Constant-temperature liquid medium circulating flow type fretting wear corrosion test device

Abstract

The invention discloses a constant-temperature liquid medium circulating flow type fretting wear corrosion test device. The device takes a fretting friction machine as a main body. The fretting friction machine comprises a friction machine grinding head and a friction machine base, and an in-situ electrochemical monitoring assembly including an electrolytic bath, a working electrode, a reference electrode, an auxiliary electrode, a conductive copper column and an electrode clamp is arranged on the friction machine base. And one side of the friction machine base is provided with a constant-temperature liquid medium circulating system comprising a main pipeline, a nozzle, a supply tank, a circulating pump, a flow meter, a thermostat and a heat exchange pipe. In addition, the abrasion and corrosion testing device is further provided with an accurate control system so as to regulate and control the temperature and the flow of the liquid medium. According to the invention, the circulating flow and constant temperature of the liquid medium are realized, the influence of the medium temperature on the fretting wear corrosion of the material under the actual working condition can be well reflected, and the problem that the existing friction wear test device cannot carry out related in-situ monitoring research is solved.

Description

Technical Field

[0001] The invention belongs to the field of friction test devices, and in particular relates to a constant temperature liquid medium circulating flow type micro-motion wear and corrosion test device. Background Art

[0002] Fretting wear and corrosion are common on mechanical contact interfaces where relative motion occurs. Wear and corrosion can destroy the structure of the contact interface and cause relative motion failures of parts. With the rapid development of industries such as aerospace, offshore equipment, nuclear power equipment, wind power equipment, drilling platforms, steam turbines, gas turbines, ships, and carrier-based aircraft, the reliability requirements for key active components in the service environment are becoming increasingly stringent. The presence of corrosion accelerates the wear process on the surface of the material, making the degree of damage more serious than in a single environment, which in turn leads to frequent failures or even scrapping of related equipment. For example, in the fasteners of gas turbines and steam turbines, the equipment is mostly in service conditions of industrial waste gas and steam environments. Cylinder vibration causes fretting wear between the fasteners and the cylinder body under high temperature and corrosive conditions, causing wear or even damage to the fastener threads, which seriously threatens the normal operation of large-scale power equipment.

[0003] The fretting wear and corrosion behavior of materials under harsh environments is the result of the dynamic coupling of multiple factors, which is characterized by nonlinearity and openness. The study of this issue has always attracted much attention, and the most direct method is to conduct fretting wear tests on materials under corrosive media. However, current research is usually limited to simple fretting or sliding wear tests and simple corrosion tests. The experimental data obtained in this way cannot accurately reflect the influence of the coupling of fretting wear and corrosion on the material failure process under harsh environments, and there is a deviation from actual engineering applications. Although there are some fretting wear and corrosion test devices at present, they cannot be used to study the influence of medium temperature on fretting wear and corrosion. In order to ensure the reliability of the experimental results and the consistency of the service conditions, it is urgent to design a constant temperature liquid circulation medium fretting wear and corrosion test device to carry out the study of fretting wear and corrosion behavior under constant temperature corrosive environment, so as to solve the existing engineering problems. Summary of the invention

[0004] In order to study the influence of the coupling of fretting wear and corrosion on the material failure process under harsh environment, reduce the deviation between the test and the actual engineering application, and improve the reliability of the experimental results, the present invention provides a constant temperature liquid medium circulating flow type fretting wear and corrosion test device, and the technical scheme of the present invention is as follows: A constant temperature liquid medium circulating flow type fretting wear and corrosion testing device, comprising a friction machine, an in-situ electrochemical monitoring component and a constant temperature liquid medium circulation system; The friction machine comprises a friction machine base and a friction machine grinding head, wherein the friction machine grinding head is vertically connected to the top of the friction machine base, and the height of the friction machine grinding head is adjustable, so as to facilitate the friction test; The in-situ electrochemical monitoring assembly includes an electrolytic cell, a working electrode, a reference electrode and an auxiliary electrode. The electrolytic cell is fixed on a friction machine base directly below the friction machine grinding head. The working electrode is fixed at the center of the bottom of the electrolytic cell and directly facing the friction machine grinding head. The reference electrode and the auxiliary electrode are fixed in the electrolytic cell. The constant temperature liquid medium circulation system is used to supply electrolyte to the electrolytic cell, and includes a supply tank, a circulation pipeline and a constant temperature unit; the supply tank is arranged on one side of the electrolytic cell for storing electrolyte, and the electrolyte in the electrolytic cell can flow back into the supply tank; the inlet of the circulation pipeline is connected to the bottom of the supply tank, and the outlet points to the bottom of the grinding head of the friction machine, and the circulation pipeline provides flowing electrolyte to the friction position; the constant temperature unit is arranged in the supply tank, and is used to adjust the temperature of the electrolyte to maintain it at the temperature required for the reaction.

