COMPOSITION COMPRISING NUCLEATED NANODIAMOND PARTICLES

Abstract

This invention relates to a production method for non-detonation synthesis nanodiamond by exposing carbonaceous feedstock to a dense plasma focus. The nucleated nanodiamond particles have characteristics that differentiate them from known forms of nanodiamond. For instance, the nucleated nanodiamond particles are substantially spherical and have a substantially smooth surface, as may be demonstrated by TEM. The nucleated nanodiamond particles are also free of graphite and detonation carbon contaminants. The identity of the nanodiamond particles has been confirmed through raman spectra, for example. The nanodiamond particles have also been found to be effective as a lubricant composition when combined with a carrier oil.

Claims

1. A process for preparing a composition comprising spherical nanodiamond particles comprising: subjecting a carbonaceous feedstock to a pulsed dense plasma radiation comprising heavy ions and having an energy of at least approximately 50 MeV, so as to produce a composition comprising spherical nanodiamond particles; wherein the spherical nanodiamond particles are characterized by a raman spectra that is indicative of diamond-like carbon; and wherein the spherical nanodiamond particles have substantially smooth surfaces.

2. The process of claim 1, wherein the composition is free from graphite.

3. The process of claim 1, wherein the spherical nanodiamond particles are characterized by a raman spectra in which the K band is absent.

4. The process of claim 1, wherein the spherical nanodiamond particles have diameters between about 0.01 and about 10 nm.

5. The process of claim 1, wherein the spherical nanodiamond particles have diameters between about 0.1 nm and about 2 nm.

6. The process of claim 1, wherein the spherical nanodiamond particles have diameters less than 5 μm.

7. The process of claim 1, wherein the composition is in the form of a powder.

8. The process of claim 1, wherein subjecting the carbonaceous feedstock to a pulsed dense plasma radiation comprises exposing the carbonaceous feedstock to a dense plasma focus radiation produced by a pulsed plasma drive electromagnetic motor generator.

9. The process of claim 8, wherein subjecting the carbonaceous feedstock to a pulsed dense plasma radiation is performed at ambient temperature and pressure.

10. The process of claim 1, wherein the pulsed dense plasma has an energy between 50 MeV and 1000 MeV.

11. The process of claim 1, wherein the carbonaceous feedstock contains at least 5 percent carbon by weight.

12. The process of claim 11, wherein the carbonaceous feedstock contains at least 20 percent carbon by weight.

13. The process of claim 1, wherein the carbonaceous feedstock comprises graphite, lignite, coal, or a combination thereof.

14. The process of claim 1, wherein the carbonaceous feedstock comprises a synthetic hydrocarbon, an organic oil, a crude oil, a petroleum distillate, or a combination thereof.

15. The composition produced by the process of claim 1.

16. A lubricant comprising the composition produced by the process of claim 1 and a carrier oil.

17. The lubricant of claim 16, in which the lubricant comprises less than 5 grams of the composition per gallon of carrier oil.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] A clear conception of the advantages and features of one or more embodiments will become more readily apparent by reference to the exemplary, and therefore non-limiting, embodiments illustrated in the drawings:

[0015] FIG. 1 is a Transmission Electron Microscopy (TEM) image of nanodiamond particles produced in accordance with the present invention, which shows the substantially spherical nature of the nanodiamond particles.

[0016] FIG. 2 is a Transmission Electron Microscopy (TEM) image of nanodiamond particles produced in accordance with the present invention, which shows the substantially spherical nature of the nanodiamond particles, such as at the portion labeled “D”.

[0017] FIG. 3 is a Transmission Electron Microscopy (TEM) image of nanodiamond particles produced in accordance with the present invention, which shows the clustering of the substantially spherical nanodiamond particles.

[0018] FIG. 4 is a Raman Spectrum of nanodiamond particles produced in accordance with the present invention, which is generally indicative of diamond-like carbon, DLC.

[0019] FIG. 5 is a Raman Spectrum of nanodiamond particles produced in accordance with the present invention, which is generally indicative of a hydrogenated diamond-like carbon, DLC.

[0020] FIG. 6 is an Electron Diffraction Pattern (EDP) of nanodiamond particles produced in accordance with the present invention, which is generally indicative of nanodiamond.

