Preparation method of transmission electron microscope sample of cutting edge of single-point diamond cutter

Abstract

The invention belongs to the technical field of ultra-precision machining, and discloses a preparation method of a transmission electron microscope (TEM) sample of a cutting edge of a single-point diamond cutter, a Pt protective layer is deposited at the worn part of the cutting edge, the damage of a focused ion beam to the surface morphology of a notch when the sample is cut is reduced, and the TEM sample capable of observing the surface morphology and internal defects of the cutting edge at the same time is prepared. The method comprises the steps of pretreating a sample, placing the sample, covering a protective layer, etching the sample, transferring the sample, thinning the sample and the like. According to the TEM sample, the Pt protection layer is introduced in the focused ion beam machining process, damage to the surface morphology of the notch when the sample is cut by the focused ion beam is reduced, and the TEM sample with the cutting edge surface morphology and internal defects capable of being observed at the same time is prepared. According to the method, the surface morphology of the sample can be effectively protected, meanwhile, characterization of the internal defects of the cutting edge is achieved, and the method has important application value.

Description

Technical Field

[0001] The invention belongs to the technical field of ultra-precision machining, and in particular relates to a transmission electron microscope sample preparation method for a single-point diamond tool edge. Background Art

[0002] The basic tool for ultra-precision machining - nano-scale sharp diamond tools will change shape and form defects inside the cutting edge due to wear after cutting. Characterizing its microstructural characteristics is very important for optimizing the performance of diamond tools and determining their service life. Scanning electron microscopes are an important tool for observing the microstructure of materials because they can characterize a wide variety of samples, observe fine structures clearly, and do not destroy, contaminate or damage samples during observation. They are widely used in the characterization of tool edges. However, the inability to characterize the defects inside the tool edge is its main disadvantage. To achieve this goal, transmission electron microscopy characterization technology is required. Transmission electron microscopy (TEM) is an important characterization method in the field of materials research. It has high spatial and temporal resolution accuracy and can obtain crystallographic information of materials. The use of transmission electron microscopy requires the electron beam to penetrate thin samples vertically, so sample preparation is required.

[0003] At present, the main method for sample preparation is focused ion beam micro-nano cutting (FIB). This method uses a high-energy ion beam to cut samples through physical collision, which will inevitably cause damage to the sample surface. Summary of the invention

[0004] The present invention aims to provide a transmission electron microscope sample preparation method for a single-point diamond tool edge, so as to solve the technical problem that the surface morphology and internal defects of the edge cannot be observed simultaneously.

[0005] In order to solve the above technical problems, the specific technical scheme of the transmission electron microscope sample preparation method of a single-point diamond tool edge of the present invention is as follows: A method for preparing a transmission electron microscope sample of a single-point diamond tool edge comprises the following steps: Step 1: Pre-treat the sample: spray gold on the edge of the worn diamond tool to obtain the initial sample; Step 2: Place the sample: Glue the initial sample to the sample nail table with conductive glue, so that the cutting edge is facing upward and the front and rear blades have the same angle with the vertical surface; Step 3: Covering with protective layer: At zero tilt angle, find the notch of the sample edge in the ion beam window and rotate it to the edge level, tilt the sample stage so that one of the blade faces is parallel to the ion beam, and deposit a platinum (Pt) protective layer on the notch area of ​​the other blade face; Step 4: Etching the sample: At zero tilt angle, find the notch of the sample edge in the ion beam window and rotate it until the edge is vertical. Tilt the sample stage so that you can look down at the edge under the ion beam window. The focused ion beam will remove the diamonds in the upper and lower adjacent areas of the protective layer under the current to obtain the original thin slice sample. Step 5: Transfer the sample: Rotate to zero inclination, extend the easylift needle to contact the thin sample, and use platinum to bond the needle to the sample, and finally completely cut off the connection with the cutter at the bottom of the thin sample; Step 6: Thinning the sample: Transfer the original thin film sample to a vertical focused ion beam, and under electric current, remove the damaged areas on the front and back surfaces of the original rectangular thin film sample to reduce its thickness to 400nm. Further, the focused ion beam trims the front and back surfaces of the thin film sample under electric current to reduce its thickness to 150nm, reduce the focused ion beam voltage, and blow away the amorphous layer of the thinned overall sample to obtain the final sample.

[0006] Furthermore, in step 3, the covering shape of the platinum protective layer is a 5 μm*20 μm rectangle with a thickness of 0.5 μm.

