CN106525710B

CN106525710B - Electrochemical testing device for detecting corrosion performance of material by acoustic emission and application method thereof

Info

Publication number: CN106525710B
Application number: CN201611178470.2A
Authority: CN
Inventors: 徐连勇; 张志强; 韩永典; 荆洪阳; 赵雷
Original assignee: Tianjin University
Current assignee: Tianjin University
Priority date: 2016-12-19
Filing date: 2016-12-19
Publication date: 2023-07-21
Anticipated expiration: 2036-12-19
Also published as: CN106525710A

Abstract

The invention discloses an electrochemical testing device for detecting corrosion performance of a material by acoustic emission and a using method thereof. The invention integrates the acoustic emission dynamic nondestructive testing technology and the electrochemical testing technology, and realizes the online, dynamic and real-time detection of the electrochemical corrosion process of the material.

Description

Electrochemical testing device for detecting corrosion performance of material by acoustic emission and application method thereof

Technical Field

The invention relates to the field of material corrosion performance testing devices, in particular to an electrochemical testing device for detecting corrosion performance of a material by acoustic emission and a use method thereof.

Background

Corrosion is a slow damage process of materials in a severe service environment, and has the characteristics of extremely strong concealment, contingency, sudden property, serious destructiveness and the like. Electrochemical is a commonly used test method for rapidly evaluating corrosion resistance of materials, such as potentiodynamic polarization, potentiostatic polarization, cyclic potentiodynamic polarization, electrochemical impedance test and the like. The electrochemical technology is mainly aimed at destructive detection of small samples, and aims at predicting or afterwards evaluating the corrosion resistance of materials in advance, but cannot detect the corrosion condition of large in-service components on line. The acoustic emission technology is an online nondestructive testing technology with high sensitivity. Passivation film cracking associated with corrosion, bubble cracking, stress corrosion cracking, and the like are typical sources of acoustic emissions. The acoustic emission technology is successfully applied to the fields of long-distance oil pipeline leakage detection, storage tank corrosion degree online evaluation and the like. However, the application research of quantitatively evaluating the corrosion degree by an acoustic emission mechanism and acoustic emission in the corrosion damage process is still in a starting stage. The main defects of the existing testing device for simultaneously detecting the corrosion performance of the material by adopting the acoustic emission technology and the electrochemical technology are as follows: (1) The conventional test device requires a test sample of too large size to perform the test of the minute test sample. The test sample is in contact with the corrosive medium and requires a sufficient area for connection to the waveguide or directly to the acoustic emission sensor, which requires that the test sample be sized sufficiently large. The welding joint is usually the weakest link of the structural member, if acoustic emission and electrochemical detection are required to be carried out on different areas (weld root, cover surface, weld center, high temperature and low temperature influences and the like) of the welding joint, the existing testing device cannot be realized based on the limitation of sampling; (2) In order to facilitate the installation of the acoustic emission sensor, the tested sample is usually required to be installed at the bottom of the electrolytic cell as a working electrode, so that the existing testing device limits the heating and heat preservation of corrosive media; (3) Acoustic emission detection and electrochemical detection of corrosion performance of materials in various mixed gas environments cannot be simulated; (4) the operations of mounting and dismounting the sample are complicated.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a sample clamp for electrochemical corrosion test and a use method thereof;

the invention also aims at providing a clamp for detecting the corrosion performance of the material by acoustic emission and a use method thereof;

another object of the present invention is to provide a corrosion electrochemical test device and a method of using the same;

the invention also aims at providing an electrochemical testing device for detecting the corrosion performance of the material by acoustic emission and a using method thereof.

A sample anchor clamps for electrochemical corrosion test comprises ladder screw thread waveguide pole, one-level sleeve, second grade sleeve, tertiary sleeve and sealing washer, and ladder screw thread waveguide pole, one-level sleeve, second grade sleeve, tertiary sleeve and sealing washer coaxial setting, wherein: the stepped thread waveguide rod is provided with a first external thread and a second external thread, the first external thread is connected with the internal thread of the primary sleeve, so that the front end of the stepped thread waveguide rod is arranged in a first cavity and a second cavity of the primary sleeve, and the second external thread is arranged outside the second cavity of the primary sleeve; a fixed end is arranged at the rear end of the stepped thread waveguide rod; the external threads of the first-stage sleeve are connected with the internal threads of the third-stage sleeve, so that the first-stage sleeve is arranged in the third cavity and the fourth cavity of the third-stage sleeve; the second-level sleeve is sleeved outside the third-level sleeve, and a sealing ring is arranged between the second-level sleeve and the third-level sleeve.

In the above technical scheme, the sealing ring is a rubber sealing ring.

In the technical scheme, the diameter of the test surface of the sample is 5+/-0.01 mm, and the length is 7-8 mm.

In the above technical solution, the stepped thread waveguide rod is a metal material, such as ferritic stainless steel.

In the above technical solution, the primary sleeve, the secondary sleeve and the tertiary sleeve are all made of insulating materials, such as polytetrafluoroethylene.

When the device is used, the second external thread of the stepped thread waveguide rod is connected with the internal thread of the sample, a couplant layer is arranged on the circumferential surface of the sample, and the fixed end of the stepped thread waveguide rod is rotated so that the test surface of the sample connected with the second external thread of the stepped thread waveguide rod is flush with the first alignment surface of the primary sleeve and the second alignment surface of the tertiary sleeve; the internal thread of the second sleeve is fixedly connected with the testing device, electrochemical corrosion testing is carried out on the sample, the sample is used as a working electrode, and the lead is connected with the stepped thread waveguide rod positioned at the outer side of the testing device so as to collect electrochemical corrosion signals on the sample.

The fixture for detecting corrosion performance of materials by acoustic emission comprises a stepped thread waveguide rod, a primary sleeve, a secondary sleeve, a tertiary sleeve, a sealing ring and an acoustic emission sensor, wherein the stepped thread waveguide rod, the primary sleeve, the secondary sleeve, the tertiary sleeve, the sealing ring and the acoustic emission sensor are coaxially arranged: the stepped thread waveguide rod is provided with a first external thread and a second external thread, the first external thread is connected with the internal thread of the primary sleeve, so that the front end of the stepped thread waveguide rod is arranged in a first cavity and a second cavity of the primary sleeve, and the second external thread is arranged outside the second cavity of the primary sleeve; a fixed end is arranged at the rear end of the stepped thread waveguide rod, and an acoustic emission sensor contacted with the fixed end is arranged on the fixed end; the external threads of the first-stage sleeve are connected with the internal threads of the third-stage sleeve, so that the first-stage sleeve is arranged in the third cavity and the fourth cavity of the third-stage sleeve; the second-level sleeve is sleeved outside the third-level sleeve, and a sealing ring is arranged between the second-level sleeve and the third-level sleeve.

In the above technical scheme, the sealing ring is a rubber sealing ring.