[0021] FIG. 7A is an image of a wear mark from a four ball wear test performed using ASTM D 2714 after application of a lubricant comprising a carrier oil and nanodiamond particles produced in accordance with the present invention.

[0022] FIG. 7B is an image of a wear mark from a four ball wear test performed using ASTM D 2714 after application of a lubricant comprising only the carrier oil.

DETAILED DESCRIPTION OF THE INVENTION

[0023] The present invention encompasses a method whereby dense plasma focus irradiation of bulk carbonaceous material at low pressure (e.g. 10.sup.−1 Torr) or higher and ambient temperature or higher, transforms the carbonaceous material into diamond-like carbon (DLC). Specifically, nanometer-sized diamond-like carbon particles are formed under specific protocols, while alterations allow larger polycrystallites to be created.

[0024] The method comprises exposing carbonaceous material to a dense plasma focus radiation, such as may be produced by the pulsed plasma drive electromagnetic motor generator of U.S. Pat. No. 6,271,614 B1, at suitable temperature and pressure, and using a flux rate and irradiation time sufficient to transform the carbonaceous material into nanoparticles of diamond-like carbon (DLC). The dense plasma focus device may comprise one or more DC power sources and one or more magnetic elements, one or more electromagnetic elements, one or more focus elements, and a reaction chamber. The DC power source may be above 12 volts, alternatively above 45 volts, and preferably below 65 volts. The one or more magnetic or electromagnetic elements may form an arcuate or circular sleeve, such as a circular inner assembly. The device may also comprise a rotor, to which the one or more focus elements, the one or more magnetic elements, and/or the one or more electromagnetic elements may be affixed.

[0025] The method can be utilized to produce diamonds from any high-carbon content carbonaceous material via heavy ion (e.g. mass greater than approximately 60 amu) irradiation having energies greater than 50 MeV. The energy of the radiation may vary, but must be adequate to first produce damage to the lattice of the carbonaceous material. Conversely, the energy must not be so high as to have the ion completely pass through the carbonaceous material with no transference of energy to the carbonaceous material. In some embodiments, energy between 50 MeV and 1000 MeV is suitable.

[0026] Without being bound by theory, it is believed that the carbonaceous feedstock to split into ionized elemental forms during the momentary irradiation of the dense plasma focus. Then, when the plasma energy is reduced, and thus falls below the ionization energies of the constituents, the elemental forms recombine and reconstitute into solid and gaseous forms. It is believed that this unique formation mechanism is responsible for the unique properties of the diamond-like carbon nanoparticles that are produced.

[0027] Time of exposure to the carbonaceous material to the ion radiation will depend on the fluence and flux rates. If a particular process time is desired, the fluence and flux rates may be adjusted to arrive at the exposure duration. In some embodiments, the fluence may be between about 10.sup.12 ions per cm.sup.2 and about 10.sup.16 ions per cm.sup.2. In some embodiments, the flux rate may be between 10.sup.10 ions per cm.sup.2 per second and about 10.sup.12 ions per cm.sup.2 per second.

[0028] In some embodiments, the carbonaceous feedstock material may comprise liquid hydrocarbons, solid hydrocarbons, or gaseous hydrocarbons. Preferably the carbonaceous feedstock contains at least 5 percent carbon by weight, alternatively at least 20 percent carbon by weight. In some embodiments, the carbonaceous material may comprise graphite, lignite, coal, or combination thereof. In some embodiments, the carbonaceous material may comprise a hydrocarbon, such as a synthetic hydrocarbon, an organic oil, crude oil, petroleum distillates, and combinations thereof.

[0029] Acid dissolution may produce a discrete benefit such as increasing particle surface attractions, however such processing is not required to remove graphite or detonation contaminants which are present in other nanodiamond, as no graphite or detonation contaminants are present in the nanodiamond of the present invention.

[0030] The nucleated nanodiamond particles prepared in accordance with the present invention may be produced to have a range of diameters. In some embodiments, the nanodiamond particles having diameters between about 0.01 and about 10 nm, alternatively between about 0.1 nm and about 2 nm. In some embodiments, the particles have diameters less than 5 micrometers.

[0031] The nucleated nanodiamond particles, produced as described above, were characterized using a number of tests. For example, the nucleated nanodiamond particles prepared in accordance with the present invention were characterized using high resolution and analytical Transmission Electron Microscopy (TEM). Sample results are shown in FIG. 1, FIG. 2, and FIG. 3.

