Electrochemical method for controlling activated dissolution of carbon steel grain boundary

Abstract

The invention provides an electrochemical method for controlling activated dissolution of a carbon steel grain boundary. The method comprises the following steps: 1) dropwise adding an acidic medium into an inorganic solution with a high oxidizing property till the pH of the solution is 3-5 to obtain an electrolyte; and 2) in the electrolyte, applying kinetic level scanning to carbon steel at 0.05-0.2 mV/s from a cathode level and gradually transiting the level to an anode level, and when the kinetic level reaches a passivating region, stopping scanning. By taking the inorganic salt with the high oxidizing property and the acidic medium as the electrolyte and applying kinetic level scanning to carbon steel at a certain speed, on the one hand, the grain boundary and the grains of the carbonsteel are separately located in an activated dissolved state and a passivation protecting state, and on the other hand, the grain boundary of the carbon steel can be controlled effectively to be in activated dissolved state and the grains can be controlled effectively to be in a time of passivation protection by controlling the level change of the electrolyte, so that the activated dissolving process of the grain boundary is controlled effectively. The state control difficulty of the whole grains and grain boundary of the carbon steel is reduced greatly.

Description

technical field [0001] The invention relates to the technical field of material corrosion and protection, in particular to an electrochemical method for controlling activation and dissolution of carbon steel grain boundaries. Background technique [0002] The microstructure of carbon steel mainly includes two parts: grains and grain boundaries. When carbon steel is served in a corrosive environment, in most acidic corrosion environments, the grains and grain boundaries are simultaneously in a state of activation and dissolution; while in most alkaline corrosion environments, the grains and grain boundaries are both in a passivation state at the same time protected status. At present, it is technically impossible or difficult to effectively control the grains and grain boundaries of carbon steel to be in different electrochemical states (activated dissolution state or passivation protection state). [0003] In some special corrosive environments, such as: in the nitric acid...

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Problems solved by technology

[0004] In view of this, the present invention aims to propose an electrochemical method for controlling the activation and dissolution of carbon steel grain boundaries, so as to solve the problems of high difficulty in controlling the chemical dissolution of carbon steel grain boundaries and poor control effect

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