A method for characterizing a transfer film for ring block friction pairs

Abstract

The application discloses a kind of characterization protection methods for ring block friction pair transfer film, belong to the field of friction testing technology.The method effectively protects the transfer film on the surface of friction pair material by using back type protective tape, avoids the pollution caused by cutting fluid to the surface during cutting process, and ensures the structural integrity of transfer film and the composition and bonding structure analysis of transfer film.According to the difference of test environment conditions, the thickness and material of the second functional layer can be adjusted and optimized to effectively maintain the original state of the analyzed area of the ring sample after friction test under different test environment conditions, so that the subsequent characterization analysis result is more accurate, which helps to further analyze the ring block friction and wear mechanism under different conditions.The method is simple in operation, economical in cost, suitable for transfer film protection of ring samples of various sizes and various conditions, and can effectively protect the transfer film without affecting the accuracy of friction and wear characterization results.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of friction test, and particularly relates to a characterization protection method for a transfer film of a ring-block friction pair. BACKGROUND

[0002] A friction pair refers to a part of friction and wear between the surfaces of objects in relative motion, and a suitable friction pair material can slow down the wear process, prolong the service life of components and reduce maintenance costs. During the friction process, the wear debris generated by the wear of the polymer material is transferred to the metal surface and generates a thin film through a series of physical and chemical actions, and the film is called a transfer film. In tribology research, a ring-block friction test is a commonly used test method, which is widely used to evaluate the friction and wear performance of materials in rotary motion. In order to analyze the friction and wear mechanism in depth, the transfer film attached to the wear surface of the ring sample (i.e. the circumferential surface of the ring sample) needs to be characterized in detail in terms of composition and structure, such as by using a scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and the like. However, these characterization techniques have strict requirements on the size of the sample, for example, the height of the sample required by the analysis chamber of some types of XRD is not more than 15 mm, while the diameter of the ring sample in the friction test is usually not less than 50 mm, so it is impossible to directly test and it is difficult to directly put the ring sample into the XRD analysis chamber for analysis and characterization.

[0003] To solve this problem, the operator usually needs to cut the ring sample to meet the size requirements of the instrument. In the cutting process, the wire cutting technology is often used. Wire cutting technology uses the principle of local melting of metal by electric spark, although it can achieve high-precision cutting, but it needs to use cooling fluid (cutting fluid) to prevent overheating. However, the transfer film is usually thin and fragile, and is easily damaged by external forces or environmental factors. And the cutting fluid used usually has complex chemical composition and certain solubility, which may cause the transfer film to dissolve or peel off, thereby affecting the fixing effect of the transfer film generated on the surface of the ring sample. The composition of the cutting fluid is complex, containing various organic solvents, if the transfer film attached to the surface of the ring sample is not protected and directly subjected to wire cutting, the sample surface may be contaminated, thereby affecting the accuracy of subsequent characterization. In actual operation, the technician usually chooses to wrap the ring sample surface with adhesive tape to block the pollution. But this kind of way is more primitive, it is difficult to fully protect the structural integrity of the transfer film. And in the friction test, the test environment conditions change constantly, and a single protection method is increasingly difficult to meet the test requirements under various application conditions. The above technical problems restrict the analysis of the composition and bonding structure of the transfer film, and the more in-depth analysis of the ring block friction and wear mechanism under different working conditions.

[0004] Therefore, how to effectively protect the circumferential surface of the ring sample from the pollution of the wire cutting cutting fluid while cutting the ring sample, so that the final characterization test results can truly reflect the element types and friction chemical mechanism after the surface wear of the ring sample has become a technical problem in tribology research. SUMMARY

[0005] In view of the above defects of the prior art, in the first aspect of the present application, a characterization protection method for the transfer film of the ring block friction pair is provided, which is strong in protection and widely applicable, comprising the following steps:

[0006] In the cutting process of the ring sample, the transfer film of the ring block friction pair of the ring sample is protected by using the back-shaped protective adhesive tape;

[0007] The back-shaped protective adhesive tape comprises a three-layer composite structure, which is a protective layer, a functional layer and an adhesive layer in sequence;

[0008] The functional layer is a functional adhesive tape with adjustable thickness and material according to the test environment conditions;

[0009] The adhesive layer includes an inner region and an outer region; the outer region is an adhesive, which is in contact with the two side end faces of the ring sample through its adhesion and is fixed; the inner region is a groove region without adhesive in the adhesive layer, which covers the wear surface of the transfer film of the ring block friction pair to be analyzed.

