Electrochemical test device for simulating crevice corrosion

Abstract

The invention relates to an electrochemical test device for simulating crevice corrosion. An air inlet pipe and an exhaust pipe are arranged on the top cover of an outer solution tank; an external test sample is hung in the outer solution tank via an auxiliary electrode lead; the bottom of the outer solution tank is connected with the bottom of an internal solution tank via a liquid feed pipe; a suction pipe, a minitype pH electrode and a luggin capillary salt bridge are arranged at the top of the internal solution tank; the internal solution tank is sealed by a test sample indenter; an internal test sample is arranged at the left end of the test sample indenter; the internal test sample is connected with a working electrode; the external solution tank simulates the corrosion environment outside a crevice; the internal solution tank simulates the corrosion environment inside a crevice; the air inlet pipe introduces CO2 and H2S different gases to the external solution tank; the suction pipe vacuumizes the internal solution tank; and a three-electrode system comprising the external test sample, the internal test sample and the luggin capillary salt bridge can collect electrochemical data in real time. The electrochemical test device disclosed by the invention can evaluate the crevice corrosion properties under different solution, atmosphere, temperature and crevice size conditions, and can test the anti-crevice corrosion property of materials at different electrochemical parameters.

Description

technical field [0001] The invention belongs to the technical field of crevice corrosion simulation, in particular to an electrochemical test device for crevice corrosion simulation. Background technique [0002] For components such as riveting, welding, threaded connections, and flange end faces, when there is a gap between metal and metal or between metal and non-metal, and the corrosive medium in the gap is in a stagnant state, it is easy to get stuck in the gap. The localized corrosion of metal materials is generally called crevice corrosion. When crevice corrosion occurs, the outward diffusion of the products of the anodic dissolution process inside the crevice is restricted, which increases the concentration of metal cations and excess positive charge in the crevice, and promotes the migration of Cl- outside the crevice to the crevice. The hydrolysis of metal chlorides makes the pH value drop in the gap, which further accelerates the anodic dissolution. The accelerat...

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Problems solved by technology

However, the methods specified in these two standards are carried out under specific conditions, that is, they cannot reflect the crevice corrosion resistance of materials under actual working conditions, nor can they reflect the process and mechanism of crevice corrosion.

Although the test device disclosed in the patent document [CN 103528944A] can collect electrochemical information during crevice corrosion in real time and help to obtain part of the mechanism of crevice corrosion, on the one hand, it cannot obtain the real-time change of the pH value that is most critical to crevice corrosion , on the other hand, there are also problems such as the inability to simulate the corrosion environment closer to the working condition

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