Acquisition and analysis method and system for simulating metal corrosion information in deep sea environment under hydrostatic pressure-microorganism-electrochemical action

Abstract

The invention discloses a collection and analysis method and system for simulating metal corrosion information in a deep sea environment under hydrostatic pressure-microorganism-electrochemical action. The method comprises the following steps: expanding culture of deep sea pressure-resistant microorganisms; the method comprises the following steps: preparing a metal sample to be detected, carrying out electrochemical tests under different hydrostatic pressures and soaking times, and carrying out surface topography characterization and weightlessness detection on the soaked metal sample to complete collection of metal corrosion information. According to the invention, the characteristics of the deep sea environment are combined, and the corrosion condition research of ocean engineering application metal materials in the deep sea environment can be simulated under laboratory conditions; metal corrosion electrochemical testing, corrosion morphology characterization and weightlessness detection under the working condition are carried out at the same time, interaction analysis of microorganisms and metal materials in the deep sea environment can be achieved, the deep sea microorganism corrosion mechanism is analyzed, and then data support is provided for safe service of the metal materials in the deep sea environment; and a theoretical basis is provided for designing and improving metal materials suitable for serving in the deep sea environment.

Description

Technical Field

[0001] The present invention belongs to the field of material damage evaluation, and specifically relates to a method and system for collecting and analyzing metal corrosion information in a simulated deep-sea environment under hydrostatic pressure-microorganism-electrochemical action. Background Art

[0002] The deep sea occupies the vast majority of Earth's oceans. Its environment, characterized by high pressure, low temperature, low light levels, and oligotrophic conditions, creates a unique and extreme ecosystem. In recent years, with the continued advancement of deep-sea resource development, such as deep-sea oil and gas extraction, human interaction with the deep-sea environment has become increasingly frequent, and the problem of deep-sea microbial corrosion has become increasingly prominent, posing a serious threat to the long-term stability and safety of related equipment and materials.

[0003] Microbial corrosion is a process in which microorganisms and their metabolites directly or indirectly affect the corrosion laws of materials. Microbial corrosion is also one of the important marine environmental factors that lead to material corrosion and failure. It is an important factor that needs to be considered in material environmental testing and research.

[0004] For example, Reference 1 (Corrosion Behavior of Aluminum Alloys under the Action of Marine Microorganisms SRB, Journal of the Chinese Society of Nonferrous Metals, Vol. 25, No. 4) used scanning electron microscopy to observe the microscopic morphology of bacteria attached to the surface of aluminum alloys, used spectrophotometry and microbial plate count methods to study the growth patterns of sulfate-reducing bacteria (SRB), tested the open circuit potential, anodic polarization curve, and electrochemical impedance spectroscopy of 6063 aluminum alloy under the action of marine microorganisms SRB, and used intermittent bacterial culture to conduct natural corrosion. The corrosion rate of the aluminum alloy and the morphological characteristics after microbial corrosion were studied. It was found that sulfate-reducing bacteria can obtain electrons from the alloy, accelerating the corrosion of the alloy.

[0005] For example, the invention patent with publication number CN112033882A discloses a test method for microbial corrosion in marine tidal areas, which includes the following steps: Step 1, preparation of bacterial strains and seawater: selecting and preparing a suitable culture medium for bacterial strain cultivation; taking clean seawater from the ocean and filtering to remove impurities in the seawater; sterilizing the culture medium, seawater and the utensils used with high-temperature steam; Step 2, preparation of test samples and electrodes: preparing a test plate, placing the test sample, auxiliary electrode and reference electrode, and placing the test plate in a test device; Step 3, sterilization of the test device: placing the test device in a room that can be sterilized by ultraviolet light and performing ultraviolet sterilization; Step 4, sterilization of the test device: placing the test device in a room that can be sterilized by ultraviolet light; Step 5, sterilization of the test device: Step 4: Seawater filling and microbial inoculation: inject an appropriate amount of sterilized seawater into the brine pool; seal the gas exchange holes with breathable silicone, and inoculate microorganisms through the microbial inoculation and test holes; Step 5: Tidal and environmental parameter control: connect the control box to the computer, start the corresponding execution program, input parameters such as tidal cycle and form, ambient temperature, seawater flow rate and sea breeze speed, and start the program; Step 6: Online monitoring: connect the test sample, auxiliary electrode, and reference electrode to the external electrochemical test system through wires, and start monitoring the microbial corrosion process and behavior of the sample in the ocean tidal zone; perform microbial counting at intervals, and the counting technology adopts existing methods.