In the above technical solution, both the stepped thread waveguide rod and the fixed end are made of metal materials, such as ferritic stainless steel.

In the above-described technical solution, an adhesive layer is provided between the fixed end and the acoustic emission sensor.

In the above technical solution, the acoustic emission sensor is fixed on the fixed end by means of a magnetic clamp.

When the device is used, the second external thread of the stepped thread waveguide rod is connected with the internal thread of the sample, a couplant layer is arranged on the circumferential surface of the sample, and the fixed end of the stepped thread waveguide rod is rotated so that the test surface of the sample connected with the second external thread of the stepped thread waveguide rod is flush with the first alignment surface of the primary sleeve and the second alignment surface of the tertiary sleeve; the internal thread of the second sleeve is fixedly connected with the testing device, electrochemical corrosion testing is carried out on the sample, the sample is used as a working electrode, and the lead is connected with a stepped thread waveguide rod positioned at the outer side of the testing device so as to collect electrochemical corrosion signals on the sample; acoustic emission elastic wave emitted by the sample in the corrosion process is transmitted to the acoustic emission sensor through the stepped threaded waveguide rod, and displacement signals are converted into electric signals and transmitted outwards.

The corrosion electrochemical testing device comprises an electrolytic cell, an electrochemical testing device, a heating device and a heat preservation device;

the electrolytic cell comprises a reaction cell, a reaction cell cover, a sealing gasket, a fastening device and a sample mounting device, wherein the reaction cell is cylindrical, a flange is arranged at the edge of the upper end of the reaction cell, the sealing gasket is filled at the tops of the reaction cell cover and the reaction cell, and the reaction cell cover and the reaction cell are sealed by the fastening device; the reaction tank cover is provided with an air inlet pipe threaded hole, an exhaust pipe threaded hole, an auxiliary electrode threaded hole, a digital display thermometer probe threaded hole and a Ruhr capillary threaded hole; the air inlet pipe threaded hole is connected with the air inlet pipe, the air outlet pipe threaded hole is connected with the air outlet pipe, the auxiliary electrode threaded hole is connected with the auxiliary electrode, and the digital thermometer probe threaded hole is connected with the digital thermometer; the method comprises the steps that a threaded hole of a gold capillary is connected with an external thread of a liquid injection port of the gold capillary, so that a bending part of the gold capillary is positioned in a reaction tank, an opening part of the gold capillary is opposite to a sample serving as a working electrode, and an internal thread of the liquid injection port of the gold capillary is connected with an external thread of a reference electrode, so that reference liquid in the reference electrode can flow to the opening part aiming at the sample; the opening of the Rujin capillary tube, the sample as working electrode and the auxiliary electrode are positioned on the same horizontal plane; the sample installation device constitute by ladder screw thread waveguide pole, one-level sleeve, second grade sleeve, tertiary sleeve, sealing washer, ladder screw thread waveguide pole, one-level sleeve, second grade sleeve, tertiary sleeve and the coaxial setting of sealing washer, wherein: the stepped thread waveguide rod is provided with a first external thread and a second external thread, and the rear end of the stepped thread waveguide rod is provided with a fixed end; the first external thread is connected with the internal thread of the first-stage sleeve, so that the front end of the stepped thread waveguide rod is arranged in a first cavity and a second cavity of the first-stage sleeve, and the second external thread is arranged outside the second cavity of the first-stage sleeve; the external threads of the first-stage sleeve are connected with the internal threads of the third-stage sleeve, so that the first-stage sleeve is arranged in the third cavity and the fourth cavity of the third-stage sleeve; the secondary sleeve is sleeved outside the tertiary sleeve, and a sealing ring is arranged between the secondary sleeve and the tertiary sleeve;

The electrochemical testing device comprises an auxiliary electrode chuck, a reference electrode chuck, a working electrode chuck and an electrochemical data processing system; the auxiliary electrode clamp, the reference electrode clamp and the working electrode clamp are respectively connected with an auxiliary electrode, a reference electrode and fixed ends of stepped thread waveguide rods on the electrolytic cell and then connected with an electrochemical data processing system through a signal transmission line;

the heating device is arranged on the outer side of the reaction tank, the heat preservation device is arranged on the outer side of the heating device, and a temperature sensor is arranged on the inner wall of the heating device and used for detecting the temperature change of electrolyte in the reaction tank.

In the technical scheme, the number of the fastening devices is 6-8 groups, the fastening devices consist of an arc-shaped fastening device chuck, fastening screws and fastening gaskets, and the fastening device chuck is made of 316 austenitic stainless steel; the clamping head of the fastening device comprises a first horizontal section, a vertical section and a second horizontal section, wherein the upper surface of the second horizontal section is provided with a fastening gasket with the thickness of 2-3 mm, and the material of the fastening device gasket is polytetrafluoroethylene so as to prevent the glass pool from being broken due to too large fastening force.

In the technical scheme, the stainless steel positioning ring is arranged on the reaction tank cover, 6-8 fastening screw positioning grooves are uniformly distributed on the stainless steel positioning ring, the diameter of each fastening screw positioning groove is 4-5 mm, the depth of each fastening screw positioning groove is 0.5-0.6 mm, the fastening screw positioning grooves are used for positioning the fastening screws, and the other function of the stainless steel positioning ring is to bear the fastening force exerted by the fastening screws, so that the fastening screws are prevented from damaging the reaction tank cover.

In the technical scheme, the number of the threaded holes of the air inlet pipe is 3-4, the number of the threaded holes of the air outlet pipe is 1-2, the number of the threaded holes of the Rumex capillary is 1, the number of the threaded holes of the auxiliary electrode is 1, and the number of the threaded holes of the probe of the digital display thermometer is 1-2; correspondingly, the number of the air inlet pipes is 3-4, the number of the exhaust pipes is 1-2, the number of the Rujin capillaries is 1, the number of the auxiliary electrodes is 1, and the number of the digital display thermometer probes is 1-2; the air inlet pipe, the exhaust pipe, the Rujin capillary, the auxiliary electrode and the digital thermometer probe are respectively provided with a sealing ring between the air inlet pipe, the exhaust pipe, the Rujin capillary, the auxiliary electrode and the digital thermometer probe after being connected with the air inlet pipe threaded hole, the exhaust pipe threaded hole, the Rujin capillary threaded hole, the auxiliary electrode threaded hole and the digital thermometer probe threaded hole.

In the technical scheme, the air inlet pipe and the air outlet pipe are glass pipes with external threads; one end of the air inlet pipe is provided with porous foam for dispersing bubbles, so as to disperse the input gas and accelerate the dissolution of the gas in corrosive media; the air inlet pipe is filled with one of high-purity nitrogen, carbon dioxide or hydrogen sulfide, the high-purity nitrogen deoxidizes a corrosive medium, and the carbon dioxide and the vulcanization can simulate the actual corrosive environment; the unused air inlet pipe threaded hole is provided with a sealing screw for sealing, and the sealing screw is made of polytetrafluoroethylene.