[0005] Furthermore, the working electrode is fixed to the electrolytic cell by screws through a sealing plate, and the working electrode lead is elastically connected to the conductive copper column below the working electrode, and the working electrode lead is used to connect to the electrochemical workstation.

[0006] Furthermore, a spring is provided between the conductive copper column and the working electrode, and the spring disconnects the electrical connection between the conductive copper column and the working electrode; during the test, the test piece and the working electrode press the spring downward under the action of the friction load, and the spring shortens to connect the working electrode to the conductive copper column, and the electrical signal is connected; at the end of the test, the friction load disappears, the spring recovers, and the electrical signal is disconnected.

[0007] Furthermore, a "door"-shaped electrode fixture is fixed in the middle of the electrolytic cell, and two parallel holes are opened on the top of the electrode fixture. The reference electrode and the auxiliary electrode are vertically inserted into the two holes and fixed with screws.

[0008] Furthermore, an opening is provided on one side of the electrolytic cell, and the opening is connected to a guide groove on the outer edge; the replenishing groove is located on one side of the opening of the electrolytic cell, and the electrolyte in the electrolytic cell flows back to the replenishing groove through the opening and the guide groove.

[0009] Furthermore, the circulation pipeline includes a main pipeline, a circulation pump and a flow meter are connected to the main pipeline along the liquid flow direction, and a nozzle is also connected to the outlet of the main pipeline, the nozzle is directly facing the bottom of the friction machine grinding head, and the electrolyte sprayed from the nozzle flushes the friction action area.

[0010] Furthermore, the constant temperature unit includes a heat exchange tube, a thermostat and a temperature sensor. The heat exchange tube is located at the bottom of the supply tank, the thermostat is located at the top of the supply tank, the thermostat and the heat exchange tube are connected by a pipeline, and the thermostat is used to drive the flow of the medium in the heat exchange tube and adjust the temperature of the medium; the lower end of the temperature sensor extends into the supply tank and is connected to the thermostat signal.

[0011] A constant temperature liquid medium circulating flow type fretting wear and corrosion test method, the test method comprising the following steps: Step 1: Load the friction sample and fix it with the working electrode sealing plate and screws; Step 2: Apply a load to the grinding head of the friction machine and adjust the frequency and stroke of the micro-motion friction machine; Step 3: inject liquid medium into the supply tank, turn on the thermostat, turn on the circulating water pump, and control the temperature of the liquid medium in the supply tank to maintain the required temperature for the reaction; Step 4: The liquid medium is sprayed onto the sample surface through a nozzle and then injected into the electrolytic cell, and the liquid level change of the liquid medium is monitored to ensure that the liquid medium circulation reaches a dynamic balance; Step 5: Connect the electrochemical workstation and turn it on. Turn on the friction machine until the entire system reaches dynamic equilibrium and then start the test.