[0032] FIG. 1 shows a number of substantially spherical nanodiamond particles having sizes on the nanometer scale. The substantially spherical nanodiamond particles shown in FIG. 1 are clustered together. FIG. 2 shows a number of substantially spherical nanodiamond particles, including one—labeled D—having a diameter of about 10 nm. FIG. 2 also demonstrates the substantially smooth surface of the nanodiamond particles. FIG. 3 shows a number of substantially spherical nanodiamond particles having diameters less than 20 nm clustered together. Together, these Figures illustrate nanodiamond particles that are substantially spherical and have a substantially smooth surface. These Figures also indicate that the nanodiamond particles are substantially free of graphite.

[0033] The nucleated nanodiamond particles prepared in accordance with the present invention were also characterized using raman spectroscopy. Sample results are shown in FIG. 4 and FIG. 5.

[0034] FIG. 4 shows the raman spectroscopy signature of a sample of nanodiamond particles that is indicative of diamond-like carbon. However, the raman spectra is also characterized by the complete absence of an 1100 K band. In contrast, it is believed that all previously known diamond-like carbon, nanodiamond films, and detonation nanodiamond have the K band.

[0035] FIG. 5 shows the raman spectroscopy signature of a sample of nanodiamond particles that is indicative of hydrogenated diamond-like carbon. More specifically, the raman spectroscopy signature is similar to a plasma-deposited films of tetrahedral hydrogenated amorphous carbon (ta-C:H) or Hydrogenated Diamond-Like Carbon (HDLC). Nanophase diamond is well known to adsorb and store hydrogen, an effect that was also indicated by the absence of hydrogen in the plasma reactor after preparation of the nanodiamond particles. Also similar with HDLC, the nanodiamond particles prepared in accordance with the present invention are electrically conductive.

[0036] The nucleated nanodiamond particles prepared in accordance with the present invention were also characterized using Electron Diffraction Patterns. FIG. 6 shows the Electron Diffraction Pattern (EDP) of nanodiamond particles produced in accordance with the present invention, which is generally indicative of nanodiamond and serves to further confirm the identity of the particles as nanodiamond.

[0037] The nanodiamond particles prepared in accordance with the present invention were also tested for application in a lubricant. For instance, testing at Falex, Inc. of Sugar Grove, Ill. revealed that a lubricant comprising a carrier oil and the nanodiamond particles greatly reduced contact bearing wear, reduced friction, and extended the useful life of the parent lubricant.

[0038] The testing included a four ball wear test with a 40 kg load that was performed in accordance with ASTM D 4172 B. The results of the test showed that once a bearing seat was worn in, friction produced by the sample of carrier oil containing the nanodiamond particles was reduced by about 48% over the sample of pure carrier oil. Also revealed in this test were the anti-scoring properties of the solution containing the nanodiamond particles, which produced a smooth satin finished bearing seat in contrast to the deeply scored surface of the sample tested using only the carrier oil. The sample containing the nanodiamond particles produced a virtually circular bearing seat, in contrast to the deeply scored oval bearing seat formed by testing with pure carrier oil. The test revealed that the lubricant containing the nanodiamond particles protected the finish while the carrier oil was virtually helpless in providing protection. As such, a lubricant comprising the diamond nanoparticles in a carrier oil may be effective to provide a smooth bearing seat that is substantially free of scoring, as demonstrated by a test run in accordance with ASTM D 4172 B.

[0039] The testing also included a test performed in accordance with ASTM D 2714, which involved the application of a heavier load, about 150 lbs. Two drops of each sample lubricant were used to perform this test. The lubricant comprising the nanodiamond particles protected the bearing surface, which wore 90% less than that tested with the pure carrier oil. The results of this test are reproduced below in Tables 1 and 2. The results indicate that a lubricant comprising the diamond nanoparticles in a carrier oil may be effective to reduce volumetric wear by greater than 15% compared against the pure carrier oil, as demonstrated by a test run in accordance with ASTM D2714.

