JP7191379B2 - Friction observation method and observation device - Google Patents

Description

The present invention relates to a friction observation method and observation device.

Friction occurs at the "interface" where two surfaces contact and slide. The interface, the region sandwiched between solids, is very difficult to observe 'in situ', and observation and analysis are performed after friction. On the other hand, for example, in Non-Patent Document 1, an attempt is made to observe the frictional interface using an optical microscope.

V. Chauveau, D. Mazuyer, F. Dassenoy, and J. Cayer-Barrioz, Tribol. Lett., 2012, pp. 467-480.

However, at the friction interface, submicron-order phenomena such as shape change and physico-chemical reaction are presumed to change dynamically, but there are many black-box phenomena that remain unexplained. Observation using an optical microscope as in Non-Patent Document 1 does not have enough resolution to clarify this friction phenomenon. Therefore, in-situ observation of the frictional interface using an electron microscope such as a scanning electron microscope with very high resolution is indispensable, but it has not been realized at all at present. SUMMARY OF THE INVENTION It is an object of the present invention to provide a friction observation method and an observation device capable of observing submicron-order phenomena occurring at the friction interface during friction. do.

The method for observing friction according to the present invention includes the step of causing friction by moving the pressing member along the plane direction of the electron-permeable membrane while pressing the pressing member against the first surface of the electron-permeable membrane. irradiating a second surface of the electron permeable film opposite to the first surface with an electron beam; detecting electrons or electromagnetic waves generated at the interface by irradiating the interface, and obtaining an image of the region in which the friction occurs in the electron-transmitting film. Note that the step of irradiating the electron beam may be performed after the step of generating friction.

In the method for observing friction, the thickness of the electron-transmitting film may be 1 to 200 nm.

In the method for observing friction, the pressing member may have a curved surface, and the curved surface may be pressed against the electron permeable film.

In the friction observation method, the electron _- transmitting film can be made of _Si3N4 , _SiO2 , SiC, Si, DLC, amorphous carbon, graphene, or graphene oxide.

The friction observation method may further comprise the step of providing a container having an opening closed by the electron permeable membrane and having a sealed interior space, wherein the first surface of the electron permeable membrane is in the step of causing the friction by facing the internal space, applying lubricant to the first surface of the electron permeable film, and applying the friction to the region coated with the lubricant by the pressing member. can be configured to cause

A friction observation device according to the present invention is an observation device for observing friction with an electron microscope, comprising: an electron-transmitting film having a first surface and a second surface opposite to the first surface; a supporting portion for supporting the electron-transmitting film, a pressing member for contacting the first surface of the electron-transmitting film, and the a moving mechanism for generating friction by pressing a pressing member against the first surface of the electron permeable film and moving it along the first surface; By irradiating the interface between the electron permeable film and the pressing member with an electron beam, electrons or electromagnetic waves generated at the interface are detected, and the friction occurring in the electron permeable film is observed with the electron microscope. is configured as

In the friction observation device, the thickness of the electron-transmitting film may be 1 to 200 nm.

In the friction observation device, the pressing member may have a curved surface, and the curved surface may be pressed against the electron permeable film.

In the above-mentioned friction observation device, the electron-transmitting film can be made of Si ₃ N ₄ , SiO ₂ , SiC, Si, DLC, amorphous carbon, graphene, or graphene oxide.

In the above friction observation device, the support includes a container having an opening and a sealed internal space, and the first surface of the electron permeable film faces the internal space. The opening is closed by an electron permeable film, the first surface of the electron permeable film is coated with lubricating oil, and the pressure member causes the friction to occur in the region coated with the lubricating oil. be able to.

According to the present invention, it is possible to observe submicron-order phenomena that occur at friction interfaces during friction.

1 is a schematic configuration diagram of an observation device according to a first embodiment of the present invention; FIG. FIG. 5 is a schematic configuration diagram of an observation device according to a second embodiment of the present invention; It is a photograph of the friction interface observed with the observation device according to the example of the present invention.

<A. First Embodiment>
A first embodiment of an observation device according to the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of this observation device.

