CN115046876A - Fretting wear experiment clamp under liquid medium and experiment method thereof - Google Patents

Abstract

The invention provides an experimental fixture for fretting wear under liquid medium and an experimental method thereof, comprising a fixture main body and a clamping part. The fixture main body includes a fixing plate, a liquid medium storage groove, a sample fixing groove and a thread groove. The fixing plate is used for Connected to the experimental workbench, the liquid medium storage tank and the fixing plate are integrally formed, the liquid medium storage tank is provided with a sample fixing groove, the sample fixing groove is installed with the sample, and the liquid medium storage tank is provided with two threads The two clamping parts are fixed in the liquid medium storage tank by the action of bolts and threaded holes. During the experiment, the sample is placed in the sample fixing groove and the sample is fixed by the clamping parts, and then the liquid medium is added to make the experiment meet the liquid state. In the medium immersion state, the two through holes of the fixing plate are fixed on the friction and wear testing machine through the bolt structure for the experiment. The invention solves the fretting wear experiment in the liquid medium immersion state, and proposes a set of effective experimental methods. Wide range of applications.

Description

An experimental fixture for fretting wear under liquid medium and its experimental method

technical field

The invention belongs to the technical field of fretting experimental methods, and in particular relates to a fretting wear experimental fixture under liquid medium and an experimental method thereof.

Background technique

Fretting wear refers to a composite type of wear caused by small-amplitude vibration between metal surfaces that are pressed against each other. In a liquid environment, mechanical components often vibrate slightly due to fluid motion and energy transfer. Mechanical components of different materials are in contact with each other due to vibration, which leads to fretting wear. For example, in a lead-based reactor, the heat transfer tube of the steam generator often operates in the environment of high temperature and high pressure and flowing medium. Due to the small vibration between the tube and the supporting parts caused by fluid movement and energy transfer, fretting occurs, and in this work Under certain circumstances, the lead-bismuth medium will have a corrosive effect on the structural materials of the reactor. Under the action of multi-field coupling, material failure is caused, and its mechanism is complex and difficult to predict. Therefore, in-depth research is required to evaluate and predict the performance and life of key components, which is conducive to the safe operation of nuclear power plants.

However, the existing wear testing machines are mainly in the form of dry friction. For fretting wear experiments in liquid medium, only a small amount of liquid can be used to cover the surface of the sample, which is inconvenient for fretting wear experiments in the state of immersion in liquid medium. Unable to meet the requirements of various liquid medium immersion state experiments.

Based on this, an experimental fixture for fretting wear under liquid medium and its experimental method are proposed.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide an experimental fixture for fretting wear under liquid medium and an experimental method thereof in view of the deficiencies of the above-mentioned prior art, so as to solve the problems raised in the above-mentioned background art.

In order to solve the above-mentioned technical problems, the technical solution adopted in the present invention is: a micro-motion wear test fixture under liquid medium, comprising a fixture body and a clamping part, and the fixture body includes a fixing plate, a liquid medium storage tank, and a sample fixing groove. and threaded groove, the fixing plate is used to connect with the experimental workbench, the liquid medium storage tank and the fixing plate are integrally formed, a sample fixing groove is opened in the middle of the liquid medium storage groove, and the sample fixing groove is The sample is installed inside, the liquid medium storage tank is provided with two threaded grooves, the clamping pieces are provided with two, and the two clamping pieces are fixed to the liquid medium storage tank by the action of bolts and threaded holes. in the slot.

Further, the fixing plate is provided with two threaded through holes, and the fixing plate is fixed on the workbench of the friction and wear testing machine through the threaded through holes and the bolt structure to conduct experiments.

Further, the liquid medium storage tank is used for adding a sufficient amount of liquid medium to meet the experimental conditions in the liquid medium immersion state, and the sample fixing tank is located at the bottom center of the liquid medium storage tank.

Further, the clamping members are provided with three groups of different lengths, which are used to cooperate to complete the experiments of three cases of impact, sliding and impact-sliding compound fretting of the sample.

