JP3704071B2 - Lubrication system with carbon ball molecules or carbon tube molecules - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The invention of this application relates to a lubrication system using carbon ball molecules or carbon tube molecules. More specifically, the invention of this application relates to a lubrication system having superlubricity with almost zero frictional force that can be applied to a nanometer scale structure in a micromachine, a nanomachine, or the like.
[0002]
[Prior art and its problems]
2. Description of the Related Art Conventionally, the development of interfacial lubricants and the like for the purpose of lubricating the motion of macro objects, that is, reducing friction between objects on a macro scale has been actively conducted. For example, the development of lubricants and lubrication systems that are used at high temperatures in the atmosphere, and recently, the development of lubricants and lubrication systems that can be used in vacuum that can also be used in space development are active.
[0003]
On the other hand, commercialization of micromachines and nanomachines may occur explosively over the next 10 years, but the problem is the size and nature of the lubrication system (lubricant). For example, the lubrication system applied to structures that contact at the nanometer scale in micromachines, nanomachines, etc., such as the friction gap of ultra-precision micromachines is on the nanometer scale, is equivalent to, or better than, micromachines and nanomachines. Smaller size is required. However, the lubrication system used for macro objects as described above is too large to apply to the nanometer scale.
[0004]
Also, micromachines and nanomachines are called “small engines that cannot move” and the problem of static friction is so serious that if these problems cannot be solved, there is no practical use of micromachines and nanomachines. It is said. At present, this is a serious problem even in micro mechatronics systems (MEMS) such as micro devices aimed at practical use.
[0005]
In other words, when the object is made smaller, the mass becomes smaller in proportion to the cube of the size, whereas the surface area becomes smaller in proportion to the square of the size, so the influence of the surface increases. In the nanometer scale, the sliding friction mechanism on the macro scale cannot be applied, and the friction needs to be extremely small.
[0006]
Accordingly, there is a strong need for a completely new lubrication system that can be applied to the nanometer scale.
[0007]
Accordingly, the invention of this application has been made in view of the circumstances as described above, and solves the problems of the prior art and provides a new lubrication system having superlubricity useful on the nanometer scale. It is an issue.
[0008]
[Means for Solving the Problems]
In order to solve the above problems, the invention of this application firstly provides a lubrication system characterized in that carbon ball molecules or carbon tube molecules are sandwiched between graphite substrates.
[0009]
Second, the invention of this application provides the lubrication system according to the first invention, wherein the carbon ball molecules are deposited on one graphite substrate.
[0010]
Furthermore, a third aspect of the present invention provides the lubrication system according to the first or second invention, wherein the carbon ball molecules are sandwiched between carbon graphite molecules on a graphite substrate.
[0011]
According to a fourth aspect of the present invention, there is provided the lubrication system according to the first invention, wherein the carbon tube molecules are sandwiched between carbon graphite molecules on a graphite substrate.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
The lubrication system with carbon ball molecules or carbon tube molecules of the invention of this application solves the conventional problem and provides a new lubrication system that can be applied to structures contacting on the nanometer scale.
[0013]
First, in the invention of this application, the inventors focused on carbon ball molecules and carbon tube molecules having a nanometer-scale size, which can be applied to the nanometer scale.
[0014]
Carbon ball _{molecules, C 70, C 76, C} 78, C 80, C 82, C 84 C 86, C 88, C 90, C 92, C 94, and C ₉₆ and the like are known to C ₆₀ as a first It has a hollow shell shape closed by a network of 6-membered and 5-membered rings made of carbon, and is also called fullerene. The carbon tube molecule is shaped like a conduit made by rolling a graphite layer (graphite sheet). Like the carbon ball molecule, the carbon tube molecule is a hollow closed by a network of 6-membered and 5-membered rings of carbon. It has a shell shape.