<1. Overview of Observation Device>
As shown in FIG. 1, an observation apparatus 10 according to this embodiment is placed on a sample observation stage 80 in a vacuum chamber of a scanning electron microscope (SEM), and observes friction occurring on the surface of the electron permeable film 1. It is for Specifically, the observation device 10 includes an electron permeable membrane 1, a support section 2 that supports the electron permeable membrane 1, a pressing member 3 that is pressed against the electron permeable membrane 1, and an operation of the pressing member 3. and a control unit (moving mechanism) 4 that controls the . Each member will be described in detail below.

<1-1. Electron Permeable Film>
The electron permeable film 1 transmits an electron beam B irradiated in the SEM. The material forming the electron-transmitting film ₁ is not particularly limited as long as electrons pass through it, but examples include _Si3N4 , _SiO2 , SiC, Si, DLC, amorphous carbon, graphene, graphene oxide, and the like. can be adopted. Among these, Si ₃ N ₄ is particularly preferable because it is a hard and hard-to-break material.

Although the thickness of the electron permeable film 1 is not particularly limited, it is preferably, for example, 1 to 200 nm, more preferably 5 to 100 nm, particularly preferably 20 to 50 nm. This is because if the thickness of the electron permeable film 1 is small, a clear image can be obtained in the SEM, but if it is too small, it may be broken by friction. On the other hand, if the thickness of the electron permeable film 1 is too large, electrons may not pass through.

<1-2. Supporting part>
The support unit 2 includes a support plate 21 for supporting the electron permeable film 1, and a base 22 for supporting the support plate 21 in a horizontal state on the sample observation stage 80 of the vacuum chamber of the SEM. A circular through hole 211 is formed in the support plate 21 , and the electron permeable membrane 1 is fixed to the lower surface of the support plate 21 so as to block the through hole 211 . The base 22 includes a rectangular fixed plate 221 to which the support plate 21 is fixed, and four leg members 222 extending downward from the four corners of the fixed plate 221 . 21 is held at a predetermined height. A notch may be formed in the support plate 21 instead of the through hole 211, and the electron permeable membrane 1 may be attached so as to cover at least a part of the notch.

<1-3. Pressing member>
Next, the pressing member 3 will be described. In this embodiment, the pressing member 3 is formed of a sphere and supported by a cantilever beam 41 of the control section 4, which will be described later. The operation of the cantilever beam 41 is controlled by a piezo stage 42 of the control unit 4, which will be described later. Thereby, the pressing member 3 presses the lower surface (first surface) of the electron permeable membrane 1 and the electron permeable membrane. It is designed to move in the plane direction of 1. That is, the pressing member 3 rubs the lower surface of the electron permeable membrane 1 to generate friction.

For the pressing member 3, various materials such as metals, ceramics, and resin materials that do not transmit electrons can be used. Among them, metals are suitable for SEM observation because they are conductive.

<1-4. Control section>
Next, the controller 4 will be explained. The control unit 4 includes the cantilever beam 41 that supports the pressing member 3 as described above, the piezo stage 42 that operates the cantilever beam 41, and the detection unit 43 that detects the position of the cantilever beam 41. ing. The cantilever beam 41 can be made of an elastically deformable plate, wire, or the like. The other end of the cantilever beam 41 is fixed to the piezo stage 42 . The piezo stage 42 is a well-known device that moves three-dimensionally (X-direction, Y-direction, and Z-direction) by a piezo actuator. Here, the direction perpendicular to the electron permeable film 1 (vertical direction) is defined as the Z direction, and the surface directions of the electron permeable film 1 orthogonal thereto are defined as the X direction and the Y direction.

The detection unit 43 includes a laser source 431 fixed to the piezo stage 42, a mirror 432 attached to the lower surface of one end of the cantilever 41, a mirror 433 attached to the piezo stage 42, and the piezo stage 42. and a photodiode 434 fixed to the . With this configuration, the laser light emitted from the laser source 431 is reflected by the two mirrors 432 and 433 , and the reflected laser light is received by the photodiode 433 . Since the two mirrors 432 and 433 are positioned corresponding to the pressing member 3 , the position of the pressing member 3 can be detected by receiving laser light reflected by these mirrors 432 and 433 . Note that the configuration of the detection unit 4 is not particularly limited, and a laser beam is used, and the laser beam reflected by at least one or more mirrors is received. It is only required that the position to be detected can be detected.

