Corrosion-inhibiting nickel-based alloy electrolytic polishing liquid and polishing method thereof

Abstract

The invention relates to a nickel base alloy electrolytic polishing solution and a polishing method and belongs to the field of electrolytic polishing. The nickel base alloy electrolytic polishing solution comprises, by weight, 50-75 parts of phosphoric acid, 10-20 parts of formic acid, 0.1-3 parts of polyacrylamide, 10-50 parts of ethylene glycol, 3-20 parts of ethyl alcohol, 0.05-8 parts of hexamethylene tetramine and 1-5 parts of rodine. The nickel base alloy electrolytic polishing solution provided by the invention is small in internal resistance and excellent in corrosion inhibition performance. A nickel base alloy workpiece is subjected to activating treatment through the proper electrolyte and current density and by selecting different electrolytic time and electrolyte temperature to achieve the good electrolytic polishing effect. The electrolytic polished surface of the nickel base alloy workpiece is good in appearance and has obvious metallic luster, has the roughness Ra reaching up to 0.08 microns or below and is free of the problems such as white points, mottles and intergranular corrosion. The corrosion resistant performance of equipment is greatly improved.

Description

technical field [0001] The invention relates to a corrosion-inhibiting nickel-based alloy electrolytic polishing liquid and a polishing method thereof, belonging to the field of electrolytic polishing. Background technique [0002] Nickel-based alloys are widely used in many fields, especially in aerospace and nuclear power fields. Since the 1990s, nickel-based alloys, as a new material with excellent performance, have entered the field of nuclear power plant manufacturing in large quantities, such as steam generators The important reason for using nickel-based alloys for key equipment in nuclear islands such as water tanks and make-up water tanks is that in addition to the excellent high-temperature resistance of nickel-based alloys, it also has good corrosion resistance. The corrosion resistance is closely related to the surface state of the equipment. Compared with other polishing methods, electrolytic polishing is highly praised by the nuclear power plant design departme...

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Problems solved by technology

[0003] Electrolytic polishing is an important polishing method. Although a lot of research has been done on the electrochemical principle of polishing, the material of the workpiece, and the electrolytic polishing process for a long time, the polishing materials in practical applications are mainly concentrated in ordinary stainless steel and aluminum alloy. There are a few materials such as copper alloy, and there are still many difficulties in obtaining a good polished surface for other materials

The fundamental reason is that electrolytic polishing is not a quantitative science, it is basically qualitative, whether it is the choice of electrolyte, or the current size used in electrolytic polishing, voltage, polishing time, temperature and other parameters are obtained through trial and error, and It is difficult to transfer the parameters obtained from one material experiment to another material in parallel

For example, the application number is CN201410754930.6 Chinese invention patent "Hastelloy electrolytic polishing process" proposes to use Isopol 140 as the electrolyte, and the electrolytic polishing process parameters are: temperature: 50-65°C, voltage: 8-12V, polishing time 60-120s , using titanium wire as the cathode, the area of ​​the plate is 1 / 3-1 / 5 of the area of ​​the part. Since the electrolyte is the key process material in electropolishing, Isopol 140 is used as a code, and its specific composition cannot be determined, and the voltage It is related to the geometric dimensions, distance, and solution temperature of the workpiece and cathode. Therefore, there are many difficulties in obtaining a good electrolytic polishing surface for nickel-based alloys in the implementation of this patent.

[0004] In addition, the Chinese invention patent with the application number CN201310084678.8 "A Cu-Ni alloy electrolytic polishing method for EBSD test", since the object of electrolytic polishing in this patent is a Cu-Ni alloy sample for electron back diffraction analysis, The size is fixed and small, which cannot be compared with the large equipment of nuclear power plants

In other known information such as the third issue of "Guangzhou Chemical Industry" in 1996, there are technical methods for polishing nickel-based alloys using electrolytes such as perchloric acid, glacial acetic acid or phosphoric acid, tyrosine, sulfuric acid, glycerin, but these technical methods all exist Several defects, according to which nickel-based alloy products are electrolytically polished, and the ideal polished surface cannot be obtained after implementation

Our own invention patent, the application number is 2016111771971 Nickel-based alloy electrolytic polishing solution and its polishing method, there is also a large internal resistance of the electrolyte, especially when the high current intensity is passed, the solution temperature rises rapidly, not only the surface of the polished workpiece occurs Corrosion, and the components in the solution are oxidized and even carbonized

In addition, the patent application number 2007101482764 "Electrolyte for Electropolishing and Polishing Method" discloses an electrolyte, but the electrolyte is mainly suitable for the polishing of Cu, and is not suitable for the polishing of nickel-based alloys. The components contain strong acids with sulfonic acid groups, which are highly corrosive. Using them as electrolytes for polishing nickel-based alloys will lead to rougher products after polishing , and there will be intergranular corrosion

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