[0010] The material of the protective layer can be selected from various materials having a protective and insulating effect on the cooling liquid, such as waterproof adhesive tape, etc.

[0011] Preferably, the test environment conditions include seawater environment, low speed and low load, and high temperature environment.

[0012] Further preferably, when the test environment conditions are seawater environment, the seawater concentration is divided into low concentration, medium concentration, and high concentration; the low concentration simulates natural seawater, and the NaCl concentration is less than 3.5 wt.%; the medium concentration simulates high-salt sea areas, and the NaCl concentration is 3.5 wt.%-5.0 wt.%; and the high concentration simulates an extreme saltwater environment, and the NaCl concentration is higher than 5.0 wt.%.

[0013] The thickness of the functional layer is 2.0-3.5 mm, and the material composition includes resin matrix, water absorbent, and chloride ion absorbent.

[0014] Further, under the low-concentration seawater condition, the mass ratio of the resin matrix, the water absorbent, and the chloride ion absorbent is 88-92:5:3-7; under the medium-concentration seawater condition, the mass ratio of the resin matrix, the water absorbent, and the chloride ion absorbent is 83-87:5:8-12; and under the high-concentration seawater condition, the mass ratio of the resin matrix, the water absorbent, and the chloride ion absorbent is 78-82:5:13-17.

[0015] Ordinary protective measures are difficult to meet the test requirements of seawater environment, and mainly face the following technical problems:

[0016] 1. Ion contamination: the ion components (Cl - , etc.) in seawater may react with the sample material, causing the chemical composition of the transfer film surface to change, affecting the subsequent characterization analysis results;

[0017] 2. Hydrate formation: in a high-humidity environment, additional hydrates may form on the rubbing sample surface, affecting the judgment of the friction properties and wear behavior of the real ring block friction pair material.

[0018] Therefore, the present application changes the ratio of chloride ion absorbent in the functional layer material according to the different concentrations of seawater salt ions in the friction test, avoids the degradation of residual Cl - to the transfer film. The water absorbent is used to avoid the formation of a high-humidity environment inside the back-type protective adhesive tape.

[0019] Further, the resin matrix comprises one of polyurethane, epoxy resin, polyvinylidene fluoride; the water absorbent comprises one of sodium polyacrylate, polyvinyl alcohol, cellulose derivative; and the chloride ion absorbent comprises one of hydroxide type strong alkali anion exchange resin, quaternary ammonium type cation adsorption resin, and zinc oxide nanoparticles.

[0020] Further preferably, the test environment condition is low speed and low load, the speed of the low speed and low load is 0-100 rpm, and the load is 0-50 N; and the thickness of the functional layer is 0.5-1.5 mm.

[0021] When the friction condition of the ring-block friction pair is low speed and low load, the transfer film generated is usually thin (thickness within several microns) due to the low speed and low load friction condition, and when the thickness of the functional layer is too large, stress concentration will occur in the weak area of the transfer film, thereby causing damage to the transfer film. Therefore, based on the test application requirements of the present application, the thickness of the functional layer is preferably controlled within the range of 0.5-1.5 mm. The present application avoids damaging the transfer film by applying excessive pressure in the weak area of the transfer film by adjusting the optimal thickness of the functional layer. It should be particularly noted that this parameter is determined according to the specific design process of the inventor and is not a routine selection of a person skilled in the art:

[0022] Through experiments, the inventor measured the thickness of the transfer film under different friction conditions, for example, when the speed is 50 rpm and the load is 20 N, the average thickness of the transfer film is X μm, and when the speed is 100 rpm and the load is 50 N, the average thickness is Y μm. Subsequently, a linear regression analysis is used to establish the relationship between the thickness of the transfer film and the thickness of the functional layer, which is in the form of T transfer = k × T function + b, where T transfer is the thickness of the transfer film, T function is the thickness of the functional layer, and k and b are undetermined parameters.