<2. Observation Method of Friction Using Observation Device>
Next, a method of observing friction using the observation device 10 configured as described above will be described. First, the observation device 10 is arranged on the sample observation stage 80 in the vacuum chamber of the SEM. Next, the piezo stage 42 is driven to move the cantilever beam 41 upward. As a result, the pressing member 3 fixed to one end of the cantilever beam 41 presses the electron permeable membrane 1 . At this time, the force for pressing the electron permeable film 1 can be appropriately changed depending on the type and thickness of the electron permeable film 1 and the shape of the pressing member 3 . Therefore, the pressing force is not particularly limited, but if the pressing member 3 has a diameter of several millimeters, it can be 1 mN or less, for example. In the examples described later, the electron permeable membrane 1 is pressed at 15 μN.

Subsequently, the piezo stage 42 is driven to reciprocate the cantilever beam 41 in the X direction. As a result, the pressing member 3 moves in the surface direction of the electron permeable film 1 while pressing the electron permeable film 1 . For example, on the electron permeable film 1, it may be moved only in one direction, or may be moved two-dimensionally. Thus, friction is generated between the electron permeable film 1 and the pressing member 3 . At this time, since the position of the tip of the cantilever 41 is measured by the above-described laser, the bending displacement of the cantilever 41 and the like can be obtained based on the position of the tip. Therefore, for example, by keeping the position of the tip portion constant, the pressing force on the electron permeable membrane 1 can be made constant. Further, by calibrating the relationship between the bending displacement and the pressing force, the pressing force on the electron permeable membrane 1 can be adjusted by controlling the movement of the piezo stage 42 . Additionally, the torsion of the cantilever beam 41 is also measured. Torsion can be calibrated to translate into friction force.

Following this, the observation device 10 is irradiated with an electron beam B in the SEM. That is, the electron beam B is irradiated toward the through hole 211 of the support plate 21 . The electron beam B passes through the upper surface (second surface) of the electron permeable film 1 and irradiates the interface between the electron permeable film 1 and the pressing member 3 . Secondary electrons are thereby generated from the interface. After passing through the electron-transmitting film 1, the secondary electrons are detected by the detector of the SEM and formed into an image. That is, the SEM allows observation of the friction occurring between the electron permeable membrane 1 and the pressing member 3 .

<3. Features>
As described above, according to the present embodiment, friction is generated by rubbing the lower surface of the electron permeable film 1 with the pressing member 3, and the electron beam B is irradiated from the upper surface of the electron permeable film 1. and the pressing member 3 is irradiated. Thereby, friction can be observed by SEM by detecting secondary electrons generated from the interface and forming an image. Therefore, it is possible to observe submicron-order phenomena occurring at the friction interface during friction, which has not been possible until now. Therefore, it is expected to contribute to the elucidation of the mechanism of friction.

Since the observation device 10 according to the present embodiment has a small size and a simple configuration, it is possible to observe friction at low cost using an SEM.

<B. Second Embodiment>
Next, a second embodiment of an observation device according to the present invention will be described with reference to the drawings. FIG. 2 is a schematic configuration diagram of an observation device according to the second embodiment. In the following, the parts that are different from the first embodiment will be mainly described, and the same components will be denoted by the same reference numerals, and descriptions thereof may be omitted.

The observation device 20 according to this embodiment differs from the first embodiment in that it has a container 5 instead of the support section 2 . The pressing member 3 and the control unit 4 described above are accommodated in the container 5 in a sealed state. That is, the internal space of the container 5 is airtight with respect to the vacuum chamber of the SEM.

The container 5 is formed in a rectangular parallelepiped shape, and a through hole 52 is formed in an upper wall portion 51 . The electron permeable film 1 is fixed so as to block the through hole 52 from the lower surface side of the upper wall portion 51 . The pressing member 3 accommodated in the container 5 is installed so as to press the electron permeable membrane 1 from the lower surface side. Further, the cantilever beam 41 supporting the pressing member 3 is driven in the X, Y, and Z directions by the piezo stage 42 as in the first embodiment. friction occurs.