Further, the lengths of the clamps are set to 4 mm, 5 mm and 6 mm, the clamps with a length of 4 mm are used for the sliding fretting experiment, the clamps with a length of 6 mm are used for the impact test, and the clamps with a length of 5 mm are used for the impact test. The clamps are used for impact sliding compound fretting.

An experimental method for a fretting wear experimental fixture under a liquid medium, comprising the following steps:

S1. The sample is made into a block that meets the specifications of the sample fixing groove, and the upper surface of the sample is ground and polished;

S2. Then install the prepared sample into the sample fixing groove, and then fix the sample in the sample fixing groove through the action of the clamp, the bolt and the threaded hole, that is, press the sample through the clamp In order to prevent the sample from being dragged during the experiment, the main body of the fixture is fixed on the workbench through the threaded through hole on the fixing plate and the threaded through hole on the workbench of the SRV high temperature friction and wear testing machine through the bolt structure;

S3. Set the experimental parameters of the SRV high temperature friction and wear test machine. If the liquid medium added in the liquid medium storage tank is solid at room temperature, the temperature is first heated until the liquid medium is melted into a liquid state, and then the force is loaded;

S4. After the installation process of S2-S3, the effect of simulating the fretting wear behavior of the sample under liquid medium in actual working conditions can be achieved. The liquid medium storage tank plays the role of liquid medium storage, so that the sample is in a liquid soaking state. The service conditions of the samples under actual working conditions are simulated, and then the fretting wear problem is analyzed through the data recorded by the SRV high temperature friction and wear testing machine;

S5. After the sample is taken out, wipe the surface of the sample with alcohol, use a 3D laser profiler or a white light interference microscope to analyze the surface of the sample to obtain a three-dimensional surface contour result. The wear volume can be obtained by calculating the difference; at the same time, the deepest pit can be found through the surface analysis of the sample, and the wear depth can be obtained;

S6. Then analyze the wear morphology of the sample, observe the surface morphology of the wear scar with a field emission scanning electron microscope, and determine the wear type: abrasive wear, adhesive wear or fatigue wear by analyzing the characteristics of the wear scar morphology;

S7. Perform EBSD analysis on the wear scar section. In order not to destroy the characteristics of the sample, use a diamond wire saw to cut the wear scar, and put the sample into a scanning electron microscope equipped with a secondary electron backscatter probe. Data collection is carried out in the test area, and then the data analysis software Channel 5 is used to analyze the collected data;

S8. Then use Origin software to compare and analyze the data collected in S6, judge the type of wear, and complete the experiment.

Further, in S2, since the experimental samples of the SRV high-temperature friction and wear testing machine are all standard parts, after adding the main body of the fixture, the parameters of the sample should be adjusted to meet the experimental requirements, and the thickness of the bottom of the sample fixing groove is 3 mm. The sample is made into a height of 4.9 mm to meet the experimental requirements of the instrument, and then the liquid medium required for the experiment is added to immerse the sample. When adding the liquid medium, the depth of the liquid medium only needs to be controlled at 2.5 mm.

Further, in S3, the experimental parameters of the SRV high temperature friction and wear testing machine include medium temperature, normal pressure, tangential displacement amplitude, number of experimental cycles, loading frequency and dissolved oxygen content.

Further, in S3, if the liquid medium to be added is solid at normal temperature, then it is necessary to calculate the mass of the solid medium according to the conditions such as the density of the liquid medium at the experimental temperature and the required volume, and then add it at room temperature. After the solid liquid medium at the bottom is melted into a liquid state, the bolts and threaded holes on the clamping part should be loosened and then re-tightened to facilitate the loading of force.

Further, in S7, before the test, the test area of the sample needs to be ground and electropolished to make it meet the test requirements, specifically, the sample is ground to 2000 mesh, and then electropolished.

Further, in S8, the drawn curve includes a friction coefficient-cycle number curve and a Fτ-D-N three-dimensional curve, and the fretting working condition is analyzed in combination with step S6.

