WO1990005701A1 - Production de diamant - Google Patents

Production de diamant Download PDF

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Publication number
WO1990005701A1
WO1990005701A1 PCT/AU1989/000494 AU8900494W WO9005701A1 WO 1990005701 A1 WO1990005701 A1 WO 1990005701A1 AU 8900494 W AU8900494 W AU 8900494W WO 9005701 A1 WO9005701 A1 WO 9005701A1
Authority
WO
WIPO (PCT)
Prior art keywords
plasma
diamond powder
production
polycrystalline diamond
methane
Prior art date
Application number
PCT/AU1989/000494
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English (en)
Inventor
Andrew Carey Good
Original Assignee
Andrew Carey Good
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Andrew Carey Good filed Critical Andrew Carey Good
Publication of WO1990005701A1 publication Critical patent/WO1990005701A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J12/00—Chemical processes in general for reacting gaseous media with gaseous media; Apparatus specially adapted therefor
    • B01J12/002—Chemical processes in general for reacting gaseous media with gaseous media; Apparatus specially adapted therefor carried out in the plasma state
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/25—Diamond
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/25—Diamond
    • C01B32/26—Preparation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J2219/0894—Processes carried out in the presence of a plasma

Definitions

  • This invention relates to the production of diamond crystals, and more particularly the production of polycrystalline diamon powder by vapor phase condensation using a thermal plasma.
  • an electric discharge conducted for 30 minutes with an input of 70 kilowatts in a vacuum tube, supplying a gas mixture at the rate of 400ml/min of propane and 4 litre/min of argon, 25 litre/min of argon and hydrogen gas mixture in the rate of 2.5:1, produced 0.1 grams of diamond powder having a particle size of 100/300A.
  • Such production has been typical of other reports, and the comment has frequently been made that all attemps heretofore to produce commercial quantities of diamonds with plasma have been unsuccessful.
  • Particulate carbon as been produced previously mostly by applying laser and radio frequency energy to various carbonaceous substances among which is methane gas.
  • Methane is preferred because the basic molecular structure is somewhat similar to the tetrahedral structure of the diamond crystal and therefore a minimum rearrangement of structure is required if the methane is disassociated into ionic carbon and hydrogen.
  • phase diagram for carbon which indicated the pressures required and the temperatures required to produce graphite, graphite plus metastable diamond, diamond plus metastable graphite, diamond crystals and liquid carbon.
  • a diamond-like crystal can be harder than a diamond crystal but is so highly stressed internally that fracture is likely to occur, while in another state, it can be softer than diamond. These states can be ascertained by Raman assay. If prior art methods are used, they are subject to a number of disabilities:
  • the prior art crystals are formed at temperatures which are usually below 2000 * C. , and some graphite and diamond ⁇ like products are usually produced along with the crystals.
  • the rate of production is relatively slow, thirdly, production sometimes takes place in a vacuum or alternatively at very high pressure if high production rates are required (as in explosive based production methods). In all instances .
  • the "Scientific American" article refers to plasma sprayed coatings and provides an indepth report on the spraying of powder through an arc plasma gun.
  • reference is made to spraying various materials including aluminium oxide, and refers to "the forces holding together the individually solidified splats in the coating, this process being the subject of intensive investigation. It is certain that excessive splats interlock mechanically at least and affect the purity of the product. In metal coatings interdiffusion may also take place and in some ceramic coatings an analogous process called sintering can unify the deposit".
  • sintering can unify the deposit.
  • the important properties inherent in such films include: high electrical resistivity, optical transparency, extreme hardness, large energy gap, .high thermal conductivity, chemical inertness, low friction, and good adhesion to a wide number of substances.
  • Mose of the diamond-like films are predominantly amorphous but in some cases the single crysstalline diamond particles are grown in the background amorphous phase.
  • the deposition rate was said to increase with gas pressure, the experiment confirmed that hard carbon films were predominantly amorphous and contained crystalline grains, and reference was made to the fact that the carbon films which were deposited included a mechanically soft, yellow carbon film and a hard, light-brown film, the former being a pressures below 0.1 torr.
  • the objects of this invention are to provide a method of production of polycrystalline diamond powder by vapour phase condensation using thermal plasma, wherein the production rates are much higher than have been achieved heretofore, and to provide a method which is sufficiently inexpensive in equipment labour, time and power consumption, to be commercially viable.
  • a Very high temperature for example 10000K
  • a lower temperature for example 5000 * K
  • the plasma is said to be "saturated” an even lower temperature (for example below 3000K) the plasma will contain more carbon than can be supported, and is
