1. A preparation method of a metal friction layer transmission electron microscope sample is characterized by comprising the following steps:

(1) cutting a metal sheet from a sample, and polishing to obtain a polished metal sheet;

(2) embedding the polished metal sheet in the step (1) in a metal tube, and sticking the embedded part with resin to obtain a sheet sample;

(3) polishing the front surface and the back surface of the sheet sample obtained in the step (2) respectively to obtain a polished sheet sample, and then performing ion thinning treatment until a hole is formed in the sheet sample to obtain an ion thinned sample;

(4) and (4) carrying out ion polishing treatment on the sample subjected to ion thinning in the step (3) to obtain the metal friction layer transmission electron microscope sample.

2. The method for preparing a transmission electron microscope sample of a metal friction layer according to claim 1, wherein the thickness of the metal flake of step (1) is 0.8-1 mm; and cutting the sample by using a wire-cut electric discharge machine or a diamond circular saw to obtain a metal sheet.

3. The method for preparing a transmission electron microscope sample of a metal friction layer according to claim 2, wherein when the sample is cut by a diamond circular saw, the linear velocity of the diamond circular saw is less than 6 mm/s.

4. The method for preparing a transmission electron microscope sample of a metal friction layer according to claim 1, wherein the grinding in step (1) is performed by using a waterproof abrasive paper with a size of 1000# or less, and the thickness of the metal sheet after the grinding in step (1) is 0.4-0.6 mm.

5. The method for preparing a transmission electron microscope sample with a metal friction layer according to claim 1, wherein the metal tube in the step (2) is a copper tube; the length of the metal pipe is 0.4-0.6mm, the inner diameter of the metal pipeline is 2.5mm, and the outer diameter of the metal pipe is 3 mm.

6. The method for preparing a transmission electron microscope sample of a metal friction layer according to claim 1, wherein the resin in the step (2) is an epoxy resin.

7. The method for preparing a transmission electron microscope sample of a metal friction layer according to claim 1, wherein the polishing of step (3) comprises: the front and back surfaces of the sheet sample were sequentially sanded with 1000#, 2000#, 3000#, 5000# and 7000# sandpaper.

8. The method for preparing a transmission electron microscope sample with a metal friction layer as claimed in claim 1, wherein the thickness of the polished thin slice sample in the step (3) is 30-50 μm.

9. The method for preparing a transmission electron microscope sample with a metal friction layer according to claim 1, wherein the ion thinning treatment in the step (3) is a double-sided ion thinning treatment; the ion beam energy of the ion thinning treatment is 4-8keV, and the rotation angle of the ion gun is within +/-8 degrees.

10. The method for preparing a transmission electron microscope sample of a metal friction layer according to any one of claims 1 to 9, wherein the ion polishing treatment of the step (4) comprises: firstly, carrying out first ion polishing treatment on a sample subjected to ion thinning under the conditions that the ion beam energy is 5-8keV and the ion gun rotation angle is +/-6 degrees, wherein the time of the first ion polishing treatment is not less than 3min, then carrying out second ion polishing treatment under the conditions that the ion beam energy is 5-8keV and the ion gun rotation angle is +/-4 degrees, wherein the time of the second ion polishing treatment is not less than 3min, and finally carrying out third ion polishing treatment under the conditions that the ion beam energy is 3-4keV and the ion gun rotation angle is adjusted to +/-3 degrees, wherein the time of the third ion polishing treatment is not less than 4 min.

Background

The metal friction material generates friction and abrasion in the process of interacting with a pair of friction pairs, so that a friction layer is formed on the surface layer of the metal friction material, the analysis of the microstructure morphology of the friction layer is an important way for understanding the abrasion condition of the metal friction material and analyzing the friction and abrasion mechanism, a transmission electron microscope has high spatial resolution which can reach 0.1-0.2nm often, can analyze information of the microstructure, chemical components, morphology, element distribution, atom distribution and the like of the material, and is one of the most effective means for representing the microscopic characteristics, so the microstructure observation and analysis based on the transmission electron microscopy analysis technology is an important means for analyzing the metal friction layer.

