High-resistivity copper-phosphorus-antimony brazing filler metal and preparation method and application thereof

Abstract

The invention relates to high-resistivity copper-phosphorus-antimony brazing filler metal and a preparation method and application thereof, the high-resistivity copper-phosphorus-antimony brazing filler metal is composed of, by mass, 5.0%-8.0% of phosphorus, 0.3%-2.0% of antimony and the balance copper and impurities, and the total amount of the impurities is smaller than 0.2%. The preparation method of the high-resistivity copper-phosphorus-antimony brazing filler metal comprises the following steps: S1, medium-frequency induction melting: firstly melting pure copper and Cu-P intermediate alloy; s2, gradient antimony adding, wherein antimony is wrapped with copper foil and then added into a molten pool for multiple times to be smelted at the temperature of 800-900 DEG C; s3, extrusion forming: heating to 450-500 DEG C for hot extrusion forming; and S4, hot and cold drawing processing: drawing and reducing to obtain a finished product, wherein the percentage reduction of area is less than or equal to 20% per time during drawing. The resistivity is greatly improved, the percentage elongation after fracture is kept to be larger than or equal to 5.0%, the metallographic structure is kept to be of a uniform solid solution structure, real self-fluxing welding is achieved, energy is saved, environmental protection is facilitated, the welding time is short, and the efficiency is high.

Description

Technical Field

[0001] The present application relates to a high-resistivity copper-phosphorus-antimony brazing filler metal and a preparation method and application thereof, which is mainly suitable for self-fluxing resistance welding applications. Background Art

[0002] Existing copper-phosphorus brazing filler metals (Cu~P) have the following technical defects in resistance welding applications: 1. The basic resistivity is low (0.361 mΩ.mm), resulting in insufficient Joule heat generation during welding; 2. Traditional alloying methods significantly reduce material ductility and affect forming processing; 3. Conventional additive elements (such as Ag, Sn, etc.) have limited effect on improving resistivity (<5% increase), increasing manufacturing costs. Summary of the Invention

[0003] The technical problem solved by the present application is to overcome the above-mentioned deficiencies in the prior art and provide a high-resistivity copper-phosphorus-antimony brazing filler metal and its preparation method and application, innovatively introducing antimony element (Sb), significantly improving the resistivity of the alloy while maintaining good processing performance, and facilitating direct self-melting welding.

[0004] The technical solution adopted by the present application to solve the above technical problems includes: a high-resistivity copper-phosphorus-antimony solder, characterized in that the high-resistivity copper-phosphorus-antimony solder is composed of the following mass percentages: phosphorus 5.0%~8.0%, antimony 0.3~2.0%, and the remainder copper and unavoidable impurities, and the total amount of impurities is less than 0.2%.

[0005] As a further improvement, the high resistivity copper-phosphorus-antimony brazing filler metal is composed of the following mass percentages: phosphorus 6.0%-7.2%, antimony 1-1.8%, and the balance copper and unavoidable impurities, with the total amount of impurities being less than 0.2%.

[0006] The technical solution adopted by the present application to solve the above technical problems also includes: a method for preparing the above high resistivity copper phosphorus antimony brazing material, which is characterized by comprising the following steps: S1 medium frequency induction melting: first melt pure copper and Cu~P master alloy; S2 gradient antimony addition: Wrap the antimony element with 0.1mm copper foil and add it into the molten pool several times (more than twice, three times in special cases). The molten pool temperature is between 800~900℃, and then cool and cast into ingots; S3 extrusion molding: the ingot is heated to 450~500℃ and hot extruded; S4 Hot and cold drawing: drawing and reducing the diameter to the finished product, the cross-sectional shrinkage rate during drawing is ≤20% / time.

[0007] In step S3, the copper phosphorus antimony brazing wire is hot extruded into a 1.8 mm thick wire.

[0008] In step S4, the copper phosphorus antimony brazing wire is drawn and reduced in diameter to 1.6 mm.