  • the plasma may be subjected to a thermal shock, which will increase the temperature gradient of the plasma, and reduce its size. When this occurs, there is an increase of carbon density in the plasma at the point of thermal shock, and .
  • a hydrocarbon gas is passed through the arc zone of a plasma gun, where the arc zone is at a temperature above 10000K, plasma is passed from the arc zone having a temperature gradient from at least 5000K to less than 1500K, the plasma is quenched by subjecting it to a flow of sufficient relatively cold gas to induce thermal shock, the temperature gradient of the plasma is increased, and its size reduced in turn increasing carbon density in the plasma and the value of carbon super saturation ratio, and in turn producing diamond powder substantially free of graphite.
  • the gas which is most suitable for use is methane because of the molecular structure referred to above, and the use of TiCl. for seeding is also preferred because of the crystal structure of -the seeding product, titanium carbide.
  • Diamonds are inherently very stable particles, and do not readily adhere to a surface. Once a single layer of diamond particles have adhered electrostatically to a metal surface, for example, those particles will tend to repel further particles, and consequently only a single layer of particles can be built up on a substrate.
  • the size of the diamond particles produced by these methods is very consistent, but can be adjusted to some extent by use of seeding, the control of the flow rate of both quenching and gas ionising flows.
  • the relative flow rates of the ionising and quenching gases and the resultant super saturation of the plasma, and the speed of the combined gas and particulate stream all affect particle size, but typically the diamond particulate size is in the order of 0.5 micron. This is the basis for an extremely valuable characteristic for many applications such as lapping paste, matrix cutting saws (etc.), cutting blades of various types (razor, knife, saw, router etc.), optical surfaces, bearing surfaces, and other applications wherein a very hard but very fine poiser or thin film is required.
  • the diamond particles do not readily adhere to substrate surfaces other than by electrostatic deposition, and if it is required for the particles to be adhered to a metallic surface for example, this can be achieved in this invention by a second stage of operation wherein the workpiece is removed from the deposition chamber and placed into the metallic vapour deposition chamber, and overlayed with a metal which suitably adheres to the surface of the workpiece and functions as a cementing means to retain the particulate diamond material to that surface.
  • a metal which suitably adheres to the surface of the workpiece and functions as a cementing means to retain the particulate diamond material to that surface.
  • a metal which suitably adheres to the surface of the workpiece and functions as a cementing means to retain the particulate diamond material to that surface.
  • a metal which suitably adheres to the surface of the workpiece and functions as a cementing means to retain the particulate diamond material to that surface.
  • a metal which suitably adheres to the surface of the workpiece and functions as a cementing means to retain
  • FIG. 1 is a diagrammatic representation of a chamber for the production and deposition of diamond crystal onto a substrate
  • FIG. 2 is a diagrammatic representation of a plasma gun showing the-manner in which a plasma is subjected to thermal shock by a cooling gas,
  • FIG. 3 is a diagrammatic representation showing a different configuration of chamber, and recovery means for both a dry product and a wet product,
  • FIG. 4 shows the arrangement for the introduction of TiCl.
  • FIG. 5a shows the motional potential reaction zone for low density as used in prior art
  • FIG. 5b is a diagrammatic representation similar to FIG. 4 showing the notional reaction zone according to the invention which has been condensed in volume and subjected to thermal shock such that the temperature gradient is increased
  • FIG. 6 is a Raman spectragraph which indicates the polycrystalline, lonsdaleite nature of the diamond product (Raman shift of 1321 RCM-1)
  • a chamber 10 has strong steel walls (to resist damage in the unlikely event of explosion) , the walls being cylindrical for most of the length, the upper wall 11 being upwardly convex, and a heat diffusing lower wall 12 comprising a series of helical convolutions of metal which will allow slow diffusion outwardly of gases introduced through the plasma gun 13.
  • the electrostatic deposition is in accordance with known art, and applies a positive charge to the outer walls of the chamber 10 and a negative charge to the substrate (target) 15 of a 300- 400 V D.C. potential.
  • This negative charge is applied through a conductor 16 which enters the chamber 10 through a surrounding tube 17 which is of glass and provides a safe entry into the chamber, unlikely to cause any explosion of gases within the chamber.
  • the surrounding positive charge has the effect of "tunnelling" the stream of particulate diamond between the plasma gun 13 and the substrate 15, and reducing the loss to the surrounding walls.
  • a further focusing tube 18 is located to more positively direct the minute particulate diamonds to the target.
  • the distance of the arc zone from the target is approximately 10cm. The optimum distance can vary dependent on the setting of characteristics such as the methane flow rate, the quenching gas flow rate, the electrostatic focusing potential, and consequently the temperature profile from the arc zone to the target.