In the above technical solution, the auxiliary electrode is a platinum mesh electrode; the reference electrode is arranged in the Rumex capillary, the liquid injection port of the Rumex capillary is of a structure with internal and external double threads, the external threads of the Rumex capillary are connected with the screw holes of the Rumex capillary on the glass pool, and the internal threads of the Lu Jinmao tube are connected with the external threads of the reference electrode through a screw structure and are sealed by adopting a rubber sealing ring; the opening of the tip of the Rujin capillary is aligned with the center of the test surface opening of the sample and keeps a distance of 0.5-1 mm with the sample to be tested.

In the technical scheme, the number of the temperature sensors is 1-8; the heating device heats the electrolytic cell in a resistance heating water bath or oil bath mode, the temperature sensor automatically controls the heating speed and the temperature of water or oil through a closed loop method, the reaction cell is placed into the water or oil in the heating and heat preserving device, and the water level or the oil level in the heating device is 2-5 cm lower than the lower end of the stepped thread waveguide rod; in the heating device and the heat preservation device, water or oil in the heating device is heated by setting a heating target temperature and a heating speed, after the water or oil is heated to the target temperature, the heating device stops heating, and the water or oil in the heating device is ensured to be always maintained at the target temperature +/-0.1 ℃.

In the above technical solution, the stepped thread waveguide rod is a metal material, such as ferritic stainless steel; the primary sleeve, the secondary sleeve and the tertiary sleeve are all made of insulating materials, such as polytetrafluoroethylene.

In the above technical scheme, the sealing ring is a rubber sealing ring.

When the corrosion electrochemical testing device is used, the second external thread of the stepped thread waveguide rod is connected with the internal thread of the sample, a couplant layer is arranged on the circumferential surface of the sample, and the fixed end of the stepped thread waveguide rod is rotated so that the testing surface of the sample connected with the second external thread of the stepped thread waveguide rod is level with the first alignment surface of the primary sleeve and the second alignment surface of the tertiary sleeve; the internal thread of the second sleeve is fixedly connected with the testing device, electrochemical corrosion testing is carried out on the sample, the sample is used as a working electrode, and the lead is connected with a stepped thread waveguide rod positioned at the outer side of the testing device so as to collect electrochemical corrosion signals on the sample; the digital thermometer probe and the temperature sensor detect the real temperature of the corrosive medium in the electrolytic cell, and the test can be started after the temperature reaches the test requirement temperature and keeps stable.

An electrochemical testing device for detecting corrosion performance of a material by acoustic emission comprises an electrolytic cell, an electrochemical testing device, a heating device and a heat preservation device;

the electrolytic cell comprises a reaction cell, a reaction cell cover, a sealing gasket, a fastening device and a sample mounting device, wherein the reaction cell is cylindrical, a flange is arranged at the edge of the upper end of the reaction cell, the sealing gasket is filled at the tops of the reaction cell cover and the reaction cell, and the reaction cell cover and the reaction cell are sealed by the fastening device; the reaction tank cover is provided with an air inlet pipe threaded hole, an exhaust pipe threaded hole, an auxiliary electrode threaded hole, a digital display thermometer probe threaded hole and a Ruhr capillary threaded hole; the air inlet pipe threaded hole is connected with the air inlet pipe, the air outlet pipe threaded hole is connected with the air outlet pipe, the auxiliary electrode threaded hole is connected with the auxiliary electrode, and the digital thermometer probe threaded hole is connected with the digital thermometer; the method comprises the steps that a threaded hole of a gold capillary is connected with an external thread of a liquid injection port of the gold capillary, so that a bending part of the gold capillary is positioned in a reaction tank, an opening part of the gold capillary is opposite to a sample serving as a working electrode, and an internal thread of the liquid injection port of the gold capillary is connected with an external thread of a reference electrode, so that reference liquid in the reference electrode can flow to the opening part aiming at the sample; the opening of the Rujin capillary tube, the sample as working electrode and the auxiliary electrode are positioned on the same horizontal plane; the sample installation device constitute by ladder screw thread waveguide pole, one-level sleeve, second grade sleeve, tertiary sleeve, sealing washer and acoustic emission sensor, ladder screw thread waveguide pole, one-level sleeve, second grade sleeve, tertiary sleeve, sealing washer and acoustic emission sensor coaxial setting, wherein: the stepped thread waveguide rod is provided with a first external thread and a second external thread, the first external thread is connected with the internal thread of the primary sleeve, so that the front end of the stepped thread waveguide rod is arranged in a first cavity and a second cavity of the primary sleeve, and the second external thread is arranged outside the second cavity of the primary sleeve; a fixed end is arranged at the rear end of the stepped thread waveguide rod, and an acoustic emission sensor contacted with the fixed end is arranged on the fixed end; the external threads of the first-stage sleeve are connected with the internal threads of the third-stage sleeve, so that the first-stage sleeve is arranged in the third cavity and the fourth cavity of the third-stage sleeve; the secondary sleeve is sleeved outside the tertiary sleeve, and a sealing ring is arranged between the secondary sleeve and the tertiary sleeve;

The electrochemical testing device comprises an auxiliary electrode chuck, a reference electrode chuck, a working electrode chuck and an electrochemical data processing system; the auxiliary electrode clamp, the reference electrode clamp and the working electrode clamp are respectively connected with an auxiliary electrode, a reference electrode and a stepped thread waveguide rod on the electrolytic cell and then connected with an electrochemical data processing system through a signal transmission line;

In the above technical scheme, the sealing ring is a rubber sealing ring.

When the electrochemical testing device for detecting the corrosion performance of the material by acoustic emission is used, the second external thread of the stepped thread waveguide rod is connected with the internal thread of the sample, a couplant layer is arranged on the circumferential surface of the sample, and the fixed end of the stepped thread waveguide rod is rotated so that the testing surface of the sample connected with the second external thread of the stepped thread waveguide rod is level with the first alignment surface of the first-stage sleeve and the second alignment surface of the third-stage sleeve; the internal thread of the second sleeve is fixedly connected with the testing device, electrochemical corrosion testing is carried out on the sample, the sample is used as a working electrode, and the lead is connected with a stepped thread waveguide rod positioned at the outer side of the testing device so as to collect electrochemical corrosion signals on the sample; acoustic emission elastic waves emitted by the test sample in the corrosion process are transmitted to the acoustic emission sensor through the stepped threaded waveguide rod, and displacement signals are converted into electric signals and transmitted outwards; the digital thermometer probe and the temperature sensor are matched to detect the real temperature of the corrosive medium in the electrolytic cell, and the test can be started after the temperature reaches the test requirement temperature and keeps stable.