[0023] When analyzing the effect of pressure, the formula P = F / A is used to calculate the pressure, where P is the pressure acting on the transfer film, F is the applied force, and A is the contact area. The contact area can be calculated by the diameter (d) of the ring and the thickness of the functional layer, specifically A = π × d × T function , so that the corresponding contact area can be calculated according to different thicknesses of the functional layer. In terms of quantifying softness, Shore A hardness is selected as the evaluation standard to record the hardness values of different materials, and it is related to the performance under low speed and low load conditions, and the formula Softness Index = 1 / H shore is used to quantify the softness of the material.

[0024] In the pressure analysis, the pressure of the weak area is ensured to be less than the index parameter (less than 50 kPa) applied in the application. Thus, the inventor determines the optimal thickness range of the functional layer, thereby ensuring the stability of the transfer film under low-speed and low-load conditions. Those skilled in the art can also complete further thickness design under the guidance of the design process.

[0025] Further preferably, when the temperature is 150-300 ℃, the material of the functional layer 025 includes one of polyimide, polyether ether ketone, and phenolic resin-based composite material; and when the temperature is 300-1000 ℃, the material of the functional layer 025 includes one of ceramic fiber, alumina fiber, and silicon carbide fiber.

[0026] When the friction condition of the ring-block friction pair is a high-temperature environment, if the friction product is characterized immediately after the temperature of the friction pair has not cooled, the physical and chemical states of the material under high-temperature conditions can be observed more closely in real time, and the micro-morphology and chemical composition of the friction product are more likely to remain in the "original" state. However, when the characterization is performed after cooling, the oxides, thermal decomposition products, and surface microstructure of the transfer film change during the cooling process. The temperature drop can cause oxidation or structural shrinkage, which can cause deviations in the characterization analysis results. During the cooling process, a new oxide layer can be formed on the surface, or the micro-morphology can change due to the release of thermal stress, thereby affecting the accurate evaluation of the true friction behavior of the material.

[0027] Under the high-temperature environmental condition, the functional layer material of the application is designed as a heat insulation layer to reduce the impact of the rapid temperature drop on the structure of the friction product. The function of the heat insulation layer is to maintain the temperature of the friction surface and reduce the speed of heat conduction during the cooling process, thereby delaying the changes in the morphology or chemical composition caused by the temperature drop, helping to preserve the state of the friction product at high temperature, and reducing the difference between the characterization before and after cooling.

[0028] Preferably, the bending line is arranged at the bending part of the outer region in contact with the two side end faces of the ring sample.

[0029] The arrangement of the bending line enables the adhesive tape to better fit on the corner bending part of the ring sample, thereby enhancing the adhesion performance, improving the flexibility and adaptability, and preventing the tape from loosening or peeling off at the bending part.

[0030] Preferably, the characterization protection method for the transfer film of the ring-block friction pair in the friction test includes the following steps:

[0031] (1) The ring sample and the block sample are respectively installed in the clamps of the experimental device, and the friction test is started according to the preset friction test conditions, including the rotation speed, load, temperature, and time parameters;

[0032] (2) After the friction test, the ring sample is removed; the transfer film on its worn surface is observed and the area to be analyzed is determined; the area to be analyzed is the part whose surface morphology and state are significantly different from the unworn area after the friction test, which is convenient for further characterization and analysis of the friction and wear mechanism;

[0033] (3) Align the inner area of ​​the adhesive layer of the loop-shaped protective tape with the area to be analyzed of the ring sample, so that the inner area covers the wear surface to be analyzed in the transfer film of the ring block friction pair, and the outer area is attached to the two end faces of the ring sample to complete the fixation, so as to prevent the loop-shaped protective tape from shifting during the cutting process.

[0034] (4) Perform wire cutting along the outer contour of the protective tape. After completion, remove the small ring sample piece obtained by cutting, clean the residual contaminants, and dry it for further testing.

[0035] (5) Before characterization and testing, remove the protective tape covering the small ring sample piece and then perform characterization and testing.

[0036] Preferably, in step (5), the characterization detection includes scanning electron microscopy analysis, X-ray diffraction analysis, energy dispersive spectrometry (EDS) analysis, and X-ray photoelectron spectroscopy analysis.

