Apparatus for coating diamond-like networks onto particles

Details Apparatus for coating diamond-like networks onto particles Apparatus for coating diamond-like networks onto particles

1999-08-24

2001-03-06

Lund, Jeffrie R. (Department: 1763)

Coating apparatus

Gas or vapor deposition

Means to coat or impregnate particulate matter

C118S7230ER

Reexamination Certificate

active

06197120

ABSTRACT:

TECHNICAL FIELD
This invention relates to a method of and apparatus for depositing diamond-like networks comprising carbon and optionally comprising at least one of hydrogen, nitrogen, oxygen, fluorine, silicon, sulfur, titanium, or copper onto particles.
BACKGROUND ART
Carbon coatings or films are known to be quite hard, chemically inert, corrosion resistant, and repellent to water vapor and oxygen. Such coatings are beneficial for their mechanical and chemical protective properties. Carbon thin films or coatings can be deposited on planar substrates in the form of, for example, graphite, crystalline diamond, and amorphous diamond-like networks (DLN). These films have differing physical and chemical properties.
DLN coatings have been applied to a wide variety of planar substrates, such as organic materials, polymeric films, ceramic substrates (e.g., aluminum oxide, barium titanate, and boron nitride), semiconductor substrates (such as silicon, germanium, gallium arsenide, cadmium telluride, and the like), and metal substrates (e.g., aluminum, stainless steel, nickel, and copper). Specific applications include magnetic rigid disks, sunglasses, ophthalmic lenses and infrared windows.
A number of methods have been developed for depositing carbon coatings on planar substrates, using solid carbon and hydrocarbon sources. Techniques using solid carbon sources include methods such as sputtering, laser evaporation, pulsed discharge rail gun, and cathodic arc deposition.
Several methods also exist to deposit types of organic or inorganic thin films onto particles. These include wet chemical methods, powder transfer onto particles in a mechanically or magnetically agitated particle bed, and fluidized bed chemical vapor deposition. None of these methods is useful for the deposition of densely packed diamond-like networks onto particles.
DISCLOSURE OF THE INVENTION
Diamond-like networks are desirable as coatings because they provide both chemical and mechanical protection. An unmet need in the art is a method to deposit densely packed diamond-like networks onto the surface of particles. An essential requirement for creating a densely packed coating is ion bombardment during the deposition process. None of the techniques available for coating particles facilitates ion bombardment during deposition of the coatings. Additionally, it was not expected that the process for depositing DLN on planar substrates would work for particles.
One object of this invention is to deposit densely packed coatings of amorphous materials comprising carbon and further optionally comprising hydrogen, nitrogen, oxygen, fluorine, silicon, sulfur, titanium, and copper onto particles. It is a further object of this invention to apply densely packed coatings in a uniform manner on each particle surface.
In one aspect, this invention is a method of depositing a diamond-like network onto particles comprising:
providing a capacitively coupled reactor system, comprising two electrodes in an evacuable reaction chamber;
placing a multiplicity of particles on or near one of the electrodes;
evacuating the chamber;
applying radio frequency (RF) power to one electrode, and grounding the other electrode;
introducing a carbon-containing source into the reaction chamber thereby forming a plasma comprising reactive species in proximity to the multiplicity of particles and further forming ion sheaths around the electrodes;
agitating the multiplicity of particles in such a manner as to expose their surfaces to the reactive species in the plasma while keeping the particles substantially within an ion sheath.
In another aspect, this invention is an apparatus for coating a diamond-like network onto particles, comprising:
an evacuable chamber containing two electrodes;
means for introducing a carbon-containing source into the chamber;
an RF power source connected to one electrode; and
means for agitating a multiplicity of particles in proximity to one of the electrodes.
In this application, “diamond-like network” (DLN) refers to amorphous films or coatings comprised of carbon and optionally comprising one or more additional components selected from the group consisting of hydrogen, nitrogen, oxygen, fluorine, silicon, sulfur, titanium, and copper. The diamond-like networks comprise approximately 30 to 100 atomic percent carbon, with optional additional components making up the remainder. An individual additional component may comprise up to approximately 50 atomic percent of the coating. Almost all diamond-like networks contain hydrogen, usually in an amount of 5 to 50 atomic percent. However, for some compositions, hydrogen is not a preferred component. The total amount of components other than carbon may comprise up to approximately 70 atomic percent of the entire coating. The diamond-like networks have a gram atom density of between approximately 0.20 and approximately 0.28 gram atoms per cubic centimeter, and are composed of approximately 50 to 90% tetrahedral bonds.
As used in the application, “amorphous” means a randomly-ordered non-crystalline material having no x-ray diffraction peaks.
As used in this application, “parallel plate reactor” means a reactor containing two electrodes wherein the primary mechanism for current flow between the electrodes is capacitive coupling. The electrodes may be asymmetric, meaning that they may be of different size, shape, surface area, etc. and need not necessarily be parallel to each other. One electrode may be grounded. One electrode may be the reaction chamber itself. Further, the linear dimensions, e.g., the length or diameter, of the electrodes are large compared to the depth or thickness of the ion sheaths which form around the electrodes.
The advantages of the present invention include (i) the efficient deposition of DLN onto particles at high deposition rates, (ii) the deposition of densely-packed DLN coatings, (iii) the ability to perform in situ surface cleaning of particles by ion bombardment with oxygen- and argon-containing plasmas prior to deposition of DLN, and (iv) the ability to tailor the bulk and surface properties of the coatings by manipulating the composition of the coating and the intensity of ion bombardment during the coating process.
Other advantages of the invention will be apparent from the following description, figures, examples, and from the appended claims.