The invention has the following beneficial effects:

1. the invention integrates the acoustic emission dynamic nondestructive testing technology and the electrochemical testing technology, thereby realizing the online, dynamic and real-time detection of the electrochemical corrosion process of the material; the sample mounting device is arranged on the side surface of the glass pool, and the heating and heat-preserving device can heat or preserve heat of corrosive media in a water bath or oil bath mode.

2. The tested sample is a cylindrical tiny sample, and the area of the testing surface is 19-20 mm ² The length is only 7mm, so that the damage to the actual components caused by the sampling process can be reduced. In addition, the invention can realize sampling of tiny parts of the actual component, such as different areas of a welded joint (weld root, cover surface, weld center, high temperature and low temperature influence and the like).

3. The test sample is installed in a threaded connection mode, corrosion acoustic emission signals and electrochemical signals are transmitted through the stepped threaded waveguide rod, and compared with the traditional epoxy resin sealing and conducting mode, the test sample is more portable and efficient in installation, disassembly and cleaning.

4. The invention comprises a plurality of air inlet pipes, and can simulate the material corrosion process under various complex corrosive gas environments; the invention fixes the distance between the tip of the Rugold capillary and the tested sample, and unifies the influence of the distance between the tip of the Rugold capillary and the tested sample on the test result.

5. Is not limited by the material of the object to be inspected, and is conductive.

6. The automatic detection device can be used under severe and complex working conditions, an operator can remotely control the automatic detection device only under safe and proper environments, the automatic detection degree is high, the operation is simple, the test efficiency is high, the labor intensity can be greatly reduced, the energy consumption of the detection device is low, the carrying is convenient, and the detection of an operation site is convenient.

Drawings

FIG. 1 is a flow chart of the operation of an electrochemical test device for detecting corrosion performance of a material by acoustic emission according to the present invention;

FIG. 2 is a front view of the electrolytic cell of the present invention;

FIG. 3 is a side view of the electrolytic cell of the present invention;

FIG. 4 is a top view of the electrolytic cell of the present invention;

FIG. 5 is a schematic diagram of a reaction cell of the present invention;

FIG. 6 is a schematic view of a fastening device of the present invention;

FIG. 7 is a schematic view of a reaction cell cover of the present invention;

FIG. 8 is a schematic view of a sample mounting apparatus of the present invention;

FIG. 9 is a cross-sectional view of FIG. 8;

FIG. 10 is a schematic view of a stepped threaded waveguide rod of the present invention;

FIG. 11 is a schematic view of a primary sleeve of the present invention;

FIG. 12 is a schematic view of a secondary sleeve of the present invention;

FIG. 13 is a schematic view of a three stage sleeve of the present invention;

FIG. 14 is a schematic and cross-sectional view of a sample of the present invention;

FIG. 15 is a schematic view of a luer capillary mounting of the invention;

FIG. 16 is a schematic view b of a sample mounting apparatus of the present invention;

wherein: 1 a fastening device; 2, a reaction tank sealing gasket; 3, a temperature sensor; 4 a heating device; 5, a heat preservation device; 6, a reaction tank cover; 7, a reaction tank; 8 sample mounting means; 9, a flange; 10 lateral external threaded interface;

1-1 fastening screw, 1-2 first horizontal section, 1-3 vertical section, 1-4 fastening gasket, 1-5 second horizontal section; the device comprises a 6-1 fastening screw positioning groove, a 6-2 stainless steel positioning ring, a 6-3 air inlet pipe threaded hole, a 6-4 digital display thermometer probe threaded hole, a 6-5 auxiliary electrode threaded hole, a 6-6 gold capillary threaded hole and a 6-7 exhaust pipe threaded hole; a 6-6-1 reference electrode, a 6-6-2 Rujin capillary, a 6-6-3 bending part and a 6-6-4 opening; the device comprises an 8-1 stepped threaded waveguide rod, an 8-2 fixed end, an 8-3 primary sleeve, an 8-4 secondary sleeve, an 8-5 tertiary sleeve, an 8-6 sealing ring, an 8-7 sample and an 8-8 acoustic emission sensor; 8-1-1 first external threads, 8-1-2 second external threads; 8-3-1 first alignment surface, 8-3-2 first cavity, 8-3-3 second cavity, 8-3-4 sealing surface, 8-3-5 first stage sleeve external screw thread, 8-3-6 first stage sleeve internal screw thread; 8-4-1 secondary sleeve internal threads; 8-5-1 second alignment surface, 8-5-2 third cavity, 8-5-3 fourth cavity, 8-5-4 third level sleeve internal thread; 8-7-1 test surface, 8-7-2 sample circumference surface, 8-7-3 sample internal thread.

FIG. 17 is an electrochemical corrosion polarization curve of duplex stainless steel in 1mol/L NaCl aqueous solution;

FIG. 18 is a plot of electrochemical potential, current density versus test time for duplex stainless steel in 1mol/L aqueous NaCl solution;

FIG. 19 is an acoustic emission amplitude of a duplex stainless steel during electrochemical corrosion;

FIG. 20 is an acoustic emission count of duplex stainless steel during electrochemical corrosion;

FIG. 21 is acoustic emission energy of duplex stainless steel during electrochemical corrosion;

FIG. 22 is an acoustic emission waveform (point 1 in FIG. 18) of a duplex stainless steel during cathodic polarization;

FIG. 23 is an acoustic emission waveform (at 2 points in FIG. 18) of a duplex stainless steel during anodic polarization;

FIG. 24 is an acoustic emission waveform (at 3 points in FIG. 18) of a duplex stainless steel during anodic polarization;

FIG. 25 is an acoustic emission waveform (4 points in FIG. 18) of a duplex stainless steel during anodic polarization;

FIG. 26 is an acoustic emission waveform (at 5 points in FIG. 18) of a duplex stainless steel during anodic polarization;

fig. 27 is an acoustic emission waveform (6 points in fig. 18) of a duplex stainless steel during anodic polarization.

Detailed Description

The invention is further illustrated in the following figures and examples, which are not to be construed as limiting the invention.

A sample anchor clamps for electrochemical corrosion test, the sample installation device in above-mentioned figure 8 promptly comprises ladder screw thread waveguide pole, one-level sleeve, second grade sleeve, tertiary sleeve and sealing washer, and ladder screw thread waveguide pole, one-level sleeve, second grade sleeve, tertiary sleeve and sealing washer coaxial setting, wherein: the stepped thread waveguide rod is provided with a first external thread and a second external thread, the first external thread is connected with the internal thread of the primary sleeve, so that the front end of the stepped thread waveguide rod is arranged in a first cavity and a second cavity of the primary sleeve, and the second external thread is arranged outside the second cavity of the primary sleeve; a fixed end is arranged at the rear end of the stepped thread waveguide rod; the external threads of the first-stage sleeve are connected with the internal threads of the third-stage sleeve, so that the first-stage sleeve is arranged in the third cavity and the fourth cavity of the third-stage sleeve; the second-level sleeve is sleeved outside the third-level sleeve, and a sealing ring is arranged between the second-level sleeve and the third-level sleeve.