[0037] Based on the above technical solutions, the method of this invention effectively protects the transfer film on the surface of the friction pair material by using a U-shaped protective tape, avoiding surface contamination by cutting fluid during the cutting process, and ensuring the structural integrity of the transfer film and the analysis of its composition and bonding structure. Depending on the different test environment conditions, this invention can effectively maintain the original state of the area to be analyzed in the ring sample after friction testing under different test environment conditions by adjusting and optimizing the thickness and material of the second functional layer. This makes the subsequent characterization analysis results more accurate and helps to analyze the ring-block friction and wear mechanism under different working conditions more deeply. This method is simple to operate, cost-effective, and applicable to the protection of the transfer film on ring samples of various sizes and working conditions. It can achieve effective protection of the transfer film without affecting the accuracy of the friction and wear characterization results.

[0038] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0039] This invention provides a characterization and protection method for the transfer film of ring-block friction pairs. This method has the advantages of strong protection and wide applicability, and improves the accuracy of tribological research. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the structure of the U-shaped protective tape;

[0041] Figure 2Figure 1 is a schematic diagram of the explosion of the back type protective tape;

[0042] Figure 3 Figure 2 is a top view of the area to be analyzed in the back type protective tape protection ring sample;

[0043] Figure 4 Figure 3 is a schematic diagram of the overall back type protective tape fitting ring sample;

[0044] Figure 5 Figure 4 is a front view of the back type protective tape fitting ring sample;

[0045] Figure 6 Figure 5 is a side view of the back type protective tape fitting ring sample;

[0046] Figure 7 Figure 6 is an SEM and EDS distribution of the 45 steel ring wear surface in seawater environment without using the back type protective tape;

[0047] Figure 8 Figure 7 is an SEM and EDS distribution of the 45 steel ring wear surface in seawater environment using the back type protective tape;

[0048] Figure 8 is a schematic diagram of the back type protective tape fitting ring sample; DETAILED DESCRIPTION

[0049] The present application will be further described in the following examples, but the present application is not limited in the scope of the examples. The experimental methods in the following examples without specific conditions are selected according to the conventional methods and conditions, or according to the product instructions.

[0050] Example 1

[0051] The structure of the back type protective tape used in this example is shown in Figure 1 、 2 The back type protective tape 02 is a three-layer composite structure, which is a protective layer 026, a functional layer 025 and an adhesive layer in turn. The protective layer 026 is a waterproof tape; the functional layer 025 is a functional tape with adjustable thickness and material according to the test environment conditions, and in this example, it is a common test condition, and those skilled in the art can select its appropriate material and thickness according to the actual test requirements. The adhesive layer is divided into an inner area 021 and an outer area 022, and the outer area 022 is in contact with the fixed bending part of the two side end faces of the ring sample 01, which is provided with a bending line 023, which helps to optimize the fitting effect of the bending part. The inner area 021 is a recessed area without adhesive in the adhesive layer, and the outer area 022 is an adhesive, which is adhered to the ring sample 01 by its adhesion for fixation.

[0052] The characterization protection method for the transfer film of the ring-block friction pair in this embodiment uses a ring sample with a diameter of 55 mm. The EDS analysis of the friction and wear circumferential surface of the ring sample is required to evaluate the element changes on the wear surface. The specific steps are as follows:

[0053] (1) The ring sample 01 and the block sample are fixed in the clamps of the friction tester, and the friction test is performed at a speed of 300 rpm and a normal load of 100 N. The friction time is set to 60 min.

[0054] (2) After the friction test, the ring sample 01 is taken out. The wear of the surface of the ring sample 01 is observed, and it is found that there are obvious friction marks on the sample. Through preliminary optical microscope observation, it is determined that an outer region of the ring sample 01 is the analysis area 024.

[0055] (3) The return type protective tape 02 is taken out using tweezers, as shown in Figure 3 , the center part of the inner area 021 is aligned with the analysis area 024, and the whole is attached to the surface of the ring sample 01. The outer area 022 is adhered to the end faces of the ring sample 01 on both sides to complete the fixation, so as to ensure that the friction surface is completely covered. The fixed schematic diagram is shown in Figures 4-6 .

