Copper-based flux-cored solder wire easy to prepare, high in wettability and high in soldering seam strength

Abstract

The invention belongs to the field of a welding material, and particularly relates to a copper-based flux-cored solder wire easy to prepare, high in wettability and high in soldering seam strength. The copper-based flux-cored solder wire comprises outer skin and flux core powder; the flux core powder comprises 5%-8% of nano hexagonal boron nitride, 8%-12% of nano zinc carbonate, 16%-20% of zinc phosphide, 25% of borax, 18% of boric acid, 7% of potassium fluoride and the balance of tin powder; the outer skin contains 8%-12% of silver, 1.2%-2.5% of indium, 1.5%-2.2% of antimony and the balance of copper; and the mass of the flux core powder accounts for 25%-32% of the total mass of the flux-cored solder wire. According to the invention, no brittle phase exists in the outer skin; the nano hexagonal boron nitride with high lubricity is contained in the flux core powder; wires are not broken in the drawing process, and the copper-based flux-cored solder wire is easy to prepare; the wettability of brazing filler metal can be enhanced through the existence of phosphorus after zinc phosphide in the flux core powder is molten during brazing and the stirring effect of overflow of carbon dioxide; the nano hexagonal boron nitride and decomposed nano zinc oxide can effectively improve the strength of a brazing seam, and a brazing flux does not need to be matched during brazing.

Description

technical field [0001] The invention belongs to the technical field of welding materials, in particular to a copper-based flux-cored brazing wire which is easy to prepare, has strong wettability and high brazing seam strength. Background technique [0002] With the development of modern industrial technology, especially the development of aerospace, automobile, microelectronics and other industrial technologies, brazing technology has been widely used due to its unique advantages, and has become one of the most active and promising fields. And solder has also obtained great demand as the soldering material of brazing. Copper-based solder is widely used in refrigeration, electromechanical, tools, automobiles, exploration, excavation and other industries, and is used for brazing copper and copper alloys and other metal materials. [0003] There are two kinds of copper-based brazing wires commonly used now: one is solid brazing wire, and the other is flux-cored brazing wire. ...

AI Technical Summary

Problems solved by technology

However, the presence of phosphorus element is easy to form a low-melting eutectic structure Cu+Cu with a melting temperature of about 714°C in copper alloys. 3 The P brittle phase causes the skin of solid copper-based solder or flux-cored copper-based solder to increase in brittleness at room temperature, reducing its toughness. Copper-based solder wire can only be squeezed or drawn in a hot state, and it is easy to Pulling off reduces the single length of copper-based solder wire and increases the difficulty in the preparation process

[0008] (2) The skin of solid copper-based solder or flux-cored copper-based solder that does not contain phosphorus has good plasticity and is relatively easy to prepare, but the absence of phosphorus will result in poor wettability during brazing and melting After the solder has poor fluidity, it is not easy to fill the gap between the workpieces to be welded, and the obtained solder joint has low strength

[0009] (3) When preparing flux-cored copper-based solder wire, even though the copper alloy on the outer sheath does not contain phosphorus elements and has good plasticity, the inner core powder will not undergo plastic deformation during drawing and diameter reduction. Often compacted, radial and longitudinal flow is difficult, resulting in easy wire breakage during drawing

However, this technical solution has the following deficiencies: ① Although the lubricant is used to enhance the lubricating effect of the solder during drawing, it cannot change the problem that the radial and longitudinal flow of the core powder is difficult, resulting in the drawing of the core powder. There are still great difficulties when reducing the diameter. Although there is no broken wire problem in the embodiments of this patent, there is still a broken wire phenomenon in actual production and application; At least one, this is the grade of copper-zinc solder in GB / T 6418-2008 "Copper-based solder". The alloy composition does not contain phosphorus, which will cause poor fluidity and wettability of the molten solder during brazing , it is not easy to fill the gap between the workpieces to be welded; ③ After the drawing is completed, the lubricant remaining on the surface of the flux-cored copper solder or entering the core of the flux-cored solder forms a glassy slag shell during welding. During the floating process, the fluidity and wettability of the molten solder will be hindered; ④Although the glassy slag shell floats on the surface of the brazing joint to protect the brazing joint, the effect is limited, and the strength of the brazing joint has not been significantly improved , the test result of the brazing joint strength is not given in the patent text, but the test value in industrial applications is about 260MPa, which cannot fully meet the use requirements

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