Copper-based brazing filler metal capable of accurately controlling using amount of brazing flux and good in brazing seam protection effect

Abstract

The invention belongs to the field of welding materials, and particularly relates to copper-based brazing filler metal capable of accurately controlling the using amount of brazing flux and good in brazing seam protection effect. The copper-based brazing filler metal comprises a round or oval copper-based brazing filler metal inner wire and a protective film; the protective film is prepared from 10%-12% of zinc phosphide powder, 5%-7% of kyanite powder, 3%-5% of glass fibers, 2.5%-3.5% of nano silicon dioxide powder, 10%-12% of boric anhydride powder and 20%-25% of potassium fluoborate powder which are all treated by the aid of a coupling agent, 5.5%-6.5% of a curing agent and the balance epoxy resin. In the preparation process, the wire breakage phenomenon is avoided, the wettability of the brazing filler metal is high during brazing, and gaps between workpieces to be welded can be effectively filled; during brazing, the using amount of the brazing flux can be accurately controlled, and the problem that the using amount of the brazing flux is not enough during brazing or a large amount of the brazing flux is left after brazing is solved; during brazing, the protection effect on brazing seams is good, the protection layer is easy to remove, the brazing seams have few defects, and the strength is high.

Description

technical field [0001] The invention belongs to the technical field of welding materials, in particular to a copper-based solder that can precisely control the amount of flux and has a good protective effect on brazing seams. Background technique [0002] With the rapid development of industrial technologies such as automobiles, microelectronics, electrical appliances, tools, refrigeration, exploration, tunneling, aerospace, etc., brazing technology has been widely used in these fields due to its unique advantages. For copper alloys, copper-based solder is required for brazing. Generally, copper-based solder is used in conjunction with flux. Flux is used to remove the oxide film on the surface of the base metal and protect the brazed joint from oxidation. [0003] At present, there are two types of copper-based solders commonly used: solid solder and cored solder. During the preparation and use, there are the following technical problems: [0004] (1) When using solid coppe...

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Problems solved by technology

[0004] (1) When using solid copper-based solder: ① In order to increase the wettability during brazing and dilute the melted solder, most of the chemical composition of the solder contains phosphorus, so that it can be enhanced after the solder is melted. Fluidity, so as to achieve the purpose of filling the gap to obtain a perfect brazing joint, but the existence of phosphorus element, it is easy to form a low-melting eutectic structure Cu+Cu with a melting temperature of about 714 ° C in copper alloy 3 The P brittle phase leads to increased brittleness of the solder at room temperature and a decrease in toughness. The copper-based solder wire can only be squeezed or drawn in a hot state, and it is easy to break, reducing the single copper-based solder wire. length, which increases the difficulty in the preparation process; ② When using flux, one method is to apply it on the surface of the solder, and the other is to apply it on the surface of the workpiece to be welded, but the amount of flux added cannot be precisely controlled, and there is often flux Excessive use will cause the problem of excessive flux residue after welding. The use of excessive flux will generate a lot of smoke and dust, seriously pollute the environment, and endanger the health of operators, and there is a great potential safety hazard; ③Protection of the brazing seam during brazing The effect is not good, the obtained brazing seam has defects such as pores, and the brazing seam strength is low

[0005] (2) When using flux-cored copper-based solder: ①During the drawing process of the preparation, the outer skin copper alloy undergoes plastic deformation, the diameter of the outer tubular solder is reduced and the length is extended, and the powdered flux filled in the core is not connected. Strength, plastic deformation will not occur during drawing and diameter reduction, radial and longitudinal flow is difficult, causing the flux to be compacted, hindering the plastic deformation of the solder, making the flux-cored solder particularly easy to break, reducing the copper-based The single length of flux-cored solder wire reduces the production efficiency; ②The protective effect on the brazing seam during brazing is not good, the obtained brazing seam has defects such as pores, and the brazing seam strength is low

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