[0056] (4) The ring sample 01 is fixed on the line cutting machine, and cutting is performed along the outer contour of the return type protective tape 02. Since the return type protective tape 02 effectively isolates the cutting fluid, no pollution occurs during cutting. After cutting, the sample surface is washed with deionized water to remove residual cutting fluid and impurities, and then the sample is dried for further testing.

[0057] (5) After the waterproof tape is removed, the XPS is used to analyze the element valence state of the sample surface, and it is found that the surface element valence state and distribution are consistent with the actual dry friction working condition, and are not affected by the additional chemical elements contained in the cutting fluid.

[0058] Example 2

[0059] The return type protective tape used in this embodiment is basically the same as that of Example 1, and the only difference is that the composition of the functional layer 025 in this embodiment is polyurethane, sodium acrylate and hydrogen oxide type strong base anion exchange resin, and the mass ratio is 90:5:5. In the test, the person skilled in the art can flexibly select the specific components and proportions of the corresponding functional layer 025 according to the test requirements of the seawater environment working condition, the concentration and corresponding parameters divided by the present application.

[0060] This embodiment focuses on a transfer film characterization and protection method for ring samples in a marine environment, investigating the frictional properties of the ring samples under seawater and high-load conditions. The experimental environment simulated marine conditions, and the friction pair material was a marine coating material. Ring samples and block-shaped friction pair materials were used in the experiment. After the experiment, the sample surface was characterized and analyzed. The specific steps are as follows:

[0061] (1) Set the friction test equipment to a normal temperature environment of 25 ℃, set the normal load to 500 N, use standard ratio seawater solution to simulate the marine environment, fix the ring sample 01 and the block sample in the fixture of the friction tester respectively, and carry out friction test according to the set seawater and high load conditions for a duration of 60 min.

[0062] (2) After the friction test, take out the ring sample 01 and use a blower to dry the seawater adsorbed on its surface until the surface is dry; use an optical microscope to observe the surface of the ring sample and observe the wear of the surface of the ring sample 01. It was found that the wear under high load conditions was more obvious, and the area with large wear marks on the ring sample was identified as the area to be analyzed, 024.

[0063] (3) Use tweezers to take out the U-shaped protective tape 02 that is suitable for the sample size, align the center of its inner area 021 with the area to be analyzed 024, and attach it to the surface of the ring sample 01. The outer area 022 is attached to the two end faces of the ring sample 01 to complete the fixation, ensuring that the friction surface is completely covered.

[0064] (4) Fix the ring sample 01 on the wire cutting machine and cut along the outer contour of the spiral protective tape 02. After cutting, rinse the sample surface with deionized water to remove residual cleaning fluid and impurities. Then dry the sample for further testing.

[0065] (5) After removing the waterproof tape, the cut sample pieces were analyzed using EDS. The results showed that the friction surface was not contaminated, such as Figure 7 The figure shows the SEM and EDS distribution of the worn surface of a 45 steel ring in a seawater environment without the use of a spiral-shaped protective tape. Figure 8 This image shows the SEM and EDS distributions of the worn surface of a 45 steel ring in seawater after using a spiral-shaped protective tape. A comparison of the two images shows that without the spiral-shaped protective tape, elements such as phosphorus (P) and sulfur (S) from the cutting fluid contaminated the surface of the 45 steel ring sample. With the spiral-shaped protective tape, the intrusion of the cutting fluid was effectively prevented, and no P or S contaminants were found. The analytical results accurately reflect the friction and wear of the material.

[0066] This embodiment demonstrates that the method of the present invention can effectively avoid contamination of the transfer film on the surface of the worn ring sample in the marine environment by the cleaning fluid during wire cutting, thus ensuring the accuracy of subsequent characterization and analysis.

