherein the airtight container (9) comprises a feeding hole (2), a discharge hole (8) and an air-inlet hole (6); the airtight container is provided therein with a guide wheel 1(3), a guide wheel 2 (4) and a guide wheel 3 (7); and an induction coil (10) is provided at a bottom of the airtight container (9).

8. The device according to claim 7, wherein the feeding hole and the discharge hole are provided with seals or a sealing material for sealing an inner cavity of the container to achieve dynamic sealing of the container.

9. The device according to claim 7, wherein the sealing material is a graphite packing ring.

10. The device according to claim 7, wherein the guide wheel 1, the guide wheel 2 and the guide wheel 3 are all aluminum oxide guide wheels.

11. The device according to claim 8, wherein the sealing material is a graphite packing ring.

12. The device according to claim 8, wherein the guide wheel 1, the guide wheel 2 and the guide wheel 3 are all aluminum oxide guide wheels.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0046] In order to illustrate the technical solutions in the specific embodiments of the present disclosure or the prior art more clearly, the drawings required to be used in the description of the specific embodiments or the prior art will be described briefly in the following parts. Obviously, the drawings in the following description are some embodiments of the present disclosure. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without creative efforts.

[0047] FIG. 1 is the flow chart of the preparation process provided by an embodiment of the present disclosure (1, red copper foil; 2, feeding hole; 3, guide wheel 1; 4, guide wheel 2; 5, airtight container cover plate; 6, air-inlet hole; 7, guide wheel 3; 8, discharge hole; 9, airtight container; 10, induction coil); and

[0048] FIG. 2 shows a metallographic photograph of the section of the brazing foil of the present disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

[0049] The technical solutions of the present disclosure will be described clearly and completely below with reference to the embodiments. Obviously, the described embodiments are part of the embodiments of the present disclosure, but not all of the embodiments. Based on the embodiments of the present disclosure, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present disclosure.

Example 1

[0050] A copper-phosphorus brazing foil is composed of a two-layer structure, the inner core layer is red copper, and the outer part is copper-phosphorus alloy.

[0051] The preparation method of copper-phosphorus brazing foil as mentioned above comprises the following steps: [0052] Step (1): opening the cover plate of the medium-pressure container, putting an appropriate amount of red phosphorus of a purity 99.99% at the bottom of the airtight container; [0053] Step (2): taking a red copper foil (with the thickness of 0.5 mm), after polishing the red copper foil with sandpaper and wiping it with alcohol, coating a layer of copper flux on the surface thereof; [0054] Step (3): making the red copper foil of step (2) enter the feeding hole, pass through the guide wheel 1, guide wheel 2 and guide wheel 3 inside the container, and finally wound on the take-up reel through the discharge hole; [0055] Step (4): closing the cover plate, sleeving the induction coil over the bottom of the container, and setting the dynamic sealing material at the discharge hole and the feeding hole of the container; [0056] Step (5): filling gas into the airtight container through the air-inlet hole, when the pressure in the airtight container reaches 4300 Kpa, energizing the coil and starting heating to 720 C., such that the red phosphorus melts into a liquid state; and [0057] Step (6): turning on the motor of the take-up reel, making the red copper foil pass through the molten red phosphorus at a certain speed (5 mm/s), and winding up to get the copper-phosphorus brazing foil having a phosphorus content of 8.4% and a thickness of 0.5 mm.

[0058] In the above, the guide wheel 1, guide wheel 2, and guide wheel 3 in step (3) are made of aluminum oxide.

[0059] The dynamic sealing material in step (4) is graphite packing ring.

[0060] FIG. 1 is a schematic diagram of the preparation device used in the above steps, including a pay-off reel, an airtight container, a take-up reel and a motor placed in sequence. The inside of the airtight container is provided with guide wheel 1, guide wheel 2 and guide wheel 3. The outside of airtight container is provided with air-inlet hole, and its feeding hole and discharge hole are provided with dynamic sealing materials; and the bottom of the airtight container is sleeved into the appropriate position of the induction coil.

[0061] Firstly, the cover plate of the container is opened, an appropriate amount of red phosphorus is put on the bottom of the airtight container, and then the pretreated red copper foil is pulled by the pay-off reel, enters the feeding hole of the airtight container, is guided by the guide wheel 1, guide wheel 2, and guide wheel 3, finally passes through the discharge hole of the airtight container and is wound on the take-up reel. The cover plate is closed, the coil power supply is turned on, and the airtight container is heated to a certain temperature, such that the red phosphorus melts into metal liquid. The take-up reel motor is turned on, and the entered red copper foil is passed through the molten red phosphorus at a certain speed, and wound up to obtain the copper-phosphorus brazing foil with thickness of 0.18 mm.