[0007] Furthermore, in step 4, the diamonds in the upper and lower adjacent areas of the protective layer are planed away by a focused ion beam at a voltage of 30 KV and a current of 65 nA.

[0008] Furthermore, in step 6, the focused ion beam is used to remove the damaged areas on the front and back surfaces of the original rectangular thin slice sample at a voltage of 30 KV and a current of 0.43 nA.

[0009] Furthermore, in step 6, the front and rear surfaces of the thin film sample are trimmed with a focused ion beam at a voltage of 30 KV and a current of 40 pA to reduce its thickness to 150 nm.

[0010] Furthermore, in step 6, the focused ion beam voltage is reduced to 5KV, and a current of 41pA is used to purge 20nm of the thinned overall sample.

[0011] The present invention provides a method for preparing a transmission electron microscope sample of a single-point diamond tool edge, which has the following advantages: The present invention provides a method for preparing a worn diamond tool edge sample using a focused ion beam technique, by depositing a Pt protective layer at the worn part, reducing the damage to the surface morphology of the notch when the focused ion beam cuts the sample, and preparing a TEM sample that can simultaneously observe the surface morphology and internal defects of the edge. The method of the present invention can effectively protect the surface morphology of the sample and simultaneously realize the characterization of the internal defects of the edge, and has important application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of the horizontal cutting edge and wear notch under the ion beam, with the front and rear cutting edges distributed on the upper and lower sides respectively; Figure 2 The front cutting edge is roughly parallel to the ion beam, and a platinum protective layer is deposited on the notch area of ​​the back cutting edge; Figure 3 Schematic diagram of turning the back face to be roughly parallel to the ion beam and depositing a platinum protective layer in the notch area of ​​the front face; Figure 4 This is a schematic diagram of the ion beam looking down at the cutting edge after the platinum protective layer is covered; Figure 5 The cutting edge is rotated to vertical, and the original thin slice sample is formed by etching. The schematic diagram of etching along the upper and lower sides of the platinum protective layer on the surface of the thin slice sample; Figure 6 This is a schematic diagram of the original thin-section sample under the oblique view of the ion beam after the tilt angle is zeroed; Figure 7 Flow chart for transferring the original thin-section sample from the tool to the semi-copper mesh; Figure 8 Schematic diagram of thinning the original thin film sample on a half copper mesh. DETAILED DESCRIPTION

[0013] In order to better understand the purpose, structure and function of the present invention, the following is a further detailed description of a transmission electron microscope sample preparation method for a single-point diamond tool edge of the present invention in conjunction with the accompanying drawings.

[0014] A method for preparing a transmission electron microscope sample of a single-point diamond tool edge of the present invention comprises the following steps: Step 1: Pre-treat the sample: Figure 1 As shown, the horizontal cutting edge and the wear notch under the ion beam, the front and rear cutting edges are distributed on the upper and lower sides respectively. The worn diamond tool cutting edge is treated with gold spraying to obtain the initial sample.

[0015] Step 2: Place the sample: Glue the initial sample to the sample nail table with conductive glue, with the cutting edge facing upward and the front and rear blades roughly at the same angle to the vertical plane. Place the FIB fixture with the half copper mesh and the nail table with the initial sample on the sample table in the FIB chamber at the same time, and turn on the FIB after vacuuming.

[0016] Step 3, protective layer covering: At zero tilt, find the notch of the sample cutting edge in the ion beam window and rotate until the cutting edge is roughly horizontal. Tilt the sample stage so that one blade surface is roughly parallel to the ion beam, and deposit platinum (pt) on the notch area of ​​the other blade surface. The covering shape is a 5μm*20μm rectangle with a thickness of 0.5μm. Repeat the above operation so that the notch and the front and rear blade surfaces near it are covered with a platinum protective layer. Figure 2 As shown in the figure, the rake face is roughly parallel to the ion beam and a platinum protective layer is deposited. After completion, the tilt angle is reset to zero and the sample stage is rotated 180°, as shown in the figure. Figure 3As shown in the figure, the back face is turned roughly parallel to the ion beam, and a platinum protective layer is deposited in the notch area of ​​the front face. Figure 4 As shown in FIG. 1 , after the protective layer is covered, the ion beam looks down at the cutting edge. The notch and the adjacent front and rear blade surfaces are all covered with a protective layer.