[0067] Example 3

[0068] The back-shaped protective adhesive tape used in this example is basically the same as that of Example 1, the only difference being that the thickness of the functional layer 025 in this example is controlled within the design range corresponding to low-speed low-load working conditions. In this example, the sample is subjected to friction test at room temperature, mainly to study the wear behavior and surface characteristics at low friction speed (low-speed low-load), and the specific steps are as follows:

[0069] (1) Fix the ring sample 01 with a diameter of 60 mm and the corresponding block sample on the friction tester, set the rotation speed to 50 rpm, the normal load to 50 N, and perform friction test at 25℃ for 60 min;

[0070] (2) After the friction is completed, observe the surface of the ring sample 01 through a microscope, select the part where the friction area and the un-worn area have obvious differences as the to-be-analyzed area 024;

[0071] (3) Use tweezers to take out the back-shaped protective adhesive tape 02, align the center part of the inner area 021 with the to-be-analyzed area 024, and attach it to the surface of the ring sample, ensuring that the friction surface is completely covered;

[0072] (4) Use a wire cutting machine to cut the ring sample 01 along the outline of the back-shaped protective adhesive tape 02, and ensure that the cutting fluid does not contact the worn area; after cutting, wash the sample surface with deionized water, and then dry it for standby;

[0073] (5) After removing the protective adhesive tape, use XRD to analyze the phase composition of the sample surface, the results show that the friction surface is not contaminated by the cutting fluid, and the test results are accurate.

[0074] This example proves that under low-speed low-load working conditions, the contamination of cutting fluid is effectively isolated by using the method of the present application, making the subsequent XRD characterization analysis highly reliable.

[0075] Example 4

[0076] The back-shaped protective adhesive tape used in this example is basically the same as that of Example 1, the only difference being that the functional layer 025 in this example is polyimide (polyether ether ketone, phenolic resin-based composite material can also achieve the purpose of this example, when the temperature is higher, the technician can choose ceramic fiber, alumina fiber, silicon carbide fiber), to adapt to the test requirements of high temperature environment working conditions. This example studies the wear behavior and surface characteristics of the ring sample under high temperature environment and high load, and the specific steps are as follows:

[0077] (1) The ring sample 01 with a diameter of 55 mm and the block sample are respectively installed in the clamps of the high-temperature friction tester; the friction speed is set to 200 rpm, the normal load is set to 500 N, the temperature is set to 250 DEG C, and the friction test is performed for 60 min;

[0078] (2) After the friction test is completed, the ring sample 01 is taken out; the transfer film on the wear surface is observed, and a region with serious wear is selected as an analysis region 024,

[0079] (3) The return-shaped protective tape 02 is taken out using tweezers, the center part of the inner region 021 is aligned with the analysis region 024, and the return-shaped protective tape 02 is attached to the surface of the ring sample 01, so that the friction surface is completely covered;

[0080] (4) The ring sample 01 is cut using a wire cutting machine, the cutting is performed along the contour of the return-shaped protective tape 02, and it is ensured that the cutting fluid does not contact the wear region; after the cutting, the sample surface is cleaned using deionized water, and then the sample is dried for standby;

[0081] (5) The surface morphology of the cut sample is analyzed using SEM, and the result shows that the wear surface is not contaminated, and the surface structure is clear.

[0082] The embodiment proves that under the conditions of high-temperature environment and high load, the protective measures are still effective, and the integrity and cleanliness of the sample surface are ensured, and the characterization result truly reflects the high-temperature wear behavior of the material.

[0083] In summary, the characterization protection method for the transfer film of the ring-block friction pair can effectively avoid the pollution of the transfer film on the surface of the ring sample in the online cutting process, especially under extreme conditions such as high temperature, low speed and low load, seawater, etc., the structure and composition of the transfer film on the surface of the sample can still be maintained intact and true, and the subsequent characterization analysis result is accurate.

[0084] The above describes in detail the preferred embodiments of the present application. It should be understood that those skilled in the art can make many modifications and changes without creative labor according to the concept of the present application. Therefore, any technical solution obtained by logical analysis, reasoning or limited experiment on the basis of the prior art according to the concept of the present application shall be within the protection scope determined by the claims.