[0012] The beneficial effects of the present invention are: 1. The present invention monitors the electrochemical behavior during the fretting wear process through an in-situ electrochemical monitoring system, and uses a constant temperature liquid medium circulation system to achieve the circulation flow and constant temperature of the liquid medium in the electrolytic cell, which well simulates the effect of medium temperature on fretting wear and corrosion under actual working conditions, and solves the problem that the existing friction, wear and corrosion test device cannot carry out research on the effect of medium temperature on fretting wear and corrosion; 2. The present invention conducts fretting wear test under liquid corrosive medium, filling the blank of liquid medium constant temperature circulation flow fretting wear corrosion test device; 3. The experimental data obtained by the present invention can truly reflect the failure process of materials under the coupling effect of micro-wear and corrosion in harsh environments. Further in-depth research on the problem of material coupling failure in harsh environments can provide reference and theoretical guidance for current engineering practice. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the model structure of the test device of the present invention; Figure 2 It is a structural front view of the test device of the present invention; Figure 3 yes Figure 2 Enlarged view of part A in the middle; Figure 4 yes Figure 2Schematic diagram of the three-dimensional structure of the middle A part; Figure 5 is a polarization curve diagram of an embodiment of the present invention; In the figure: 1-friction machine base, 2-main line, 3-nozzle, 4-friction machine grinding head, 5-medium inlet, 6-thermostat, 7-medium outlet, 8-temperature sensor, 9-supply tank, 10-heat exchange tube, 11-circulation pump, 12-flow meter, 13-electrolyzer, 14-reference electrode screw, 15-reference electrode, 16-working electrode, 17-sealing pressure plate, 18-working electrode lead, 19-conductive copper column, 20-spring, 21-electrode fixture, 22-auxiliary electrode screw, 23-auxiliary electrode, 24-electrode fixture screw, 25-screw. DETAILED DESCRIPTION

[0014] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments: like Figure 1 As shown, a constant temperature liquid medium circulating flow micro-motion wear and corrosion testing device includes a friction machine, an in-situ electrochemical monitoring component and a constant temperature liquid medium circulation system. The friction machine provides a friction test environment, the in-situ electrochemical monitoring component is used for in-situ electrochemical monitoring, and the constant temperature liquid medium circulation system is used to drive the electrolyte to circulate and provide flowing electrolyte to the friction part.

[0015] The friction machine includes a friction machine base 1 and a friction machine grinding head 4. The friction machine grinding head 4 is vertically connected to the top of the friction machine base 1. The height of the friction machine grinding head 4 is adjustable, which is convenient for friction testing. The friction machine base 1 includes support legs and a work surface, and the transmission assembly is arranged below the work surface. The in-situ electrochemical monitoring assembly includes an electrolytic cell 13, a working electrode 16, a reference electrode 15 and an auxiliary electrode 23. The electrolytic cell 13 is fixed on the friction machine base 1 just below the friction machine grinding head 4. The working electrode 16 is fixed at the center of the bottom of the electrolytic cell 13 and faces the friction machine grinding head 4; the reference electrode 15 and the auxiliary electrode 23 are fixed in the electrolytic cell 13. The constant temperature liquid medium circulation system is used to supply electrolyte to the electrolytic cell 13, and includes a supply tank 9, a circulation pipeline and a constant temperature unit; the supply tank 9 is arranged on one side of the electrolytic cell 13 for storing electrolyte, and the electrolyte in the electrolytic cell 13 can flow back into the supply tank 9; the inlet of the circulation pipeline is connected to the bottom of the supply tank 9, and the outlet points to the bottom of the friction machine grinding head 4, and the circulation pipeline provides flowing electrolyte to the friction position; the constant temperature unit is arranged in the supply tank 9, and is used to adjust the temperature of the electrolyte to maintain it at the temperature required for the reaction.

[0016] like Figure 2 and 3As shown, the working electrode 16 is fixed to the electrolytic cell 13 by screws through the sealing plate 17, and the working electrode lead 18 is elastically connected to the conductive copper column 19 below the working electrode 16. The working electrode lead 18 is used to connect the electrochemical workstation. A spring 20 is provided between the conductive copper column 19 and the working electrode 16, and the spring 20 disconnects the electrical connection between the conductive copper column 19 and the working electrode 16; during the test, the test piece and the working electrode 16 press the spring 20 downward under the action of the friction load, and the spring 20 is shortened to connect the working electrode 16 to the conductive copper column 19, and the electrical signal is connected; at the end of the test, the friction load disappears and the spring 20 is restored to disconnect the electrical signal. A "door"-shaped electrode fixture 21 is also fixed in the middle of the electrolytic cell 13, and two parallel holes are opened on the top of the electrode fixture 21. The reference electrode 15 and the auxiliary electrode 23 are respectively vertically passed through the two holes and fixed with screws.