[0006] Although researchers have conducted extensive research in the field of marine microbial corrosion, current studies on microbial corrosion have largely focused on the effects of aerobic and anaerobic bacteria on the corrosion of various metal materials under atmospheric conditions. However, little research has been conducted on the mechanisms of microbial corrosion in deep-sea environments. The extreme and complex nature of the deep-sea environment has led to the evolution of unique metabolic pathways in deep-sea microorganisms, resulting in more complex corrosion mechanisms.

[0007] In summary, in-depth research on the mechanism of deep-sea microbial corrosion is of great practical significance for the development of deep-sea equipment and the exploration and utilization of deep-sea resources. Therefore, developing a corresponding method to simulate and study the influence of deep-sea microorganisms on the corrosion process of metal materials is an urgent problem to be solved. Summary of the Invention

[0008] To overcome the shortcomings of the existing technology, the present invention provides a method and system for collecting and analyzing metal corrosion information in a simulated deep-sea environment under the action of hydrostatic pressure, microorganisms, and electrochemical reactions. This method addresses the difficulty in effectively testing the microbial corrosion resistance of metals in deep-sea environments, aiming to more reliably and conveniently test the microbial corrosion resistance of metals. The specific technical solutions employed are as follows:

[0009] A method for collecting and analyzing metal corrosion information in a simulated deep-sea environment under hydrostatic pressure-microorganism-electrochemical action, comprising the following steps:

[0010] (1) streaking the frozen stock of deep-sea pressure-resistant microorganisms onto a solid culture medium, culturing until a single colony appears, picking the single colony and placing it in a liquid culture medium to obtain activated deep-sea pressure-resistant microorganisms;

[0011] (2) inoculating the activated deep-sea pressure-resistant microorganisms into a liquid culture medium for expansion and centrifugation to obtain a bacterial concentrate for later use;

[0012] (3) Prepare the metal samples to be tested and record their weights before dividing them into three groups. One group of metal samples to be tested is suspended on the lid of the autoclave for electrochemical testing; the other two groups of metal samples to be tested are fixed at the bottom of the autoclave cavity for weight loss testing and morphology characterization.

[0013] (4) The immersion liquid was injected into the autoclave cavity and the bacterial concentrate was inoculated. Electrochemical tests were performed under different hydrostatic pressures and immersion times. The metal samples immersed at the bottom of the autoclave cavity were taken out for morphological characterization and weight loss detection.

[0014] The present invention is based on a method for collecting and analyzing metal corrosion information in a simulated deep-sea environment under the action of hydrostatic pressure, microorganisms, and electrochemistry. Combining the characteristics of the deep-sea environment, it can realize the study of the corrosion conditions of metal materials used in marine engineering in a simulated deep-sea environment under laboratory conditions. At the same time, through the collection and analysis of metal corrosion electrochemistry, weightlessness, and corrosion morphology information data under working conditions, the interaction analysis of microorganisms and metal materials in the deep-sea environment can be realized.

[0015] Preferably, the deep-sea pressure-resistant microorganisms can metabolize and survive normally under the action of hydrostatic pressure.

[0016] Preferably, the solid culture medium in step (1) comprises peptone, yeast powder, sodium chloride, magnesium chloride, sodium sulfate, calcium chloride, potassium chloride, sodium bicarbonate, potassium bromide, strontium chloride, boric acid, sodium fluoride and agar powder.

[0017] More preferably, the culture time after inoculation into the solid culture medium is 16 h to 20 h.

[0018] Preferably, the liquid culture medium in step (2) comprises peptone, yeast powder, sodium chloride, magnesium chloride, sodium sulfate, calcium chloride, potassium chloride, sodium bicarbonate, potassium bromide, strontium chloride, boric acid and sodium fluoride.

[0019] More preferably, the culture time after inoculation into the liquid culture medium is 12h-18h.

[0020] Preferably, the volume ratio of the activated deep-sea pressure-resistant microorganisms and the liquid culture medium in step (2) is 1:100.

[0021] Preferably, the optical density OD of the bacterial suspension obtained by the expanded culture in step (2) at a wavelength of 600 nm is 600 It is 0.6-0.8.

[0022] Preferably, the centrifugal speed in step (2) is 5000 rpm and the centrifugal time is 5 min.