The preparation of a metal friction layer transmission electron microscope sample is a very critical step in the TEM analysis technique, since it requires the acquisition of thin regions with a thickness below 100 nm. At present, the main methods for preparing the transmission electron microscope sample of the metal block material are electrolytic double-spraying thinning and ion thinning. However, the electrolytic double-spraying thinning technology has higher requirements on the toughness of the prepared material and is not suitable for preparing a metal friction layer sample. Therefore, the sample is generally prepared by ion thinning. The traditional ion thinning is to thin the sample to 100 μm by mechanical grinding, then punch a wafer with the diameter of 3mm by a sample punch, and continuously grind the sample by 40-50 μm by using a pitter. And finally, bombarding and thinning by adopting Ar ions until breakdown is achieved, and obtaining a TEM sample. However, for a metal friction layer with a multi-layer structure, such as a micron-sized surface oxidation layer, a severe plastic deformation layer and the like, the surface oxidation layer of a sample is easy to fall off or the sample is easy to crack by adopting the traditional ion thinning method, and the sample with the whole thin area of the metal friction layer is difficult to obtain.

Disclosure of Invention

In order to overcome the defects in the prior art, the invention aims to provide a preparation method of a metal friction layer transmission electron microscope sample.

The invention solves the problem that the surface oxide layer of a sample with the section of a metal friction layer is easy to fall off or the sample is easy to crack in the prior art, and provides a preparation method of a transmission electron microscope sample with the metal friction layer, which can obtain the complete section of the metal friction layer and has short manufacturing period.

The purpose of the invention is realized by at least one of the following technical solutions.

The metal friction layer transmission electron microscope sample obtained by the preparation method provided by the invention is a metal friction layer section transmission electron microscope sample with a multi-layer structure of a micron-scale surface oxidation layer, a severe plastic deformation layer and the like.

The invention provides a preparation method of a metal friction layer transmission electron microscope sample, which comprises the following steps:

(1) preparation of a primary sample: cutting a metal sheet from a sample, and polishing to obtain a polished metal sheet;

(2) inlaying: embedding the polished metal sheet in the step (1) in a metal tube, and sticking the embedded part with resin to obtain a sheet sample;

(3) polishing the front surface and the back surface of the sheet sample obtained in the step (2) respectively to obtain a polished sheet sample, and then performing ion thinning treatment until a hole is formed in the sheet sample to obtain an ion thinned sample;

(4) and (4) carrying out ion polishing treatment on the sample subjected to ion thinning in the step (3) to obtain the metal friction layer transmission electron microscope sample.

Further, the thickness of the metal sheet in the step (1) is 0.8-1 mm; and cutting the sample by using a wire-cut electric discharge machine or a diamond circular saw to obtain a metal sheet.

Preferably, the thickness of the metal sheet in the step (1) is 1 mm.

Preferably, when the sample is cut by using a diamond disk saw, the linear speed of the diamond disk saw is below 6 mm/s.

Further, the polishing in the step (1) is performed by using waterproof abrasive paper with the thickness of less than 1000#, and the thickness of the polished metal sheet in the step (1) is 0.4-0.6 mm.

Preferably, the thickness of the polished metal sheet in the step (1) is 0.5 mm.

Further, the length and width of the metal sheet in the step (1) can be determined according to the width of the grinding mark of the original sample.

Further, the metal pipe in the step (2) is a copper pipe; the length of the metal pipe is 0.4-0.6mm, the inner diameter of the metal pipeline is 2.5mm, and the outer diameter of the metal pipe is 3 mm.

Preferably, the length of the metal pipe in the step (2) is the same as the thickness of the ground metal sheet.

Further, the resin in the step (2) is epoxy resin.

Preferably, in the step (2), after the resin is adhered to the inlaid part, the resin overflowing after curing can be removed by using sand paper.

Further, the grinding in the step (3) comprises: the front and back surfaces of the sheet sample were sequentially sanded with 1000#, 2000#, 3000#, 5000# and 7000# sandpaper.

Preferably, in the grinding process of step (3), the number of times of grinding of each kind is increased by times as the number of the water-ground sandpaper is changed from 1000# to 7000 #.

Further, the thickness of the polished slice sample in the step (3) is 30-50 μm.

Further, the ion thinning treatment in the step (3) is double-sided ion thinning treatment; the ion beam energy of the ion thinning treatment is 4-8keV, the rotation angle of the ion gun is within +/-8 degrees, and the ion thinning treatment is carried out until the ion gun is drilled.

Further, the ion polishing process of step (4) includes: firstly, carrying out first ion polishing treatment on a sample subjected to ion thinning under the conditions that the ion beam energy is 5-8keV and the ion gun rotation angle is +/-6 degrees, wherein the time of the first ion polishing treatment is not less than 3min, then carrying out second ion polishing treatment under the conditions that the ion beam energy is 5-8keV and the ion gun rotation angle is +/-4 degrees, wherein the time of the second ion polishing treatment is not less than 3min, and finally carrying out third ion polishing treatment under the conditions that the ion beam energy is 3-4keV and the ion gun rotation angle is adjusted to +/-3 degrees, wherein the time of the third ion polishing treatment is not less than 4 min.