  • the workpiece After the workpiece has been coated electrostatically with diamond particles, the adhesion is very fragile the workpiece is then carefully removed from the chamber 10 and transferred to a second vapour deposition chamber where the workpiece is again subject to an ionic vapour flow, but of titanium metal.
  • This has the effect of cementing the particles of diamond to the substrate and holding them mechanically in position with sufficient strength that dislodgement is resisted, then the composite material can be used for example for reinforcing the wearing surfaces of high-speed steel milling cutters and drills, ceramic and carbide machining inserts, scalpels, knives, razors disposable cutting blades or the like.
  • the deposition of titanium coating is in accordance with known art, but known art does not include the use of titanium or other metals (e.g. Cu and Ag) and alloys to cement in place polycrystalline diamond particles which otherwise do not properly adhere to a substrate.
  • Methane with variable quantities of hydrogen, and in some instances, minute quantities of titanium tetrachloride, is introduced into the plasma gun 13 to pass through the arc zone thereof, the gas flow is from a supply at about 40 p.s.i. through an orifice exceeding 1mm diameter but sufficient to deliver 10 litre per/min. , and is surrounded by an annulus of hydrogen as best seen in FIG. 2, flowing at about one hundred times the rate.
  • the chamber is open to normal atmospheric pressure.
  • the plasma gun used is a commercial gun supplied by the Australian Company The C.I.G. Ltd.
  • FIG. 6 The very rapid quenching of the plasma by the hydrogen to which it is subjected, gives the effect of causing the diamonds to form without the formation of graphite or amorphous carbon. This is illustrated in FIG. 6.
  • the vertical excursion of the Raman read-out indicates the presence of hexagonal crystals, but only in very small numbers, and hexagonal crystals are equally as valuable as cubic crystals for abrasive purposes. It will be noted tha FIG. 6 does not identify any graphite or amorphous carbon.
  • the plasma gun 13 is in accordance with known art, being provided with a thoriated tungsten cathode 20 and a wate cooled copper anode 21 from which it is insulated by an annular insulator 22.
  • the shield 24 is provided with an inwardly directed annular rib 25, and this directs a relatively massive flow of quencing hydrogen from the valve 26 at the upper end of plasma 27 just below the arc zone 28.
  • the methane and hydrogen mixture enters the space 29 between the insulators 22 and arc zone 28 through a conduit 30 from a control valve 21.
  • the deposition is on to the substrate 15, whereas in the embodiment of FIG. 3, the exhaust gas from the plasma torch carries the particulate diamond crystals with it and is through a first cyclone 32 which is cooled by cooling water passing through an inlet conduit 33 and exhaust through outlet conduit 34, the dry powder being released by a rotary valve 35 in the lower end of the cyclone 32 and collected in a container 36.
  • the particle size can be in the order of 0.5 to 1 micron, and can be entrained in the exhausting gas which flows in considerable quantities.
  • the outlet of the cyclone 32 is through a central conduit 38, where the gas is reduced in velocity in a larger conduit 39 and has an oil mist injected into it from a nozzle 40, the oil being recirculated from a container 41 by means of a pump 42.
  • a second cyclone 43 separates the mixture of oil and particles which is again released into the container 42 by a rotary valve 44.
  • the gas which is exhausted from the chamber 10 will be methane, some hydrogen which was mixed with methane, and a cooling hydrogen and this can be reused as quench gas, being stored from an outlet conduit 46.
  • the following two examples are typical of production which has been proved by the Applicants:
  • a chamber similar to that shown in FIG. 1 was fed with 6 litres per minute of methane gas with a minimum quantity of hydrogen added to it to allow the plasma to become "steady" (approx. 1 litre/min.) Without the presence of hydrogen in the ionising gas, the plasma tends to become slightly unstable but it is found that good results can be achieved when the methane is mixed with a very small quantity of hydrogen gas, but always less than 20% by volume.
  • About 7500 litres/min. of hydrogen was used to quench the plasma, and the deposition particle size ranged between 0.25 and 1 micron. The range which is regarded as useful is from 0.5 to 4 litres/min. of methane and from 50 to 300 litres/min. of hydrogen, per kilowatt of power. About 10% of the methane was converted to diamond particles.
  • titanium chloride was bubbled by by-passing a small amount of the methane from bottle 50 (FIG. 4) through a container 51 which contains titanium tetrachloride, into a mixing box 52 which also received a small quantity of hydrogen from bottle 53, metered through valve 54, and the control of the ionising gas was effected by control of valve 55.
  • the control of flow rate of quench gas was by means of valve 56.
  • the quantity of titanium tetrachloride which was entrained in the ionising gas as a mist was so minute that it was not measurable, but nevertheless it increased the yield rate from 10% to about 12% of the methane, and the particle size was increased slightly from the size achieved in the second example. All other parameters were the same.
  • FIG. 6 Raman spectrograph of sample product indicating high purity, polycrystalline diamond product. (A 1321 Raman Shift). The vertical axis indicates level of photoluminescence, and the horizontal axis, the shift frequency.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Inorganic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)
  • Carbon And Carbon Compounds (AREA)