[0017] An opening is provided on one side of the electrolytic cell 13, and the opening is connected to a guide groove on the outer edge; the supply tank 9 is located on one side of the opening of the electrolytic cell 13, and the electrolyte in the electrolytic cell 13 flows back to the supply tank 9 through the opening and the guide groove. The circulation pipeline includes a main line 2, and a circulation pump 11 and a flow meter 12 are connected to the main line 2 along the liquid flow direction. The outlet of the main line 2 is also connected to a nozzle 3, and the nozzle 3 is directly facing the bottom of the friction machine grinding head 4. The electrolyte sprayed from the nozzle 3 flushes the friction action part. The constant temperature unit includes a heat exchange tube 10, a thermostat 6 and a temperature sensor 8. The heat exchange tube 10 is located at the bottom of the supply tank 9, and the thermostat 6 is located at the top of the supply tank 9. The thermostat 6 is connected to the heat exchange tube 10 through a pipeline. The thermostat 6 is used to drive the medium in the heat exchange tube 10 to flow and adjust the temperature of the medium; the lower end of the temperature sensor 8 extends into the supply tank 9 and is connected to the thermostat 6 signal.

[0018] Test example: A constant temperature liquid medium circulating flow type fretting wear and corrosion test method, the test method comprising the following steps: Step 1: Load the friction sample and fix it with the working electrode 16, sealing plate 17 and screws; Step 2: Apply a load to the grinding head of the friction machine and adjust the frequency and amplitude of the fretting friction by the fretting friction machine; Step 3: inject 3.5wt% NaCl solution into the supply tank 9, turn on the thermostat 6, start the circulating water pump, and control the temperature of the liquid medium in the supply tank 9 to maintain 13°C; Step 4: The liquid medium is sprayed on the sample surface through the nozzle 3 and then injected into the electrolytic cell 13, and the liquid level change of the liquid medium is monitored to ensure that the liquid medium circulation reaches a dynamic balance, and the flow rate of the flow meter is controlled to be 0.8 m / s; Step 5: Connect the electrochemical workstation and turn it on. Turn on the friction machine until the entire system reaches dynamic equilibrium and then start the test.

[0019] Comparative Example: The difference between the comparative example and the test example lies in step 2 and step 3, wherein the temperature of the liquid medium is controlled to maintain 22° C., the circulation pump is not started, and the working electrode is placed in a static liquid for testing. Figure 5 The polarization curves of the test example and the comparative example are obtained respectively.

[0020] It can be seen from the figure that the self-corrosion potential and self-corrosion current density of the sample are -0.554V and 1.205×10 -5 A / cm 2 , reflecting its corrosion tendency and corrosion rate in this environment. After the self-corrosion potential, the polarization curve shows a significant fluctuation and a gradually rising trend in the current density, indicating that the electrochemical behavior of the material has changed significantly at this stage. This phenomenon can be attributed to the repeated formation and rupture of the passivation film at a higher potential. This dynamic balance leads to more active surface exposure, which in turn intensifies the corrosion reaction. In addition, in an environment with a water flow rate of 0.8 m / s, the flow of the electrolyte may further affect the integrity of the passivation film, resulting in fluctuations in the current density.

Claims

1. A constant temperature liquid medium circulating flow fretting wear and corrosion test device, characterized in that: It includes a friction machine, an in-situ electrochemical monitoring component and a constant temperature liquid medium circulation system; The friction machine comprises a friction machine base (1) and a friction machine grinding head (4); the friction machine grinding head (4) is vertically connected to the top of the friction machine base (1); the height of the friction machine grinding head (4) is adjustable, so as to facilitate the friction test; The in-situ electrochemical monitoring assembly comprises an electrolytic cell (13), a working electrode (16), a reference electrode (15) and an auxiliary electrode (23); the electrolytic cell (13) is fixed on a friction machine base (1) directly below a friction machine grinding head (4); the working electrode (16) is fixed at the center of the bottom of the electrolytic cell (13) and directly facing the friction machine grinding head (4); the reference electrode (15) and the auxiliary electrode (23) are fixed in the electrolytic cell (13); The constant temperature liquid medium circulation system is used to supply electrolyte to the electrolytic cell (13), and comprises a supply tank (9), a circulation pipeline and a constant temperature unit; The supply tank (9) is arranged on one side of the electrolytic tank (13) for storing electrolyte, and the electrolyte in the electrolytic tank (13) can flow back into the supply tank (9); the inlet of the circulation pipeline is connected to the bottom of the supply tank (9), and the outlet is directed to the bottom of the grinding head (4) of the friction machine, and the circulation pipeline provides flowing electrolyte to the friction position; The constant temperature unit is arranged in the supply tank (9) and is used to adjust the temperature of the electrolyte to maintain it at a temperature required for the reaction.