[0015]
As shown in FIG. 1, since the shape of the C ₆₀ molecule, which is an example of the carbon ball molecule, is almost spherical, it can be expected to roll and the surface tension is small. The C ₆₀ molecule has a molecular weight of 720.66 and a mass number of 720. As shown in FIG. 2, the diameter of the C ₆₀ molecule is about 0.7 nm, and the distance between particles in the C ₆₀ crystal is about 1. 0 nm. In addition, since the carbon tube molecule is also tubular, it can be expected to roll in the same manner as the carbon ball molecule, and by utilizing these rolling properties, the carbon ball molecule and the carbon tube molecule can be useful lubricants on the nanometer scale. Can be expected.
[0016]
In addition to C ₆₀ , other carbon ball molecules such as C ₇₀ , C ₇₆ , C ₇₈ , C ₈₀ , C ₈₂ , C ₈₄ C ₈₆ , C ₈₈ , C ₉₀ , C ₉₂ , C ₉₄ , and C ₉₆ are also as described above. The carbon ball molecules can be expected to be a useful lubricating substance because the frictional force is extremely small.
[0017]
In addition, in order for the carbon ball molecules and the carbon tube molecules to roll, the molecules and the underlying material that becomes the substrate are important, and the substrate is made of graphite having the same elements and structure as the carbon ball molecules and the carbon tube molecules. As a result, the 6-membered ring of graphite meshes with the 6-membered ring of carbon ball molecules or carbon tube molecules, and the carbon ball molecules and the carbon tube molecules can roll on the graphite, so that friction that can be used on a nanometer scale is possible. Can provide a lubrication system having near zero superlubricity.
[0018]
When carbon ball molecules are used as a lubricant, a lubricating system can be provided by depositing the carbon ball molecules on a graphite substrate to form a film made of carbon ball molecules and sandwiching the film with the graphite substrate.
[0019]
When carbon tube molecules are used as a lubricant, a lubrication system can be provided by placing the carbon tube molecules on a graphite substrate in the state of a carbon tube molecule array and sandwiching the carbon tube molecules with the graphite substrate.
[0020]
That is, as shown in FIG. 3, a film of carbon ball molecules (1) (or a carbon tube molecule) is sandwiched between two graphite substrates (2) and rides on the graphite substrate (2). By placing the micro object (3) to be moved on the graphite substrate (2) on the other side, the micro object (3) can be moved without causing friction.
[0021]
Hereinafter, embodiments will be described with reference to the accompanying drawings, and embodiments of the present invention will be described in more detail. Of course, the present invention is not limited to the following examples, and it goes without saying that various aspects are possible in detail.
[0022]
【Example】
<Example 1>
In order for the carbon ball molecules and the carbon tube molecules to roll, the base material serving as the substrate is important. Therefore, the present inventor has examined how the carbon ball molecules are ground on graphite and KCl. An experiment was conducted to examine whether or not to deposit.
[0023]
First, as shown in FIG. 4, the inventor uses C ₆₀ and C ₇₀ as examples of carbon ball molecules, and deposits a C ₆₀ film and a C ₇₀ film on the surface of graphite and KCl (001). Formed by.
[0024]
As shown in FIG. 4, C ₆₀ or C ₇₀ is put in a BN crucible installed in a vacuum chamber, and the BN crucible is heated to 400 ° C., thereby evaporating C ₆₀ and C _70. And deposited on the surface of KCl (001). At this time, the temperatures of graphite and KCl (001) were maintained at 150 ° C. to 200 ° C. in order to control the growth rate of the C ₆₀ film and the C ₇₀ film.
[0025]
Here, an atomic force microscope (AFM) was used to examine the deposition state of the C ₆₀ film and the C ₇₀ film on the graphite and KCl (001) surfaces.
[0026]
The upper diagram of FIG. 5 is an AFM image (an uneven image viewed with an atomic force microscope) of C ₆₀ island (island) and C ₇₀ island (island) on the surface of KCl (001). From the height distribution in the lower diagram of FIG. 5, the C ₆₀ island is 20 to 30 nm, and it can be seen that if the diameter of one C ₆₀ molecule is about 1 nm, it is composed of 20 to 30 molecular layers. Moreover, it can be seen that the C ₇₀ island is about 60 nm, and is composed of about 60 molecular layers.