Abstract

Le procédé décrit, qui sert à produire une poudre de diamant polycristalline, consiste à faire passer un gaz hydrocarbure à travers la zone d'arc (28) d'un pistolet pulvérisateur de plasma (13), la zone d'arc étant à une température supérieure à 10 000 K, à faire passer le plasma (27) depuis la zone d'arc (28) ayant un gradient thermique allant d'au moins de 5000 K à moins de 1 500 K, à refroidir par trempe le plasma (27) en le soumettant à un courant de gaz relativement froid suffisant pour induire un choc thermique, à augmenter le gradient thermique du plasma et à réduire sa taille, ce qui accroît la densité du carbone dans le plasma et la valeur du rapport de supersaturation de carbone et produit une poudre de diamant sensiblement exempte de graphite.
PCT/AU1989/000494 1988-11-16 1989-11-16 Production de diamant WO1990005701A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AUPJ150788 1988-11-16
AUPJ1507 1988-11-16

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WO1990005701A1 true WO1990005701A1 (fr) 1990-05-31

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Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000078674A1 (fr) * 1999-06-18 2000-12-28 Carbo-Tec Gesellschaft Für Nano-Und Biotechnische Produkte Mbh Procede de production dynamochimique de stuctures de charbon du type diamant, structures de charbon du type diamant et utilisation de celles-ci
CN1066417C (zh) * 1997-11-05 2001-05-30 中国科学技术大学 一种金属溶剂热还原合成金刚石及其类似材料的方法
DE102004041146A1 (de) * 2004-01-17 2005-08-18 Nanocompound Gmbh Nano-Carbon-Fullerene (NCF), Verfahren zur Herstellung von NCF und Verwendung von NCF in Form von Nano-Compounds
US7866342B2 (en) 2002-12-18 2011-01-11 Vapor Technologies, Inc. Valve component for faucet
US7866343B2 (en) 2002-12-18 2011-01-11 Masco Corporation Of Indiana Faucet
US8123967B2 (en) 2005-08-01 2012-02-28 Vapor Technologies Inc. Method of producing an article having patterned decorative coating
US20150274534A1 (en) * 2014-03-31 2015-10-01 Case Western Reserve University Nanoscale diamond particles and method of forming nanoscale diamond particles
US9388910B2 (en) 2002-12-18 2016-07-12 Delta Faucet Company Faucet component with coating