2. The constant temperature liquid medium circulating flow fretting wear and corrosion testing device according to claim 1 is characterized in that: The working electrode (16) is fixed to the electrolytic cell (13) by means of a sealing pressure plate (17) with screws, and the working electrode lead (18) is elastically connected to a conductive copper column (19) below the working electrode (16). The working electrode lead (18) is used to connect to an electrochemical workstation.

3. The constant temperature liquid medium circulating flow fretting wear and corrosion testing device according to claim 2 is characterized in that: A spring (20) is provided between the conductive copper column (19) and the working electrode (16), and the spring (20) disconnects the electrical connection between the conductive copper column (19) and the working electrode (16). During the test, the test piece and the working electrode (16) press the spring (20) downward under the action of the friction load, and the spring (20) shortens so that the working electrode (16) and the conductive copper column (19) are connected, and the electrical signal is connected. When the test is finished, the friction load disappears, the spring (20) recovers, and the electrical signal is disconnected.

4. The constant temperature liquid medium circulating flow fretting wear and corrosion testing device according to claim 3 is characterized in that: A "door"-shaped electrode fixture (21) is also fixed in the middle of the electrolytic cell (13). Two parallel holes are provided on the top of the electrode fixture (21). The reference electrode (15) and the auxiliary electrode (23) are respectively vertically inserted into the two holes and fixed with screws.

5. The constant temperature liquid medium circulating flow fretting wear and corrosion testing device according to claim 4 is characterized in that: An opening is provided on one side of the electrolytic cell (13), and the opening is connected to a guide groove at the outer edge; the replenishment groove (9) is located on one side of the opening of the electrolytic cell (13), and the electrolyte in the electrolytic cell (13) flows back into the replenishment groove (9) through the opening and the guide groove.

6. The constant temperature liquid medium circulating flow fretting wear and corrosion testing device according to claim 1 is characterized in that: The circulation pipeline comprises a main pipeline (2), a circulation pump (11) and a flow meter (12) are connected to the main pipeline (2) along the liquid flow direction, and a nozzle (3) is also connected to the outlet of the main pipeline (2), the nozzle (3) is directly facing the bottom of the friction machine grinding head (4), and the electrolyte sprayed from the nozzle (3) flushes the friction action site.

7. The constant temperature liquid medium circulating flow fretting wear and corrosion testing device according to claim 6 is characterized in that: The constant temperature unit comprises a heat exchange tube (10), a thermostat (6) and a temperature sensor (8); the heat exchange tube (10) is located at the bottom of the supply tank (9); the thermostat (6) is located at the top of the supply tank (9); the thermostat (6) and the heat exchange tube (10) are connected via a pipeline; the thermostat (6) is used to drive the flow of the medium in the heat exchange tube (10) and adjust the temperature of the medium; the lower end of the temperature sensor (8) extends into the supply tank (9) and is signal-connected to the thermostat (6).

8. A constant temperature liquid medium circulating flow fretting wear and corrosion test method, characterized in that: The constant temperature liquid medium circulating flow fretting wear and corrosion test device comprises any one of claims 1 to 7, and the test method comprises the following steps: Step 1: Load the friction sample and fix it with a working electrode (16), a sealing plate (17) and screws; Step 2: Apply a load to the grinding head of the friction machine and adjust the frequency and stroke of the micro-motion friction machine; Step 3: injecting liquid medium into the supply tank (9), turning on the thermostat (6), turning on the circulating water pump, and controlling the temperature of the liquid medium in the supply tank (9) to maintain the temperature required for the reaction; Step 4: The liquid medium is sprayed onto the surface of the sample through the nozzle (3) and then injected into the electrolytic cell (13), and the liquid level change of the liquid medium is monitored to ensure that the circulation of the liquid medium reaches a dynamic balance; Step 5: Connect the electrochemical workstation and turn it on. Turn on the friction machine until the entire system reaches dynamic equilibrium and then start the test.

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