In the above technical scheme, the sealing ring is a rubber sealing ring.

When the device is used, the second external thread of the stepped thread waveguide rod is connected with the internal thread of the sample, the couplant layer is arranged on the circumferential surface of the sample, and the fixed end of the stepped thread waveguide rod is rotated, so that the test surface of the sample connected with the second external thread of the stepped thread waveguide rod is flush with the first alignment surface of the primary sleeve and the second alignment surface of the tertiary sleeve. The internal thread of the second sleeve is fixedly connected with the testing device, electrochemical corrosion testing is carried out on the sample, the sample is used as a working electrode, and the lead is connected with the stepped thread waveguide rod positioned at the outer side of the testing device so as to collect electrochemical corrosion signals on the sample.

The fixture for detecting corrosion performance of materials by acoustic emission, namely the sample installation device in the attached figure 16, comprises a stepped thread waveguide rod, a first-stage sleeve, a second-stage sleeve, a third-stage sleeve, a sealing ring and an acoustic emission sensor, wherein the stepped thread waveguide rod, the first-stage sleeve, the second-stage sleeve, the third-stage sleeve, the sealing ring and the acoustic emission sensor are coaxially arranged: the stepped thread waveguide rod is provided with a first external thread and a second external thread, the first external thread is connected with the internal thread of the primary sleeve, so that the front end of the stepped thread waveguide rod is arranged in a first cavity and a second cavity of the primary sleeve, and the second external thread is arranged outside the second cavity of the primary sleeve; a fixed end is arranged at the rear end of the stepped thread waveguide rod, and an acoustic emission sensor contacted with the fixed end is arranged on the fixed end; the external threads of the first-stage sleeve are connected with the internal threads of the third-stage sleeve, so that the first-stage sleeve is arranged in the third cavity and the fourth cavity of the third-stage sleeve; the second-level sleeve is sleeved outside the third-level sleeve, and a sealing ring is arranged between the second-level sleeve and the third-level sleeve.

In the above technical scheme, the sealing ring is a rubber sealing ring.

When the device is used, the second external thread of the stepped thread waveguide rod is connected with the internal thread of the sample, the couplant layer is arranged on the circumferential surface of the sample, and the fixed end of the stepped thread waveguide rod is rotated, so that the test surface of the sample connected with the second external thread of the stepped thread waveguide rod is flush with the first alignment surface of the primary sleeve and the second alignment surface of the tertiary sleeve. The internal thread of the second sleeve is fixedly connected with the testing device, electrochemical corrosion testing is carried out on the sample, the sample is used as a working electrode, and the lead is connected with a stepped thread waveguide rod positioned at the outer side of the testing device so as to collect electrochemical corrosion signals on the sample; acoustic emission elastic wave emitted by the sample in the corrosion process is transmitted to the acoustic emission sensor through the stepped threaded waveguide rod, and displacement signals are converted into electric signals and transmitted outwards.

The corrosion electrochemical testing device comprises an electrolytic cell, an electrochemical testing device, a heating device and a heat preservation device; the electrolytic cell comprises a reaction cell, a reaction cell cover, a sealing gasket, a fastening device and a sample mounting device, wherein the reaction cell is cylindrical, a flange is arranged at the edge of the upper end of the reaction cell, the sealing gasket is filled at the tops of the reaction cell cover and the reaction cell, and the reaction cell cover and the reaction cell are sealed by the fastening device; the reaction tank cover is provided with an air inlet pipe threaded hole, an exhaust pipe threaded hole, an auxiliary electrode threaded hole, a digital display thermometer probe threaded hole and a Ruhr capillary threaded hole; the air inlet pipe threaded hole is connected with the air inlet pipe, the air outlet pipe threaded hole is connected with the air outlet pipe, the auxiliary electrode threaded hole is connected with the auxiliary electrode, and the digital thermometer probe threaded hole is connected with the digital thermometer; the method comprises the steps that a threaded hole of a gold capillary is connected with an external thread of a liquid injection port of the gold capillary, so that a bending part of the gold capillary is positioned in a reaction tank, an opening part of the gold capillary is opposite to a sample serving as a working electrode, and an internal thread of the liquid injection port of the gold capillary is connected with an external thread of a reference electrode, so that reference liquid in the reference electrode can flow to the opening part aiming at the sample; the opening of the Rujin capillary tube, the sample as working electrode and the auxiliary electrode are positioned on the same horizontal plane; the sample installation device constitute by ladder screw thread waveguide pole, one-level sleeve, second grade sleeve, tertiary sleeve, sealing washer, ladder screw thread waveguide pole, one-level sleeve, second grade sleeve, tertiary sleeve and the coaxial setting of sealing washer, wherein: the stepped thread waveguide rod is provided with a first external thread and a second external thread, and the rear end of the stepped thread waveguide rod is provided with a fixed end; the first external thread is connected with the internal thread of the first-stage sleeve, so that the front end of the stepped thread waveguide rod is arranged in a first cavity and a second cavity of the first-stage sleeve, and the second external thread is arranged outside the second cavity of the first-stage sleeve; the external threads of the first-stage sleeve are connected with the internal threads of the third-stage sleeve, so that the first-stage sleeve is arranged in the third cavity and the fourth cavity of the third-stage sleeve; the secondary sleeve is sleeved outside the tertiary sleeve, and a sealing ring is arranged between the secondary sleeve and the tertiary sleeve; the electrochemical testing device comprises an auxiliary electrode chuck, a reference electrode chuck, a working electrode chuck and an electrochemical data processing system; the auxiliary electrode clamp, the reference electrode clamp and the working electrode clamp are respectively connected with an auxiliary electrode, a reference electrode and fixed ends of stepped thread waveguide rods on the electrolytic cell and then connected with an electrochemical data processing system through a signal transmission line; the heating device is arranged on the outer side of the reaction tank, the heat preservation device is arranged on the outer side of the heating device, and a temperature sensor is arranged on the inner wall of the heating device and used for detecting the temperature change of electrolyte in the reaction tank.

In the technical scheme, the air inlet pipe and the air outlet pipe are glass pipes with external threads; one end of the air inlet pipe is provided with porous foam for dispersing bubbles, so as to disperse the input gas and accelerate the dissolution of the gas in corrosive media; the air inlet pipe is filled with one of high-purity nitrogen, carbon dioxide or hydrogen sulfide, the high-purity nitrogen deoxidizes a corrosive medium, and the carbon dioxide and the vulcanization can simulate the actual corrosive environment; the unused air inlet pipe threaded hole is provided with a sealing screw for sealing, and the sealing screw is made of polytetrafluoroethylene;

In the above technical scheme, the sealing ring is a rubber sealing ring.