Claims

1. A method for characterizing and protecting the transfer film of a ring-block friction pair, characterized in that, Includes the following steps: In the cutting process of the ring specimen (01), the ring block friction pair transfer film of the ring specimen (01) is protected by the back-shaped protective tape (02); the back-shaped protective tape (02) includes a three-layer composite structure, namely a protective layer (026), a functional layer (025) and an adhesive layer; the functional layer (025) is a functional tape whose thickness and material are adjusted according to the test environment conditions; the adhesive layer includes an inner area (021) and an outer area (022); the outer area (022) is an adhesive, which is fixed to the two end faces of the ring specimen (01) by its adhesiveness; the inner area (021) is a groove area in the adhesive layer without adhesive, which covers the wear surface to be analyzed in the ring block friction pair transfer film; The operational procedure for friction testing includes the following steps: (1) Install the ring sample and the block sample into the fixture of the experimental device respectively, and start the friction test according to the preset friction test conditions, including rotation speed, load, temperature and time parameters; (2) After the friction test, the ring sample is removed; the transfer film on its worn surface is observed and the area to be analyzed is determined; the area to be analyzed is the part whose surface morphology and state are significantly different from the unworn area after the friction test, which is convenient for further characterization and analysis of the friction and wear mechanism; (3) Align the inner area of ​​the adhesive layer of the loop-shaped protective tape with the area to be analyzed of the ring sample, so that the inner area covers the wear surface to be analyzed in the transfer film of the ring block friction pair, and the outer area is attached to the two end faces of the ring sample to complete the fixation, so as to prevent the loop-shaped protective tape from shifting during the cutting process. (4) Perform wire cutting along the outer contour of the U-shaped protective tape. After completion, remove the small ring sample piece obtained by cutting, clean the residual contaminants, and dry it for further testing. (5) Before characterization and testing, remove the protective tape covering the small ring sample piece and then perform characterization and testing.

2. The characterization and protection method for the transfer film of the ring-block friction pair according to claim 1, characterized in that: The test environment conditions include seawater environment, low speed and low load, and high temperature environment.

3. The method for characterizing and protecting the transfer film of a ring-block friction pair according to claim 2, characterized in that: When the test environment is a seawater environment, the seawater concentration is divided into low concentration, medium concentration and high concentration; low concentration simulates natural seawater, with a NaCl concentration of less than 3.5 wt.%; medium concentration simulates high salinity sea area, with a NaCl concentration of 3.5 wt.%-5.0 wt.%; high concentration simulates extreme saline environment, with a NaCl concentration of more than 5.0 wt.%; the thickness of the functional layer (025) is 2.0-3.5 mm, and its material composition includes resin matrix, water absorbent and chloride ion absorbent.

4. The characterization and protection method for the transfer film of the ring-block friction pair according to claim 3, characterized in that: Under low-concentration seawater conditions, the mass ratio of resin matrix, absorbent, and chloride ion absorbent is 88-92:5:3-7; under medium-concentration seawater conditions, the mass ratio is 83-87:5:8-12; and under high-concentration seawater conditions, the mass ratio is 78-82:5:13-17.

5. The characterization and protection method for the transfer film of the ring-block friction pair according to claim 3, characterized in that: The resin matrix includes one of polyurethane, epoxy resin, and polyvinylidene fluoride; the water absorbent includes one of sodium polyacrylate, polyvinyl alcohol, and cellulose derivatives; and the chloride ion absorbent includes one of hydroxide-type strong base anion exchange resin, quaternary ammonium-type cationic adsorption resin, and zinc oxide nanoparticles.

6. The method for characterizing and protecting the transfer film of a ring-block friction pair according to claim 2, characterized in that: The test environment is under low speed and low load conditions, with a speed of 0-100 rpm and a load of 0-50 N; the thickness of the functional layer (025) is 0.5-1.5 mm.

7. The method for characterizing and protecting the transfer film of a ring-block friction pair according to claim 2, characterized in that: When the test environment is a high-temperature environment, the material of the functional layer (025) is one of polyimide, polyether ether ketone, and phenolic resin-based composite material when the temperature is 150-300 ℃; when the temperature is 300-1000 ℃, the material of the functional layer (025) is one of ceramic fiber, alumina fiber, and silicon carbide fiber.

8. The method for characterizing and protecting the transfer film of a ring-block friction pair according to claim 1, characterized in that: The outer region (022) is provided with a bend line (023) at the bend where it contacts and is fixed to the two end faces of the ring sample (01).

9. The method for characterizing and protecting the transfer film of a ring-block friction pair according to claim 1, characterized in that: In step (5), the characterization and detection include scanning electron microscopy analysis, X-ray diffraction analysis, energy dispersive spectroscopy analysis, and X-ray photoelectron spectroscopy analysis.

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