TABLE-US-00001 TABLE 1 Results using oil comprising diamond nanoparticles Method: ASTM D 2714, Calibration and Operation of the Falex Block on Ring Test Machine Test Parameters Speed (rpm):  72 Test Load (lb):  150 Temperature (C.): Ambient Fluid: 4GQ Duration cycles: 5000 Falex TL #: 9317 Test Specimens Block Type: Falex H-30 Ring Type: Falex S-10 Material: SAE 01 Tool Material: SAE 4620 Steel Steel Finish (rms): 4-8 Finish (rms):  6-12 Hardness (Rc): 27-33 Harness (Rc): 58-63 Test Results Mass Data: Block Ring Block Scar Data: Initial: 7.8452 22.2135 Measurement 1 1.400 (mm): Final: 7.8448 22.2135 Measurement 2 1.453 (mm): Loss: 0.0004 0.0000 Measurement 3 1.400 (mm): Average Scar 1.418 (mm): Standard 0.025 Deviation: Coefficient of 1.762 Variation (%): Volumetric Wear 0.0862 (mm.sup.3): Friction Data Friction Force, Coefficient of Duration lb Friction 0 42.8 0.285 200 25.4 0.169 400 23.4 0.156 600 23.5 0.157 4500 22.3 0.149 5000 21.1 0.141 Average: 0.154 Comments: ASTM Test modified by use of special fluid application. One drop of lubricant applied to the test block and one drop applied to the test ring circumference. Fluid appeared clean and same color as originally applied at end of the test.

TABLE-US-00002 TABLE 2 Results using carrier oil Method: ASTM D 2714, Calibration and Operation of the Falex Block on Ring Test Machine Test Parameters Speed (rpm):  72 Test Load (lb):  150 Temperature (C.): Ambient Fluid: QSD3 Duration cycles: 5000 Falex TL #: 9320 Test Specimens Block Type: Falex H-30 Ring Type: Falex S-10 Material: SAE 01 Tool Material: SAE 4620 Steel Steel Finish (rms): 4-8 Finish (rms):  6-12 Hardness (Rc): 27-33 Harness (Rc): 58-63 Test Results Mass Data: Block Ring Block Scar Data: Initial: 7.8643 22.4047 Measurement 1 2.440 (mm): Final: 7.8614 22.4040 Measurement 2 2.400 (mm): Loss: 0.0029 0.0007 Measurement 3 2.333 (mm): Average Scar 2.391 (mm): Standard 0.044 Deviation: Coefficient of 1.846 Variation (%): Volumetric Wear 0.4140 (mm.sup.3): Friction Data Friction Force, Coefficient of Duration lb Friction 0 40 0.267 200 25.1 0.167 400 22 0.147 600 21.4 0.143 4500 21.2 0.141 5000 19.8 0.132 Average: 0.146 Comments: ASTM Test modified by use of special fluid application. One drop of lubricant applied to the test block and one drop applied to the test ring circumference. Fluid appeared contaminated and darkened or burnt at the end of the test.

[0040] FIGS. 7A and 7B further demonstrate the difference in volumetric wear between the sample containing the diamond nanoparticles and the sample containing only carrier oil. Specifically the wear mark in the center of FIG. 7A, the result of performing the test using the carrier oil comprising the diamond nanoparticles, is greatly reduced from the wear mark in the center of FIG. 7B, the result of performing the test using only carrier oil.

[0041] From this testing, it was demonstrated that (1) wear was reduced by an estimated 90% compared with pure carrier oil; (2) surface abrasion and scoring were virtually eliminated when compared with pure carrier oil; (3) surfaces were evenly worn compared to those using pure carrier oil; and (4) thermal breakdown did not occur in samples treated with the diamond nanoparticles, as it did with samples treated with pure carrier oil. These tests also indicated the effects of increased protection from wear as a lubricant comprising the nanodiamond particles is subjected to increased loads, though additional research is needed to confirm this effect.

[0042] The lubricant compositions can be prepared by adding the nanodiamond to a carrier oil. In some embodiments, the carrier oil may be selected from the petroleum and/or synthetic oils. The lubricant may comprise less than 5 grams of the nanodiamond particles per gallon of carrier oil. The nanodiamond may provide thermal protection to the lubricant, thereby extending the useful life of the lubricant.

[0043] It can be seen that the described embodiments provide unique and novel compositions and lubricants that have a number of advantages over those in the art. While there is shown and described herein certain specific structures embodying the invention, it will be manifest to those skilled in the art that various modifications and rearrangements of the parts may be made without departing from the spirit and scope of the underlying inventive concept and that the same is not limited to the particular forms herein shown and described except insofar as indicated by the scope of the appended claims.