WO2003089552A1

WO2003089552A1 - Carbon nano-horn solid lubricant

Info

Publication number: WO2003089552A1
Application number: PCT/JP2003/004181
Authority: WO
Inventors: Sumio Iijima; Masako Yudasaka; Kazunori Umeda; Akihiro Tanaka
Original assignee: Japan Science And Technology Agency; Nec Corporation; National Institute Of Advanced Industrial Science And Technology
Priority date: 2002-04-19
Filing date: 2003-04-01
Publication date: 2003-10-30
Also published as: JP2003313571A

Abstract

A novel carbon nano-horn solid lubricant, characterized in that it comprises a single layer carbon nano-horn aggregate. The lubricant can be used for reducing the friction and abrasion in sliding sections in various devices and on sliding surfaces in a micro-machine, a living device, a space device or the like.

Description

Description Carbon nanohorn solid lubricant Technical field

The invention of this application relates to a carbon nanohorn solid lubricant. More specifically, the invention of the present application relates to a new force-bonding nanohorn solid lubricant capable of reducing the friction and wear of sliding parts of various devices and sliding surfaces of micromachines, biological devices, space devices, and the like. It is. Background art

Fullerenes, single-walled or multi-walled carbon nanotubes, single-walled carbon nanohorn aggregates, etc., have been attracting attention in various fields as new nano-structured graphite (graphite) materials, and their physical properties have been investigated, and There have been many studies on the application of.

However, for the tribological performance of these carbon materials, there only have been examined for c _{6 Q} or a single layer or a multi-walled carbon nanotubes, it has not been reported yet bought for single-layer carbon nanohorn aggregate.

On the other hand, the sophistication and integration of processing technology in recent years has led to the remarkable development of so-called nanotechnology. In micromachines and biological devices used in this nanotechnology environment, lubricants are required to reduce friction and wear of objects on the order of nanometers. On the other hand, recently, solid lubricants that can be used in space and that can be used in vacuum have been actively developed.

Therefore, the invention of this application was made in view of the above circumstances, and as a new application of the single-walled carbon nanohorn aggregate, The challenge is to provide a new carbon nanohorn solid lubricant that can reduce the friction and wear of the sliding surfaces of micromachines, biological devices, space devices, etc., as well as the sliding parts of various general equipment. And Disclosure of the invention

Therefore, the invention of this application provides the following inventions. That is, first, the invention of the present application provides a carbon nanohorn solid lubricant characterized by containing a single-layer force-bonded Bonnanohorn aggregate.

The invention of this application relates to the above invention, secondly, a carbon nanohorn solid lubricant characterized in that a single-walled carbon nanohorn aggregate is contained in a dispersion medium, and thirdly, a single carbon nanohorn solid lubricant. Laminar force The carbon nanohorn solid lubricant is characterized in that the one-bon nanohorn aggregate has been subjected to a heat treatment at a temperature of 1200 or more, and the fourth characteristic is that it is a film-like body. To provide solid lubricants. BRIEF DESCRIPTION OF THE FIGURES

Figure 1 is a schematic diagram illustrating the structure of (a) the single-walled carbon nanohorn aggregate and (b) the tip of the single-walled carbon nanohorn, and (c) the transmission type of the single-walled carbon nanohorn aggregate. Example of electron microscope image! ^.

FIG. 2 is a diagram illustrating the results of a friction test of a graphite powder (average particle size: 0.6 m).

FIG. 3 is a diagram exemplifying a result of observing the surfaces of the substrate and the pole after a friction test using a graphite powder (average particle size: 0.6 m) with an optical microscope.

Figure 4 shows an example of the friction test result of a single-walled carbon nanohorn aggregate. FIG.

FIG. 5 is a diagram exemplifying a result of observing the surfaces of the substrate and the pole after the friction test using the single-walled carbon nanohorn aggregate with an optical microscope.

FIG. 6 is a diagram illustrating the average friction coefficient of each material. BEST MODE FOR CARRYING OUT THE INVENTION

The invention of this application has the features as described above, and embodiments thereof will be described below.

The inventors of the present application studied further applications of the single-walled carbon nanohorn aggregates, and focused on the performance of tripology, and as a result, found that the single-walled carbon nanohorn aggregates were useful as a solid lubricant. I came to find sex. That is, the carbon nanohorn solid lubricant provided by the invention of this application is characterized by containing a single-walled carbon nanohorn aggregate.

The single-walled carbon nanohorn aggregate is a new carbon allotrope discovered by the inventors of the present application. For example, as illustrated in FIGS. 1 (a) to 1 (c), one end of a single-walled carbon nanotube has a square shape. A plurality of closed single-walled carbon nanohorns are assembled with their horn-shaped ends outside, and exist as spherical particles as a whole. This single-walled carbon nanohorn aggregate has a Darrie type single-walled carbon nanohorn aggregate in which the corners of the single-walled carbon nanohorn project outward, and a smooth surface without horn-like protrusions on the surface. There is a bud-type single-walled carbon nanohorn aggregate having the same, and any of them can be used in the invention of this application.

