Electrochemical metallographic etching method universal for nickel-based alloys

Abstract

The invention discloses an electrochemical metallographic etching method universal for nickel-based alloys and relates to the electrochemical etching of the metallographic structure of a metal material. The method adopts the electrochemical metallographic etching method and takes an etching solution as a conducting medium, a metallographic specimen to be observed as an anode and a platinum electrode as cathode; the etching-control conditions comprise: the constant etching voltage: 2V / cm<2>-8Vcm<2>, the etching time: 1min-5min, the etching solution thereof contains in percentage by weight, 65%-85% of phosphoric acid, 5%-15% of sulfuric acid, 8%-15% of chromic acid and 3%-8% of glycerol, the prepared high-temperature corrosion-proof nickel-based alloys such as G-3, 825, X750 and the like have flat surface of metallograph, clear crystal boundary and clear crystal grain. Compared with chemical etching method, the electrochemical metallographic etching method has easily-controlled experimental conditions, good experimental repeatability and high experimental efficiency and is suitable for Ni-Fe-Cr alloys.

Description

technical field [0001] The invention relates to an electrochemical etching method related to the metallographic structure of metal materials. Background technique [0002] During electrochemical etching, the processed sample is used as an anode, and a certain voltage is applied between the cathode and anode, the anode sample dissolves, and the grains and grain boundaries are exposed, so that a picture of the metallographic structure can be obtained . The recognized mechanism is to form a polarized film on the surface of the metal anode, so that metal ions diffuse through this film, and the current density of the microscopic and macroscopic bumps on the surface or the high points of the roughness and the burr area on the surface is higher than that of the surface. The remaining part is larger and dissolves at a faster speed, so as to achieve the purpose of leveling and deburring. By controlling the experimental conditions such as polishing time, experimental temperature and...

AI Technical Summary

Problems solved by technology

However, for nickel-based alloys that are etched by chemical methods, the metallographic phase is often difficult to control because the etching time is difficult to control, resulting in poor clarity of the obtained metallographic phase, and the obtained metallographic structure is difficult to distinguish; electrochemical etching of nickel-based alloys Few studies have been reported in this field, so there are a lot of gaps to be filled in this field

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