An electrochemical testing device for detecting corrosion performance of a material by acoustic emission comprises an electrolytic cell, an electrochemical testing device, a heating device and a heat preservation device; the electrolytic cell comprises a reaction cell, a reaction cell cover, a sealing gasket, a fastening device and a sample mounting device, wherein the reaction cell is cylindrical, a flange is arranged at the edge of the upper end of the reaction cell, the sealing gasket is filled at the tops of the reaction cell cover and the reaction cell, and the reaction cell cover and the reaction cell are sealed by the fastening device; the reaction tank cover is provided with an air inlet pipe threaded hole, an exhaust pipe threaded hole, an auxiliary electrode threaded hole, a digital display thermometer probe threaded hole and a Ruhr capillary threaded hole; the air inlet pipe threaded hole is connected with the air inlet pipe, the air outlet pipe threaded hole is connected with the air outlet pipe, the auxiliary electrode threaded hole is connected with the auxiliary electrode, and the digital thermometer probe threaded hole is connected with the digital thermometer; the method comprises the steps that a threaded hole of a gold capillary is connected with an external thread of a liquid injection port of the gold capillary, so that a bending part of the gold capillary is positioned in a reaction tank, an opening part of the gold capillary is opposite to a sample serving as a working electrode, and an internal thread of the liquid injection port of the gold capillary is connected with an external thread of a reference electrode, so that reference liquid in the reference electrode can flow to the opening part aiming at the sample; the opening of the Rujin capillary tube, the sample as working electrode and the auxiliary electrode are positioned on the same horizontal plane; the sample installation device constitute by ladder screw thread waveguide pole, one-level sleeve, second grade sleeve, tertiary sleeve, sealing washer and acoustic emission sensor, ladder screw thread waveguide pole, one-level sleeve, second grade sleeve, tertiary sleeve, sealing washer and acoustic emission sensor coaxial setting, wherein: the stepped thread waveguide rod is provided with a first external thread and a second external thread, the first external thread is connected with the internal thread of the primary sleeve, so that the front end of the stepped thread waveguide rod is arranged in a first cavity and a second cavity of the primary sleeve, and the second external thread is arranged outside the second cavity of the primary sleeve; a fixed end is arranged at the rear end of the stepped thread waveguide rod, and an acoustic emission sensor contacted with the fixed end is arranged on the fixed end; the external threads of the first-stage sleeve are connected with the internal threads of the third-stage sleeve, so that the first-stage sleeve is arranged in the third cavity and the fourth cavity of the third-stage sleeve; the secondary sleeve is sleeved outside the tertiary sleeve, and a sealing ring is arranged between the secondary sleeve and the tertiary sleeve; the electrochemical testing device comprises an auxiliary electrode chuck, a reference electrode chuck, a working electrode chuck and an electrochemical data processing system; the auxiliary electrode clamp, the reference electrode clamp and the working electrode clamp are respectively connected with an auxiliary electrode, a reference electrode and a stepped thread waveguide rod on the electrolytic cell and then connected with an electrochemical data processing system through a signal transmission line; the heating device is arranged on the outer side of the reaction tank, the heat preservation device is arranged on the outer side of the heating device, and a temperature sensor is arranged on the inner wall of the heating device and used for detecting the temperature change of electrolyte in the reaction tank.

In the above technical scheme, the sealing ring is a rubber sealing ring.

The test device is formed by the four technical schemes for electrochemical and acoustic emission detection, and the method is as follows:

referring to fig. 7 for a specific structure of the reaction tank cover, the 3 air inlet pipes and 1 air outlet pipe (not shown in the figure) are respectively connected with the corresponding air inlet pipe threaded hole and air outlet pipe threaded hole on the reaction tank cover, and are sealed by adopting a rubber sealing ring, one end of each air inlet pipe is packaged with porous foam for dispersing air bubbles and inserted into the bottom of the reaction tank, the other end of each air inlet pipe is connected with a corresponding air cylinder for inputting air through a rubber pipe, and the air flow is controlled through a flowmeter; one end of the exhaust pipe is slightly inserted into the reaction tank to ensure that the exhaust pipe is positioned above the liquid level of corrosive medium, the other end of the exhaust pipe is connected with a 5L sealed volumetric flask filled with alkali liquor through a rubber pipe, and a sufficient amount of sodium hydroxide alkali liquor (3L) is filled in the volumetric flask for absorbing discharged acid gas. The interfaces of all the glass tubes and the rubber tubes are sealed by silica gel. And filling the gold capillary with saturated potassium chloride aqueous solution by using an injector to ensure that no bubble exists in the gold capillary, and then connecting the reference electrode with the internal thread of the gold capillary through an external thread and a thread structure, wherein the reference electrode is a calomel electrode, and the reference solution is saturated potassium chloride aqueous solution. Referring to fig. 8 and 9, a proper amount of vacuum grease is smeared on the second external thread of the stepped screw waveguide rod to reduce corrosion acoustic emission signal attenuation, a rubber sealing ring is sleeved on the second external thread of the stepped screw waveguide rod, then a small amount of silica gel is uniformly smeared on the circumferential surface of the mechanically polished sample, the second external thread of the reversely-screwed sample stepped screw waveguide rod is connected with the threads of the second external thread, after the sample is tightly screwed, the stepped screw waveguide rod is rotated backwards, the sample is slowly pulled into the first-stage sleeve until the test surface of the sample is completely parallel to the first alignment surface and the second alignment surface, the extruded excessive silica gel is scraped off by dust-free paper, the test surface of the sample is scrubbed by alcohol for a plurality of times, the sample mounting device is placed into a drying box for 24 hours, the rubber sealing ring is sleeved on the second-stage sleeve after the silica gel is completely solidified, and then the whole sample mounting device is connected with a lateral external thread interface of a reaction tank through the internal thread of the second-stage sleeve.

Slowly introducing the prepared etching solution into the reaction tank, wherein the volume of the etching solution injected into the reaction tank is required to be 1-1.4L in order to ensure that the test surface of the sample is completely immersed in the etching solution and does not overflow.

And sleeving a sealing gasket of the reaction tank on the reaction tank cover, then lightly placing the sealing gasket on the reaction tank, and adjusting the direction of the reaction tank cover to enable the tip of the Rumex capillary to be opposite to the center of the test surface of the sample.

And installing the 6 fastening devices, firstly, tightly attaching the fastening gaskets to the lower edge of the flange of the reaction tank, simultaneously aligning the fastening screws to the fastening screw positioning grooves on the stainless steel positioning ring, and then sequentially screwing the 6 fastening devices in a diagonal order.