Compared with the prior art, the present invention has the following advantages:

1. The present invention can provide conditions under which the experiment can be carried out in a state of being immersed in a liquid medium.

2. The present invention provides an experimental method for fretting wear experiments in a state of immersion in a liquid medium.

3. The present invention can be used as a fixture for experiments on various testing machines.

Description of drawings

Fig. 1 is the overall structure schematic diagram of the present invention;

Fig. 2 is the schematic diagram of the main structure of the fixture of the present invention;

3 is a top view of the overall structure of the present invention;

4 is a graph of friction coefficient-cycle number in Example 2 of the present invention;

5 is a three-dimensional graph of Fτ-D-N in Example 2 of the present invention;

FIG. 6 is a KAM diagram obtained by EBSD of the wear scar section in Example 2 of the present invention.

FIG. 7 is an inverse pole figure obtained by EBSD of the wear scar section in Example 2 of the present invention.

Description of reference numbers:

1- Fixture main body; 11- Fixing plate; 12- Liquid medium storage tank; 13- Sample fixing groove; 14- Thread groove; 2- Clamping part; 21- Bolt; 3- Sample.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Embodiment 1, as shown in FIGS. 1-3 , the present invention provides a technical solution: a micro-motion wear test fixture under liquid medium, comprising a fixture body 1 and a clamping member 2 , and the fixture body 1 includes a fixing plate 11 , liquid medium storage tank 12, sample fixing groove 13 and thread groove 14, fixture body 1 is 70 mm long, 40 mm wide, 4 mm thick side wall, 5 mm deep, 6 mm thick at the bottom, and 3 mm deep for the sample fixing groove mm, is a circular slot with a diameter of 25 mm.

The fixing plate 11 is provided with two threaded through holes, and the fixing plate 11 is fixed on the workbench of the friction and wear testing machine through the threaded through holes and the bolt structure to conduct experiments.

The liquid medium storage tank 12 and the fixing plate 11 are integrally formed. The liquid medium storage tank 12 is provided with a sample fixing tank 13 in the middle. The liquid medium storage tank 12 is used to add a sufficient amount of liquid medium to meet the liquid The experimental conditions in the medium immersion state, the sample fixing tank 13 is located at the bottom center of the liquid medium storage tank 12 .

A sample 3 is installed in the sample fixing groove 13 , and the sample 3 is made into a round ingot with a direct diameter of 25 mm and a height of 4.9 mm.

The liquid medium storage tank 12 is provided with two threaded grooves 14 , the clamping members 2 are provided with two, and the two clamping members 2 are fixed to the liquid medium storage tank by the action of the bolts 21 and the threaded holes 14 . in slot 12.

The clamps 2 are provided with three groups of different lengths. The lengths of the clamps 2 are set to 4 mm, 5 mm, and 6 mm. The clamps 2 with a length of 4 mm are used for the sliding fretting experiment, and the length is 6 mm. Gripper 2 with a length of 2 was used for impact experiments, and gripper 2 with a length of 5 mm was used for impact-sliding compound fretting.

Embodiment 2, the experimental method of the fretting wear test fixture under the liquid medium in Embodiment 1, comprising the following steps:

S1. The sample 3 is made into a block shape that meets the specifications of the sample fixing groove 13, specifically a round ingot shape with a direct 25 mm and a height of 4.9 mm, and the upper surface of the sample 3 is ground and polished;

S2. Select a ball with a diameter of 9 mm as the counter-grinding pair, first fix the counter-grinding pair in the upper frame, then install the prepared sample 3 into the sample fixing groove 13, and then pass the clamping piece 2 and the bolt 21 and the threaded hole 14 fix the sample in the sample fixing groove 13, that is, the sample 3 is pressed by the clamping member 2 to avoid the sample being dragged during the experiment, and then the sample is passed through the fixing plate 11. The threaded through holes and the threaded through holes on the workbench of the SRV high temperature friction and wear testing machine fix the fixture main body 1 on the workbench through the bolt structure;

Since the experimental samples of the SRV high temperature friction and wear testing machine are all standard parts, after adding the fixture body 1, the parameters of the sample 3 should be adjusted to meet the experimental requirements. The thickness of the bottom of the sample fixing groove 13 is 3 mm. A height of 4.9 mm is required to meet the experimental requirements of the instrument, and then the liquid medium required for the experiment is added to immerse the sample. When adding the liquid medium, the depth of the liquid medium only needs to be controlled at 2.5 mm.