[0023] Preferably, the metal sample to be detected is any metal material used in marine engineering.

[0024] Further preferably, the metal sample to be tested is carbon steel Q235, including C element: 0.18%, Mn element: 0.35%, P element: 0.029%, S element: 0.018%, Si element: 0.14% and Fe element: 99.16%.

[0025] Preferably, the step (3) of suspending one of the groups of metal samples to be tested on the autoclave cover for electrochemical testing includes: connecting the working electrode, auxiliary electrode, and reference electrode suspended on the autoclave cover to an electrochemical testing device through copper wires for electrochemical testing, wherein the working electrode is one of the groups of metal samples to be tested, and the non-working surface is encapsulated with epoxy resin.

[0026] Further preferably, the electrochemical tests include electrochemical impedance spectroscopy, linear polarization resistance and open circuit potential tests, and all electrochemical tests are performed under working conditions.

[0027] Further preferably, the open circuit potential test is performed by controlling a multi-channel potentiometer through LabVIEW programming.

[0028] By programming with LabVIEW to control the high-precision digital instrument and matrix switch in Agilent's multi-channel potentiometer, low-cost, high-precision, and highly concurrent multi-channel electrochemical open-circuit potential data acquisition can be achieved. This can be used for long-term multi-channel monitoring of the open-circuit potential changes of multiple samples.

[0029] Preferably, when the other two groups of metal samples to be tested are fixed at the bottom of the autoclave cavity, the metal samples to be tested are insulated from the autoclave cavity and are arranged at intervals.

[0030] This method prevents the formation of electrochemical pairs between the metal sample and the autoclave due to potential differences, which can lead to galvanic corrosion. This ensures that the weight loss data reflects only the corrosion rate of the metal sample itself in a specific environment. This maintains the authenticity of the corrosion morphology and eliminates interference from localized corrosion (such as pitting and crevice corrosion) caused by the galvanic effect.

[0031] Preferably, the soaking solution in step (4) is different from the liquid culture medium only in that the contents of peptone and yeast powder are halved.

[0032] More preferably, the initial inoculation concentration of the soaking solution is 10 6 CFU / ml-10 8 CFU / ml.

[0033] The initial inoculum concentration of the immersion solution can be increased or decreased within the above range according to experimental requirements. The environmental conditions simulated by the initial inoculum concentration within the above range are closer to the corrosion laws of metal materials in the actual environment, and highly simulate the microbial corrosion phenomenon in the deep-sea environment, which can better observe the impact of microorganisms on the corrosion process of metal materials.

[0034] Preferably, all culture media were sterilized by high pressure steam at 121°C for 15 min before use.

[0035] Preferably, the hydrostatic pressure in step (4) is normal pressure or high pressure.

[0036] More preferably, the normal pressure is 0.1 MPa and the high pressure is 15 MPa.

[0037] Preferably, the morphology characterization includes surface corrosion morphology characterization using a scanning electron microscope and pitting pit area and depth analysis using a 3D optical profilometer;

[0038] The surface corrosion morphology characterization using a scanning electron microscope comprises: taking out a metal sample immersed under different hydrostatic pressures, fixing it in glutaraldehyde, dehydrating it with a gradient ethanol solution, and spraying it with gold, and then characterizing the surface morphology of the metal sample using a scanning electron microscope; removing corrosion products according to the standard GT / T 16545-2015, and then characterizing the surface morphology of the metal sample after the corrosion products are removed using a scanning electron microscope;

[0039] The pitting pit area and depth analysis using a 3D optical profilometer includes: using the 3D optical profilometer to randomly count at least 5 fields of view of the metal sample after immersion under different hydrostatic pressures, and calculating the pitting area and depth of the metal sample surface in the selected fields of view.

[0040] Preferably, the weight loss test includes: removing corrosion products according to the standard GT / T 16545-2015, recording the weight after removing the corrosion products, and calculating the weight loss corrosion rate of the metal sample according to the following formula:

[0041]

[0042] Where V is the weight loss corrosion rate of the metal sample, in millimeters per year (mm / y); m1 is the weight of the metal sample to be tested, in grams (g); m2 is the weight of the sample after removing the corrosion products, in grams (g); S is the surface area of ​​the metal sample exposed to the corrosive environment, in square millimeters (mm 2 ); T is the immersion time of the metal sample, in years (y); ρ is the density of the metal sample, in grams per cubic millimeter (g / mm 3 ).

