Preparation method of stop-off agent for stainless steel vacuum brazing

Abstract

The invention relates to the technical field of welding, and aims to provide a preparation method of a stop-off agent for stainless steel vacuum brazing. The method includes the steps that zirconium oxide powder and titanium oxide powder are ball-milled and then a first mixture is obtained; the first mixture, aluminum oxide powder and neodymium oxide powder are ball-milled and then a second mixture is obtained; after propylene glycol and deionized water are evenly mixed, VAE emulsion is added to be evenly stirred, and accordingly a third mixture is obtained; methylcellulose and Carbomer 940 are added into the third mixture to be stirred and then a fourth mixture is obtained; the second mixture is added into the fourth mixture to be stirred and then a fifth mixture is obtained; and ammoniumhydroxide is added into the fifth mixture to adjust the pH to 8-10 while stirring is conducted, and then the stop-off agent for stainless steel vacuum brazing can be obtained after grinding. By the adoption of the method, the problem that oxide components in the stop-off agent are sintered in the course of stainless steel vacuum brazing processing to form hard agglomerate or cakes is solved, thehard agglomerate or cakes can be removed in non-destructive modes like water scrubbing and air blowing after brazing, and the surfaces of workpieces cannot be damaged.

Description

technical field [0001] The invention relates to the field of welding technology, in particular to a preparation method of a flow blocking agent for stainless steel vacuum brazing. Background technique [0002] The anti-flow agent is a material used to protect the surface of the metal to be welded during the brazing process. It is a stable suspension system made by mixing oxides and binders. It can be formulated to have a suitable The combination of viscosity and rheological properties can effectively prevent the molten solder from flowing freely on the surface of the metal to be brazed at the brazing temperature, and its requirement is that it can be removed in a certain way after brazing without pollution and corrosion metal workpiece. [0003] The brazing temperature of nickel-based brazing filler metals used in stainless steel vacuum brazing is relatively high, generally around 1000°C, and the commonly used flow-stopping oxide fillers include alumina, chromium oxide, tit...

AI Technical Summary

Problems solved by technology

[0003] The brazing temperature of nickel-based brazing filler metals used in stainless steel vacuum brazing is relatively high, generally around 1000°C, and the commonly used flow-stopping oxide fillers include alumina, chromium oxide, titanium oxide, and magnesium oxide. Under normal circumstances, the oxides used in conventional flow blocking agents, including alumina, chromium oxide, titanium oxide, magnesium oxide, etc., will sinter to varying degrees, resulting in hard agglomeration or agglomeration, which makes it impossible to pass non- Destruction methods (such as water washing, air blowing, solvent washing, etc.) to remove the residual flow blocking agent

However, although destructive methods such as grinding and polishing can effectively remove the flow blocking agent residue, it also causes permanent damage to the surface of the workpiece.