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3401019A (en) * 1965-11-24 1968-09-10 Du Pont Process for synthesizing diamond
GB1349832A (en) * 1972-02-03 1974-04-10 I Fizicheskoi Khim Akademii Na Process of growing diamond crystals
DE3624310A1 (de) * 1985-08-12 1987-02-12 Gen Electric Verfahren zur umwandlung von uranhexafluorid in uranoxid in einem gasfoermigen reaktionsmedium und verbrennungsreaktor zur durchfuehrung des verfahrens
AU8195187A (en) * 1986-12-22 1988-06-23 General Electric Company Synthetic diamond by chemical vapour deposition process
US4767608A (en) * 1986-10-23 1988-08-30 National Institute For Research In Inorganic Materials Method for synthesizing diamond by using plasma
JPS6433096A (en) * 1987-04-03 1989-02-02 Fujitsu Ltd Gaseous phase synthesis for diamond
JPH01138197A (ja) * 1987-11-24 1989-05-31 Asahi Glass Co Ltd 人工ダイヤモンドの製造方法
JPH01157496A (ja) * 1987-12-12 1989-06-20 Fujitsu Ltd ダイヤモンド膜の合成方法
JPH01164795A (ja) * 1987-12-19 1989-06-28 Fujitsu Ltd ダイヤモンド粒子の合成方法

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3401019A (en) * 1965-11-24 1968-09-10 Du Pont Process for synthesizing diamond
GB1349832A (en) * 1972-02-03 1974-04-10 I Fizicheskoi Khim Akademii Na Process of growing diamond crystals
DE3624310A1 (de) * 1985-08-12 1987-02-12 Gen Electric Verfahren zur umwandlung von uranhexafluorid in uranoxid in einem gasfoermigen reaktionsmedium und verbrennungsreaktor zur durchfuehrung des verfahrens
US4767608A (en) * 1986-10-23 1988-08-30 National Institute For Research In Inorganic Materials Method for synthesizing diamond by using plasma
AU8195187A (en) * 1986-12-22 1988-06-23 General Electric Company Synthetic diamond by chemical vapour deposition process
JPS6433096A (en) * 1987-04-03 1989-02-02 Fujitsu Ltd Gaseous phase synthesis for diamond
JPH01138197A (ja) * 1987-11-24 1989-05-31 Asahi Glass Co Ltd 人工ダイヤモンドの製造方法
JPH01157496A (ja) * 1987-12-12 1989-06-20 Fujitsu Ltd ダイヤモンド膜の合成方法
JPH01164795A (ja) * 1987-12-19 1989-06-28 Fujitsu Ltd ダイヤモンド粒子の合成方法

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN, C-598, page 103; & JP,A,1 033 096 (FIJITSU LTD), 2 February 1989 (02.02.89). *
PATENT ABSTRACTS OF JAPAN, C-631, page 10; & JP,A,01 138 197 (ASAHI GLASS CO LTD), 31 May 1989 (31.05.89). *
PATENT ABSTRACTS OF JAPAN, C-637, page 84; & JP,A,01 157 496 (FUJITSU LTD), 20 June 1986 (20.06.89). *
PATENT ABSTRACTS OF JAPAN, C-639, page 107; & JP,A,01 164 795 (FUJITSU LTD), 28 June 1989. *

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1066417C (zh) * 1997-11-05 2001-05-30 中国科学技术大学 一种金属溶剂热还原合成金刚石及其类似材料的方法
WO2000078674A1 (fr) * 1999-06-18 2000-12-28 Carbo-Tec Gesellschaft Für Nano-Und Biotechnische Produkte Mbh Procede de production dynamochimique de stuctures de charbon du type diamant, structures de charbon du type diamant et utilisation de celles-ci
US7866342B2 (en) 2002-12-18 2011-01-11 Vapor Technologies, Inc. Valve component for faucet
US7866343B2 (en) 2002-12-18 2011-01-11 Masco Corporation Of Indiana Faucet
US9388910B2 (en) 2002-12-18 2016-07-12 Delta Faucet Company Faucet component with coating
US9909677B2 (en) 2002-12-18 2018-03-06 Delta Faucet Company Faucet component with coating
DE102004041146A1 (de) * 2004-01-17 2005-08-18 Nanocompound Gmbh Nano-Carbon-Fullerene (NCF), Verfahren zur Herstellung von NCF und Verwendung von NCF in Form von Nano-Compounds
US8123967B2 (en) 2005-08-01 2012-02-28 Vapor Technologies Inc. Method of producing an article having patterned decorative coating
US20150274534A1 (en) * 2014-03-31 2015-10-01 Case Western Reserve University Nanoscale diamond particles and method of forming nanoscale diamond particles
US9969620B2 (en) * 2014-03-31 2018-05-15 Case Western Reserve University Nanoscale diamond particles and method of forming nanoscale diamond particles

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