[0009] The technical solution adopted by the present application to solve the above technical problems also includes: application of the high-resistivity copper-phosphorus-antimony brazing filler metal prepared by the above-mentioned preparation method of the high-resistivity copper-phosphorus-antimony brazing filler metal in self-fluxing resistance welding.

[0010] Compared with the existing technology, the present application has the following advantages and effects: when 2% Sb is added, the resistivity is increased by 19%, the elongation after fracture is maintained at ≥5.0%, the metallographic structure maintains a uniform solid solution structure, and in resistance welding applications, the welding current can be reduced by 10.0~15.0%, achieving true autogenous welding, saving energy, and being beneficial to environmental protection. At the same time, the welding time is short and the efficiency is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 A schematic curve diagram showing the effect of different antimony contents on the resistivity of copper-phosphorus solder.

[0012] Figure 2 This is a schematic diagram of the metallographic structure (200×) of Example 2 of the present application. DETAILED DESCRIPTION

[0013] The present application will be further described in detail below with reference to the accompanying drawings and examples. The following examples are intended to explain the present application but the present application is not limited to the following examples.

[0014] When the original mass percentage composition of copper-phosphorus solder is 6.8% phosphorus, the rest copper and impurities, and the impurities are less than 0.2%, the antimony content in the original copper-phosphorus solder is gradually increased, and the resistivity test results are as follows: Figure 1 shown.

[0015] Based on the above principles, this application conducted 17 tests with phosphorus content ranging from 5.0% to 8.0% and antimony content ranging from 0% to 2.0%. The experimental results are as follows (accurate to 2 decimal places): The above experiments demonstrate that this application significantly improves resistivity through the lattice distortion effect of Sb, while simultaneously controlling the Sb addition to ≤2.0% to avoid the formation of brittle phases. Tests have shown that this solder can reduce welding current by 10.0-15.0% in resistance welding applications. Using a 15-30V voltage to heat the wire, automatic wire feeding allows for precise control of wire usage and heat input, resulting in a 21% improvement in welding time efficiency, shortening welding time by 2-5 seconds.

Claims

1. A high resistivity copper-phosphorus-antimony brazing filler metal, characterized by: The high resistivity copper-phosphorus-antimony solder is composed of the following mass percentages: phosphorus 5.0%-8.0%, antimony 0.3%-2.0%, and the remainder copper and inevitable impurities, with the total amount of impurities being less than 0.2%.

2. The high resistivity copper-phosphorus-antimony brazing filler metal according to claim 1, wherein: The high resistivity copper-phosphorus-antimony solder comprises the following mass percentages: phosphorus 6.0%-7.2%, antimony 1-1.8%, and the remainder copper and inevitable impurities, with the total amount of impurities being less than 0.2%.

3. The method for preparing the high resistivity copper-phosphorus-antimony solder according to claim 1, wherein The following steps are involved: S1 medium frequency induction melting: first melt pure copper and Cu~P master alloy; S2 gradient antimony addition: Antimony is wrapped with 0.1mm copper foil and added to the molten pool in several times. The molten pool temperature is between 800~900℃; S3 extrusion molding: The molten alloy is cooled to 450~500℃ and then hot extruded; S4 Hot and cold drawing: drawing and reducing the diameter to the finished product, the cross-sectional shrinkage rate during drawing is ≤20% / time.

4. The method for preparing the high resistivity copper-phosphorus-antimony solder according to claim 3, wherein: Hot extruded into 1.8mm copper phosphorus antimony brazing wire.

5. The method for preparing the high resistivity copper-phosphorus-antimony solder according to claim 4, wherein: Copper phosphorus antimony brazing wire is drawn and reduced to 1.6mm in diameter.

6. Use of the high resistivity copper-phosphorus-antimony solder prepared according to any one of claims 3 to 5, characterized in that: Application of the high-resistivity copper-phosphorus-antimony solder in self-fluxing resistance welding.

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