Preferably, the ion polishing process of step (4) includes: firstly, carrying out first ion polishing treatment on a sample subjected to ion thinning under the conditions that the ion beam energy is 5-8keV and the ion gun rotation angle is +/-6 degrees, wherein the time of the first ion polishing treatment is 3-10min, then carrying out second ion polishing treatment under the conditions that the ion beam energy is 5-8keV and the ion gun rotation angle is +/-4 degrees, wherein the time of the second ion polishing treatment is 3-10min, and finally carrying out third ion polishing treatment under the conditions that the ion beam energy is 3-4keV and the ion gun rotation angle is adjusted to +/-3 degrees, wherein the time of the third ion polishing treatment is 4-8 min.

Further preferably, the ion polishing process of step (4) includes: firstly, carrying out first ion polishing treatment on a sample subjected to ion thinning under the conditions that the ion beam energy is 5-8keV and the ion gun rotation angle is +/-6 degrees, wherein the time of the first ion polishing treatment is 10min, then carrying out second ion polishing treatment under the conditions that the ion beam energy is 5-8keV and the ion gun rotation angle is +/-4 degrees, wherein the time of the second ion polishing treatment is 10min, and finally carrying out third ion polishing treatment under the conditions that the ion beam energy is 3-4keV and the ion gun rotation angle is adjusted to +/-3 degrees, wherein the time of the third ion polishing treatment is 8 min.

Preferably, the metal friction layer transmission electron microscope sample obtained in the step (4) can be transferred to a TEM sample box, and a drying agent is put into the TEM sample box, and the TEM sample box is vacuum-packaged and sealed.

The invention provides a metal friction layer transmission electron microscope sample prepared by the preparation method. If the observation effect of the metal friction layer transmission electron microscope sample under TEM is not ideal, the metal friction layer transmission electron microscope sample can be further thinned by adopting an ion polishing process until a good thin area is obtained.

Compared with the prior art, the invention has the following advantages and beneficial effects:

the metal friction layer transmission electron microscope sample prepared by the invention is a metal friction layer section transmission electron microscope sample with a multi-layer structure of a micron-scale surface oxidation layer, a severe plastic deformation layer and the like, and the preparation method avoids the falling off of the friction layer in the sand paper polishing process and avoids the sample fragmentation which is easy to occur in the pit instrument thinning process; in addition, the graded ion polishing which gradually reduces the ion bombardment energy is adopted, the dropping of the friction layer micro-area in the thinning process is also avoided, the graded ion polishing mode which gradually reduces the rotation angle of the ion gun is adopted, the thickness of the thin area around the hole is gradually changed, and the sufficient transparent thin area of electrons of the friction layer is ensured.

Drawings

FIG. 1 is a flow chart of a fabrication process of a TEM sample of a metal friction layer according to an embodiment;

FIG. 2 is a schematic diagram of a Cu-15Ni-8Sn copper alloy material after GCr15 double-grinding in the example;

FIG. 3 is a profile view of a cross section of a friction layer of a Cu-15Ni-8Sn copper alloy sample in an example, which is observed under a scanning electron microscope;

FIG. 4 is a flow chart of primary sample preparation in the examples;

FIG. 5 is a transmission electron micrograph of a cross-sectional sample of the metallic friction layer prepared in example 1;

FIG. 6 is a transmission electron micrograph of a cross-sectional sample of the metallic friction layer prepared in example 2;

FIG. 7 is a transmission electron micrograph of a cross-sectional sample of the metallic friction layer prepared in example 3.

Detailed Description

The following examples are presented to further illustrate the practice of the invention, but the practice and protection of the invention is not limited thereto. It is noted that the processes described below, if not specifically described in detail, are all realizable or understandable by those skilled in the art with reference to the prior art. The reagents or apparatus used are not indicated to the manufacturer, and are considered to be conventional products available by commercial purchase.

The samples used in the following examples were prepared as follows.

And (3) performing a test on the ground copper alloy wear-resistant material by using Cu-15Ni-8Sn and GCr15 through ring-block type friction and wear to obtain a sample after friction. A schematic of the resulting post-friction sample is shown with reference to fig. 2. The overall size of the sample is 10mm multiplied by 10mm, a grinding mark with certain width and depth is formed on the abrasion surface, the abrasion surface is uneven, a layer of black oxide is adhered, and the TEM observation direction is vertical to the grinding mark direction.

