High-efficiency electrolytic etching solution for nickel-based superalloy

By optimizing the mixed acid system, the problems of uneven corrosion and low efficiency of electrolytic etching solutions for nickel-based superalloys were solved, enabling rapid and precise etching of metallographic samples of nickel-based superalloys and clearly revealing their internal structure.

CN122105592APending Publication Date: 2026-05-29HARBIN TURBINE +1
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
HARBIN TURBINE
Filing Date
2026-03-18
Publication Date
2026-05-29

AI Technical Summary

Technical Problem

Existing electrolytic etching solutions for nickel-based superalloys are insufficient to clearly display grain boundaries and the second phase, resulting in incomplete removal of oxide films and low sample preparation efficiency, which affects the observation of metallographic morphology.

Method used

By using an electrolytic etching solution containing a mixture of nitric acid, sulfuric acid, and phosphoric acid, and by optimizing the acid ratio and electrolysis parameters, rapid and precise etching of nickel-based superalloys is achieved, exposing grain boundaries and clearly revealing the γ′ and γ′′ phases.

Benefits of technology

Rapid corrosion of nickel-based superalloy metallographic samples was achieved at room temperature, clearly revealing grain boundaries and the second phase, improving sample preparation efficiency, avoiding over-corrosion and grain shedding, and ensuring corrosion effect.

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Abstract

The application discloses a high-efficiency metallographic electrolytic etching solution for nickel-based high-temperature alloy. The electrolytic etching solution is mixed by nitric acid, sulfuric acid and phosphoric acid, wherein the nitric acid accounts for 30-50% in volume percentage, the sulfuric acid accounts for 40-50% in volume percentage, and the phosphoric acid accounts for 10-20% in volume percentage. In the application, the nitric acid dissolves the surface layer metal and preliminarily shows the grain boundary; the sulfuric acid compensates for the defect of a single acid system in displaying the hard phase; and the phosphoric acid compensates for the defect of a single acid system in displaying the hard phase, and clearly presents the internal fine organization such as gamma' and gamma'' phases. After the nickel-based high-temperature alloy metallographic sample is etched by the high-efficiency metallographic electrolytic etching solution, only 3-5s of electrolytic etching of the sample is needed, so that the grain boundary is clear, the gamma' and gamma'' phases are free from over-etching phenomenon, the smoothness of the sample surface after etching is good, and there is no grain falling phenomenon. The electrolytic etching solution in the application not only guarantees the etching effect, but also greatly shortens the etching time and improves the sample preparation efficiency.
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