[0043] The present invention also provides a system for collecting metal corrosion information in a simulated deep-sea environment under hydrostatic pressure-microbial-electrochemical action, which is used to collect metal corrosion information in a simulated deep-sea environment under hydrostatic pressure-microbial-electrochemical action, and includes:

[0044] Constant temperature shaking incubator, used for expanding the culture of deep-sea microorganisms;

[0045] Electrochemical workstation, used to collect electrochemical impedance and linear polarization resistance during metal corrosion in simulated deep-sea environments;

[0046] The multi-channel potentiometer controlled by LabVIEW is used to monitor the open circuit potential changes of multiple metal samples over a long period of time.

[0047] Autoclave, used to simulate the high-pressure environment in the deep sea;

[0048] Scanning electron microscopy was used to analyze the surface morphology of metal samples before and after corrosion products were removed after immersion at different hydrostatic pressures;

[0049] 3D optical profilometer is used to analyze the pitting area and depth of metal samples after immersion under different hydrostatic pressures.

[0050] Compared with the prior art, the present invention has the following beneficial effects:

[0051] (1) The present invention simulates the metal corrosion process in the deep-sea environment through the hydrostatic pressure-microorganism-electrochemical effect. Combining the characteristics of the deep-sea environment, it can realize the corrosion research of marine engineering metal materials in the deep-sea environment under laboratory conditions.

[0052] (2) Through the electrochemical testing of metal corrosion, corrosion morphology characterization and weight loss detection under working conditions, the interaction between microorganisms and metal materials in the deep-sea environment is analyzed, the deep-sea microbial corrosion mechanism is analyzed, and data support is provided for the safe service of metal materials in the deep-sea environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 It is the change in open circuit potential of a metal sample under normal pressure and high pressure conditions.

[0054] Figure 2 These are the Nyquist and Bode diagrams of metal samples under normal pressure and high pressure conditions.

[0055] Figure 3 are scanning electron micrographs (SEM) of metal samples after immersion at atmospheric and high pressure.

[0056] Figure 4 These are SEM images of metal samples after immersion under normal pressure and high pressure to remove corrosion products.

[0057] Figure 5 This is the result diagram of pitting area and depth on the surface of metal samples after immersion under normal pressure and high pressure.

[0058] Figure 6 is the weight loss corrosion rate of metal samples after immersion at normal pressure and high pressure. DETAILED DESCRIPTION

[0059] The present invention will be further described below with reference to the following examples and accompanying drawings. It should be understood that these examples are only intended to illustrate the present invention and are not intended to limit the scope of the present invention.

[0060] The culture medium involved in the following examples includes:

[0061] Improved version 2216E liquid culture medium, used for the propagation of deep-sea microorganisms, consists of 5.00 g / L peptone, 1.00 g / L yeast extract, 23.48 g / L sodium chloride, 4.98 g / L magnesium chloride, 3.92 g / L sodium sulfate, 1.10 g / L calcium chloride, 0.66 g / L potassium chloride, 0.19 g / L sodium bicarbonate, 0.10 g / L potassium bromide, 0.024 g / L strontium chloride, 0.026 g / L boric acid, and 0.0030 g / L sodium fluoride.

[0062] The improved version 2216E solid medium is based on the improved version 2216E liquid medium plus 15g / L agar powder.

[0063] The oligotrophic improved version 2216E liquid medium was used as the soaking liquid in the experiment. Compared with the improved version 2216E liquid medium, other components remained unchanged, and the nutrients were reduced to 2.50g / L peptone and 0.50g / L yeast powder.

[0064] All culture media were sterilized by high-pressure steam at 121°C for 15 min before use.

[0065] The metal sample used in the following examples is carbon steel Q235, including C element: 0.18%, Mn element: 0.35%, P element: 0.029%, S element: 0.018%, Si element: 0.14% and Fe element: 99.16%.

[0066] Example 1

[0067] (1) Cultivation of deep-sea microorganisms

[0068] The deep-sea pressure-resistant microorganism frozen stock solution was streaked onto a modified version of 2216E solid medium, and cultured in a 30°C incubator for 16-20 hours until a single colony appeared. The single colony was picked and placed in a liquid medium, and cultured in a shaking incubator at 30°C and 150 rpm for 12-18 hours to obtain activated deep-sea pressure-resistant microorganisms.