In this embodiment, a 4 mm clamp is selected for the sliding fretting experiment;

S3. Set the experimental parameters of the SRV high temperature friction and wear testing machine, including medium temperature, normal pressure, tangential displacement amplitude, number of experimental cycles, loading frequency and dissolved oxygen content;

If the liquid medium added in the liquid medium storage tank 12 is solid at room temperature, the mass of the solid medium needs to be calculated according to the conditions such as the density and the required volume of the liquid medium at the experimental temperature, and then the solid medium is added. The liquid medium is melted into a liquid state, and after melting into a liquid state, the bolts 21 and the threaded holes 14 on the clamping piece should be loosened and then re-tightened, so as to facilitate the loading of force.

S4. After the installation process of S2-S3, the effect of simulating the fretting wear behavior of sample 3 under liquid medium in actual working conditions can be achieved. The soaking state simulates the service conditions of sample 3 under actual working conditions, and then analyzes the fretting wear problem through the data recorded by the SRV high-temperature friction and wear testing machine;

S5. Then take out the sample 3, wipe the surface of the sample 3 with alcohol, use a 3D laser profiler or a white light interference microscope to analyze the surface of the sample 3, and obtain the three-dimensional surface contour results. The wear volume can be obtained by calculating the difference of the contour after wear; at the same time, the deepest pit can be found through the surface analysis of sample 3, and the wear depth can be obtained;

During the test, it is best to repeat the measurement for each wear spot three times or more to reduce the error and obtain more accurate data;

S6. Then analyze the wear morphology of sample 3, observe the surface morphology of the wear scar with a field emission scanning electron microscope, and determine the type of wear by analyzing the characteristics of the wear scar morphology: abrasive wear, adhesive wear or fatigue wear ;

S7. Perform EBSD analysis on the wear scar section. In order not to destroy the characteristics of sample 3, use a diamond wire saw to cut the wear scar. Before testing, the test area of sample 3 needs to be ground and electropolished to meet the test requirements. Requirements, specifically grinding the sample to 2000 mesh, and then electropolishing, the electrolytic polishing solution is 20% perchloric acid and 80% glacial acetic acid solution, the polishing voltage is 40V, the time is 15-20s, and the temperature is 0°C;

Put the sample 3 into a scanning electron microscope equipped with a secondary electron backscatter probe to collect data from the test area of the sample 3, and then use the data analysis software Channel 5 to analyze the collected data, as shown in Figure 6. The KAM diagram obtained by the EBSD of the wear scar section shown in Figure 7 and the inverse pole diagram shown in Figure 7 are used to judge the stress concentration and so on;

It can be seen in Figure 6 that the sample has a large stress concentration, which is conducive to the initiation and expansion of cracks; it can be seen in Figure 7 that it is textured with a density of 7.73%; the degree of plastic deformation reflects the grain orientation distribution and texture. structure density. The larger the plastic deformation, the more obvious the texture of the crystal orientation distribution. In addition, the greater the plastic deformation of the specimen during the fretting process, the stronger the fatigue behavior; this suggests that the existence of the wear mechanism in the specimen may be related to surface fatigue.

The results show that the plastic deformation of the sample is strong, but the adjustment ability is weak, resulting in a large fretting wear loss. The KAM distribution is a positioning misdirection calculation method used to evaluate the positioning misdirection. For the plastic deformation caused by fretting, the positional orientation deviation can be used to represent the local strain after deformation.