[0017] Step 4: Etching the sample: Figure 5 As shown in the figure, at zero tilt, find the notch of the sample edge in the ion beam window and rotate it until the edge is vertical. Tilt the sample stage so that the focused ion beam looks down at the edge (52°), and the platinum protective layer is horizontal in the ion beam screen. The focused ion beam removes the diamond in the upper and lower adjacent areas of the protective layer at a voltage of 30KV and a current of 65nA, leaving a sample under the protective layer to obtain the original thin slice sample.

[0018] Step 5: Transfer samples: Figure 6 As shown in the figure, rotate to zero tilt angle, and you can see the oblique picture of the original thin slice sample under the ion beam window. Cut off most of the diamond material at the junction of the bottom of the thin slice sample and the diamond tool, but do not cut it off completely. Figure 7 As shown, the EasyLift needle is extended to contact the thin slice sample, and platinum is used to bond the EasyLift needle to the sample, and finally the connection between the sample and the cutter is completely cut off and the EasyLift needle is withdrawn. Subsequently, the original thin slice sample is pasted on the half copper grid.

[0019] Step 6: Thin the sample: Figure 8 As shown, the original thin slice sample is transferred to the focused ion beam to look down on the sample. At a voltage of 30KV and a current of 0.43nA, the damaged areas on the front and back surfaces of the original rectangular thin slice sample are removed to reduce its thickness to about 400nm. Further, the focused ion beam trims the front and back surfaces of the thin slice sample at a voltage of 30KV and a current of 40pA to reduce its thickness to about 150nm. The focused ion beam voltage is reduced to 5KV, and a current of 41pA is used to purge 20nm of the thinned overall sample to reduce the surface amorphous layer. The final sample is obtained.

[0020] It is to be understood that the present invention is described by some embodiments, and it is known to those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the scope of protection of the present invention.

Claims

1. A method for preparing a transmission electron microscope sample of a single-point diamond tool edge, characterized in that: The following steps are involved: Step 1: Pre-treat the sample: spray gold on the edge of the worn diamond tool to obtain the initial sample; Step 2: Place the sample: Glue the initial sample to the sample nail table with conductive glue, so that the cutting edge is facing upward and the front and rear blades have the same angle with the vertical surface; Step 3: Covering with protective layer: At zero tilt angle, find the notch of the sample edge in the ion beam window and rotate it to the edge level, tilt the sample stage so that one of the blade faces is parallel to the ion beam, and deposit a platinum (Pt) protective layer on the notch area of ​​the other blade face; Step 4: Etching the sample: At zero tilt angle, find the notch of the sample edge in the ion beam window and rotate it until the edge is vertical. Tilt the sample stage so that you can look down at the edge in the ion beam window. The focused ion beam will remove the diamonds in the upper and lower adjacent areas of the protective layer under the current to obtain the original thin slice sample. Step 5: Transfer the sample: Rotate to zero inclination, extend the easylift needle to contact the thin sample, and use platinum to bond the needle to the sample, and finally completely cut off the connection with the cutter at the bottom of the thin sample; Step 6: Thinning the sample: Transfer the original thin film sample to a vertical focused ion beam, and under low current, remove the damaged areas on the front and back surfaces of the original rectangular thin film sample to reduce its thickness to 400nm. Further, the focused ion beam trims the front and back surfaces of the thin film sample under current to reduce its thickness to 150nm. The focused ion beam voltage is reduced to purge the amorphous layer of the thinned overall sample to obtain the final sample.

2. The method according to claim 1, characterized in that In the step 3, the platinum protective layer has a covering shape of a 5 μm*20 μm rectangle and a thickness of 0.5 μm.

3. The method according to claim 1, characterized in that In step 4, the diamonds in the upper and lower adjacent areas of the protective layer are planed away by a focused ion beam at a voltage of 30 KV and a current of 65 nA.

4. The method according to claim 1, characterized in that: In step 6, the focused ion beam is used to remove the damaged areas on the front and back surfaces of the original rectangular thin slice sample at a voltage of 30 KV and a current of 0.43 nA.

5. The method according to claim 1, characterized in that: In step 6, the front and rear surfaces of the thin slice sample are trimmed by a focused ion beam at a voltage of 30 KV and a current of 40 pA to reduce its thickness to 150 nm.

6. The method according to claim 1, characterized in that In step 6, the focused ion beam voltage is reduced to 5KV, and a current of 41pA is used to purge 20nm of the thinned whole sample.

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