Flux-cored silver filler metal with good liquidity

Abstract

The present invention provides a flux-cored silver filler metal with good liquidity, belonging to the technical field of braze welding materials. The flux-cored silver filler metal comprises brazing flux powder and a sliver brazing filler metal strap coated with the brazing flux powder, the sliver brazing filler metal strap is Bag30CuZnSn, the mass ratio of each component in the brazing flux powder comprises: 30-35% of K3BF6, 2-5% of potassium fluoride, 20-25% of boric acid, 30-32% of boric oxide, 2-6% of sodium carbonate, 0.5-1.5% of potassium metasilicate, and the balance being KBF4. The ratio of the sodium carbonate and the sodium carbonate is 4:1, and the mass of the brazing flux powder is 15-30% of the total mass. In the invention, the brazing flux powder reduces the fluoride and adds the sodium carbonate, the sodium carbonate, the potassium tetrafluoroborate and the KBF4 so as to improve the moisture absorption of the brazing flux powder, improve the liquidity of the brazing flux powder, have an effect on lubrication of the brazing flux powder in the flux-cored silver filler metal drawing process and achieve the smooth diameter reduction of the flux-cored silver filler metal.

Description

technical field [0001] The invention belongs to the technical field of brazing materials, in particular to a flux-cored silver brazing material with excellent fluidity. Background technique [0002] Silver-based solder is widely used in brazing low-carbon steel, stainless steel, high-temperature alloys, copper and copper alloys because of its suitable melting point, good electrical and thermal conductivity, good wetting and filling ability and brazing process performance. , Kovar and refractory alloys, involving household appliances, building materials, aerospace and other fields. [0003] In the brazing process, silver-based solder is generally used in conjunction with flux to improve the wetting and spreading properties of the solder and the mechanical properties of the brazing joint. Among them, brazing flux is usually in the form of paste or powder. No matter what the form is, there are problems in the process of use that the amount of brazing cannot be accurately contr...

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Problems solved by technology

[0004] However, the existing flux-cored silver solder has the following deficiencies in the preparation process: 1, the plasticity and strength of the silver solder strip are lower than that of the steel strip, and longitudinal cracks are prone to occur in the rolling process; The powder filled in the core silver solder is a flux powder with a lighter density (the density is generally ≤1.5g / cm 3 ), the fluidity of the powder is poor, and the flux-cored silver solder is prone to clogging and broken wires during the drawing process. Once the wires are broken, it is difficult to weld them. In the case of drawing and then breaking the wire, this brings great difficulties to the drawing and reducing of the flux-cored silver solder; 3. The flux powder in the flux-cored silver solder contains fluoride, which will not only interact with Ag, Cu , Zn oxidation reaction will affect the quality of brazed joints, and it will make the flux powder easy to absorb moisture, and it is easy to stick to the roller during the rolling and drawing process. After the finished product is formed, if it cannot be used in time, the flux powder The powder is easy to fail, which deteriorates the welding performance of the flux-cored silver solder; 4. In the brazing process, the wire diameter of the silver solder is required to be 2.0mm to 1.8mm. When FB102, FB308 brazing flux, etc.) are used as core powder, it is extremely difficult to draw the core silver solder to a wire diameter of 2.0mm to 1.8mm

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