S8. Then use Origin software to compare and analyze the data collected by S7. The drawn curve includes the friction coefficient-cycle number curve. As shown in Figure 4, the COF curve of the fretting experiment is a typical fretting experiment COF curve, namely There is a sharp increase in the initial cycle, and subsequently, the COF drops abruptly from the peak due to the formation of the third bulk layer. After the abrupt drop, the curve continues to increase slightly until the COF value reaches a relatively stable value.

This indicates that the fretting behavior of the specimen has reached a relatively stable stage, in which the plastic deformation of the subsurface plays a significant role.

The Fτ-D-N three-dimensional curve is shown in Fig. 5. The shape of the Fτ-D diagram represents the fretting state, the linear shape represents the local slip state, the parallelogram shape represents the total slip state, and the elliptical shape represents the mixed fretting state. From the shape of the ring shown in Figure 5, it can be seen that the fretting state transitions from a total slip state to a mixed fretting state. Combined with step S6, the wear type obtained by judging the fretting working condition is used to complete the experiment.

It should be noted that, in this document, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any relationship between these entities or operations. any such actual relationship or sequence exists. Moreover, the terms "comprising", "comprising" or any other variation thereof are intended to encompass a non-exclusive inclusion such that a process, method, article or device that includes a list of elements includes not only those elements, but also includes not explicitly listed or other elements inherent to such a process, method, article or apparatus.

Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, and substitutions can be made in these embodiments without departing from the principle and spirit of the invention and modifications, the scope of the present invention is defined by the appended claims and their equivalents.

Claims (11)