Regarding the size of these single-walled carbon nanohorn aggregates, typically, the diameter is in the range of 80 to 10 O nm, and a single spherical particle or a soot-like material in which a plurality of spherical particles are aggregated. Get as be able to. Such single-walled carbon nanohorn aggregates can be expected to exhibit rolling characteristics because they are spherical particles, and have a nanometer order of magnitude. Further, although it is uncertain whether or not it is due to the characteristic shape as described above, good tribological performance can be exhibited without being greatly affected by the material of the substrate and the like. In other words, a carbon nanohorn solid lubricant useful as a solid lubricating substance that can also reduce the friction and wear of the sliding surface in various devices and the like is realized. In addition, this carbon nanohorn solid lubricant can be used in equipment in the order of nanometers, equipment used in the space environment, and the like.

The carbon nanohorn solid lubricant of the invention of the present application can essentially function as a lubricant with only a single-layer carbon nanohorn aggregate, but considering the ease of use, etc. For example, it can be added to a dispersion medium or the like. Examples of the dispersion medium include hydrocarbons such as benzene, toluene, xylene, hexane, and ethyl acetate; alcohols such as methanol, ethanol, ethylene glycol, and glycerin; ethers such as ethyl ether and getyl ether; and esters. Various organic solvents such as its derivatives, etc., resins such as polyimide, polytetrafluoroethylene (PTFE), polyetheretherketone (PEEK), water, water glass, oil, etc. , Etc. can be used. In the use of the carbon nanohorn solid lubricant as a lubricant, these dispersion media exist on the base material (sliding surface) so as to hold the individual single-layer carbon nanohorn aggregates. It may be removed or may be removed by volatilization in advance. The content of the monolayer nanohorn in the dispersion medium can be appropriately adjusted according to the use and purpose.

Further, the carbon nanohorn solid lubrication provided by the invention of this application The agent is characterized in that the single-walled carbon nanohorn aggregate has been subjected to a heat treatment at 1200 or more. The heat treatment at a temperature above 1200 is intended to promote the formation of dalaphy in the single-walled carbon nanohorn aggregates, and strengthens the entanglement of the plurality of single-walled carbon nanohorn aggregates. Can be something. Therefore, for example, a single-walled carbon nanohorn aggregate that has been heat-treated and a single-walled carbon nanohorn aggregate that has not been heat-treated can be selectively used according to the material of the sliding surface, the sliding conditions, and the like. Solid lubricant will be provided. For example, a specific example of using a heat-treated single-walled carbon nanohorn aggregate is as follows. A carbon nanohorn solid lubricant is prepared by including a heat-treated single-walled carbon nanohorn aggregate in a lubricating oil or the like. By applying this to a sliding surface of a brake, a clutch, a continuously variable transmission, or the like, it can be used as a friction modifier.

In addition, in the dahlia-type and bud-type single-layer carbon nanohorn aggregates, it is considered that the bud-type single-layer carbon nanohorn aggregate has a higher friction reducing effect. It is also considered to be provided.

In addition, the carbon nanohorn solid lubricant provided by the invention of this application can be realized as, for example, a film. The film thickness, area, and the like of the film can be arbitrary. Further, the dispersion medium may or may not be present. The carbon nanohorn solid lubricant of the invention of the present application as a film can be realized by various methods depending on its film thickness, size, and the like. For example, as one example, it will be provided more easily by the following method.

<1> Single-layer nano-horn assembly is dispersed in, for example, one of the above-described dispersion media, applied on a smooth surface, and solidified or evaporated to form a single-layer from the smooth surface. Carbon nanohorn aggregate By peeling off, a carbon nanohorn solid lubricant as a film is obtained.

<2> The single-layer carbon nanohorn assembly is dispersed in, for example, any of the above-described dispersion media, applied to a target substrate (sliding surface), and then the dispersion medium is solidified or evaporated to form a substrate. (Sliding surface) A carbon nanohorn solid lubricant as a film is obtained on the sliding surface.

By applying the above carbon nanohorn solid lubricant on the substrate (sliding surface), a new solid lubricant that can reduce friction and wear will be realized.

Examples are shown below, and the embodiments of the present invention will be described in more detail. Example

A friction test was performed to examine the trilogy performance of the carbon nanohorn solid lubricant of the present invention. The samples used were (a) a single-walled carbon nanohorn aggregate and (b) a heat-treated single-layered carbon nanohorn aggregate. The (a) a monolayer force one Bon'nanoho down assembly was made by co ₂ laser evaporation method, the average diameter. 2 to 3 nm in the tube section, average length 3 0 to 5 0 nm, as a whole about the diameter A spherical, Dariya-type single-layer nanobonnet horn aggregate of 80 to 10 O nm was used. The (b) heat-treated single-walled carbon nanohorn aggregate is obtained by heat-treating the obtained (a) single-walled carbon nanohorn aggregate at 196 to progress graphitization. Was used.