[0027]
The upper diagrams of FIGS. 6A and 6B are AFM images at the initial stage of growth of the C ₆₀ film and the C ₇₀ film on graphite. As shown by the height distribution in the middle diagram of FIG. 6A, the thickness of the C ₆₀ film is about 1 nm, which indicates that the C ₆₀ film is a single layer film.
[0028]
Further, as shown in the lower diagram of FIG. 6B, since the thickness of the C ₇₀ film is about 2 nm, it can be seen that the C ₇₀ film is a two-layer film. In this experiment, no C ₇₀ monolayer was found on the graphite, because the six-membered ring of the C ₇₀ molecule is not located at the top of this ellipsoidal molecule, It is thought that it is difficult to grow with shape.
[0029]
Since the results of this experiment, KCl (001) thin single-layer or two-layer C ₆₀ film as compared with the C ₆₀ islands and C ₇₀ islands can on the substrate, C ₇₀ film is formed on a graphite substrate, C ₆₀ to the C ₇₀ and lubricant in the nanometer scale and is said to base is suitable graphite substrate. Further, since the C ₆₀ film and the C ₇₀ film on the graphite substrate are single-layer films or two-layer films, it is possible to make good use of the rolling properties of C ₆₀ and C ₇₀ .
[0030]
Further, graphite is the same element as the C _60, C _70, due to its structure, C ₆₀ meshing six-membered ring of 6-membered ring and C _60, C ₇₀ graphite by using a graphite as the substrate, C ₇₀ is the graphite Can roll on.
[0031]
<Example 2>
Also it was how much force (shearing force) measure necessary or experiment molecular manipulation C ₆₀ films on graphite. This means that the smaller the shear force, the easier the molecular operation, and the higher the lubricity.
[0032]
The upper diagram of FIG. 7 shows how the AFM image of the C ₆₀ monolayer film of FIG. 6A changes with increasing load. In the upper diagram of FIG. 7, it can be seen that the C ₆₀ monolayer film on the graphite is swept as the load increases from −9 nN to 0 nN. The contact radius with respect to the chip load evaluated using a pulling force of −10 nN and a chip radius of 15 nm is shown in the lower left diagram of FIG. With a load of 0 nN, the contact radius between the probe tip and the C ₆₀ monolayer film is evaluated as 1.3 nm. This gives a contact area of about 7 molecules within a large circle in the lower right diagram of FIG. Since the average friction force at this time was 3 nN, assuming that 7 molecules move with a horizontal force of 3 nN, the shear force required to move 1 molecule of C ₆₀ on the graphite was about 0.4 nN. Thus, it is a value that is 1 to 2 orders of magnitude smaller than the shear force of normal molecules, and it is considered that the lubricity of C ₆₀ is extremely high.
[0033]
Also in a similar experiment C ₇₀ on graphite, C ₇₀ molecules had been swept with smaller force as compared with the C ₆₀ molecule. This suggests that the interaction at the C ₇₀ -graphite interface is weaker than the interaction at the C ₆₀ -graphite interface, and it can be said that C ₇₀ has higher lubricity than C ₆₀ on graphite.
[0034]
<Example 3>
In addition, the present inventor examined the characteristics of the carbon tube on the KCL (001) surface and graphite using a friction force microscope (FFM).
[0035]
As shown in FIG. 8 (a), many carbon tubes on the KCL (001) surface are bent. In contrast, as shown in FIG. 8 (b), it was found that many carbon tubes on graphite were not bent and aligned in a certain direction. That is, it can be said that the carbon tube molecules are oriented in parallel on the graphite (in a state of a carbon tube molecule array), and thereby rolling can be expected.
[0036]
Further, when the slip of the carbon tube on the KCl (001) surface and graphite was examined, the slip of the carbon tube was found only on the KCl (001) surface. This means that the shear strength between the carbon tube and the graphite is larger than the shear strength between the carbon tube and KCl (001). This is because the 6-membered ring of the carbon tube molecule and the 6-membered ring of graphite are engaged. If the shear strength is high, rolling is more likely to occur than slipping. Therefore, considering the fact that the carbon tubes are oriented in parallel on the graphite as described above, a lubrication system that uses the rolling of the carbon tubes on the graphite can be used. It becomes possible.