1. An experimental fixture for fretting wear under a liquid medium, characterized in that it comprises a fixture main body (1) and a clamping member (2), and the fixture main body (1) comprises a fixing plate (11), a liquid medium storage tank ( 12), a sample fixing groove (13) and a thread groove (14), the fixing plate (11) is used for connecting with the experimental workbench, and the liquid medium storage groove (12) is integrally formed with the fixing plate (11) Structure, a sample fixing groove (13) is opened in the middle of the liquid medium storage tank (12), the sample (3) is installed in the sample fixing groove (13), and the liquid medium storage tank (12) is Two threaded grooves (14) are provided, two of the clamping members (2) are provided, and the two clamping members (2) are fixed in the liquid state by the action of the bolts (21) and the threaded holes (14). Inside the media storage slot (12). 2. The fretting wear test fixture under a liquid medium according to claim 1, wherein the fixing plate (11) is provided with two threaded through holes, and the fixing plate (11) is threaded through the fixing plate (11). The hole and bolt structure were fixed on the workbench of the friction and wear testing machine for experiments. 3. The fretting wear test fixture under a liquid medium according to claim 1, wherein the liquid medium storage tank (12) is used to add a sufficient amount of liquid medium to satisfy the experiment in the liquid medium immersion state Conditionally, the sample fixing groove (13) is located at the bottom center of the liquid medium storage groove (12). 4. The fretting wear test fixture under a liquid medium according to claim 1, wherein the clamping member (2) is provided with three groups of different lengths, which are used to cooperate with the completion of the sample (3). Experiments for three cases of shock, sliding and shock-sliding compound fretting. 5. The fretting wear test fixture under a liquid medium according to claim 4, wherein the length of the clamping member (2) is set to 4 millimeters, 5 millimeters and 6 millimeters of length, and the clamp of 4 millimeters of length The holder (2) was used for the sliding fretting experiment, the 6 mm length holder (2) was used for the impact experiment, and the 5 mm length holder (2) was used for the impact sliding compound fretting. 6. the experimental method of fretting wear test fixture under a kind of liquid medium according to any one of claims 1-5, is characterized in that, comprises the following steps: S1. The sample (3) is made into a block conforming to the specification of the sample fixing groove (13), and the upper surface of the sample (3) is ground and polished; S2. Install the prepared sample (3) into the sample fixing groove (13), and then fix the sample on the sample through the action of the clamp (2), the bolt (21) and the threaded hole (14). In the fixing groove (13), that is, the sample (3) is pressed by the clamping member (2) to avoid the sample being dragged during the experiment, and then the sample (3) is passed through the threaded through hole on the fixing plate (11) and the high temperature of the SRV. The threaded through hole on the workbench of the friction and wear testing machine fixes the fixture main body (1) on the workbench through a bolt structure; S3. Set the experimental parameters of the SRV high temperature friction and wear test machine. If the liquid medium added in the liquid medium storage tank (12) is solid at room temperature, the temperature is first heated until the liquid medium is melted into a liquid state, and then the force is loaded; S4. After the installation process of S2-S3, the effect of simulating the fretting wear behavior of the sample (3) in the liquid medium in the actual working condition can be achieved. The liquid medium storage tank (12) plays the role of liquid medium storage, so that the test The sample (3) is in a liquid soaking state, and the service conditions of the sample (3) under actual working conditions are simulated, and then the fretting wear problem is analyzed by the data recorded by the SRV high temperature friction and wear testing machine; S5. After taking out the sample (3), wipe the surface of the sample (3) with alcohol, and use a 3D laser profiler or a white light interference microscope to analyze the surface of the sample (3) to obtain a three-dimensional surface profile result. The wear volume can be obtained by calculating the difference between the surface profile before wear and the profile after wear; at the same time, the deepest pit can be found through the surface analysis of the sample (3), and the wear depth can be obtained; S6. Then analyze the wear morphology of the sample (3), use a field emission scanning electron microscope to observe the surface morphology of the wear scar, and determine the wear type by analyzing the characteristics of the wear scar morphology: abrasive wear, adhesive wear or fatigue wear; S7, carry out EBSD analysis on the wear scar section, in order not to destroy the characteristics of the sample (3), use a diamond wire saw to cut the wear scar, and put the sample (3) into a scanning electron equipped with a secondary electron backscatter probe Data collection is performed on the test area of the sample (3) in the microscope, and then the collected data is analyzed by the data analysis software Channel 5 software; S8. Then use the Origin software to draw and compare the data collected in step S7, judge the type of wear, and complete the experiment. 7. the experimental method of the fretting wear experimental fixture under a kind of liquid medium according to claim 6, it is characterized in that, in S2, because the SRV high temperature friction and wear testing machine experimental samples are all standard parts, when adding fixture main body (1) After that, the parameters of the sample (3) should be adjusted to meet the experimental requirements. The thickness of the bottom of the sample fixing groove (13) is 3 mm, and the height of the sample is made 4.9 mm to meet the experimental requirements of the instrument. The liquid medium required for the experiment immerses the sample, and the depth of the liquid medium only needs to be controlled at 2.5 mm when adding the liquid medium. 8. The experimental method of a fretting wear test fixture under a liquid medium according to claim 6, wherein in S3, the experimental parameters of the SRV high temperature friction and wear test machine include medium temperature, normal pressure, tangential displacement Amplitude, number of experimental cycles, loading frequency, and dissolved oxygen content. 9. the experimental method of fretting wear test fixture under a kind of liquid medium according to claim 6, is characterized in that, in S3, if the liquid medium required to add is solid at normal temperature, then need according to this liquid medium After the mass of the solid medium is calculated from the density and required volume at the experimental temperature, the mass of the solid medium is added. After the solid liquid medium at room temperature is melted into a liquid state, the bolts (21) on the clamping piece and the threaded holes ( 14) Re-tighten after loosening to facilitate the loading of force. 10. The experimental method of fretting wear experimental fixture under a kind of liquid medium according to claim 6, it is characterized in that, in S7, before testing, need to carry out grinding and electropolishing to the test area of sample (3) To make it meet the test requirements, the sample is first ground to 2000 mesh, and then electropolished. 11. the experimental method of fretting wear experimental fixture under a kind of liquid medium according to claim 6, is characterized in that, in S8, the curve drawn comprises friction coefficient-cycle number curve, Fτ-D-N three-dimensional curve, combined with S6 The fretting conditions are analyzed according to the wear type determined in the step.

Images