The morphology of the friction layer cross section of the Cu-15Ni-8Sn copper alloy sample observed under a scanning electron microscope is shown in FIG. 3. As can be seen, the cross section of the metal friction layer is as follows from outside to inside in sequence: an oxide layer, a nano layer, a deformation layer and a substrate.

Example 1

A method for preparing a metal friction layer transmission electron microscope sample comprises the following steps (as shown in figure 1):

(1) primary sample preparation (as can be seen in fig. 4): cutting a metal sheet (the length and the width are both 10mm) with the thickness of 0.8mm from the rubbed sample by an electric spark wire, and sequentially performing double-side grinding by using No. 600, No. 800 and No. 1000 water sand paper to obtain a ground metal sheet (namely a primary sample, the thickness of which is 0.4 mm);

(2) cutting the polished metal sheet obtained in the step (1), wherein the length, the width and the thickness of the cut metal sheet are 2mm, 1.5mm and 0.4mm, embedding the cut metal sheet in a copper pipe (the inner diameter is 2.5mm, the outer diameter is 3mm and the length is 0.4mm), adhering the embedded part with epoxy resin, and after the epoxy resin is cured, grinding the overflowing epoxy resin with No. 1000 abrasive paper to obtain a sheet sample;

(3) polishing the front surface and the back surface of the sheet sample obtained in the step (2) by using 1000#, 2000#, 3000#, 5000# and 7000# waterproof abrasive paper respectively in sequence to obtain a polished sheet sample (the thickness is 30 micrometers), then performing ion thinning treatment to perform double-surface thinning, wherein the energy of an ion beam of the ion thinning treatment is 6keV, the rotation angle of an ion gun of the ion thinning treatment is +/-8 degrees, and the sample is obtained until the sheet sample is provided with a hole;

(4) performing ion polishing treatment on the sample subjected to ion thinning in the step (3), wherein the ion polishing treatment is divided into three steps, and in the first step, a target area is polished for 5min by adopting a process that the energy of an ion beam is 5.5keV and the rotation angle of an ion gun is +/-6 degrees; step 2, adjusting the ion beam energy to be 5keV, adjusting the rotation angle of an ion gun to be +/-4 degrees and setting the time to be 5 min; step 3, adjusting the energy of the ion beam to 3keV, wherein the rotation angle of the ion gun is +/-3 degrees, and the polishing time is 5 min; and obtaining the metal friction layer transmission electron microscope sample.

And transferring the obtained metal friction layer transmission electron microscope sample to a TEM sample box, putting a drying agent, and carrying out vacuum packaging and sealing for storage.

The morphology of the metal friction layer transmission electron microscope sample (metal friction layer cross section sample) obtained in this example at different magnifications is shown in fig. 5.

As can be seen from FIG. 5, the TEM sample had holes; a large-area thin area is arranged around the hole, so that the oxide layer, the deformation layer and the substrate can be distinguished; can take transmission electron diffraction contrast image, selective area electron diffraction, point, line and surface scanning of energy spectrum, high-angle annular dark field image and high-resolution electron microscopic image (listing high-resolution sample image).

Example 2

A preparation method of a metal friction layer transmission electron microscope sample comprises the following steps:

(1) cutting a metal sheet (the length and the width are both 10mm) with the thickness of 0.9mm from the rubbed sample by using a diamond disk saw, wherein the diameter of a diamond disk saw blade is 100mm, the revolution is 60rpm, the linear velocity of the outer edge of the diamond saw blade is about 5.2mm/s, and performing double-side grinding by using No. 600, No. 800 and No. 1000 waterproof abrasive paper in sequence to obtain a ground metal sheet (the thickness is 0.5 mm);

(2) cutting the polished metal sheet obtained in the step (1), wherein the length, the width and the thickness of the cut metal sheet are 2mm, 1.5mm and 0.5mm respectively, embedding the cut metal sheet in a copper pipe (the inner diameter is 2.5mm, the outer diameter is 3mm and the length is 0.5mm), adhering the embedded part with epoxy resin, and after the epoxy resin is cured, grinding the overflowing epoxy resin with No. 1000 abrasive paper to obtain a sheet sample;

(3) polishing the front surface and the back surface of the sheet sample obtained in the step (2) by using 1000#, 2000#, 3000#, 5000# and 7000# waterproof abrasive paper respectively in sequence to obtain a polished sheet sample (the thickness is 40 mu m), then performing ion thinning treatment to perform double-surface thinning, wherein the energy of an ion beam of the ion thinning treatment is 7keV, the rotation angle of an ion gun of the ion thinning treatment is +/-8 degrees, and the sample is obtained until the sheet sample is provided with a hole;