REFERENCES:
patent: 4806246 (1989-02-01), Nomura
patent: 4859493 (1989-08-01), Lemelson
patent: 5132105 (1992-07-01), Remo
patent: 5156885 (1992-10-01), Budd
patent: 5234529 (1993-08-01), Johnson
patent: 5418062 (1995-05-01), Budd
patent: 5439705 (1995-08-01), Budd
patent: 5494523 (1996-02-01), Steger et al.
patent: 5534231 (1996-07-01), Savas
patent: 5556521 (1996-09-01), Ghanbari
patent: 5587207 (1996-12-01), Gorokhovsky
patent: 5811022 (1998-09-01), Savas et al.
patent: 6015597 (2000-01-01), David
patent: 6099687 (2000-08-01), Yamazaki
patent: 41 22 834 A1 (1993-01-01), None
patent: 361 542 A1 (1986-12-01), None
patent: 0 448 227 A1 (1991-09-01), None
patent: 2 760 755 (1998-09-01), None
patent: 59-137311 (1984-08-01), None
patent: 63-270394 (1988-11-01), None
patent: 03 040 953 (1991-02-01), None
patent: 4-304290 (1992-10-01), None
patent: 6-184533 (1994-07-01), None
patent: 6-299146 (1994-10-01), None
patent: 8-176540 (1996-07-01), None
patent: 8-316205 (1996-11-01), None
patent: 8-319483 (1996-12-01), None
patent: WO 97 46484 (1997-12-01), None
patent: WO 98/20185 (1998-05-01), None
Silva S R P et al; Diamond-like carbon thin film deposition using a magnetically confined r.f. PECVD system, Diamond and Related Materials, vol. 4, No. 4, May 15, 1995, pp. 977-983.
David M., Padiyath, R., Babu, S.V., Plasma Deposition and Etching of Diamond-Like Carbon Films, vol. 37, No.3 AICHE Journal (Mar., 1991) pp. 367-376.
Chia-Fu Chen et al, “Microwave Plasma Chemical Vapour Deposition of Diamond: Its growth and characterization”,: Surface and Coatings Technology, vol. 43-44, No. 1-3, pp. 53-62, Dec. 5 1990.

Affiliated with

Also associated with

Rating

Apparatus for coating diamond-like networks onto particles does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Apparatus for coating diamond-like networks onto particles, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus for coating diamond-like networks onto particles will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2486530