[0069] The activated deep-sea pressure-resistant microorganisms were inoculated into the modified 2216E liquid culture medium at a volume percentage of 1%, and cultured at 30°C and 150 rpm until the OD 600 =0.6-0.8, and centrifuged at 5000 rpm for 5 min to concentrate to obtain bacterial concentrate, which was stored at 4°C for future use.

[0070] (2) Preparation of metal samples to be tested

[0071] Prepare the metal samples to be tested and record their weight before dividing them into three groups for electrochemical testing, weight loss testing, and corrosion morphology testing.

[0072] Electrochemical testing sample preparation: Carbon steel Q235, 10 mm in diameter and 4 mm thick, was connected with copper wire and encapsulated with epoxy resin on the non-working surface. Before the experiment, the working surface was polished to 3000#. The working electrode was ultrasonically cleaned with anhydrous ethanol for 5 minutes and sterilized with 75% alcohol for 15 minutes.

[0073] Weight loss and corrosion morphology testing samples were 10 mm in diameter and 4 mm thick. Before the experiment, the exposed surface was polished to 3000#, ultrasonically cleaned with anhydrous ethanol for 5 minutes, and sterilized with 75% alcohol for 15 minutes. After ultrasonic cleaning and drying, the weight loss samples were weighed using an analytical balance, and the actual thickness was measured with a vernier caliper.

[0074] (3) Autoclave sterilization

[0075] The autoclave cavity was disinfected and sterilized by soaking it in 75% alcohol for 30 minutes, and the relevant parts were wiped and sterilized with alcohol cotton balls.

[0076] (4) Assembly of metal corrosion information collection system

[0077] The electrochemical test sample is suspended from the autoclave lid via a special sealing adapter. The weight loss test and corrosion morphology test samples are secured to the bottom of the autoclave chamber with double-sided tape. A modified oligotrophic 2216E liquid medium is added as an immersion solution, followed by inoculation with a bacterial concentrate. The reference electrode and platinum electrode (counter electrode) are assembled. The autoclave is sealed, pressurized, and connected to a multi-channel potentiometer or electrochemical workstation controlled by LabVIEW.

[0078] (5) Electrochemical information collection

[0079] Real-time OCP data acquisition and analysis: The working electrode and saturated calomel reference electrode were connected to a multi-channel potentiometer controlled by LabVIEW. The measurement time was 1.0 second and the scan interval was 5 seconds. The open circuit potential (OCP) of carbon steel was monitored in an immersion solution at atmospheric pressure (0.1 MPa).

[0080] Electrochemical impedance spectroscopy (EIS) and linear polarization refractive index (LPR) tests: EIS and LPR tests of carbon steel in immersion solution were performed using an electrochemical workstation (Reference 600+, Gamry Instruments) at atmospheric pressure (0.1 MPa). The EIS test was performed with a sinusoidal voltage of 10 mV and a frequency range of 10 5 Hz-10 -2 The LPR scan range was OCP ± 500 mV, and data were collected daily.

[0081] (6) Corrosion morphology characterization and pitting analysis

[0082] After the immersion test under normal pressure, the carbon steel sample was taken out, and the unbound bacteria and other debris were cleaned with deionized water. It was fixed with 2.5% glutaraldehyde at room temperature for 2 h, and then dehydrated step by step with 30%, 50%, 70%, 80%, 90% and 100% ethanol solutions for 10 minutes. After drying, it was sprayed with gold, and the corrosion products were observed under a scanning electron microscope (SEM).

[0083] After removing the corrosion products according to the standard GT / T 16545-2015, the surface corrosion morphology of the carbon steel sample was observed again using SEM, and the pit area and depth were analyzed using a 3D optical profilometer.

[0084] (7) Weightlessness detection

[0085] After the atmospheric pressure immersion test, the carbon steel sample was removed and the corrosion products were removed according to the GT / T 16545-2015 standard. After complete drying, the sample weight was recorded. The corrosion rate (V) of carbon steel was calculated as follows:

[0086]

[0087] Where V is the weight loss corrosion rate of the metal sample, in millimeters per year (mm / y); m1 is the weight of the metal sample to be tested, in grams (g); m2 is the weight of the sample after removing the corrosion products, in grams (g); S is the surface area of ​​the metal sample exposed to the corrosive environment, in square millimeters (mm 2 ); T is the immersion time of the metal sample, in years (y); ρ is the density of the metal sample, in grams per cubic millimeter (g / mm 3 ).