Furthermore, in this embodiment, the lower surface of the electron permeable film 1 is coated with the lubricating oil 6 , and the pressing member 3 is in contact with the region of the electron permeable film 1 to which the lubricating oil 6 is applied. As in the first embodiment, if the electron beam of the SEM is irradiated to the electron permeable film 1 while the pressing member 3 is moved, the friction reduced by the lubricating oil 6 can be observed. Therefore, this observation device 20 can be used to verify the effects of various lubricating oils 6 . Lubricating oil is not particularly limited, and includes grease, water-based lubricant, and powder.

In this embodiment, the observation device 20 has a sealed container 5 in which the pressing member 3 and the like are accommodated. This is because there is a risk of evaporation in the The pressure in the inner space of the container 5 may be normal pressure, but may be reduced because the electron permeable membrane 1 in contact with the vacuum chamber may be destroyed due to the pressure difference.

<C. Variation>
Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention. Note that the following modified examples can be combined as appropriate.

<1>
The configuration of the supporting portion 2 that supports the electron permeable film 1 is not particularly limited. That is, if the electron permeable film 1 is supported so that the electron beam of the SEM can be irradiated onto the electron permeable film 1 and it can be installed in a vacuum chamber, the support plate 21 and A configuration other than the base 22 may be used.

<2>
In the above embodiment, the pressing member 3 is fixed to the end of the cantilever beam 41, and the cantilever beam 41 is moved by the piezo stage 42. However, the present invention is not limited to this. That is, as long as the pressing member 3 can be moved in the plane direction while pressing the pressing member 3 against the electron permeable membrane 1, various moving mechanisms can be applied. In addition, in the above embodiment, a laser is used to measure the pressing force and the frictional force on the electron permeable film 1, but the present invention is not limited to this. That is, various methods such as strain gauge, displacement measurement, capacitance method, and load cell method can be used to measure the pressing force and the frictional force.

<3>
Although the pressing member 3 in the above embodiment is formed in a spherical shape, it can have various shapes as long as it can press the electron permeable membrane 1 . That is, in the pressing member 3, the shape of the portion in contact with the electron permeable membrane 1 can be made into various shapes such as a spherical surface, a curved surface, and a flat surface. However, in the case of a flat surface, if the parallelism with the electron permeable film 1 is not accurate, pressing becomes difficult, so a spherical surface or a curved surface is preferable. In addition, if the surface is spherical or curved, it will contact the electron permeable membrane 1 not at a point but at a predetermined area by pressing, so there is an advantage that the friction can be easily observed.

<4>
The shape of the container 5 used in the second embodiment is not particularly limited. In addition, in the second embodiment, the controller 4 is housed in the internal space of the container 5, but the invention is not limited to this. That is, at least the opening 52 of the container 5 is closed by the electron permeable film 1 , and the lubricating oil 6 and the pressing member 3 are arranged on the surface of the electron permeable film 1 on the inner space side of the container 5 . Therefore, at least part of the control section 4 that controls driving of the pressing member 3 can be arranged outside the container 5 .

<5>
In the above embodiment, secondary electrons generated at the interface between the electron permeable film 1 and the pressing member 3 are observed by SEM, but reflected electrons and X-rays generated from the pressing member 3 can also be detected. can also be imaged and observed. In addition to the SEM, it is possible to irradiate the pressing member 3 with an electron beam through the electron permeable film 1, detect electrons, electromagnetic waves, etc. generated by the pressing member 3, form an image, and observe various types of electrons. A microscope or the like can be employed.

Examples of the present invention will be described below. However, the present invention is not limited to the following examples.

First, an observation apparatus shown in FIG. 1 similar to that of the first embodiment was prepared. That is, a support plate having through holes formed therein was prepared, and an electron permeable membrane was fixed to the lower surface thereof so as to close the through holes. This electron-transmitting film is made of Si ₃ N ₄ and has a thickness of about 50 nm. In order to observe the friction, nanocarbon oxide (wood-derived nanocarbon oxide; oWNCs) dispersion water was dropped on the lower surface of the electron permeable film and dried to form a film. oWNCs are spherical substances with graphite layers serving as shells, and have a diameter of several tens of nanometers. In addition, the thickness of the oWNCs coating is considered to be approximately 50 to 100 nm.