Further, for comparison, with (c) an average particle size of 2 2 tm, and two graphs eye bets powder 0. 6 / zm, (d) C 6 Q, (e) the multilayer force one Bon'nano tube . (D) C _6. Was prepared by the arc discharge method, and purified by liquid chromatography with a purity of 3 N, which was pulverized in an agate mortar before use. (E) Multi-walled carbon nanotubes are multi-walled carbon nanotubes with a diameter of 10 to 50 nm and a length of several meters, which are produced by hydrocarbon catalytic decomposition. An aggregate of bon nanotubes was used.

The friction test piece was prepared by mixing the above samples with alcohol on a slide glass to form a paste, immersing the paste in a petri dish containing purified water, and floating the film-like paste on the water surface. Was scooped up on a SUS304 substrate having an average surface roughness of 2 and temporarily dried in the air, followed by vacuum drying. The thickness of this test piece was about 10 m.

In the friction test, rotational friction under conditions of a load of 0.1 N and a speed of 25 cmZmin was performed using a SUS304 pole having a diameter of 3Z16 inches as a counterpart. The rubbing time was 50 minutes (the number of rubbing was 100,000 times), and the atmosphere was air at a relative humidity of 25 to 40%. The friction test was repeated for the same sample three or four times.

First, as a result of examining the coefficient of friction between the SUS304 pole and the SU S304 substrate on which the test piece was not mounted, the initial value of the test was about 0.3. It rose to about 8. Observation of the surface of the substrate and the pole after the test confirmed that the surface was severely roughened.

Next, (c) the friction coefficient of the two types of graphite powders with average particle diameters of 22 wm and 0.6 m was as low as about 0.1 from the beginning of the test and almost the same until the end of the test. Was kept. Fig. 2 shows an example of the results of examining the coefficient of friction of the graphite powder (average particle size 0.6 m). This result is consistent with data for conventional graphite lubricants. The effect of the difference in the particle size of the graphite powder is also seen in the variation of the friction coefficient. It was small and stable. Fig. 3 shows the results of observing the surface of the substrate and pole after the test using an optical microscope. A transfer that appeared to be graphite was observed in the traces of friction between the substrate and the pole, but when the transfer was wiped off, little wear was observed. (D) C _6. The coefficient of friction was 0.2-0.3 at the beginning of the test, but it increased with time and reached a high value of 0.55-0.65 at the end of the test. However, friction fluctuations were observed on the way. C _6. Had the lowest lubricity in this test. Observation of the surface of the substrate and the pole after the test showed that a transferred substance was observed in the friction mark between the substrate and the pole, but the material was a hard material that was not a graphite.

(e) For multi-walled carbon nanotubes, the coefficient of friction at the beginning of the test is 0.25 to 0.35, and at the end of the test it is about 0, 35 to 0.45. In this test, (d) C _6. It was the second highest coefficient of friction. In addition, (d) C _6. In the same way as above, there were many fluctuations in friction. Transfers were observed on the substrate and the pole surface after the test, and slight wear of the pole was observed in some cases.

On the other hand, regarding the carbon nanohorn solid lubricant of the invention of this application, (a) the single-layer carbon nanohorn aggregate has a friction coefficient of about 0.2 to 0.1 in the initial stage of the test, and (c) a graphite powder. Although the value was slightly larger, the value immediately dropped, and at the end of the test, it was stable in the range of about 0.05 to 0.1, showing a value lower than (c) graphite on average. Was. Fig. 4 shows an example of changes in the coefficient of friction. In addition, when observing the surface of the board and the pole after the test, the transferred matter was observed on the trace of friction between the board and the ball, but the transferred matter to the pole could be easily wiped off, and the friction No trace was observed. Figure 5 shows an example of the results of observation of friction marks by an optical microscope.

(b) The coefficient of friction of the heat-treated single-walled carbon nanohorn aggregate is (d) C ₆ . (E) It was lower than the multi-walled carbon nanotube, but (a) the overall value was slightly higher than that of the single-walled carbon nanohorn aggregate.

FIG. 6 shows the average friction coefficients of the above (a) to (e). (A) The carbon nanohorn solid lubricant of the invention of this application It was confirmed that the coefficient of friction varied more than the friction coefficient of the (C) graphite powder, but exhibited low friction equivalent to or superior to that of the (C) graphite powder.

Of course, the present invention is not limited to the above-described example, and it goes without saying that various aspects can be applied to the details. Industrial applicability

As described above in detail, according to the present invention, the invention of this application is a new carbon material capable of reducing friction and wear of sliding parts of various devices and sliding surfaces of micromachines, biological devices, space devices, and the like. A nanohorn solid lubricant is provided.

Claims

The scope of the claims

1. A carbon nanohorn solid lubricant characterized by containing a single-layer carbon nanohorn aggregate.

2. The carbon nanohorn solid lubricant according to claim 1, wherein the single-layer carbon nanohorn aggregate is contained in a dispersion medium.

3. The carbon nanohorn solid lubricant according to claim 1, wherein the single-layer carbon nanohorn aggregate has been subjected to a heat treatment at a temperature of 1200 or more.

4. The carbon nanohorn solid lubricant according to any one of claims 1 to 3, wherein the solid lubricant is a film.