[0088] Example 2

[0089] The experimental process of Example 1 is the same as that of Example 1, except that the hydrostatic pressure environment is high pressure (15 MPa).

[0090] The electrochemical information, surface morphology and weight loss test results under normal pressure and high pressure are as follows:

[0091] like Figure 1 As shown in the figure, the early OCP potential of carbon steel under working conditions gradually shifts positively, indicating that corrosion products (biofilm) are forming on the carbon steel surface, including bacterial adhesion and adsorption of extracellular polymers. The late OCP potential tends to stabilize, indicating that a relative equilibrium between adsorption and dissociation has been reached. However, the positive shift of the OCP of carbon steel is greater under high pressure, indicating that there are differences in the corrosion products formed under different net water pressures.

[0092] Figure 2 The Nyquist and Bode plots under normal and high pressure conditions are presented. The Nyquist plot results show that under both hydrostatic pressure tests, the impedance arc radius of carbon steel increased significantly after one day, and then did not change significantly, indicating that the corrosion products on the carbon steel surface had almost fully grown within 24 hours, and the structure of the corrosion products did not change significantly during the 8 days of data collection. In addition, compared with normal pressure, the impedance arc radius of carbon steel in the high pressure group was larger, indicating that the corrosion products formed on the carbon steel surface by deep-sea pressure-resistant microorganisms under high pressure have a greater obstruction to the charge transfer process. The Bode plot results show that the phase angle of carbon steel under high pressure increases compared to normal pressure, indicating that the thickness of the corrosion products formed on the surface of carbon steel under high pressure is greater.

[0093] The surface morphology of carbon steel after atmospheric and high pressure immersion showed that compared with the atmospheric pressure group, the corrosion products formed in the high pressure group contained a large number of bacteria, were thicker, but not uniform (see Figure 3 After removing the corrosion products, it was found that pitting pits existed on the surfaces of both carbon steels, but the number of pitting pits in the high pressure group was greater (see Figure 4 ). The pitting area and depth analysis showed that the pitting area formed under high pressure was larger than that under normal pressure, while the depth had no significant difference (see Figure 5 ).

[0094] The results of the weight loss test show that the weight loss corrosion rate under normal pressure is 0.014mm / y, and the weight loss corrosion rate under high pressure is 0.039mm / y. The corrosion rate of carbon steel increases significantly under high pressure ( Figure 6 ).

[0095] In summary, microorganisms in high-pressure environments will accelerate the corrosion rate of carbon steel. The main mechanism is that under high-pressure conditions, deep-sea pressure-resistant microorganisms form uneven biofilms on the surface of carbon steel as corrosion products, which promote pitting corrosion of carbon steel and accelerate the weight loss corrosion rate of carbon steel.

[0096] The embodiments described above provide a detailed description of the technical solutions of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, supplements or similar substitutions made within the scope of the principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for collecting and analyzing metal corrosion information in a simulated deep-sea environment under hydrostatic pressure-microorganism-electrochemical action, characterized in that: The following steps are involved: (1) streaking the frozen stock of deep-sea pressure-resistant microorganisms onto a solid culture medium, culturing until a single colony appears, picking the single colony and placing it in a liquid culture medium to obtain activated deep-sea pressure-resistant microorganisms; (2) inoculating the activated deep-sea pressure-resistant microorganisms into a liquid culture medium for expansion and centrifugation to obtain a bacterial concentrate for later use; (3) Prepare the metal samples to be tested and record their weights before dividing them into three groups. One group of metal samples to be tested is suspended on the lid of the autoclave for electrochemical testing; the other two groups of metal samples to be tested are fixed at the bottom of the autoclave cavity for weight loss testing and morphology characterization. (4) The immersion liquid was injected into the autoclave cavity and the bacterial concentrate was inoculated. Electrochemical tests were performed under different hydrostatic pressures and immersion times. The metal samples immersed at the bottom of the autoclave cavity were taken out for morphological characterization and weight loss detection.