Example 2

[0062] The preparation method of the brazing filler metal in this example is identical to that in Example 1.

[0063] The difference is that the wire diameter of the red copper foil in step (2) is 0.4 mm; the heating temperature in step (5) is 710 C., and the certain speed in step (6) is 8 mm/s.

[0064] In this example, the thickness of the brazing foil obtained is 0.42 mm, and the content of P in the brazing foil is 8%.

Example 3

[0065] The preparation method of the brazing filler metal in this example is identical to that in Example 1.

[0066] The difference is that the wire diameter of the red copper foil in step (2) is 0.3 mm; the heating temperature in step (5) is 700 C., and the certain speed in step (6) is 10 mm/s.

[0067] In this example, the thickness of the brazing foil obtained is 0.35 mm, and the content of P in the brazing foil is 7.8%. (FIG. 2 shows the cross-sectional metallographic structure of the brazing foil).

Example 4

[0068] The preparation method of the brazing filler metal in this example is identical to that in Example 1.

[0069] The difference is that the wire diameter of the red copper foil in step (2) is 0.2 mm; The heating temperature in step (5) is 680 C.; and the certain speed in step (6) is 12 mm/s.

[0070] In this example, the thickness of the brazing foil obtained is 0.25 mm, and the content of P in the brazing foil is 7.5%.

Example 5

[0071] The preparation method of the brazing filler metal in this example is identical to that in Example 1.

[0072] The difference is that the wire diameter of the red copper foil in step (2) is 0.1 mm; the heating temperature in step (5) is 650 C., and the certain speed in step (6) is 15 mm/s.

[0073] In this example, the thickness of the brazing foil obtained is 0.15 mm, and the content of P in the brazing foil is 7%.

Comparative Example 1

[0074] In order to investigate the efficiency and the yield of the preparation method of the present disclosure, 10 kg of BCu93P brazing filler metal with a thickness of 0.45 mm is prepared by using the hot drawing and rolling in the prior art and the method of the present disclosure, respectively.

[0075] If using the method in the prior art (hot drawing and rolling), at least 10 times of rolling (1.8, 1.6, 1.4, 1.2, 1.0, 0.8, 0.7, 0.6, 0.5, 0.45) are needed for the hot-extruded brazing strip with a thickness of 2.0 mm, each rolling takes about 10 minutes, totally 100 minutes.

[0076] By adopting the preparation method of the present disclosure, it only needs to take red copper foil with a thickness of 0.4 mm, which is wound up in the take-up reel through the guide wheels in the airtight container, which takes about 20 minutes. Therefore, the efficiency of the present disclosure is 5 times that of the existing method.

[0077] In addition, when using the existing method to prepare BCu93P brazing foil with 0.45 mm thickness, 6 kg of 0.45 mm of brazing foil can be finally obtained from 10 kg of 2.0 mm of BCu93P brazing strip. In the present disclosure, 11.5 kg of BCu93P brazing wire with a thickness of 0.45 mm can be finally obtained from 10 kg of red copper foil with a thickness of 0.4 mm, and the yield is much higher than that of the existing method.

[0078] The comparison is shown in Table 1.

TABLE-US-00001 TABLE 1 Comparison of the two methods Production Efficiency Yield (%) (kg/hour) Existing Method 60 1.6 Method of the Present 100 30 Disclosure

[0079] To sum up, the existing preparation method is difficult to prepare copper-phosphorus brazing foil with the same composition and specification and having a thickness below 0.5 mm, and its yield is low. The present disclosure overcomes the limitation of the existing method, and is able to produce copper-phosphorus brazing foil with the same composition and specification and having a thickness below 0.5 mm with high yield. Taking 0.2 mm BCu93P brazing filler metal as an example, the probability of brittle rupture and edge cracking in the prior art is 100%, the brittle rupture is serious, and the yield is extremely low. However, if the present disclosure is adopted, the brittle rupture and edge cracking will not occur.

[0080] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present disclosure, but not to limit it; although the present disclosure has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that it is still possible to modify the technical solutions recorded in the forementioned embodiments, or perform equivalent replacement to some or all of the technical features therein; and these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present disclosure.