And opening data acquisition and analysis software, and setting electrochemical test parameters and acoustic emission acquisition parameters. The electrochemical test parameters include an electrochemical test method and corresponding test parameters, such as open-circuit potential stabilization time, scanning potential range, potential scanning speed and the like, which are required to be set for potentiodynamic polarization. The acoustic emission acquisition parameter settings comprise amplification factors, threshold values, sampling frequencies, filtering ranges, real-time display parameters and the like of the signal amplifier. It should be noted that the electrochemical test parameters and the acoustic emission acquisition parameters need to be adjusted according to specific sample materials, corrosion environment and electrochemical test methods; and then, carrying out a standard lead breaking experiment to evaluate the coupling condition of the acoustic emission sensor and the stepped thread waveguide rod. Conducting a lead breaking experiment on the installation end of the acoustic emission sensor on the stepped thread waveguide rod, wherein the acoustic emission sensor is close to the acoustic emission sensor, and when the amplitude of the acquired lead breaking acoustic emission signal is higher than 90dB, the acoustic emission sensor is well coupled with the stepped thread waveguide rod; then, the gas cylinder valve of the input gas is opened, and the input gas amount is controlled by the flow meter.

Finally, the experiment was formally started. During the experiment, a quiet environment is ensured as much as possible and touching of the electrolytic cell and related connecting lines is avoided. When the test is completed, the experiment will automatically stop.

The device is used for testing a polarization curve and an acoustic emission signal (an electrochemical testing device: gamry, interface 1000, an acoustic emission testing device: PAC, PCI-2, an acoustic emission sensor: R15A, a signal amplifier: 2/4/6-AST) in the process of polarizing the electrokinetic potential of the UNS 31803 duplex stainless steel, and the testing solution is 1mol/L NaCl aqueous solution. After the device is installed according to the steps, the data acquisition and analysis software is opened to set experimental parameters. The heating target temperature was set to 60 ℃. Electrochemical test parameter settings: the electrochemical test method comprises electrokinetic polarization, potential scanning range of-0.75 VSCE-0.6 VSCE, scanning speed of 0.5mVSCE/s, open circuit potential temperature time of 30min, and setting current density continuously exceeding 100 μA/cm ² When the test is stopped automatically. Acoustic emission acquisition parameter setting: the signal amplifier has the amplification factor of 40dB, the threshold value of 30dB, the sampling frequency of 2MSPS, the filtering range of 20kHz-1MHz, and the real-time acquisition parameters of amplitude, energy, count and waveform.

Before the test, a valve of a high-purity nitrogen bottle is opened, the high-purity nitrogen is controlled by a flowmeter to deoxidize the test solution at a flow rate of 0.1mL/min, and the deoxidization time is 1h. Meanwhile, clicking starts to heat until the temperature of the solution in the electrolytic cell is stabilized at 60+/-0.1 ℃. Then, the start test button is clicked, and the test is formally started. The test results are shown in FIGS. 17-27.

FIG. 17 is an electrochemical corrosion polarization curve of duplex stainless steel in 1mol/L NaCl aqueous solution (60 ℃). The polarization curve of fig. 17 is divided into two branches: cathodic polarization (shown as 1) and anodic polarization (shown as 2,3,4,5, 6). Hydrogen evolution reaction mainly occurs in the cathode polarization process, and hydrogen bubbles are generated on the surface of the sample. The anodic polarization process mainly comprises dissolving metal, forming a passivation film, dissolving the passivation film, and the like. From the corrosion potential, as the potential increases, a passivation film is gradually formed on the metal surface, and in a local area, the passivation film is dissolved to generate sub-pitting, and the formed sub-pitting can be repaired by passivating again, as shown in fig. 17, 2,3,4 and 5. When the potential exceeds the pitting potential, the current density increases sharply due to the formation of stable pitting, as shown at 6 in fig. 17.

FIG. 18 is a graph showing electrochemical potential, current density and test time of duplex stainless steel in 1mol/L NaCl aqueous solution (60 ℃).

Fig. 19 is an acoustic emission amplitude of a duplex stainless steel during electrochemical corrosion. The 1,2,3,4,5,6 acoustic emission amplitudes in fig. 19 correspond to the 1,2,3,4,5,6 polarization potentials and current densities, respectively, in fig. 16.

Fig. 20 and 21 are acoustic emission counts and energies, respectively, of duplex stainless steel during electrochemical corrosion. The amplitude, the count and the energy of the acoustic emission signal generated by the hydrogen bubble cracking have no obvious difference with the amplitude, the count and the energy of the acoustic emission signal generated by the metastable point etching pit formed by the passivation film cracking. The stable pit produces an acoustic emission signal of higher amplitude and energy than the acoustic emission signal produced by the metastable spot pit, but without a significant increase in count value.

FIGS. 22-27 are graphs of acoustic emission waveforms of duplex stainless steel during potentiodynamic polarization corresponding to 1,2,3,4,5,6 in FIG. 17 or FIG. 19, respectively. Hydrogen bubble collapse produces a typical burst acoustic emission signal, while localized passivation film collapse and formation of stable pitting produces a mixed acoustic emission signal. The device can completely realize the purpose of simultaneously adopting the acoustic emission technology and the electrochemical technology to test the corrosion performance of the material.

Claims

1. An electrochemical testing device for detecting corrosion performance of a material by acoustic emission, which is characterized in that: comprises an electrolytic cell, an electrochemical testing device, a heating device and a heat preservation device; the electrolytic cell comprises a reaction cell, a reaction cell cover, a sealing gasket, a fastening device and a sample mounting device, wherein the reaction cell is cylindrical, a flange is arranged at the edge of the upper end of the reaction cell, the sealing gasket is filled at the tops of the reaction cell cover and the reaction cell, and the reaction cell cover and the reaction cell are sealed by the fastening device; the reaction tank cover is provided with an air inlet pipe threaded hole, an exhaust pipe threaded hole, an auxiliary electrode threaded hole, a digital display thermometer probe threaded hole and a Ruhr capillary threaded hole; the air inlet pipe threaded hole is connected with the air inlet pipe, the air outlet pipe threaded hole is connected with the air outlet pipe, the auxiliary electrode threaded hole is connected with the auxiliary electrode, and the digital thermometer probe threaded hole is connected with the digital thermometer; the method comprises the steps that a threaded hole of a gold capillary is connected with an external thread of a liquid injection port of the gold capillary, so that a bending part of the gold capillary is positioned in a reaction tank, an opening part of the gold capillary is opposite to a sample serving as a working electrode, and an internal thread of the liquid injection port of the gold capillary is connected with an external thread of a reference electrode, so that reference liquid in the reference electrode can flow to the opening part aiming at the sample; the opening of the Rujin capillary tube, the sample as working electrode and the auxiliary electrode are positioned on the same horizontal plane; the sample installation device constitute by ladder screw thread waveguide pole, one-level sleeve, second grade sleeve, tertiary sleeve, sealing washer and acoustic emission sensor, ladder screw thread waveguide pole, one-level sleeve, second grade sleeve, tertiary sleeve, sealing washer and acoustic emission sensor coaxial setting, wherein: the stepped thread waveguide rod is provided with a first external thread and a second external thread, the first external thread is connected with the internal thread of the primary sleeve, so that the front end of the stepped thread waveguide rod is arranged in a first cavity and a second cavity of the primary sleeve, and the second external thread is arranged outside the second cavity of the primary sleeve; a fixed end is arranged at the rear end of the stepped thread waveguide rod, and an acoustic emission sensor contacted with the fixed end is arranged on the fixed end; the external threads of the first-stage sleeve are connected with the internal threads of the third-stage sleeve, so that the first-stage sleeve is arranged in the third cavity and the fourth cavity of the third-stage sleeve; the secondary sleeve is sleeved outside the tertiary sleeve, and a sealing ring is arranged between the secondary sleeve and the tertiary sleeve; the electrochemical testing device comprises an auxiliary electrode chuck, a reference electrode chuck, a working electrode chuck and an electrochemical data processing system, wherein the auxiliary electrode chuck, the reference electrode chuck and the working electrode chuck are respectively connected with an auxiliary electrode, a reference electrode and a stepped thread waveguide rod on the electrolytic cell, and then are connected with the electrochemical data processing system through a signal transmission line; the heating device is arranged at the outer side of the reaction tank, the heat preservation device is arranged at the outer side of the heating device, and the inner wall of the heating device is provided with a temperature sensor for detecting the temperature change of electrolyte in the reaction tank;