(4) performing ion polishing treatment on the sample subjected to ion thinning in the step (3), wherein the ion polishing treatment is divided into three steps, and in the first step, a target area is polished for 8min by adopting a process that the energy of an ion beam is 6.5keV and the rotation angle of an ion gun is +/-6 degrees; step 2, adjusting the ion beam energy to 5.5keV, the rotation angle of an ion gun to be +/-4 ℃ and the time to be 8 min; step 3, adjusting the energy of the ion beam to 3keV, wherein the rotation angle of the ion gun is +/-3 degrees, and the polishing time is 8 min; and obtaining the metal friction layer transmission electron microscope sample.

And transferring the obtained metal friction layer transmission electron microscope sample to a TEM sample box, putting a drying agent, and carrying out vacuum packaging and sealing for storage.

The morphology of the metal friction layer transmission electron microscope sample (metal friction layer cross section sample) obtained in this example at different magnifications is shown in fig. 6.

As can be seen from FIG. 6, the TEM sample has holes; a large-area thin area is arranged around the hole, so that the oxide layer, the deformation layer and the substrate can be distinguished; can take transmission electron diffraction contrast image, selective area electron diffraction, point, line and surface scanning of energy spectrum, high-angle annular dark field image and high-resolution electron microscopic image (listing high-resolution sample image).

Example 3

A preparation method of a metal friction layer transmission electron microscope sample comprises the following steps:

(1) cutting a metal sheet (the length and the width are both 10mm) with the thickness of 1mm from the rubbed sample by using a diamond disk saw, wherein the diameter of a saw blade of the diamond disk saw is 100mm, the revolution is 60rpm, the linear velocity of the outer edge of the diamond saw blade is about 5.2mm/s, and performing double-side grinding by using No. 600, No. 800 and No. 1000 waterproof abrasive paper in sequence to obtain a ground metal sheet (the thickness is 0.6 mm);

(2) cutting the polished metal sheet obtained in the step (1), wherein the length, the width and the thickness of the cut metal sheet are 2mm, 1.5mm and 0.6mm respectively, embedding the cut metal sheet in a copper pipe (the inner diameter is 2.5mm, the outer diameter is 3mm and the length is 0.6mm), adhering the embedded part with epoxy resin, and after the epoxy resin is cured, grinding the overflowing epoxy resin with No. 1000 abrasive paper to obtain a sheet sample;

(3) polishing the front surface and the back surface of the sheet sample obtained in the step (2) by using 1000#, 2000#, 3000#, 5000# and 7000# waterproof abrasive paper respectively in sequence to obtain a polished sheet sample (the thickness is 50 mu m), then performing ion thinning treatment to perform double-surface thinning, wherein the energy of an ion beam of the ion thinning treatment is 7keV, the rotation angle of an ion gun of the ion thinning treatment is +/-8 degrees, and the sample is obtained until the sheet sample is provided with a hole;

(4) performing ion polishing treatment on the sample subjected to ion thinning in the step (3), wherein the ion polishing treatment is divided into three steps, and in the first step, a target area is polished for 10min by adopting a process that the energy of an ion beam is 7.5keV and the rotation angle of an ion gun is +/-6 degrees; step 2, adjusting the ion beam energy to 5.5keV, the rotation angle of an ion gun to be +/-4 degrees and the time to be 10 min; step 3, adjusting the energy of the ion beam to 3keV, wherein the rotation angle of the ion gun is +/-3 degrees, and the polishing time is 10 min; and obtaining the metal friction layer transmission electron microscope sample.

And transferring the obtained metal friction layer transmission electron microscope sample to a TEM sample box, putting a drying agent, and carrying out vacuum packaging and sealing for storage.

The morphology of the metal friction layer transmission electron microscope sample (metal friction layer cross section sample) obtained in this example at different magnifications is shown in fig. 7.

As can be seen from FIG. 7, the TEM sample had holes; a large-area thin area is arranged around the hole, so that the oxide layer, the deformation layer and the substrate can be distinguished; can take transmission electron diffraction contrast image, selective area electron diffraction, point, line and surface scanning of energy spectrum, high-angle annular dark field image and high-resolution electron microscopic image (listing high-resolution sample image).

The above examples are only preferred embodiments of the present invention, which are intended to be illustrative and not limiting, and those skilled in the art should understand that they can make various changes, substitutions and alterations without departing from the spirit and scope of the invention.