[0037]
<Example 4>
Furthermore, the present inventor conducted an experiment to measure the friction force in order to investigate the lubricity of the lubrication system of the present invention. The value of the frictional force was measured using a strip type cantilever spring during scanning. Specifically, the frictional force was determined by making the axial direction of the cantilever spring perpendicular to the scanning direction and measuring the amount of torsion of the cantilever spring obtained during scanning.
[0038]
FIG. 9 is a sample for confirming the lubricity of the lubricating system of the present invention. C ₆₀ is deposited on a graphite substrate (4) to form a C ₆₀ film (5), and a graphite flake (6) is further formed thereon. A measurement sample (7) was prepared.
[0039]
FIG. 10 (a) shows a scan with a load of 0 nN applied only to the graphite substrate (4), and the frictional force was 2 nN.
[0040]
FIG. 10 (b) obtained by scanning over a load 0nN to that by depositing C ₆₀ to form a C ₆₀ film (5) to the graphite substrate (4), the friction force was 10 nN.
[0041]
Also FIG. 10 (c) obtained by scanning over a load 0nN~0.1nN the measurement sample (7) carrying the graphite flake (6) to the C ₆₀ film (5) on shown in FIG. 10 (b) The frictional force was 0.5 nN.
[0042]
As is clear from these, the frictional force of the measurement sample (7) in FIG. 10C is the smallest, and it can be said that the lubrication system of the present invention has high lubricity.
[0043]
【The invention's effect】
As described above in detail, the present invention provides a lubrication system having superlubricity with almost zero friction applicable to the nanometer scale in molecular bearings, molecular rollers, molecular gears, micromachines, nanomachines, etc. It is expected to bring about great progress.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a molecular structure of C ₆₀ as an example of a carbon ball molecule constituting a lubrication system of the present invention.
FIG. 2 is a diagram illustrating a crystal structure of C ₆₀ as an example of a carbon ball molecule constituting the lubrication system of the present invention.
FIG. 3 is a conceptual diagram showing a lubrication system of the present invention.
FIG. 4 is a conceptual diagram illustrating a vapor deposition apparatus for performing vapor deposition on C ₆₀ and C ₇₀ substrates constituting the lubrication system of the present invention.
FIG. 5 is a diagram showing an AFM image on a KCl (001) surface of C ₆₀ and C ₇₀ and a line profile thereof forming the lubrication system of the present invention.
FIG. 6 is a diagram showing an AFM image on a C ₆₀ and C ₇₀ graphite surface and a line profile thereof forming the lubrication system of the present invention.
7 is a diagram showing a change with respect to an increase in load of the C ₆₀ monolayer film of FIG. 6. FIG.
FIG. 8 is a diagram showing an FFM image and a line profile thereof on a KCL (001) surface and a graphite surface of a carbon tube.
FIG. 9 is a view showing a measurement sample of an experiment for examining the lubricity of the lubrication system of the present invention.
FIG. 10 is a diagram showing a measurement method of an experiment for examining the lubricity of the lubrication system of the present invention.
[Explanation of symbols]
1 Carbon ball (carbon tube)
2 Graphite substrate 3 Micro object 4 Graphite substrate 5 C ₆₀ film 6 Graphite flake 7 Measurement sample

Claims (4)

A lubrication system, wherein carbon ball molecules or carbon tube molecules are sandwiched between graphite substrates. The lubrication system of claim 1, wherein the carbon ball molecules are deposited on one of the graphite substrates. The lubrication system according to claim 1 or 2, wherein the carbon ball molecules are sandwiched in a carbon ball molecular layer state on the graphite substrate. 2. The lubrication system according to claim 1, wherein the carbon tube molecules are sandwiched in a carbon tube molecule array on the graphite substrate.

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