2. The collection and analysis method according to claim 1, characterized in that: The solid culture medium in step (1) comprises peptone, yeast powder, sodium chloride, magnesium chloride, sodium sulfate, calcium chloride, potassium chloride, sodium bicarbonate, potassium bromide, strontium chloride, boric acid, sodium fluoride and agar powder; The culture time after inoculation into the solid culture medium is 16h-20h; The liquid culture medium in step (2) comprises peptone, yeast powder, sodium chloride, magnesium chloride, sodium sulfate, calcium chloride, potassium chloride, sodium bicarbonate, potassium bromide, strontium chloride, boric acid and sodium fluoride; The culture time after inoculation into the liquid culture medium is 12h-18h.

3. The collection and analysis method according to claim 1, characterized in that: The optical density OD of the bacterial suspension obtained by the expanded culture in step (2) at a wavelength of 600 nm is 600 It is 0.6-0.

8.

4. The collection and analysis method according to claim 1, characterized in that: The step (3) of suspending one of the metal samples to be tested on the autoclave cover for electrochemical testing comprises: connecting a working electrode, an auxiliary electrode, and a reference electrode suspended on the autoclave cover to an electrochemical testing device via copper wires for electrochemical testing, wherein the working electrode is one of the metal samples to be tested, and the non-working surface is encapsulated with epoxy resin; The electrochemical tests include electrochemical impedance, linear polarization resistance and open circuit potential tests, and all electrochemical tests are performed under working conditions; among them, the open circuit potential test is performed by controlling a multi-channel potentiometer through LabVIEW programming.

5. The collection and analysis method according to claim 1, characterized in that: When the other two groups of metal samples to be tested are fixed at the bottom of the autoclave cavity, the metal samples to be tested are insulated from the autoclave cavity and are arranged at intervals.

6. The collection and analysis method according to claim 1, characterized in that: The soaking solution described in step (4) is different from the liquid culture medium only in that the content of peptone and yeast powder is halved; The initial inoculation concentration of the soaking solution is 10 6 CFU / ml-10 8 CFU / m1.

7. The collection and analysis method according to claim 1, characterized in that: The hydrostatic pressure in step (4) is normal pressure or high pressure.

8. The collection and analysis method according to claim 1, characterized in that: The morphology characterization in step (4) includes surface corrosion morphology characterization using a scanning electron microscope and pitting pit area and depth analysis using a 3D optical profilometer; The surface corrosion morphology characterization using a scanning electron microscope comprises: taking out a metal sample immersed under different hydrostatic pressures, fixing it in glutaraldehyde, dehydrating it with a gradient ethanol solution, and spraying it with gold, and then characterizing the surface morphology of the metal sample using a scanning electron microscope; removing corrosion products according to the standard GT / T 16545-2015, and then characterizing the surface morphology of the metal sample after the corrosion products are removed using a scanning electron microscope; The pitting pit area and depth analysis using a 3D optical profilometer includes: using the 3D optical profilometer to randomly count at least 5 fields of view of the metal sample after immersion under different hydrostatic pressures, and calculating the pitting area and depth of the metal sample surface in the selected fields of view.

9. The collection and analysis method according to claim 1, characterized in that: The weight loss test described in step (4) includes: removing corrosion products according to standard GT / T 16545-2015, recording the weight after removing the corrosion products, and calculating the weight loss corrosion rate of the metal sample according to the following formula: Where V is the weight loss corrosion rate of the metal sample, in millimeters per year; m1 is the weight of the metal sample to be tested, in grams; m2 is the weight of the sample after removing corrosion products, in grams; S is the surface area of ​​the metal sample exposed to the corrosive environment, in square millimeters; T is the immersion time of the metal sample, in years; ρ is the density of the metal sample, in grams per cubic millimeter.

10. A system for collecting metal corrosion information in a simulated deep-sea environment under hydrostatic pressure-microorganism-electrochemical action, characterized in that: Used for collecting metal corrosion information in a simulated deep-sea environment under the hydrostatic pressure-microorganism-electrochemical action of any one of claims 1 to 9, comprising: Constant temperature shaking incubator, used for expanding the culture of deep-sea microorganisms; Electrochemical workstation, used to collect data on electrochemical impedance and linear polarization resistance during metal corrosion in simulated deep-sea environments; The multi-channel potentiometer controlled by LabVIEW is used to monitor the open circuit potential changes of multiple metal samples over a long period of time. Autoclave, used to simulate the high-pressure environment in the deep sea; Scanning electron microscopy was used to analyze the surface morphology of metal samples before and after corrosion products were removed after immersion at different hydrostatic pressures; 3D optical profilometer is used to analyze the pitting area and depth of metal samples after immersion under different hydrostatic pressures.

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