Then, this support plate was fixed to the support base. A wire was used as the cantilever beam, and a SUJ2 ball having a diameter of about 1 mm was fixed to the tip of the wire as a pressing member. The other end of the cantilever beam was fixed to a piezo stage, and the pressing member was positioned so as to press the region provided with the oWNCs on the lower surface of the electron-transmitting film. Then, the pressing member is controlled to press the lower surface of the electron permeable membrane with a force of about 15 μN, and the pressing member that presses the electron permeable membrane is moved in one direction in the surface direction of the electron permeable membrane with a length of about 200 μm. set to reciprocate.

The observation apparatus as described above was installed in a vacuum chamber of a scanning electron microscope, and driving by the piezo stage was started. Next, an electron beam was irradiated toward the electron-transmitting film. By detecting secondary electrons generated from the interface between the electron permeable film and the pressing member, an image of friction was obtained as shown in FIG. FIG. 3(a) shows the initial state of the pressing member when the driving is started, and FIG. 3(b) shows the state after the pressing member has been reciprocated 1000 times.

The white area shown in FIG. 3(a) is the area where the oWNCs are applied, but the oWNCs are not applied uniformly and the thickness is uneven. And, as shown in FIG. 3(b), after 1000 times of friction, the white area is thinner than in FIG. 3(a). This is because the oWNCs were rubbed and peeled off by the pressing member. 3(a) and 3(b), the shape of the white region is smaller in FIG. 3(b). It can be observed that the In addition, although still images are used for explanation in this embodiment, moving images are used for observation in the actual test.

Thus, the friction interface during friction could be observed by using the observation device according to the present invention.

1 Electron Permeable Film 2 Supporting Part 3 Pressing Member 4 Control Part (Moving Mechanism)
5 container 6 lubricating oil

Claims (10)

a step of generating friction by moving the pressing member along the surface direction of the electron-permeable film while pressing the pressing member against the first surface of the electron-permeable film;
a step of irradiating an electron beam onto a second surface of the electron transmissive film opposite to the first surface;
By irradiating the interface between the electron permeable film and the pressing member with the electron beam that has passed through the electron permeable film, the electrons or electromagnetic waves generated at the interface are detected, and the friction is generated in the electron permeable film. obtaining an image of a region of friction. 2. The method for observing friction according to claim 1, wherein the thickness of said electron-transmitting film is 1 to 200 nm. 3. The method of observing friction according to claim ₁ , wherein the electron-transmitting film is made of _Si3N4 , _SiO2 , SiC, Si, DLC, amorphous carbon, graphene, or graphene oxide. 4. The method for observing friction according to claim 1, wherein said pressing member has a curved surface and presses said curved surface against said electron permeable film. further comprising providing a container having an opening blocked by the electron permeable membrane and having a sealed interior space;
the first surface of the electron permeable film faces the internal space;
5. In the step of generating friction, a lubricant is applied to the first surface of the electron permeable film, and the friction is generated by the pressing member against the region coated with the lubricant. The method for observing friction according to any one of . An observation device for observing friction with an electron microscope,
an electron permeable film having a first surface and a second surface opposite to the first surface;
a support for supporting the electron-transmitting film so that the second surface of the electron-transmitting film is irradiated with the electron beam of the electron microscope;
a pressing member in contact with the first surface of the electron permeable film;
a moving mechanism that causes friction by pressing the pressing member against the first surface of the electron permeable film and moving the pressing member along the first surface;
with
By irradiating the interface between the electron permeable film and the pressing member with the electron beam that has passed through the electron permeable film, the electrons or electromagnetic waves generated at the interface are detected, and the electron beam generated in the electron permeable film is detected. A friction observation device configured to observe friction with the electron microscope. 7. The friction observation device according to claim 6, wherein the thickness of said electron permeable film is 1 to 200 nm. 8. The friction observation device according to claim ₆ , wherein said electron transparent film is made of _Si3N4 , _SiO2 , SiC, Si, DLC, amorphous carbon, graphene, or graphene oxide. 9. The friction observation device according to claim 6, wherein said pressing member has a curved surface, and said curved surface is pressed against said electron permeable film. The support includes a container having an opening and a closed internal space,
the opening is closed by the electron permeable film such that the first surface of the electron permeable film faces the internal space;
10. The structure according to any one of claims 6 to 9, wherein a lubricating oil is applied to the first surface of the electron permeable film, and the friction is generated by the pressing member against the region to which the lubricating oil is applied. The friction observation device according to .

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