Variable-scale boron-nitrogen graphene modified layer brazing filler metal as well as preparation method and application thereof

Abstract

The invention discloses a variable-scale boron-nitrogen graphene modified layer brazing filler metal. The brazing filler metal comprises a variable-scale modified layer composed of a boron-nitrogen graphene reinforced alloy layer which is formed in an upper surface layer, a brazing filler metal layer which is formed in a middle layer and a boron-nitrogen graphene coated foam metal layer which is formed in the lower surface layer, and the preparation method comprises the following steps that a silver brazing material sheet or a gold brazing filler metal sheet is selected, firstly, a boron-nitrogen graphene reinforced nickel-based alloy is sputtered on the upper surface of the brazing filler metal sheet, wherein the nickel-based alloy is a binary or ternary nickel-based alloy consisting of nickel, palladium, gold and copper, then a boron-nitrogen graphene coated foam metal layer is subjected to vapor deposition on the lower surface of the brazing filler sheet, wherein the foam metal is binary nickel-based alloy consisting of nickel-chromium, nickel-gold, nickel-silver or nickel-copper; and the prepared modified layer brazing filler metal can be used for connection of high-nitrogen steel and high-strength steel, the tensile strength of the high-nitrogen steel and the high-strength steel subjected to braze connection is not lower than 500 MPa. The brazing filler metal prepared through the method has a variable-scale layer and can generate a nano-scale effect, so that the mechanical property of the brazing filler metal can be synergistically enhanced, and the welding strength ofthe high-strength steel and the high-nitrogen steel can be improved.

Description

technical field [0001] The invention relates to the field of welding, and more specifically relates to a variable-scale boron-nitrogen graphene modified layer solder, a preparation method and an application thereof, which can be used for special connections of high-strength steel and high-nitrogen steel. Background technique [0002] High-nitrogen austenitic stainless steel is corrosion-resistant, wear-resistant, and oxidation-resistant. It is one of the key materials for manufacturing oil drilling tools and medical bone joint products. Its connectors have also become an important part of aviation, weapons, ships and other fields. At present, non-magnetic drill collars are severely worn locally during long-term oil drilling, and the brazing method can be selected for repair; due to the embrittlement effect of interstitial nitrogen atoms, pores and nitrides are easily generated in the repaired braze joint structure, which induces brittleness. phase, which makes the mechanical...

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Problems solved by technology

[0003] In the prior art, the layered silver-based composite solder is prepared by means of the base solder, the metal electroforming layer coated outside the base solder, and the interface transition layer, which breaks through the limit of the melting element of the solder prepared by the traditional method, but the connection strength Not high; there is also copper foil as the substrate, followed by chemical silver plating, tin plating and diffusion treatment to obtain ultra-thin silver-copper-tin solder, but the silver content is too high (over 50%), and the diffusion interface is prone to brittle phases , so that the connection strength is low; there is also a method of using laser-MIG arc hybrid welding technology to connect high nitrogen steel, and the method of magnetic control and temperature control combined to solve the welding porosity of high nitrogen steel and the poor toughness of welding heat-affected zone However, the above methods still have defects such as base metal melting, nitrogen loss, pores, and nitride precipitation during the welding process, which cannot ensure the inherent "nitrogen" characteristics of high nitrogen steel; Sputter silver-copper and tungsten layers to prepare nano-multilayer brazing material for brazing stainless steel, but the joint connection strength is low (below 80MPa)

[0004] Silver-nickel and gold-nickel solders have high strength and corrosion resistance, low vapor pressure, especially high-temperature strength, increasing nickel content can reduce costs, and have a wider range of applications. They are used in stainless steel, precision alloys and titanium alloys. It is widely used in the field and can be used for brazing connection of high nitrogen steel, but its connection strength needs to be further improved. Therefore, a variable-scale boron-nitrogen graphene modified layer brazing filler metal and its preparation method are needed to synergistically enhance the mechanical properties of the brazing filler metal. Improve the welding strength of high-strength steel and high-nitrogen steel

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