The number of the fastening devices is 6-8 groups, the fastening devices consist of an arc-shaped fastening device chuck, fastening screws and fastening gaskets, and the fastening device chuck is made of 316 austenitic stainless steel; the clamping head of the fastening device comprises a first horizontal section, a vertical section and a second horizontal section, wherein the upper surface of the second horizontal section is provided with a fastening gasket with the thickness of 2-3 mm, and the material of the fastening device gasket is polytetrafluoroethylene so as to prevent the glass pool from being broken due to too large fastening force; the reaction tank cover is provided with a stainless steel positioning ring, 6-8 fastening screw positioning grooves are uniformly distributed on the stainless steel positioning ring, the diameter of each fastening screw positioning groove is 4-5 mm, the depth of each fastening screw positioning groove is 0.5-0.6 mm, each fastening screw positioning groove is used for positioning the corresponding fastening screw, and the other function of the stainless steel positioning ring is to bear the fastening force exerted by the corresponding fastening screw, so that the reaction tank cover is prevented from being damaged by the corresponding fastening screw;

the number of the air inlet pipe threaded holes is 3-4, the number of the air outlet pipe threaded holes is 1-2, the number of the Rujin capillary threaded holes is 1, the number of the auxiliary electrode threaded holes is 1, and the number of the digital display thermometer probe threaded holes is 1-2; correspondingly, the number of the air inlet pipes is 3-4, the number of the exhaust pipes is 1-2, the number of the Rujin capillaries is 1, the number of the auxiliary electrodes is 1, and the number of the digital display thermometer probes is 1-2; the air inlet pipe, the exhaust pipe, the Runjin capillary, the auxiliary electrode and the digital thermometer probe are respectively provided with a sealing ring between the air inlet pipe, the exhaust pipe, the Runjin capillary, the auxiliary electrode and the digital thermometer probe after being connected with the air inlet pipe threaded hole, the exhaust pipe threaded hole, the Runjin capillary threaded hole, the auxiliary electrode threaded hole and the digital thermometer probe threaded hole;

The air inlet pipe and the air outlet pipe are glass pipes with external threads; one end of the air inlet pipe is provided with porous foam for dispersing bubbles, so as to disperse the input gas and accelerate the dissolution of the gas in corrosive media; the air inlet pipe is filled with one of high-purity nitrogen, carbon dioxide or hydrogen sulfide, the high-purity nitrogen deoxidizes a corrosive medium, and the carbon dioxide and the vulcanization can simulate the actual corrosive environment; the unused air inlet pipe threaded hole is provided with a sealing screw for sealing, and the sealing screw is made of polytetrafluoroethylene; the auxiliary electrode is a platinum mesh electrode; the reference electrode is arranged in the Rumex capillary, the liquid injection port of the Rumex capillary is of a structure with internal and external double threads, the external threads of the Rumex capillary are connected with the screw holes of the Rumex capillary on the glass pool, and the internal threads of the Rumex capillary are connected with the external threads of the reference electrode through a screw structure and sealed by adopting a rubber sealing ring; the opening of the tip of the Rujin capillary tube is aligned with the center of the test surface opening of the sample and keeps a distance of 0.5-1 mm with the sample to be tested; the number of the temperature sensors is 1-8; the heating device heats the electrolytic cell in a resistance heating water bath or oil bath mode, the temperature sensor automatically controls the heating speed and the temperature of water or oil through a closed loop method, the reaction cell is placed into the water or oil in the heating and heat preserving device, and the water level or the oil level in the heating device is 2-5 cm lower than the lower end of the stepped thread waveguide rod; in the heating device and the heat preservation device, water or oil in the heating device is heated by setting a heating target temperature and a heating speed, after the water or oil is heated to the target temperature, the heating device stops heating, and the water or oil in the heating device is ensured to be always maintained at the target temperature +/-0.1 ℃.

2. An electrochemical test device for acoustic emission testing of corrosion properties of materials as defined in claim 1, wherein: the diameter of the test surface of the sample is 5+/-0.01 mm, and the length is 7-8 mm; the stepped thread waveguide rod is made of a metal material, and the metal material is ferrite stainless steel; the first-stage sleeve, the second-stage sleeve and the third-stage sleeve are all made of insulating materials, and the insulating materials are polytetrafluoroethylene; the sealing ring is a rubber sealing ring; disposing an adhesive layer between the fixed end and the acoustic emission sensor; the acoustic emission sensor is fixed on the fixed end by a magnetic clamp.

3. Use of an electrochemical testing device for detecting corrosion properties of materials by acoustic emission according to claim 1 or 2, in an electrochemical corrosion test, characterized in that: the second external thread of the stepped thread waveguide rod is connected with the internal thread of the sample, a couplant layer is arranged on the circumferential surface of the sample, and the fixed end of the stepped thread waveguide rod is rotated so that the test surface of the sample connected with the second external thread of the stepped thread waveguide rod is flush with the first alignment surface of the primary sleeve and the second alignment surface of the tertiary sleeve; the internal thread of the second sleeve is fixedly connected with the testing device, electrochemical corrosion testing is carried out on the sample, the sample is used as a working electrode, and the lead is connected with a stepped thread waveguide rod positioned at the outer side of the testing device so as to collect electrochemical corrosion signals on the sample; acoustic emission elastic waves emitted by the test sample in the corrosion process are transmitted to the acoustic emission sensor through the stepped threaded waveguide rod, and displacement signals are converted into electric signals and transmitted outwards; the digital thermometer probe and the temperature sensor are matched to detect the real temperature of the corrosive medium in the electrolytic cell, and the test can be started after the temperature reaches the test requirement temperature and keeps stable.